Operator enable pedal

Field of the Invention

The invention generally relates to footrests and pedals for drivers. A particular embodiment of the present invention relates to an operator enable foot pedal for a train.

Background of the Invention

The following discussion of the background to the invention is intended to provide context for the development of the invention only and is not intended as, and should not be interpreted as, an admission that the information or problems discussed form part of the common general knowledge in any jurisdiction.

The basic safety systems of most trains require the train drivers to actively operate a control system for the train. Without active operation of the control system, the safety system is designed to cause the train to stop. One method of detecting for the presence of a train driver is to detect depression of a foot pedal by the driver. Foot pedals that provide this function as part of a safety system may be called operator enable foot pedals.

On 31 January 2003, a passenger train of the State Rail Authority of New South Wales, Australia travelling from Sydney overturned at high speed two kilometres south of Waterfall, New South Wales. The driver and six passengers were killed in the accident.

A special commission of inquiry was held into the accident to identify the causes of the accident, the factors that contributed to it as well as the adequacy of the safety management systems applicable to the accident. The Commission was mandated to report on any safety improvements to rail operations which were considered necessary.

In a summary of the findings of the Commission, it was noted that expert evidence before the Commission indicated that an incapacitated driver weighing more than 110 kilograms could, by the static weight of his legs, hold the foot pedal in the set position whilst the train was in motion, preventing an emergency brake application. It was therefore recommended that driver vigilance testing be required, to test the responsiveness of a driver in addition to the mere presence of a driver.

In addition, an operator enable pedal should be reliable in its operation. Further, the ergonomics of the pedal should be considered and in particular the pedal should accommodate a range of driver heights.

Summary of the Invention

According to one aspect of the invention, there is provided an operator enable pedal including: an assembly supporting a pedal, the pedal being moveable between a released position and a fully depressed position so as to move a plurality of triggers physically connected to the pedal; sensor circuitry within the assembly, the sensor circuitry including a plurality of sensors that each detect a said trigger as the pedal moves from the released position to the fully depressed position, a first of the sensors detecting its associated trigger when the pedal is moved a first distance from the released position and a second of the sensors detecting its associated trigger when the pedal is moved a second distance from the released position, the second distance being greater than the first distance; and a signal output that, under the control of the signal circuitry, provides signals indicating when the pedal has moved the first distance from the released position and indicating when the pedal has moved the second distance from the released position.

One or both of the first and second sensors may include a plurality of sensor elements, to ensure continued operability when one of those sensor elements fails or malfunctions. The sensor elements may be arranged in series.

The sensor circuitry of at least the first sensor is in a normally open configuration so as to normally not provide said signal indicating when the pedal has moved the first distance from the released position.

The signal output may include one output terminal for the signal indicating when the pedal has moved the first distance from the released position. The signal output may include another distinct output terminal for said signal indicating when the pedal has moved the second distance from the release position. In other embodiments, a single output may be provided, with different signals at that signal output indicating depression of the pedal to the first distance and the second distance.

The sensors may be located in a unitary sensor block. In one embodiment, the sensors may be removably inserted into the sensor block and in one embodiment the sensor block is a removable modular component of the operator enable pedal. The sensors may be proximity sensors and their position within the sensor block may be individually adjustable so as to adjust the position at which each of the triggers is detected by its respective sensor. The pedal may be locatable to allow access to the assembly to facilitate removal and replacement of the sensors and/or the sensor block.

The operator enable pedal may include a guide mounted inside the pedal in a fixed position relative to the pedal, the guide fixing the path along which the triggers travel when the pedal is moved past the first and second distances from the released position. The guide is preferably an integral part of the sensor block, which as described above may be a unitary block. In one embodiment, the guide is a slot provided in the sensor block and in one embodiment the slot includes an entrance that is cambered. The triggers may be on a shaped tongue that extends from the pedal at least partially into the guide in all positions of pedal movement from the released position to the fully depressed position. The pedal may be movable above its released position and the shaped tongue may move out of the guide when the pedal is moved above its released position.

