| WO2006050137A2 | 2006-05-11 |
| US5391080A | 1995-02-21 | |||
| US20040176226A1 | 2004-09-09 | |||
| DE10025139A1 | 2001-11-22 | |||
| DE4118082C1 | 1993-03-04 | |||
| US4912638A | 1990-03-27 |
CLAIMS
1. A resistance unit for an exercise machine comprising an input shaft and a resistance means coupled to said input shaft for providing a controllable resistance to the rotation of said input shaft, a user input means that can be coupled to said input shaft to allow the user to apply torque to said input shaft, said resistance means including a control means that adjusts the said resistance to rotation of said input shaft according to the output of one or more sensors, and a power means such as a battery or electric generator device from which electrical energy can be provided to one or more electrical circuits within said resistance unit without connection to a power source that is external to said resistance unit.
2. A resistance unit for an exercise machine as described in claim 1 which, under the control of said control means, produces a resistance to rotation of said input shaft that is dependent upon the speed of rotation of said input shaft.
3. A resistance unit for an exercise machine as described in claim 1 that additionally includes a wireless interface means that sends information to or receives information from an external interface device or computer without a cable connection between said resistance unit and said external interface device or computer.
4. A resistance unit for an exercise machine as described in claim 1 in which a sensor produces an output from which the speed of rotation of said input shaft can be determined.
5. A resistance unit for an exercise machine as described in claim 1 in which a sensor produces an output from which the torque applied to said input shaft can be determined.
6. A resistance unit for an exercise machine as described in claim 1 which, under the control of said control means, produces a resistance to rotation that is actively controlled to a constant level that can be set by the user.
7. A resistance unit for an exercise machine as described in claims 1 and 2 which, under the control of said control means, produces a resistance to rotation of said input shaft that is dependent upon the angular acceleration of said input shaft.
8. A resistance unit for an exercise machine as described in claims 1 and 2 which, under the control of said control means, produces a dynamic response to rotation of said input shaft that is equivalent to a simulation of the dynamic response that would be produced by a damped flywheel connected either directly or via a gear or pulley system to said user input means.
9. A resistance unit for an exercise machine as described in claims 1 and 2 which, under the control of said control means, produces a dynamic response to rotation of said input shaft that is equivalent to a simulation of the dynamic response that would be produced by a drive means connected to said user input means, said drive means being a mechanical device that uses the kinetic energy provided by the user to propel an object through a resisting medium such as a viscous fluid.
10. A resistance unit for an exercise machine as described in claim 1 in which said user input means includes a cable or drivestrap that can be coiled around a spool element that is coupled to said input shaft, the user being able to cause rotation of said input shaft by pulling said cable or drivestrap to uncoil it from said spool element.
11. A resistance unit for an exercise machine as described in claim 1 which, under the control of said control means, produces a dynamic response to rotation of said input shaft that simulates the dynamic response that would occur if a freewheel device were included within the coupling of said user input means to said resistance means, said freewheel device being a coupling means that transmits torque between two rotating elements in only one direction of relative rotation between the two said rotating elements.
12. A resistance unit for an exercise machine as described in claim 1 in which said resistance means is driven by the rotation of said input shaft such that the majority of the energy used in the control and actuation of said resistance means and said control means, the total not inclusive of the energy deliberately dissipated by a braking means, is provided by the input of energy from the user in moving said user input means.
13. A resistance unit for an exercise machine as described in claims 1 and 12, in which a clutch element, supported such that it has the same rotation axis as a rotation element driven by said input shaft, is pushed against said rotation element thus experiencing a frictional torque acting in the same direction of rotation as said rotation element, the rotation of said clutch element driving a mechanism that moves components of said resistance unit thus changing the magnitude of the resistance to rotation of said input shaft, the rotation of said clutch element being opposed by a spring element that opposes the rotation such that the resistance to rotation of said clutch element increases with the angle of rotation thus the rotation stops once the torque due to the frictional contact with said rotation elements is equally opposed by the resisting torque from said spring element, and a forcing means provides the force that pushes said clutch element towards said rotation element, said forcing means allowing adjustment of said force and hence an adjustment of the magnitude of the resistance to rotation of said input shaft.
14. A resistance unit for an exercise machine as described in claim 1 which additionally includes a user interface means that allows the user to adjust the magnitude of the resistance provided.
15. A resistance unit for an exercise machine as described in claim 1 in which said control means includes an electronic device capable of implementing a number of control algorithms and which additionally includes a user interface means that allows the user to change the control algorithm used by said control means in controlling the resistance provided.
16. A resistance unit for an exercise machine as described in claims 1 and 8 which additionally includes an indicator means that indicates the distance travelled by or speed of rotation of said simulated flywheel.
17. A resistance unit for an exercise machine as described in claims 1 and 9 which additionally includes an indicator means that indicates the distance travelled by or the speed of rotation or the linear speed of said simulated object.
18. A resistance unit for an exercise machine as described in claim 1 which additionally includes an indicator means that indicates the magnitude of the torque applied to said input shaft.
19. A resistance unit for an exercise machine as described in claims 1 and 10 which additionally includes an indicator means that indicates the magnitude of the force applied to said cable or drivestrap.
20. A resistance unit for an exercise machine as described in claim 1 in which said resistance unit includes a number of friction elements that are pushed against a rotating element that is coupled to said input shaft, the magnitude of the resistance being controlled by an adjustment of the contact force acting between said friction elements and said rotating element.
