This invention relates to a force application system and a method for controlling the same. More precisely the invention relates to a force application system adapted to be used in exercise equipment as a resistance module and a method for controlling the system.

There are a lot of training equipment related to training in a gym. Known solutions are, for example, exercising with free weights or with equipment having a cable con- nected to a weight stack. The amount of the resistance is selected with weights loaded to the weight lifting bar or with adjustable pin in the weight stack.

The problem with the training equipment utilizing weights is that this equipment typ ically weighs very much and is very bulky in size. The high weight and the large size often restrict the number of separate devices that can be included in a gym, for example.

Gym equipment using motors to create the required resistance for exercising is also known in the art. The use of motors allows utilization of variable resistance or ac- commodating resistance, for example. However, the motorized gym equipment is generally considered inferior to the traditional gym equipment utilizing constant re- sistance provided by free weights. Further, the motorized gym equipment is gener- ally not meant to replace free weight gym equipment but to provide exercisers an- other tool for exercising.

The present invention provides a lightweight force application system, which has a construction that allows smart adaptation of applied force, based on gym equipment cable position and force exerted by user. The present invention also allows training which is related to the speed of the cable of the training equipment. This force ap- plication system of the invention can be used to replace the weight stacks of existing gym equipment. The present invention also includes a method for controlling the force application system.

The present invention also provides a lightweight force application system, which allows the possibility to gather training data for later analysis. This training data can be for example the amount of the used force related to the position of the cable.

The present invention also provides a lightweight force application system, which allows a safe training session without a possibility to hurt yourself with weights when for example you get fatigued during exercise. The force application system according to the present invention monitors the applied force/user behavior and the exercise session can be safely stopped even in the middle of the performance.

The force application system of the invention for gym equipment system comprises an electric motor connected to a frame with a power supply for supplying power to the electric motor, and a controller for controlling the motor, as well as force trans- mission for converting the torque of the motor to vertical force, and a user interface for operating the system.

In the force application system of the invention the electric motor may be a rotary type motor, such as AC servo motor, DC motor, steeped motor, BLDC motor, or it may be linear motor providing linear motion.

In the force application system of the invention the force transmission may be im- plemented with a cable, belt or chain routed via pulleys. The cable, belt or chain is also preferably equipped with a suitable fixing means for fixing end of the cable, belt or chain to a carabiner. Alternatively, the force application system may also be pro- vided with other type of mechanical link than cable, belt or chain.

In the force application system of the invention the controller may comprise micro- controller and power electronics to drive the motor. The microcontroller is also pref- erably equipped with a two-way data link to control the system and read real-time data from the system. There are many well known possibilities and embodiments known in the art for a suitable controller.

In the force application system of the invention the user interface may comprise buttons for inputting data to the system and for changing preset settings, and LEDs for indicational purposes. The user interface may also be implemented with a dis play, touch display, keyboard, or combinations of these.

In the force application system of the invention the frame provides mounting for the other parts of the system, and advantageously provide fixing surface and/or fixing means for fixing the system to a frame of an exercising equipment.

In the force application system of the invention the power supply advantageously provides safe voltage level to the rest of the electric parts of the system. The power supply may be a separate part or integrated to one of the other parts of the system. The voltage provided is preferably lower than the limits specified in European Low Voltage Directive (LVD) 2006/95/EC. The force application system of the invention preferably comprises preset modes, that are selectable via the user interface or via the data link. These preset modes may comprise the following:

Constant force mode (concentric): The system can be set to maintain a con- stant force on the cable. When user is not using the system, the system is in low-force standby mode. The system transitions to the specified constant force in a couple of millimeters of cable travel. This saves power, and still ensures that the cable is reeled into the system when it is not used. To maintain con- stant force on the cable, the system resists motor movement with certain torque when cable is being pulled outwards, and drives a certain torque to the motor when the cable is traveling inwards. All this is done entirely electrome- chanically. Resisting motor with a certain torque regenerates power, and driv- ing a certain torque consumes power. Power can be stored into a device such as a capacitor or battery, or dumped into a regenerative braking resistor (power to heat) that is included in the system.

Smart eccentric mode: The force, which the system resists upwards, can be set to a specific force. On the eccentric part of the repetition (downwards), the system transitions to velocity control mode. The system monitors the re- sistance force applied by the user and adapts by either increasing or decreas- ing the power of the electric motor. This maintains a constant speed that the user resists. The transitions between the force and velocity modes are done in calibrated upper and lower move positions, that the user sets when starting the training. The calibration procedure is straightforward: first the user brings the cable to the upper position of the move, where the system acknowledges the position by a short tug on the cable. The user then brings the cable to the lower position, which the system acknowledges again by a short tug. After the tug, the training begins in the upward state, so the system transitions to the specified training force.

Combined smart concentric and eccentric mode: The speed of the repetition can be set before the repetition. In this mode the system resists the movement so that the repetition moves at the set speed both on the concentric and the eccentric part of the repetition. This allows the user to increase or decrease the training force dynamically. Users with different maximum strengths can use the same system with the same settings. This mode also has inherent safety, as the system decreases the cable force to nearly zero if the user does not apply force to the system. This allows the user to stop the exercise at any point. The same calibration as in the smart eccentric mode is used in the combined mode. After the calibration, the system transitions to a state where it expects the user to start pulling the cable upwards. The training is started with zero training force, so if the user does not exert force on the system, the system does not exert force on the cable (other than very low“idle” force, which en- sures that the cable is reeled into the system if the user stops training).

