"Joystick controller" Cross-Reference to Related Applications

The present application claims priority from Australian Provisional Patent Application No 2007904495 filed on 21 August 2007, the contents of which are incorporated herein by reference.

Field of the Invention

This invention relates, generally, to a controller and, more particularly, to a control system and to a joystick controller for use with the control system. The invention has particular, but not necessarily exclusive, application in the field of joystick controllers used in mining machinery which operate in hazardous environments.

Background to the Invention In certain applications, it is imperative, from a safety point of view, that no sparks are generated from any source. Thus, for example, in the field of coal mining, due to the presence of flammable gases, high voltage equipment cannot be used. For the purposes of equipment operating in underground coal mining environments, high voltage is regarded as any potential energy that could produce a spark. The reason for this is that any such system that could generate an electrical spark provides an unacceptable risk for ignition of flammable gases in the mining environment.

As a result, it is not possible to have electrically controlled vehicles using devices having a high voltage electrical potential in such mines. This means that equipment such as mining machinery which needs to be manipulated or moved must use mechanical systems for control such as, for example, hydraulically operable system.;. While infrequent, problems with hydraulic systems can occur so that, for example, if wheels of a vehicle are turned under hydraulic control and a hydraulic fault (such as hydraulic lock) occurs, it would not be possible to stop the vehicle. This could have far reaching and dangerous consequences. Certain low voltage systems are used by some mining machinery manufacturers.

Switches of the low voltage system can become contaminated due to the hostile nature of the environment and jam open or closed or cease working altogether.

Summary of the Invention According to a first aspect of the invention, there is provided a control system for controlling equipment, the control system including:

a control member; at least one excitation device associated with the control member; a sensing arrangement in contactless communication with the excitation device such that, when the excitation device is wilhin a region of influence of the sensing arrangement, a position of the excitation device relative to the sensing arrangement is determined Io cause an appropriate output signal to be generated; and control circuitry in communication with the sensing arrangement for receiving the output signal and for generating a control signal to be fed to at least one component of the equipment to be controlled. Dy "contactless" is meant that there is no physical contact between the excitation device and the sensing arrangement.

The control system may be used for controlling any suitable item of equipment. However, in an embodiment, the control system is used k> control mining machinery. Thus, the equipment in question may be the mining machinery. The system may include a support member relative to which the control member is displaceably arranged, the support member defining a chamber. The support member may be countersunk to define the chamber. The excitation device may be housed on a part of the control member in communication with the chamber.

The sensing arrangement may be a Hall effect sensing arrangement. To determine the relative position of the excitation device, which may be in the form of a magnet, relative to the Hall effect sensing arrangement, the Hall effect sensing arrangement may comprise a plurality of spaced Hall effect sensors arranged in spaced relationship on the support member. At least three such sensors may be arranged in spaced relationship on the support member. Instead, four, orthogonally arranged sensors may be mounted on the support member.

It will be appreciated that the sensors may be configured to measure two physical configurations of the excitation device relative to the sensors. Firstly, the sensors may detect the presence or absence of the magnet relative to the sensors, i.e. within or outside the region of influence of the sensors, and, secondly, the position of the magnet relative to the sensors.

The control circuitry may include a signal processing module which converts signals output by the Hall effect sensing arrangement into a predetermined format. The control circuitry may further include a control unit responsive to the formatted output signals. The control unit may be a programmable logic controller (PLC).

Thus, signals output from the Halt effect sensors may be sent via a bus to the PLC. The PLC. in turn, controls components of the equipment such as the mining machinery.

The PLC may determine the actual control member position in one of a number of ways, lor example, by means of look-up tables, by calculation, or by any similar method.

The I ¹ LC may control components of the equipment by, for example, activating appropriate solenoids of the components to effect the required motion of the equipment.

In a preferred implementation, the control system may include an interlock mechanism for inhibiting spurious operation of the controller. The interlock mechanism may include a carrier displaceably carried by the control member, the excitation device being carried on the carrier.