The operator enable pedal may include means for applying an operator detectable discontinuity in the resistance to depression of the pedal as the pedal is moved. The discontinuity may include a rapid change in resistance when the pedal is depressed to a predetermined extent from its released position. The assembly of the operator enable pedal may include a footrest area surrounding said pedal. The discontinuity may occur when the pedal is depressed so the pedal is substantially aligned with or co-planar to the footrest area. In one embodiment, the discontinuity occurs when the pedal is depressed more than the first distance from the released position and less than the second distance from the released position. In one embodiment, the discontinuity approximates a step function in a resistance profile for movement of the pedal. In one embodiment, outside of the step function, the resistance generally progressively increases as the pedal is depressed. An operator detectable discontinuity may be incorporated at or near the start of pedal movement, with the pedal being resistance pre-loaded when in the rest position.

According to another aspect of the invention, there is provided an operator enable pedal including an assembly supporting a pedal, which is moveable between a released position and a fully depressed position, the operator enable pedal including: sensor circuitry to detect movement of the pedal and output a signal indicating when the pedal has been depressed a first distance and a second distance from the released position; and means for applying an operator detectable discontinuity in a resistance profile of the pedal as the pedal is depressed, the discontinuity resulting in an increase in resistance to depression of the pedal.

The assembly may include a footrest area surrounding the pedal. The discontinuity may occur when the pedal is substantially aligned with or co-planar to the footrest area.

The discontinuity may occur when the pedal is depressed more than the first distance from the released position and less than the second distance from the

released position. In one embodiment, the discontinuity may occur substantially at a mid-point between the first distance and the second distance.

The discontinuity may approximate a step function. In one embodiment, outside of the step function, the resistance generally progressively increases as the pedal is depressed.

The means for applying an operator detectable discontinuity may be a plurality of compression springs, wherein at least two of the compression springs act on the pedal at different extents of depression of the pedal. At least one of the compression springs may act on the pedal throughout its range of movement from the released position to the fully depressed position. In one embodiment, the means for applying an operator detectable discontinuity may include at least three compression springs and at least two of the compression springs may act on the pedal throughout its range of movement from the released position to the fully depressed position. The at least two compression springs that act on the pedal throughout its range of movement may be located substantially equidistant from a centre line of the pedal. In one embodiment, the means for applying an operator detectable discontinuity has three compression springs only, and one of the compression springs is located on the centre line of the pedal, that compression spring causing the operator detectable discontinuity.

The resistance profile of the pedal may be adjustable without replacing the means for applying an operator detectable discontinuity. The resistance profile of the pedal may be adjustable by adjusting a pre-compression length of one or more compression springs forming the means for applying an operator detectable discontinuity. The pedal may be movable to allow access to the means for applying an operator detectable discontinuity. The means for applying an operator detectable discontinuity may include compression springs inside a housing and the housing may include an aperture through which an adjustment mechanism is accessible, the adjustment mechanism, when operated, adjusting the pre-compression length of the compression springs.

The means for applying an operator detectable discontinuity may be a replaceable modular component of the operator enable pedal.

According to a third aspect of the invention, there is provided an operator enable pedal including an upper portion supporting a pedal in a generally upwards and forward sloping orientation, and a lower portion, the pedal being moveable between a released position and a fully depressed position, the operator enable pedal including: sensor circuitry to detect movement of the pedal and output a signal indicating depression of the pedal; and two scissor arrangements extending along opposite sides of the operator enable pedal and connected to the upper portion and the lower portion so as to allow the upper portion to be raised and lowered relative to the lower portion, each scissor arrangement including an inner arm and an outer arm, which are pivotally connected to each other at a central pivot point and are both pivotally connected to the upper portion and the lower portion at connection points generally at their ends, one end connected via a slot and the other end connected via a lateral pivot point; wherein the inner arm or the outer arm of each scissor arrangement is shaped so that the central pivot point is not aligned with the connection points of that arm, resulting in the connection points towards the front of the operator enable pedal being lower than if the central pivot point was aligned with the connection points of that arm; and on the upper portion or the lower portion, the slot and the lateral pivot point are located at different distances from an upper surface of the operator enable pedal.