21. A resistance unit for an exercise machine as described in claim 1 in which said resistance unit includes a number of magnetic elements that are supported near to an electrically conductive rotating element that is coupled to said input shaft, said magnetic elements exerting an eddy-current braking effect on said rotating element, the magnitude of the resistance being controlled by an adjustment of the position or orientation of the magnetic elements relative to said rotating element.
22. A resistance unit for an exercise machine as described in claim 1 in which said resistance means is provided by a fluid drag force acting on an impeller that is coupled to said input shaft, the magnitude of the resistance being controlled by an adjustment of a fluid restriction means.
23. A resistance unit for an exercise machine as described in claim 1 in which the dynamic response of the resistance unit to rotation of said input shaft is governed by the control means, the effect on said dynamic response of the action of the control means being the dominant effect on said dynamic response and being a more significant effect on said dynamic response than the inertial characteristics of components of said resistance unit.
24. An exercise apparatus comprising of a resistance unit as described in claim 1 and a user input means as described in claim 10, a handle means to which said resistance unit or said cable or drivestrap can be fixed, a structure to which said resistance unit or said cable or drivestrap can be fixed, one or more wheels that are fixed to said structure, and a means by which the user can attach his feet to said structure, said exercise apparatus capable of being arranged such that the user can sit on a floor or a non-moving seat and perform a rowing exercise whereby the user pushes said structure away from his body using his legs while additionally extending said cable or drivestrap from said resistance unit by pulling said handle means towards his body, said structure rolling on the floor my means of said wheels.
25. An exercise apparatus comprising of a resistance unit as described in claim 1 and a user input means as described in claim 10, a handle means to which said resistance unit or said cable or drivestrap can be fixed, and a means by which the user can attach his feet to said resistance unit or said cable or drivestrap, said exercise apparatus capable of being arranged such that the user can stand upright and perform an arm curl exercise whereby the cable or drivestrap is extended from said resistance unit by the action of the user in pulling the handle means.
26. An exercise apparatus comprising of a resistance unit as described in claim 1 and a user input means as described in claim 10, a handle means to which said resistance unit or said cable or drivestrap can be fixed, and a means by which said resistance unit or said cable or drivestrap can be fixed to a doorframe, said exercise apparatus capable of being arranged such that the user can position himself below the doorframe and perform an pull-down exercise whereby the cable or drivestrap is extended from the resistance unit by the action of the user in pulling the handle means. |
EXERCISE MACHINE
This invention addresses the need for exercise equipment that can be easily transported and stowed in small spaces. Such equipment may be suitable for carriage in luggage and would allow the user to perform a range of short duration resistance exercises as well as aerobic endurance exercises. Such equipment may be of particular value to regular travellers as well as persons who do not have sufficient storage space in their homes for conventional exercise equipment.
Lifting weights, either directly or via a mechanism, is the most popular form of muscle-building resistance exercise. However, the mass required to provide useful resistance is too great to allow such equipment to be easily transported or stowed.
Existing portable exercise equipment includes a number of devices based on the stretching of elastic elements. These can be used for providing resistance for exercising a range of different muscle groups. The user can vary the number or strength of the elastic elements to achieve a number of different resistance levels. However, only a discrete number of resistance levels are achievable with such devices, with the user selecting the most suitable set of resistance elements for each exercise. These devices do not dissipate a significant amount of energy — the energy is rather stored in the elastic elements. Hence these devices are unsuitable for use in a rowing type exercise where the user is aiming to expend energy over a significant period of time.
Exercise machines that allow sustained energy expenditure are commonplace in gymnasiums and in many homes. Examples include exercise bikes and rowing machines. These machines dissipate some of the energy expended by the user. In most cases, the efforts of the user will, via a suitable mechanism, cause the angular acceleration of a flywheel. The energy stored in the spinning flywheel is dissipated at a controlled rate by a brake that applies a retarding force. This retarding force will often be either a frictional force at the edge of the flywheel, air resistance acting against a fan element connected to the flywheel, or a magnetic pull acting against the motion of the flywheel. These machines usually incorporate a flywheel and mechanism with size and mass great enough to prevent them from being comfortably carried as luggage. While many of these machines fold to occupy a smaller floor space, it is uncommon that it is possible to stow them in a small cupboard or drawer.
The aim of this invention is to provide a versatile exercise machine, in a compact and lightweight form, that allows the user to perform similar exercises to those facilitated by the equipment mentioned above.
The invention provides a resistance unit for an exercise apparatus and exercise apparatus as defined in the appended independent claims, to which reference should now be made. Preferred or advantageous features of the invention are defined in dependant sub-claims.
Accordingly, one embodiment of the invention provides a resistance unit for an exercise system comprising of a brake unit and a drive unit, and a number of accessories that allow a variety of exercises to be performed. The drive unit may be detachable from the brake unit to allow easier storage or transport.
The drive unit consists of an output drive shaft and an input drive shaft, either directly connected or with a geared transmission system between the two, and an input mechanism that allows the user to drive the input drive shaft.
The input mechanism may include a cable wound around a cylindrical element (drum) such that the application of a pulling force to the cable, tangential to the drum, results in a torque applied to the input drive shaft. Alternatively, the input mechanism may consist of a cranked handle or handles or pedals arranged such that force applied to the handles or pedals tangential to the crank axis results in a torque applied to the input drive shaft.
A recoil device may be included either within the drive unit or the brake unit such that rotation of the input shaft of the drive unit in one direction results in a torque from the recoil device that opposes the rotation. If the torque applied by the input mechanism is subsequently sufficiently reduced, the recoil device will cause a rotation of the input shaft in the direction opposite to that which resulted in the torque being developed by the recoil device. In the case of a cable and drum being used within the input mechanism, this reverse rotation results in the cable being rewound around the drum.