The control member may be a control lever. The control lever may have a ball- type arrangement at a first end which is received in a seat of the support member to achieve rotational displacement of the control member relative to the support member. The control member may define an open passageway. The carrier of the interlock mechanism may be displaceably received within the passageway of the control lever to protrude through a free end of the control lever.

Further, the carrier may be biased by an urging means to a rest position in which the excitation device is out of the region of influence of the sensing arrangement and in which the carrier protrudes through the free end of the control lever. A force may be brought to bear against the action of the urging means to bring the excitation device into the region of inlluence of the sensing arrangement in order to render the system operable. According to a second aspect of the invention, there is provided a joystick controller which includes: a support member; a control member displaceably mounted on the support member; at least one excitation device associated with the control member; and a sensing arrangement carried by the support member, the sensing arrangement being in contaciless communication with the excitation device such that, when the excitation device is within a region of influence of the sensing arrangement, a position of the excitation device relative to the sensing arrangement is determined causing an appropriate output signal to be generated by the sensing arrangement.

Brief Description of Drawings

F.mbodimcnts of the invention are now described by way of example only with reference Io the accompanying drawings in which:-

Fig. I shows a three dimensional view, from below, of an embodiment of a 5 joystick controller;

Fig 2 shows a three dimensional sectional view of the controller;

Fig. 3 shows a schematic representation of an embodiment of a control system;

Fig, 4 shows a schematic representation of another embodiment of part of the control system;

I O Fig, 5 shows a schematic representation of an embodiment of a sensor arrangement of the control system;

Fig. 6 shows a schematic representation of another embodiment of the sensor arrangement of the control system;

Fig. 7 shows a schematic plan view of the sensor arrangement of Fig. 5, in use; 15 and

Fig. 8 shows a schematic plan view of a mimic diagram of the control system.

Detailed Description of Exemplary Embodiments

Referring initially to Figs. 1 and 2 of the drawings, reference numeral 10 0 generally designates an embodiment of a joystick controller. The controller 10 comprises a support member 12 which is to be housed in a flameproof enclosure. A control member in the foπn of a control lever 14 is displaceably mounted on the support member 12, An excitation device, in the form of a magnet 16, mounted in a holder 1 8, is carrier by the control lever 14. The controller 10 further includes a 5 sensing arrangement 20 in contactless communication with the magnet 16. When the magnet 16 is within a region of influence of the sensing arrangement 20, a position of the magnet 16 relative to the sensing arrangement 20 is determined causing an appropriate output signal to be generated by the sensing arrangement 20, as will be described in greater detail below. 0 The controller 1 0 forms part of a control system 30, (Figs. 3 and 4), also in accordance with an embodiment of the invention. The control system 30 includes control circuitry 56 (omitted from Fig. 4) in communication with the sensing arrangement 20 for receiving the output signal from the sensing arrangement and for generating a control signal to be fed to at least one component 66 of the equipment,5 more particularly, mining machinery, to be controlled.

λs illustrated more clearly in Fig. 2 of the drawings, the control lever 14 defines an open passageway 20 in which a carrier, in the form of a rod 22, of an interlock mechanism 24 is slidably received. The rod 22 is received in a tubular holder 26, the holder 26 screwed threadedly engaging an interior wall of the passageway 20 υf the control lever 14 The interlock 24 includes an urging means in the form of a coil spring 28 which urges the rod 22 to a rest position in which an end 22.1 of the rod 22 projects beyond an upper, free end of the control lever 14. An opposed end of the rod 22 carries the holder 18 in which the magnet 16 is mounted.

The control lever 14 is mounted to a member 32 having a ball shaped upper portion (referred to for the sake of brevity below as the "ball") which is mounted for rotation on the support member 12. The ball 32 is held captive by a cover member 34 secured by a plurality of Alien screws 36 to the support member 12. The ball 32 is spring biased to a rest position by a plurality of sprung pins 38. Each pin 38 has a spring 40 associated with it. The pins 38 act on a planar under surface of the ball 32 to urge the control lever 14 to an upright rest, or neutral, position.

The ball 32 is received in a scat defining member 42. The seat defining member 42 is secured to the cover member 34 via a plurality of screws 44.