The slot and the lateral pivot point that are located at different distances from the upper surface of the operator enable pedal may be arranged relative to each other so that the lateral pivot point is located on the longitudinal axis of the slot.

The inner arms of the two scissor arrangements may be physically connected to each other.

The inner arm and the outer arm may each be slidably engaged with the slots via a roller.

The operator enable pedal may further include a linear actuator extending between pivotal connections with the upper portion and the lower portion, the pivotal connections located to limit the extent to which the upper portion can be raised relative to the lower portion.

The operator enable pedal may further include a spring arrangement that acts to move the upper portion upwards away from the lowest position of the upper portion. The spring arrangement may act on the upper portion for only a part of the distance that the upper portion is movable relative to the lower portion.

According to a fourth aspect of the invention, there is provided an operator enable pedal including an upper portion supporting a pedal and a lower portion, the pedal being moveable between a released position and a fully depressed position, the operator enable pedal including: means to detect movement of the pedal and output a signal indicating depression of the pedal; scissor arrangements extending along opposite sides of the operator enable pedal and connected to the upper portion and the lower portion so as to allow the upper portion to be raised and lowered relative to the lower portion; and a linear actuator to raise and lower the upper portion relative to the lower portion, the linear actuator pivotally connected to the upper assembly and the lower assembly so as to rotate to a more vertical orientation when raising the upper portion and rotate to a more horizontal orientation when lowering the upper portion.

The operator enable pedal may further include means to move the upper portion upwards away from the lowest position of the upper portion, said means to move the upper portion acting in addition to the linear actuator. The means to move the upper portion may act on the upper portion for only a part of the distance that the upper portion is movable relative to the lower portion.

According to a fifth aspect of the invention, there is provided an operator enable pedal including an upper portion supporting a pedal and a lower portion, the pedal being moveable between a released position and a fully depressed position,

the operator enable pedal including: means to detect movement of the pedal and output a signal indicating depression of the pedal; scissor arrangements extending along opposite sides of the operator enable pedal and connected to the upper portion and the lower portion so as to allow the upper portion to be raised and lowered relative to the lower portion; means to raise and lower the upper portion relative to the lower portion from a lowest position to a highest position; and a spring arrangement to assist said means to move the upper portion upwards away from the lowest position.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 : shows a rear perspective view of an operator enable pedal in a raised position. The operator enable pedal includes an upper assembly supporting a pedal and a lower assembly.

Figure 2: shows a front perspective view of the operator enable pedal of Figure 1 , with its top plate and toe plate removed and the pedal opened to facilitate access into the operator enable pedal.

Figure 3: shows a sensor module, which senses the position of the pedal of the operator enable pedal shown in Figure 1.

Figures 4-8: show operation of the sensor module shown in Figure 3.

Figure 9: shows a load module for the operator enable pedal of Figure 1.

The load module provides tactile feedback to the user as the user depresses the pedal.

Figure 10: shows a cutaway view of the load module shown in Figure 9.

Figure 11 : shows the operator enable pedal in a lowered position.

Figure 12: shows the operator enable pedal in a raised position.

Figure 13: shows a graph of a load profile of the pedal of the operator enable pedal of Figure 1.

Figure 14: shows a base platform from the operator enable pedal of Figure 1.

Figure 15: shows an inner arm of two scissor arrangements from the operator enable pedal of Figure 1. The scissor arrangements facilitate raising and lowering of the upper assembly relative to the lower assembly.

Figure 16: shows an outer arm of a scissor arrangement from the operator enable pedal of Figure 1.

Figure 17: shows an upper support, which forms a part of the upper assembly of operator enable pedal of Figure 1.