A freewheel mechanism may be included either within the drive unit or the brake unit such that torque applied by the input mechanism may only be transmitted to the brake in one rotational direction, and vice-versa.
The brake unit comprises an input shaft and a means of providing a controlled resistance to rotation of this input shaft relative to the housing of the brake unit. The output shaft of the drive unit may be coupled to the input shaft of the brake unit either permanently (in which case they may be not be separate items) or such that the drive unit may be detached from the brake unit when the machine is not in use. The two shafts, when coupled, may rotate together about the same axis.
Resistance to rotation of the input shaft is provided by a suitably controlled resistance mechanism.
This mechanism may be controlled by an electrical signal such that the opposing torque can be controlled by an electronic control unit. This electronic control unit may have a user interface consisting of a display and a number of buttons, switches and/or dials. The control unit may allow the user to select the level of resistance provided by the machine. The control unit may be able to either control the resistance at a constant level or vary the resistance during the exercise according to an algorithm. The resistance may be controlled such that response of the machine to the actions of the user represents a realistic rowing simulation.
Alternatively, the opposing torque applied by the resistance mechanism may be set by a mechanical element that is adjustable by the user. This element may be a knob or a lever.
Within the brake unit there may be a sensor that provides the control unit with an electrical signal that can be used to determine the magnitude of the opposing torque applied to the drive unit from the brake unit. Also within the brake unit there may be a sensor that provides the control unit with an electrical signal that can be used to determine the speed of rotation of the input shaft of the brake unit.
The resistance mechanism includes a rotating element that is connected to the input shaft of the brake unit either directly or via a geared transmission system. The resisting force acting on this element may be either contact friction, fluid drag, or a magnetic force.
A Motional resisting force may be controlled by controlling the reaction force between the rotating element and brake material that is pushed against it. This can be achieved mechanically by delivering the reaction force via a spring element. The spring element is put in a stressed state to produce a force that corresponds to the resistance level required. The spring element may be stressed by a mechanism that is externally adjustable. This would allow the user to adjust the resistance to the desired level for each exercise. Preferably the reaction force is provided by an electro-mechanical transducer, for example an electromagnet acting on a brake through a system of levers. This may allow the reaction force to be controlled by an electrical signal. For a portable device that may operate with no mains electricity supply connected, it is preferable that the power used by the transducer is sufficiently low that it can be provided by a battery or an electrical generator built into the machine.
Alternatively, a resistance mechanism may be produced such that the resistive force is a fluid drag on impeller blades fixed to the rotating element. It is most practical to use air as the resisting fluid as this eliminates the need for a sealed fluid circuit and also provides a convenient method of heat removal from the brake. The resistance may be controlled by controlling the flow of fluid to or from the fan elements. This may be achieved by an electrically controlled restrictor fitted to the inlet or outlet to the fan.
Alternatively, permanent magnets or electromagnets may be used to resist the rotation of the rotating element within the brake unit. In this case the rotating element should be magnetically permeable, with the magnets held close to the rotating element and mounted to a fixed part of the brake unit such that the necessary reaction torque can be generated. The resistance may be controlled by controlling the separation between the magnets and the rotating element. This may be achieved by an electromechanical transducer, such as an electromagnet or electric motor, acting on a suitable translation mechanism.
In the case where the resistance is controlled by an electrical signal, a computing device may be used to determine the resistance required and to send the necessary electrical signal to the brake device. Signals from a torque sensor and a rotation sensor may be input to the computer.
The computer may control the brake unit such that a resistive torque is only applied when the input shaft is rotated in one direction. A sensor such as a rotary encoder could provide signals to the computer that allow the direction of rotation to be determined. Such a system would act in a
similar manner to a brake unit incorporating a freewheel mechanism. If such a system were fitted with a drive unit including a cable drum and a recoil device, the absence of resistance to rotation in the recoil direction would allow the cable drum to rewind once the user stops providing a pulling force on the cable.
An algorithm may be used such that the brake unit responds in a similar manner to a unit including a flywheel connected to the input drive shaft. The algorithm may use parameters including the moment of inertia of the simulated flywheel, a drag coefficient that is used to determine the velocity dependent resistance to the rotation of the flywheel, and a level of constant friction resisting the flywheel. These parameters may be used in a governing equation that defines the behaviour of the virtual flywheel and takes the form of a second order ordinary differential equation. The computer may calculate the speed of rotation of the virtual flywheel and the driving torque acting on the virtual flywheel. In a preferred embodiment, while the input drive shaft rotation speed is less than the virtual flywheel speed, as measured by the speed sensor, the resistive torque is set to zero and the virtual flywheel speed is calculated, using real time numerical integration, from the governing equation, assuming that the driving torque on the flywheel is zero. While the input drive shaft rotation speed is greater than the virtual flywheel speed then the virtual flywheel speed is set to the input drive shaft rotation speed and the torque acting on the simulated flywheel is calculated, using the governing equation, from the speed reading and the first and second time derivatives of the speed reading. This algorithm could also be used to represent a moving vehicle, for example a boat, that is driven by the efforts of the user in rotating the input drive shaft. The governing equation of such a system takes a similar form to that used for the flywheel simulation and also includes terms for inertia, speed dependent resistance, and constant resistance.
The computer may control the resistance mechanism within a closed loop, comparing the torque sensor signal to a demand torque and sending appropriate signals to drive the resistance actuator to make the two values converge.