Isometric mode: A fixed training point can be calibrated to the system. The system will not let the cable move beyond this fixed point despite the force applied by the user. This allows static training. A small idle force remains to reel the cable into the system when the user stops training. Half of the afore- mentioned calibration routine is used to find the position of the isometric train ing.

The force application system and the method for controlling the force application system of the invention provides an exercising system with improved safety fea- tures, wherein the training can be logged, tracked and analyzed. The system is also very suitable for medical and sports related applications.

More precisely the features defining a system of the present invention are disclosed in independent claims. Dependent claims disclose advantageous features and em- bodiments of the invention.

Exemplifying embodiment of the invention and its advantages are discussed in greater detail below in the sense of example and with reference to accompanying drawings, where

Figure 1 shows schematically an embodiment of a force application system of the invention, and

Figure 2 shows a flowchart of an embodiment of the operation of a force appli cation system of the invention.

Figure 1 shows schematically an embodiment of a force application system 1 of the invention, which comprises a frame 2, an electric motor 3, a force transmission corn- prising a cable 4 and cable spool 5, controller 6, user interface 7 and power supply 8. In the force application system 1 the motor 3 provides resisting force to the cable 4 extending via cable spool 5 to outside of the system. The cable 4 is equipped with a suitable fixing means, such as a loop formed at the end of the cable, for connecting the end of the cable to a carabiner, for example (not shown). Suitable gym equip- ment can be connected to the system 1 via the carabiner.

The motor 3 is driven with the controller 6, which controller is operated with the user interface 7. The required power to the force application system 1 is provided with power supply 8 at safe voltage level.

The motor 3, the cable spool 5, the controller 6, the user interface 7 and the power supply 8 are fixed to the frame 1 , which can be in a form of a casing, for example.

The motor 3 in this embodiment is a rotary AC servo, which preferably provides position feedback from the shaft of the motor to the controller 6.

The controller 6 comprises a suitable microcontroller, such as ARM Cortex M4 based microcontroller unit (many other suitable alternative options for this are avail- able), and power electronics to drive the motor 3, such as H-bridge and current shunt. The microcontroller provides a two-way data link to control the system 1 and read real-time data from the system. This allows setting of system mode, max and current force, etc, as well as reading of force, speed, position, mode and power of the system 1 .

The user interface 7 in this embodiment comprises buttons for setting force and changing of the system mode, mode indicator LEDs and a force indicator LED bar (RGB). The force indicator LED bar allows user to set target force or velocity when the system 1 is in standby and displays real-time force when the system is active.

The frame 2 of the force application system 1 can be mounted to the floor, ceiling, wall or any solid structure and most importantly, can be used to replace weight stacks in existing and new gym equipment. Another possibility is for some training exercises to use the weight of the trainer for retaining the position of the force appli- cation system. For that purposes the frame 2 can have projecting parts (not pre- sented in the figures) on the sides of the frame for the trainer to stand on. This embodiment is advantageous if the force application system 1 should be transport- able and is for example used in many separate locations. In figure 2 is shown a flowchart of the operation of the force application system 1 of figure 1 . The shown operation phases are implemented advantageously with a soft- ware run at the controller 6 of the system 1 of figure 1 .

The system has the following steps:

- First the system observes motor force and position in the motor safety box.

- After that the system reads inputs, such as motor position, inputs from user interface and serial commands and refreshes the system mode and state.

- Check if velocity controller is active.

- If active then calculate motor velocity from system state and position.

- If first velocity controller run cycle then prepare velocity controller for smooth start and run velocity controller to resolve new motor force.

- If not first velocity controller run cycle then move directly to run velocity con- troller to resolve new motor force.

- Apply new force to the motor

- Wait for the new system run cycle and move to motor safety box.

If the velocity controller is not active then:

- Calculate motor force from system state and position

- Apply smoothing

- Apply new force to the motor

- Wait for the new system run cycle and move to motor safety box.

The system has also emergency disable bypassing everything after“Run velocity controller to resolve new motor force”. This feature stops the system and returns to the motor safety box.

The invention is suitable for use in new exercise equipment but also to replace the weight stacks of the old exercise equipment. Therefore, the old equipment can be still used without the weight stacks and the costs for the new equipment according to the invention are lower.

Method for controlling the force application system includes the following steps:

- turning the system on,

- choosing the training mode with the user interface or via the data link,

- optionally“teach” the system for example limits for movement or speed,

- controlling the training depending from the chosen training mode, - observing motor force and position and checking the motor safety.

The specific exemplifying embodiment of the invention shown in the figure and dis- cussed above should not be construed as limiting. A person skilled in the art can amend and modify the embodiment of the force application system of the invention described above in many evident ways within scope of attached claims. Thus, the invention is not limited merely to the embodiment described above.