Figure 18: shows a linear actuator from the operator enable pedal of Figure

1 , which operates to raise and lower the upper assembly relative to the base assembly.

Figure 19: shows the operator enable pedal and an arm to which it may be mounted when installed.

Figure 20: shows a fixing tongue from the operator enable pedal of Figure 1.

Figure 21 shows a block diagram of the circuitry of the operator enable pedal of Figure 1.

Detailed Description

An embodiment of the present invention in the form of an operator enable foot pedal for a train is now described.

In general, the operator enable foot pedal is a permissive device focussed on train operations that has two separate functions. One function is related to the presence of the driver and the other function is related to the responsiveness of the driver. Presence and responsiveness are determined by moving of a pedal into different positions and in the embodiment described herein separate output signals are provided for each function.

As well as providing the signalling functions, the operator enable foot pedal can be raised and lowered to meet a range of anthropometries created by physical differences of drivers. When the footrest is raised or lowered, at any stage of its height the pedal provides the driver presence and responsiveness capabilities. The height may be adjusted remotely and in one embodiment the height adjustment is electrically driven.

It will be appreciated that the description herein in effect covers an operator enable pedal and a footrest raise and lower facility within which the pedal is mounted so as to provide driver comfort and ease of operation. However, the pedal does not need to be incorporated into the raise and lower facility described herein, and indeed the pedal could be mounted into a static footrest, or a footrest which is movable by means of a different mechanism to that described herein.

Overview

Figure 1 shows a rear perspective view of an operator enable pedal 100 in accordance with an embodiment of the present invention. The operator enable pedal 100 includes a base plate assembly 1 , which is mounted to the floor of the driver's cab of a train via four fixing tongues 14 (one only indicated by a reference numeral in Figure 1) and an upper assembly 2, which is movably mounted above the base plate assembly 1 so that the distance between the base plate assembly 1 and upper

assembly 2 can be varied, as described herein below. In Figure 1 the operator enable pedal 100 is shown in a raised position.

The operator enable pedal 100 is designed to be accommodated within an alcove (not shown) which is dimensioned similarly to the operator enable pedal 100, so that the side walls and back walls of the alcove are immediately adjacent to the side and rear walls of the operator enable pedal 100.

The upper assembly 2 includes a rubber mat 3 on a top plate 15. The rubber mat 3 is partially shown in Figure 1 and in one embodiment surrounds a pedal 4 and covers the upper surface of the pedal 4. The pedal 4 may be torsionally stiffened. The rubber mat 3 may provide impact absorption and also assist in environmental protection for the operator enable pedal 100 by preventing dirt and other objects from entering the operator enable pedal 100 through its upper assembly 2. Brush seals 16 may also be provided around the perimeter of the top plate 15 to assist in environmental protection. The upper assembly 2 may include a edge frame 17 that provides a frame over which the top plate 15 is located and mounted to. The edge frame 17 includes a void area at least in the area of the pedal 4.

The upper assembly 2 is supported relative to the base plate assembly 1 by two sets of scissor arrangements 5, located at the sides of the operator enable pedal 100. The scissor arrangements 5 constrain the relative movement of the base plate assembly 1 and upper assembly 2. The front of the operator enable pedal 100 is maintained closed as the upper assembly 2 is raised and lowered by a bellows 6, which extends generally from the front edges of the base plate assembly 1 and upper assembly 2. Two auxiliary spring units 7 are provided between the base plate assembly 1 and upper assembly 2, which as described herein below may be provided to assist in moving the upper assembly 2 away from its lowest point.

The relative movement of the base plate assembly 1 and upper assembly 2 is controlled by a linear actuator 8. The linear actuator 8 is mounted on the upper assembly 2 and includes a telescoping shaft 20 connected to the base plate assembly 1 through a pivot 21. As the linear actuator 8 extends the telescoping shaft

20, the upper assembly 2 is raised relative to the base plate assembly 1. Control of the linear actuator 8 may be provided by button, dial or other user operable device. For example, a dial may have a raise and lower direction, which causes the linear actuator 8 to extend and retract the telescoping shaft 20 respectively, allowing a driver to set the height of the pedal 4 and surrounding foot rest at a comfortable height.