The electrical power required by the machine may be provided either by a battery or by means of electrical generation within the machine.
In operation, the drive unit is coupled to the brake unit. The user can set the desired resistance for the exercise being performed.
In the case of a machine fitted with handles or pedals, the machine may be secured in a fixed position in terms of both rotation and translation of the housing of the brake unit, relative to the user, by suitable fixing apparatus. The user may then move the handles or pedals in a circular motion by using either his hands or feet.
In the case of a machine fitted with a cable and drum, the machine may be equipped with a fixing bracket that is fixed in rotation and translation relative to the housing of the brake unit. The free end of the cable may be fitted with a feature that allows it to be fixed to a number of accessories. The machine provides resistance to an increase in separation of this cable feature from the fixing bracket. The user can perform a range of exercises by fixing one end of this extension system and pulling the other end.
The fixing bracket or cable feature may be connected to a fixing point such that the user can perform a rowing type exercise. In this case the other end of the system should be connected to a bar or handle that affords the user a secure hand grip.
A frame may be provided that provides a suitable fixing point. This frame may either be either static or fitted with wheels to allow it to easily roll across the floor in a straight line motion. The frame may be provided with features that allow the user to fix his feet to the frame. It may be possible to fold or disassemble the frame for ease of transport or storage. A seat fitted with wheels may be provided to run in a straight line motion either on the floor or on the frame. In the cases where there is a wheeled frame or a seat fitted with wheels, the user could easily move his feet relative to his seat to achieve a comfortable extended rowing action.
Alternatively, a device suitable for fixing to a post, wall, door, or other static object may be used as a suitable fixing point.
A device that provides a fixing point above a door frame may be provided. The fixing bracket or cable feature may be connected to this fixing point with the other end of the system connected to a bar or handle that affords the user a secure hand grip. This would enable the user to perform exercises in which he pulls the bar or handle down relative to the fixing point.
A device that allows the fixing bracket or cable feature to be fixed to the feet of the user may be provided. The other end of the system may be connected to a bar or handle that affords the user
a secure hand grip. This would enable the user to perform exercises in which he pulls the bar or handle away from his feet. Such exercises include arm curls and leg extensions.
In the case of a machine with an electronically controlled resistance mechanism, an interface to an external computer, for example a personal computer or games console, may be provided. The connection may be made either by a cable or a wireless interface. Data sent to the external computer may include torque measurements, speed measurements, stroke start and end signals, and the status of any buttons, switches or dials on the interface unit. Data sent from the external computer may include instructions to change the resistance settings, instructions to change algorithm parameters, or updates to firmware within the electronic control unit. Software may be provided for the external computer that allows the user to record performance throughout an exercise session. This exercise data may be stored for analysis and comparison with other exercise sessions. The software may have the ability to control the exercise session by instructing the user to perform selected exercises in sequence. With each new exercise, the external computer may download the necessary control parameters to the exercise machine.
The exercise machine may be fitted with additional interface buttons or switches that are fixed to a handle that is being used to drive the machine. These may be connected to either the electronic interface unit or an external computer using a cable or a wireless interface. These buttons may allow the user to interact with computer programs during exercise. These buttons could also be used to control a remote controller device in order to control video and audio equipment during exercise.
A preferred embodiment of the invention is shown in figures 1 to 15.
Figure 1 illustrates an exercise machine incorporating a resistance unit according to the invention.
Figure 2 illustrates an exercise machine according to the invention being used for an arm-curl exercise.
Figure 3 illustrates an exercise machine according to the invention being used for a seated rowing exercise.
Figure 4 illustrates a resistance unit according to the invention, showing a drum unit 1, detached from a brake unit 2.
Figure 5 illustrates a resistance unit according to the invention, showing the drum unit 1 , coupled to the brake unit 2.
Figures 6 and 7 show detailed views of the drum unit 1. Figure 6 shows the drum unit 1 with the coupling plate 10 removed.
Figures 8 to 11 show detailed views of one embodiment of the brake unit 2. Figure 8 shows the brake unit 2 with the housing 18 removed. Figure 9 shows the brake unit 2 with the housing 18 and the brake disc 14 removed. Figures 10 and 11 show section views of the brake unit 2, the cut being through the centre of the unit.
Figure 13 illustrates an exercise machine connected to a foot harness according to the invention.
Figure 14 illustrates an exercise machine connected to a doorframe fixing device according to the invention.
Figure 15 illustrates an exercise machine fitted to a wheeled rowing frame according to the invention.
Figures 1, 4 and 5 show some essential elements of a preferred embodiment of the resistance unit according to the invention. A drum unit 1 contains a coil of cable 3. The drum unit may be fixed to a brake unit 2 such that the drum 6 may rotate while the housing 7 of the drum unit is fixed. A handle 3 may be fitted to the end of the cable. A fixing hole 5 is provided as a feature of the drum housing 7.
Figures 6 and 7 show detailed views of the drum unit 1. Figure 6 shows the drum unit 1 with the coupling plate 10 removed.
The cable 3 is wound around a drum 6 such that pulling the cable results in rotation of the drum. The drum is mounted to a bearing 8. The bearing is mounted to a housing 7. The housing has castellated features 12 that engage with slots 4 of the mounting plate 13 of the brake unit such that the housing cannot rotate relative to the mounting plate. A coil spring 9 is fitted between housing 7 and drum 6 such that unwinding the cable from the drum results in the coil spring resisting the rotation of the drum and the spring becoming coiled more tightly. In the event of the pulling force on the cable being removed the coil spring acts on the cable drum to rewind the cable. A coupling plate 10 is rigidly fixed to the drum. The coupling plate is made from a magnetically soft material.