The assembly of the cover member 34, the support member 12 and the ball 32 is covered by a covering of an clastomeπc material, more particularly, a rubber boot 46. O-πng seals 48 arc provided for inhibiting the ingress of detritus.

The sensing arrangement 20 comprises a plurality of Hall effect sensors 50 mounted on a base of the support member 12 externally of the support member 12, In this regard, it is to be noted that the support member 12 is of a non-magnetic material such as a stainless steel. In the embodiment of the invention shown in Figs. I, 2 and 5 of lhe drawings, the sensor arrangement comprises fouτ orthogonally arranged Hall effect sensors 50. In another embodiment, shown in Figs. 6 of the drawings, thrue Hall effect sensors 50 are mounted on the support member 12. In the embodiment shown in Fig. 6 of the drawings, all three sensors 50 are used at any one time to determine the position of the magnet 16 relative to the sensor arrangement 20. Fn the embodiment shown in Figs. 1 , 2 and 5 of the drawings, any two of the sensors can be used at any one lime to determine the position of the magnet 16 relative to the sensors of the sensing arrangement 20 or, for redundancy, all four sensors 50 could be used.

λs described above, the controller 10 is used in a control system 30. One embodiment of the control system 30 is shown in Fig. 3 υf the drawings. This embodiment uses the controller 10 shown in Figs. I and 2 of the drawings. Thus, the

magnet 16 is earned at an operahvely inner end of the control lever 14 As the control lever 14 is displaced relative to the seniors 50 of the sensing arrangement 20, the position of the magnet 16 is detected resulting in an output .signal from the sensing arrangement 20 In the embodiment shown in Fig 4 of the drawings, a plurality of spaced magnets 16 arc provided, each magnet 16 being carried on the end of a plunger 52. It is to be noted that at least iwo plungers 52 with their associated magnets 16 are provided. The control lever 14 carries an engaging plate 54 which, as the control lever 14 is displaced relative to the .support member 12, comes into engagement with one or more of the plungers 52 urging the plungers 52 downwardly towards the sensors 50 of the sensing arrangement 20. This serves the interlock function provided by the control rod 22 in the embodiment shown in Fig.2 of the drawings.

As described above, the control system 30 includes control circuitry 56 in communication with the sensing arrangement 20 More particularly, the control circuitry 56 includes a signal processing module 58 which communicates with a control unit in the form of a programmable logic controller (PLC) 60 via a data bus 62. The PLC 60 sends control signals via a control line 64 to components 66 of mining machinery (not shown) to be controlled.

The Hall effect sensors 50 of the sensing arrangement 20 detect a magnetic field generated by the magnet 16. Thus, when the magnet 16 is within the region of influence of one or more of the sensors 50. the relevant sensors 50 are activated and the activated sensors 50 produce an output signal proportional to the strength of the detected Held as well as to the polarity of the field. The signal can either be an analogue voltage output proportional to the strength of the field and to the polarity of the field or a simple logic '0' or '1 ' signal. The voltage signals output by the sensors 50 are fed to the signal processing module 58. The signal processing module 58 converts the signals output by the sensors 50 into a numerical value sent via the bus 62 to the PLC 60. Il is to be noted that the sensitivity of the Hall effect sensors 50 can be programmed to suit the particular magnet being used. The use of the interlock mechanism 24 is such that spurious operation of the controller 10 is inhibited. Thus, a deliberate action is required on the part of an operator in order to bπng the magnet 16 into the region of influence of the sensors 50 of the sensing arrangement 20. Tn use. in the embodiment of Fig. I and 2, this is achieved by the operator pressing down on the end 22.1 of the rod 22 of the interlock mechanism 24 to bring the magnet 16 into the region of influence of the sensors 50. In the Fig 5 embodiment, the plates 54 act on the magnets 16 to bring them into the

sphere of influence of the sensors 50. When the, or each, magnet 16 is in its rest posilion, the magnet 16 either minimally influences the sensors 50 or does not influence the sensors at all. Thus, a magnetic field of a predetermined minimum strength must be detected by the sensors 50 before they become operational. The PLC 60 determines if the values output by the sensors 50 are within the necessary range for operating lhe components 66 of the mining machinery.