The train's main power supply is received from the location of the alcove and powers the operator enable pedal 100. In one embodiment, the linear actuator 8 and other components of the pedal 100 are powered by a 24 volt dc supply. The operator enable pedal 100 therefore may include a power supply to generate the 24 volt dc supply, from the train's power supply, which may be 120 volts dc. The operation of the linear actuator 8 is controlled by a motor controller 10, which is connected to both the power supply 9 and a pedal terminal board 11 to receive control signals from the aforementioned user operable device, to allow the driver to readily raise and lower the operator enable pedal 100.

The pedal terminal board 11 may also provide the connection point for the driver not present and driver not responsive signals. The contacts for the driver not present and driver not responsive signals in the pedal terminal board 11 may therefore be connected to a safety management system of the train, including a switch for the main power supply of the train. When the safety management system receives the driver not present or driver not responsive signal, then it may switch out the train's power supply, causing the train to stop.

Figure 2 shows a perspective front view of the operator enable pedal 100 with the top plate 15 and edge frame 17 removed. The pedal 4, which is pivotally mounted to the upper assembly 2 has been opened, allowing access to the internal cavity between the base plate assembly 1 and upper assembly 2 through the top of the operator enable pedal 100. The pedal 4 includes a stop 22, which abuts against the top plate 15 when the top plate 15 is in place, thereby preventing opening of the operator enable pedal 100 until after the top plate 15 has been removed.

Mounted on an inner surface of the upper assembly 2 is a load module 12. As explained in more detail herein below, the load module 12 provides feedback resistance to the driver operating the pedal 4. The load module includes three spring assemblies 23-25, which act on the lower surface of the pedal 4 to provide the resistance feedback.

Also mounted on an inner surface of the upper assembly 2 is a sensor module 13. The sensor module 13 includes a slot 26 to receive a shaped tongue 18 provided on the pedal 4. By detecting the position of the shaped tongue 18, the sensor module 13 detects the position of the pedal 4. The sensor module 13 is powered from the power supply 9 and provides the driver present and driver responsive signals to the pedal terminal board 11.

The operator enable pedal 100 may operate in parallel with one or more other safety devices. For example, a driver may confirm his or her presence and responsiveness using either the operator enable pedal 100 or another device, such as a hand-controlled device. The safety management system with which the operator enable pedal 100 communicates, implements rules regarding when the train is to be stopped. For example, the safety management system may be adapted to stop the train if a driver not present signal is received from all relevant devices for 5 second or more. Similarly, the train may be stopped if a driver not responsive signal is not received after 3 seconds of the start of an alert to the driver that he or she needs to confirm responsiveness.

Presence and responsiveness testing

The sensor module 13 provides for the detection of the presence and responsiveness of a driver. An enlarged view of the sensor module 13 is shown in Figure 3. As previously described, the sensor module 13 includes a slot 26 that receives the tongue 18 of the pedal 4 to varying extents as the pedal 4 is depressed and released.

The sensor module 13 includes three spaced apart sensors 27-29 mounted in a sensor block 30. The sensors 27-29 may each be inductive proximity sensors that are suitable for detecting the presence and absence of the shaped tongue 18 in the sensing region of the sensor, which is located within the slot 26. Alternatively, capacitive sensors may be used. Other types of sensors may be used in the operator enable pedal, provided the sensor provides sufficient robustness and reliability.

The sensors 27-29 may be screw threaded into a sensor block 30. This may allow ready replacement of a sensor 27-29 should it fail. In particular, the top plate 15 may be removed and the pedal 4 pivoted back to allow access to the sensor module 13. The sensor block 30 may also be removably mounted to the upper assembly 2, allowing for replacement if required. In one embodiment, the triggering position may be adjusted by moving the sensor toward/away from the slot 26 and in turn the shaped tongue 18.