Figures 8 to 11 show detailed views of the brake unit 1. Figure 8 shows the brake unit 1 with the housing 18 removed. Figure 9 shows the brake unit with the housing 18 and the brake disc 14 removed. Figures 10 and 11 show section views of the brake unit, the cut being through the centre of the unit.
The brake unit consists of an assembly of components fitted to a circular mounting plate 13. A brake disc 14 is supported at its centre on a hub 15. The hub is fitted to the inner race of a bearing 16. The outer race of the bearing is fitted inside a bearing housing 17 that is fixed at the centre of the mounting plate. A housing 18 is fitted to the mounting plate to enclose the entire plate assembly. A number of holes in the coupling plate 10 are arranged so that they may engage with mating protrusions 19 at the end of the hub. This allows the hub to be coupled in torsion to the coupling plate and the drum. A permanent magnet 20 is fitted at the end of the hub, such that a magnetic pull force acts on the coupling plate when it is engaged with the hub thus providing a force that resists the separation of the drum unit from the brake unit.
A brake lever assembly, shown in detail in figure 12, consists of a front brake lever 21 and a rear brake lever 22 and a wear compensation mechanism 92. One end of each brake lever (the radially outer end) is restrained by the wear compensation mechanism. A brake pad 23 is fitted to each brake lever. The brake levers are fitted either side of the brake disc 14 such that the brake pads each face the brake disc and the wear compensation mechanism is situated beyond the circumference of the disc.
The end of the rear brake lever 22 that is not fixed to the wear compensation mechanism 92 (the radially inner end) is fork shaped such that is fits around the bearing housing 17 and is fitted to
a thrust bearing 24 that is fitted around the bearing housing and thus has the same axis of rotation as the brake disc 14. This end of the lever is constrained by the fit with the bearing housing and the thrust bearing such that the lever rotates about the disc axis but may also pivot about said end while remaining radial to the disc. The end of the front brake lever 21 that is not fitted to the wear compensation mechanism 92 (the radially inner end) fits to a thrust nut 25 which is part of the screw assembly 94 described below. This end of the lever is constrained by the fit with the thrust nut such that the lever rotates about the brake disc axis but may also pivot about said end while remaining radial to the disc.
The wear compensation mechanism 92 consists of a front plate 28, a rear plate 29, and a grip plate 30. The front plate and the rear plate are fitted through a slot in the grip plate. The front brake lever 21 is fitted to the front plate and the rear brake lever 22 is fitted to the rear plate. A compression spring 31 is fitted between the rear brake lever and the grip plate such that the grip plate is forced to tilt at an angle to the rear brake lever. The angle of tilt of the grip plate is determined by the clearance between the slot in the grip plate and the two plates that pass through it. This clearance is small such that the grip plate is restrained to be almost perpendicular to the two plates that pass through it and that, with the action of the compression spring pushing the grip plate to the limit of rotation, any forces that act to pull the front plate away from the rear plate will result in frictional forces that act to further rotate the grip plate and thus be equally opposed by these frictional forces at the contact between the grip plate and the front and rear plates. Due to the action of the compression spring, the grip plate may only tilt in one direction, hence any forces that act to push the plates towards each other will produce frictional forces that act to rotate the grip plate away from the rotation limit, thus the resistance to the pushing is limited to the relatively small frictional forces that oppose the rotation of the grip plate due to the action of the compression spring. An extension spring 32 acts to pull the outer ends of the brake levers towards each other, the force exerted by the spring being weak relative to the force acting to pull the outer ends of the levers apart during braking, such that when the brake mechanism is relaxed and the force applied at the inner ends of the levers is low enough, the spring will pull the outer ends of the levers together until the brake pads rest against the brake disc. The wear compensation mechanism as a whole acts to ensure the relaxed position of the inner ends of the levers remains the same regardless of any change in size of the brake pads 23 that occurs due to wear.
The screw assembly 94, shown in figures 8, 9, 10 and 11, consists of the thrust nut 25, a thrust pin 26, and thrust bearing 27. The thrust pin is fitted so that it passes through the centre of the brake disc 14 so that one end is situated within the internal space of the disc hub 15. A flange feature at this end of the thrust pin is in contact with the thrust bearing. The opposite side of the thrust bearing is in contact with the brake disc, with the brake disc, thrust bearing, and thrust pin all having a common rotation axis. The thrust nut has an internal thread that is fitted to an external thread of the thrust pin. The thrust nut is restrained in rotation by contact with the front brake lever 21. Hence any clockwise rotation of the thrust pin about the disc rotation axis causes the thrust nut to be pulled by the screw thread towards the brake disc, the reaction to this pulling force being transferred to the thrust bearing in contact with the brake disc. The end of the front brake lever moves with the thrust nut so that, with the wear compensation device resisting extension, clockwise rotation of the thrust pin results in the two brake pads 23 each being pushed towards the brake disc. The brake lever mechanism has a finite elastic stiffness, hence the contact force between the brake pads and the brake disc is approximately linearly dependent upon the rotation of the thrust pin.