As described above, the analogue and/or digital signals output by the sensors 50 arc fed to the signal processing module 58 which converts the signals into numerical values. The signal processing module 58 forwards the numerical values to the PLC 60 via the data bus 62. The signal processing module 58 therefore acts as an expansion I/O for the PLC 60 thus reducing the need for a number of PLCs 60 reducing the amount of space required by the control system 30.

It is to be noted that the signal processing module 58 continuously updates the Hall effects values output to the PLC 60 and the PLC 60 reads and processors the data. The PLC 60 comprises a display unit and contains all the necessary software to monitor and control the relevant components 66 of the mining machine including determining the position of the control lever 14 of the joystick 10. The PLC 60 reads the values received from the signal processing module 58. The PLC 60 determines the actual position of the control lever 14 via look up tables, by calculation, or by any other similar method.

The values of the signals received from the sensors 50 by the signal processing module 5ft represent the actual voltage being received at the input of the signal processing module 58. This value is typically in the range of OV - 5V. The PLC 60 scales this voltage value to another range, for example, a range of 0-100 or -100 to + 100, or any other suitable scale. This scaled value is used in any subsequent calculations or for comparison in look-up tables.

For example, with the contτol lever 14 in the position shown in Fig. 8 of the drawings, the magnet 16 would be in the position shown in Fig. 7 of the drawings. The sensor 50 at position λ registers a reading of 2.60V, the sensor 50 at position B registers a reading of 2.55V, the sensor 50 at position C registers a reading of 4.65 V and the sensors 50 at position D registers a reading of 4.15V. These values fire output to the signal processing module 58. Assuming a scaling factor of 1000, the PLC 60 converts these readings to the following:-

Sensor 50 at position A - 2600; Sensor 50 at position B - 2550;

Sensor 50 at position C - 4650; and

Sensor 50 at position D - 415U.

The software of the PLC 50 then uses these values to determine the relative position of the control lever 14 of the controller 10. Having determined these positions, the PLC 60 controls the relative components 66 by turning on or off solenoids. An example of some possible simple computations are as FoI lows :-

Sensor 50 at position λ > 4000 AND Sensor 50 at position C ≤ 2750 THEN Activate TURN (Right) solenoid.

Sensor 50 al position B > 4000 AND Sensor 50 at position D < 2750 THEN Activate Rh)V solenoid. Sensor 50 at position C > 4000 AND Sensor 50 at position A < 2750 THEN

Activate TURN (Left) solenoid.

Sensor 50 at position D > 4000 AND Sensor 50 at position B < 2750 THEN Activate FWl) solenoid.

Based on the computations above and the values given in the example, in this case the turn (Left) and forward solenoids of the component 66 would be activated.

The complexity of the computations will depend on the required accuracy as well as the level of interlock that is needed to confirm the position of the control lever 14 of the controller 10 relative to the sensors 50 of the sensing arrangement 20. It may be that the other directional sensors are also included in the computation to confirm the position. The computations will be influenced by the sensor readings when the control lever 14 is in its rest or neutral position. This set of sensor values may be used as an offset for any calculation or to determine the point at which the control lever 14 of the controller 10 has moved from its neutral position in any given direction. Further, determining whether or not the controller 10 has been "enabled" i.e. that the interlock mechanism 24 has been operated is established in a similar way. In other words the PLC 60 determines whether or not the controller 10 has been activated or enabled based on the values it receives from the signal processing module 58.

Hence, it is an advantage of the invention that a controller 10 is provided together with a control system 30 which relies on contactless communication between an excitation device and a sensing arrangement. Thus, a controller 10 is provided which is able to be used in hostile environments where, previously, non-electrical or purely mechanical systems were required. The use of the controller 10 thus obviates the need for complex Uuid-operable and large control systems. This renders the machinery being controlled far more compact, cost effective and reliable. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific

embodiments without departing from the scope of the invention as broadly described. The present embodiments arc, therefore, to be considered in all respects as illustrative and not restrictive.