The slot 26 may include a cambered entrance 31 , which guides the shaped tongue 18 into the slot 26. The sensor block 30 may be constructed of rigid and robust material, for example a moulded plastic so that the slot 26 acts as an effective guide for the shaped tongue 18. The sensor block 30 may be non-metallic to prevent interference with the electromagnetic fields of the proximity sensors 27-29. Alternatively, appropriately shielded proximity sensors 27-29 may be used if a metallic mount is required.

The slot 26 with cambered entrance 31 also helps to laterally align the pedal 4 on its pivot axis for ongoing switching reliability. The pedal 4 is mounted to the rest of the upper assembly 2 so as to float laterally to some extent, allowing the pedal 4 to be placed in the correct position when the pedal 4 is closed from its position shown in Figure 2 to its position shown in Figure 1. The cambered entrance 31 therefore acts to align the pedal with the slot 26. Once the pedal is closed, it always extends partially into the slot 26, preventing lateral movement of the pedal 4.

The sensor block 30 may be bolted to the upper assembly 2 and moves relative to the base plate assembly 1 with the remainder of the upper assembly 2. In

particular, the sensor block 30 remains in the same position relative to both the top plate 15 and the pedal 4 as the upper assembly 2 is moved up and down by the linear actuator 8.

Figures 4 to 8 show the operation of the sensor module 13. In Figure 4 the pedal 4 is in its top position. This is the position where no external force is applied to it and the stop 22 of the pedal 4 is held up against the top plate 15 due to the action of the spring assemblies 23, 24. In this position, the pedal 4 has a higher gradient than the top plate 15 and therefore extends above the level of the top plate 15, as shown in Figure 1.

In Figure 5, the pedal 4 has been partially depressed and the sensors 28, 29 both first detect the presence of the shaped tongue 18. In this position, the pedal 4 still extends slightly above the level of the top plate 15. The presence of the driver is indicated by the pedal 4 being depressed to the position shown in Figure 5 or further (see Figures 6 to 8). It is not expected that under normal circumstances a driver would maintain the pedal 4 in this position for any significant duration of time.

In Figure 6, the pedal 4 has been depressed further and its upper surface 4a is now substantially in line with the top plate 15. This is a footrest position. The angle between the position shown in Figure 4 and the position shown in Figure 6 may be selected to so that the average driver would have to depress the pedal downwards approximately 17 mm to move between these positions.

In Figure 7, the pedal 4 has been depressed still further, so that the pedal is at a lesser incline than the top plate 15 and accordingly extends below the level of the top plate 15. In this position, the sensor 27 first detects the presence of the shaped tongue 18. Responsiveness of the driver is detected by the driver depressing the pedal 4 to at least the position shown in Figure 7.

In Figure 8, the pedal 4 is fully depressed or in other words has been pressed down to the bottom end of its movement and is stopped against the upper assembly 2. The angle required to move from the position shown in Figure 6 to that shown in

Figure 8 may be selected so that so that the average driver would have to depress the pedal downwards approximately 17 mm. It is expected that with typical dimensions of pedal 4, the angle of movement would be about 2-6 degrees from the top position to the footrest position and a further 2-6 degrees to the bottom position.

For example, if the pedal 4 is about 400 mm from its front pivot to back edge, and the drivers foot is expected to be located so as to move up and down to operate the pedal at about 240 mm from the front pivot, then the pedal would pivot about 8 degrees in total from its top position to its bottom position. While the foregoing description assumes symmetry in the range of movement from the footrest position, this is not essential.

The sensors 28, 29 are normally open inductive proximity switches that together function to control the provision by the operator enable pedal 100 of a driver presence signal at the pedal terminal board 11. Proximity type switches were selected to substantially eliminate or reduce force hysteresis on the return movement.