A pin 33 is fitted through a radial hole in the thrust pin 26. A clutch plate 34 is fitted to rotate around the thrust pin. Friction pads are fitted at each end of the clutch plate such that the pads face the brake disc 14. The pin 33 locates in a slot within the clutch plate such that the thrust pin is caused to rotate with the clutch plate. A torsion spring 36 is fitted such that one leg of the spring is located in a slot in the clutch plate, the other end of the spring being located in a slot in the housing 18, hence rotation of the clutch plate results in an opposing torque, produced by the spring, that is approximately proportional to the angle of rotation. Any force that acts to push the clutch plate against the brake disc causes a frictional force at the contact between the friction pads and the brake disc such that a torque is exerted on the clutch plate in the direction of rotation of the brake disc. The clutch plate will rotate until this frictional torque is equally opposed by the torque developed by the torsion spring and any frictional torque acting at the screw thread. Hence while the brake disc is rotating, the contact force at the brake pads 23, and therefore the resisting torque acting on the brake disc, is directly dependent upon the magnitude of the force pushing the clutch plate against the brake disc. Effectively the clutch plate contact force provides the control input to a mechanical servo system that is driven via the clutch plate by the brake disc. The clutch plate contact force moves through a negligible distance whereas the resulting torque moves through a significant angle, thus a small energy input into the system results in a much larger energy output equal to a larger force acting on the thrust nut 26 moving
through a greater distance. The frictional force at the friction pads of the clutch plate is amplified by the leverage of the clutch plate, the mechanical advantage produced by the screw thread on the thrust pin 26, and the leverage of the brake levers 21 and 22 to produce large contact forces between the brake pads and the brake disc.
An actuator lever 37 is supported with one end in contact with a washer 38. The opposite end of the actuator lever rests opposite an electromagnet 39 that is fixed to the brake unit housing 18. The actuator lever is made from a magnetically soft material. The washer is fitted around the thrust pin and is in contact with the clutch plate. The actuator lever is in contact with a step feature 93 of the brake unit housing and is free to pivot about the line of contact formed. The electromagnet is fixed such that, when energised, it may exert a magnetic pull force on the end of the actuator lever. Energising the electromagnet results in a pull force exerted on the end of the actuator lever which results in the opposite end of the actuator lever exerting a pushing force against the washer, which results in a contact force between the clutch plate friction pads and the brake disc 14. The pull force exerted on the actuator lever is dependent upon the current passed through the coil of the electromagnet, hence the torque exerted by the brake pads 23 on the brake disc is dependent on this current and said torque may be controlled by controlling the current.
A torque sensing device, shown in figure 9, includes a mounting bracket 40, a lever arm 41, a compression spring 44, a magnetic block 45, and a Hall-effect sensor 46. The mounting bracket is fixed to the mounting plate 13. The lever arm is fixed to the mounting bracket by a pin 42 such that the lever arm may pivot about the pin. A contact feature 43 of the lever arm is positioned such that it is in contact with an end of the rear plate 29 of the wear compensation mechanism 92. At the opposite end of the lever arm, the compression spring 44 is fitted such that it acts to resist this end of the lever arm 41 approaching the mounting plate. Hence rotation of the brake levers 21 and 22 about the brake disc axis is resisted by the contact force between the front plate 28 and lever arm 41, the rotation of the lever arm being resisted by the action of the compression spring. The lever arm is of a length such that the rotation of the lever arm remains approximately proportional to the torque exerted by the brake pads 23 on the brake disc 14, while the spring remains within elastic limits. The magnet block is made from a magnetically soft material and is fitted to the spring end of the lever arm. An electronic circuit board 47 is fitted to the mounting plate 13. The Hall-effect sensor is fitted on this board, mounted opposite the magnetic block. A magnet is fitted to the side of the Hall-effect sensor closest to the circuit board. Rotation of the lever ami causes the distance between the sensor
and the magnet block to change. This results in a change in the magnetic flux passing through the sensor and therefore a change in the output of the sensor. With suitable scaling and mapping, this output from the sensor can be used to determine the magnitude of the torque exerted by the brake pads on the brake disc.
An infra-red reflective object sensor 48 is fitted to the circuit board 47 such that the sensing area faces the brake disc 14. The brake disc features a circular arrangement of cut-outs at the same radial position as the reflective object sensor. During rotation of the brake disc, the output of the sensor changes as the area of the brake disc that faces the sensor changes from solid to cut-out. These transitions in the sensor output are timed by an electronic circuit, with the resulting output being used to determine the speed of rotation of the brake disc.
The current passed to the electromagnet is controlled by an electronic circuit. This circuit is powered by a number of batteries that are contained within the brake unit. The circuit uses the signals from the Hall-effect sensor 46 and the reflective object sensor 48 to determine the torque exerted by the brake pads on the brake disc, and the speed of rotation of the brake disc. A microcontroller is used to allow a number of different control algorithms to be implemented. An external interface unit 49, shown in figure 1 , is connected to the circuit. This interface unit consists of a display screen and a number of push-button switches. The interface unit displays exercise information such as load and speed and allows the user to select exercise options.
A number of control algorithms are programmed to be implemented by the microcontroller. A torque control algorithm is used to maintain the resistive torque at a set level during a pulling stroke of the cable from the drum unit. Feedback from the Hall-effect sensor is used to determine the measured resistive torque. Using standard control practice, the difference between the measured resistive torque and the demand torque is used to determine the current that is fed to the electromagnet.
A freewheel algorithm reduces the electromagnet current to zero by setting the demand torque to zero once the end of a pulling stroke has been detected. The end of the pulling stroke is defined in the algorithm as when the speed of rotation has dropped below a threshold level. The end of the return stroke is defined as when the direction of rotation has changed. A change of direction of rotation can be detected from the pattern of pulses from the reflective object sensor. At the end of the return stroke, the algorithm allows the demand torque to be set above zero
again. This algorithm has a similar effect to introducing a freewheel device, that only transmits torque in one direction of rotation, between the drum unit and the brake unit.
The torque control and freewheel algorithms are used together to allow the user to perform exercises where the resistance is maintained at a constant level throughout the stroke. Such exercises include simulated weight-lifting.
A flywheel algorithm simulates a flywheel being connected to the drum unit. The algorithm uses parameters that represent the moment of inertia of the flywheel about the axis of rotation, the level of speed-dependent damping torque, and the level of constant damping torque. Such a system can be described using the standard differential equation:
T = A d 2 φ/dt 2 + B dφ/dt + C
where T is the net torque acting on the virtual flywheel, φ is the angle of rotation of the virtual flywheel, t is time, and A, B, and C are the parameters mentioned above.
The algorithm uses a value representing the speed of the brake disc which is calculated from the timed intervals between pulses from the reflective object sensor. This shall be referred as dθ/dt.
The algorithm checks to see if the real disc speed dθ/dt is greater than or equal to the virtual flywheel speed dφ/dt. If this is true, the demand torque Ta is set according to the following equation:
Ta = A d 2 θ/dt 2 + B dθ/dt + C
(i.e. the true brake disc speed and acceleration are used rather than the virtual flywheel values) T d is the value used to control the resistance mechanism. d 2 θ/dt 2 is calculated from successive values of dθ/dt, with the time interval between the readings being known. If the check is false, T d is set to zero. This simulates a freewheel device being connected between the drum unit and the flywheel.
The values for the virtual flywheel speed dφ/dt are calculated by numerical integration of the flywheel equation as follows:
T= the torque measured by the torque sensor, T m ,
dφ/dt n+1 = dφ/dt n + d 2 φ/dt 2 .δt ,
d 2 φ/dt 2 n+1 = (T m - B.dφ/dt n+ i - C) / A (a re-arrangement of the initial equation),
where δt is the time interval between steps n+1 and n.
The algorithm continuously calculates the virtual distance travelled by performing a numerical integration of dφ/dt. The distance travelled and an indication of the virtual flywheel speed are output for display on the screen of the interface unit.
Figure 13 shows the exercise machine connected to a foot harness. Figure 2 shows a user performing an arm-curl exercise using the exercise machine with the foot harness. A handle 50 consists of two hand grips either side of a fixing point that allows the end of the cable 3 to be fixed to the handle. A foot harness 51 has two loops that the user may place his feet through. The foot harness has a fixing bracket 52 such that it can be connected to the attachment feature 5 of the dram unit using the pin 53. The user is able to place both feet through the hoops in the foot harness, and while in a standing or sitting position, perform exercises that involve pulling the cable 3, using the handle 50, out of the drum unit 1.
A door clamping device, shown in figure 14, consists of two arms that are fixed together by a pivot element such that the jaws 55 may open and close in a scissor-type action. The ends of the arms opposite to the jaw end are connected to two links 56 by pivoting joints. The opposite ends of the links are connected by a pivoting joint. A connection bar 57 is also connected at this joint. The opposite end of the connection bar may be fixed to the attachment feature 5 of the drum unit 1 by using pin 53. In practice the door clamping device is fitted above a door frame such that the two jaws are in contact with opposite sides of the wall above the door. Pulling the connection bar downwards results in the jaws being forced towards the wall. The jaws rest over the door frame such that the door frame bears any load placed on the cable. The door clamping device allows the user to fix the exercise machine such that it is hanging from a door frame. This device allows the user to perform exercises whereby the user pulls the cable, with the handle fitted, down from the exercise machine above.
A rowing frame, as shown in figure 15, consists of a framework 58 of aluminium members. A number of wheels are fitted to the framework to allow it to roll freely over level ground. A mounting bar 59 is fitted to the framework. Foot hoops 60 are fitted to a footplate 61 that is fitted to the mounting bar. The footrests allow the user to fix his feet to the rowing frame. At the end of the mounting bar is a fixing hole 62. The pin 53 may be used to fix the exercise machine to the fixing hole. The rowing frame is collapsible to allow for easy transportation and storage. The rowing frame allows the user to perform rowing simulation exercises whereby the user pulls the cable 3, using the handle 50, out of the drum unit 1 while sitting on the floor or on a static seat, using his legs to push the rowing frame away at the same time as using his arms to pull the handle towards his chest.
An alternative embodiment of a resistance unit according to the invention is illustrated in figures 16 to 20. The brake unit shown is largely similar to that described above with the difference being the use of an arrangement of permanent magnets to provide the braking torque at the brake disc rather the frictional contact of brake pads. A drum unit 1 as described previously may be fitted to this brake unit.
Figure 16 illustrates the brake unit with housing 80 removed. Figure 17 illustrates the brake unit with the housing 80 removed and brake disc 79 removed. Figures 18 and 19 show section views of the brake unit, the cut being through the centre of the brake unit. Figure 20 shows a detailed view of the magnet mechanism used in this embodiment of the resistance mechanism.
The brake disc 79 is made from a magnetic steel. Permanent magnets 63 are fixed to support brackets 65 and 66 either side of the brake disc with like poles facing each other. Movement of the magnets towards each other increases the magnetic flux in the region of the brake disc that is between the magnets. Rotation of the brake disc is resisted by a magnetic force acting on the electrons within the disc. Increasing the magnetic flux results in an increase in the resistance to motion of the brake disc. This effect is small relative to the braking effect of pushing brake pads into contact with a brake disc. In order to produce the required level of resistance to rotation of the cable drum, an epicyclic gearbox 64 is fitted between the input drive shaft of the brake unit and the brake disc.