The sensors 28, 29 are connected in series so that switching of both of the sensors 28, 29 to the closed position is deemed an indication of the presence of the driver. If just one of the switches is closed, for example due to failing in the closed position, then the series connection prevents a presence signal being provided at the pedal terminal board 11 and absent another indication of presence, the safety management system of the train causes the train to stop. As will be appreciated from the foregoing, the driver not present signal is the absence of a positive signal at the pedal terminal board 11.

The sensor 27 forms part of another normally open proximity switch, which closes when the sensor detects the shaped tongue 18. During operation, the safety management system of the train periodically requires the driver to confirm his or her responsiveness. This may be indicated by an alarm, which may be audible and/or visual. The driver is then given a certain period of time in which to confirm his or her responsiveness by depressing the pedal 4 at least down to the position shown in

Figure 7, although in practice it is expected that the drivers will depress the pedal 4 to the position shown in Figure 8. Although only one sensor is provided in the embodiment shown in the accompanying drawings, in another embodiment two (or more) sensors may be provided, operating in series in the same way as the sensors 28, 29.

The safety management system of the train is adapted to receive the presence and responsiveness signals and stop the train in the absence of either signal, which is deemed the presence of a driver not present or driver not responsive signal respectively.

The frequency with which a driver is required to confirm his or her responsiveness may in one embodiment be a function of the speed at which the train is travelling; the higher the speed, the more often the driver has to confirm responsiveness. The period provided to confirm responsiveness may also vary depending on the speed of travel. Other variables may be used to alter the frequency and/or period provided to confirm responsiveness, including for example the particular location of the train at the time. The safety management system may require release of the pedal 4 beyond the position shown in Figure 7 between responsiveness checks. This may avoid for example, the pedal 4 being jammed down.

As is apparent from Figures 4 to 8, the shaped tongue 18 provides three different triggers 18A-18C (reference numerals included on Figure 8 only) for the switching of the sensors 27-29. In addition, in the embodiment shown in the accompanying figures, the shaped tongue 18 includes an extension 18D. The extension 18D is the part of the shaped tongue 18 that enters the slot 26 at the location of the cambered entrance 31. The extension therefore helps ensure alignment of the shaped tongue 18 with the slot 26.

All three sensors 27-29 use a common mount with a common trigger alignment guide, namely the sensor block 30 and the slot 26. This arrangement helps ensure that the switching positions retain their relativity and can not be inadvertently

changed during original assembly nor during service or maintenance functions. Similarly, the triggers have been created as a combined unit. Here again a fixed relativity of the triggers is achieved precluding inadvertent alteration during assembly or while being serviced or maintained.

Tactile feedback

The load module 12 provides tactile feedback to a driver when he or she ;moves the pedal 4. An enlarged view of the load module 12 is shown in Figure 9 and a sectional view through the load module is shown in Figure 10. Like the sensor module 13, the load module 12 may be readily replaceable as a modular component part of the operator enable pedal 100. This may reduce out of service time for the operator enable pedal 100 in the event that the load module 12 requires replacement.

The load module 12 includes in this embodiment three spring assemblies 23- 25 that work together to create the loads required at specific travel positions of the pedal 4. The springs in the spring assemblies 23-25 may be helical compression springs. Two of the spring assemblies 23, 24 operate over the full travel distance of the pedal 4 from its top position to its bottom position. The third spring 25 only operates after a given position has been passed. The third spring 25 may start to operate when the pedal 4 is in the foot rest position, so that continued depression of the pedal 4 towards its bottom position (and the responsiveness confirmation switch position) requires increased force than that required to depress the pedal 4 from its top position to the foot rest position.