Figure 20 shows a detailed view of the magnet mechanism. The magnets 63 are mounted on support brackets 65 and 66. The support brackets are fitted to a threaded pin 67. Bracket 65 has a left-handed threaded mounting hole whereas bracket 66 has a right-hand threaded mounting
hole. The threaded pin has corresponding left and right handed threads. The threaded pin is supported by a bearing that is fitted to a bracket 68 that is fixed to mounting plate 69. At the end of the threaded pin is a pulley 70. Rotation of the pulley in an anti-clockwise direction results in the magnets moving towards the brake disc 79. Rotation of the pulley in a clockwise direction results in the magnets moving away from the brake disc. The pulley 70 is connected to another pulley 71 via a belt 72. This pulley is fixed to rotate with a clutch plate 73. The clutch plate is fitted with friction pads that touch the surface of the brake disc. One end of a lever 74 pushes, via a washer 75, the clutch plate against the brake disc. The lever pivots about a step edge feature of the brake unit housing 80. The opposite end of the lever rests opposite an electromagnet 81. Passing a current through the electromagnet results in this end of the lever being pulled towards the electromagnet and hence the clutch plate is pushed against the brake disc. A frictional force between the clutch friction pads and the brake disc acts to rotate the clutch plate in the same direction as the brake disc. Rotation of the clutch plate is resisted by a torsion spring 76 fitted between the clutch plate and the brake unit housing. The clutch plate will rotate to a position such that the torque due to the frictional contact is equally opposed by the spring torque. Hence the distance between the magnets and the brake disc and therefore the torque resisting rotation of the cable drum can be controlled by adjusting the current passed through the electromagnet.
Two piezoelectric pads 77 are fitted to the magnet brackets 65 and 66 such that they both also make contact with a face of the bracket 68. As the magnets produce a force opposing rotation of the brake disc, the reaction force must be resisted. The reaction force results in a moment applied to the magnet brackets about the axis of the threaded pin 67. This moment is equally opposed by the moment resulting from the contact force at the piezoelectric pads. The charge generated within the piezoelectric pads is output, via a suitable amplifier circuit, to the microcontroller. This value is then used to calculate the torque that is acting to resist the rotation of the cable drum. The speed of rotation of the brake disc is, as before, calculated from timings of the output from a reflective object sensor 78 that faces a number of holes in the brake disc.
The control algorithms used in this embodiment are identical to those described above with the exception that a mapping subroutine is used to produce a braking torque that is proportional to the demand torque input to the routine. The mapping routine is used to compensate for the nonlinear relationship between the braking torque and the separation between the magnets. This subroutine also limits the current supplied to the electromagnet such that it is never sufficient for the magnets to be driven into contact with the brake disc.
Another alternative embodiment of the resistance unit according to the invention is shown in figures 21 to 24. The brake unit shown uses a valve system to restrict airflow from an impeller in order to provide a controllable resistive torque. A drum unit 1 as described previously may be fitted to this brake unit.
Figure 22 illustrates the brake unit with end plate 84 removed. Figures 23 and 24 show section views of the brake unit, the cut being through the centre of the brake unit.
An impeller 82 is connected, via an epicyclic gearbox 83 to the input drive shaft of the brake unit. The epicyclic gearbox is required in order to increase the brake disc speed and amplify the resistive torque at the brake disc to a suitable level of resistance torque at the cable drum. Air is drawn into the impeller chamber 84 through inlet holes in the end plate 85. Rotation of the impeller forces the air radially away from the axis of rotation. The air exits from the impeller chamber through an outlet 86. A continuously variable, solenoid actuated, flow resisting valve 87 is fitted to the outlet to control the flow of air exiting the impeller chamber. A pressure sensor is fitted between the outlet and the valve. The valve is controlled by an electrical signal produced by a suitable control circuit incorporating a microcontroller. The output from the pressure sensor is processed by a suitable amplifier and input to the microcontroller.
Restriction of flow at the outlet 86 from the impeller chamber 84 results in a higher air pressure resisting the rotation of the impeller blades. Hence the resistance to rotation of the impeller 82, and therefore the resistance to rotation of the cable drum, is controllable by adjusting the control signal sent to the valve 87. The signal from the pressure sensor is used to calculate the torque that is acting to resist the rotation of the cable drum. This calculation is performed by the microcontroller. An algorithm is used that uses a look-up table that holds measured values of resistance torque at various fan rotation speeds and pressure readings. The speed of rotation of the impeller is, as before with the brake disc, calculated from timings of the output from a reflective object sensor 88 that faces the impeller blades, the impeller blade surfaces being suitably reflective to produce a suitable change in output from the sensor as they pass by.
The control algorithms used in this embodiment are similar to those described above with the exception that a mapping subroutine is used to produce a braking torque that is proportional to the demand torque input to the routine. The mapping routine is used to compensate for the nonlinear relationship between the braking torque and the output to the valve.
Another alternative embodiment of a resistance unit according to the invention is shown in figure 25. The brake unit shown is similar to the air resistance design described apart from the fact that water rather than air is used as the resisting fluid. The brake unit is shown with features as previously described with the addition of a pipe 89 that connects the outlet from the valve to an inlet chamber 90 fixed to the end plate 91. The impeller chamber is filled with water. The water is recirculated through the pipe. A drum unit 1 as described previously may be fitted to this brake unit.
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