Each of the spring assemblies 23-25 are internally adjustable, not requiring disassembly and are adjustable without external geometric consequence. In other words, the operational settings of the pedal (as angles) are unchanged when adjusting the loads of the spring assemblies 23-25. Referring to Figure 10 and the spring assembly 23, adjustment of a spring assembly 23 is provided by means of an adjustment bolt 32 which is accessed through a hole 33 at the top of the spring assembly 23. Rotating the bolt 32 causes a base platform 34 to move up and down

the thread of the bolt 32. Rotation of the base platform 34 is prevented by fixed shafts 35, which extend through apertures in the base platform. This adjustment changes the pre-compressed length of the spring 23a independently of the outer housing of the spring assembly 23. The adjustment mechanism for the spring assemblies 24, 25 operate in the same way.

Figure 13 shows an example of a load profile for a pedal 4 that operates against the load module 12. The top position of the pedal is at 32 degrees to the horizontal. The presence switching position or enable position (Figure 5) is at approximately 30 degrees; the foot rest position (Figure 6) is at approximately 28 degrees; the responsiveness switching position or acknowledge position (Figure 7) is at approximately 26 degrees; and the bottom position is at approximately 24 degrees. The total range of movement in this example is therefore 8 degrees.

In the example, the springs used in the spring assemblies 23, 24 have a free length of 120 mm, an initial set length or length when the pedal 4 is in its upper position of 80 mm, a spring rate of about 0.54 N/mm and are located about 360 mm from the pivot of the pedal 4. The spring assembly 25 is located in the same position relative to the pivot as the spring assemblies 23, 24 and has a spring of free length 75 mm, initial set length of 53 mm and rate of 0.657 N/mm. The driver is assumed to apply his or her force at about 240 mm from the pivot and the pedal 4 has a total length of 400 mm and a weight of about 5 kg.

The graph shows the force linearly increasing as the pedal 4 is moved from its top position to the foot rest position, passing through the confirm presence position at about 50 N. At the foot rest position there is an approximate step function, caused by the contact of the pedal 4 with the spring assembly 25. Following the step, the force then linearly increases, passing through approximately 124 N at the responsiveness switching position. Accordingly, the driver is provided with tactile feedback, most noticeably at the step function to indicate the location of the pedal 4. In addition, the force required to confirm responsiveness is selected to be greater than the force that would be exerted by an unconscious driver with his or her foot resting on the pedal 4.

The body of the load module 12 may be constructed from moulded plasties and the spring and adjustment mechanism may be constructed from suitable metals. However, other suitable materials may be used.

A testing arrangement may depress the pedal 4 and measure the force required to depress the pedal as it is depressed. The testing arrangement may plot or provide information to enable the plotting of a load profile like that shown in Figure 13. Based on the results of this testing, the pre-compressed length of the springs may be changed to obtain a required load profile.

Height adjustment

The scissor arrangements 5 and linear actuator 9 allow height adjustment of the operator enable pedal 100. Figure 11 shows the operator enable pedal 100 in its lowest position and Figure 12 shows the operator enable pedal 100 in its highest position. As explained below, depending on the design of the scissor arrangements 5, the top plate 15 can either be maintained at the same angle relative to the base plate assembly 1 throughout the range of movement, or may vary as the operator enable pedal 100 is raised and lowered. The scissor arrangement 5 extends from two base supports 36, which each include a pivot point 37 and a slot 38, to an upper support 39, which includes two pivot points 40 and two slots 41.

In one embodiment, the angle between the top plate 15 and the base plate assembly 1 may be approximately 18 degrees. In this embodiment the base plate assembly 1 may be mounted on a surface that is inclined by approximately 10 degrees in the same plane as the top plate 15, resulting in the top plate 15 having a total incline from horizontal of approximately 28 degrees. If the operator enable pedal 100 is to be mounted on a surface at a different orientation or if an angle other than 28 degrees was required, then it may be redesigned to provide a different angle between the top plate 15 and the base plate assembly 1 , so as to maintain a total incline of the top plate 15 from horizontal of 28 degrees. The angle of the top plate 15 may be selected according to ergonomic requirements for the driver(s) of the train.

Figure 14 partially shows the base plate assembly 1. The slots 38 extend parallel to the bottom of the base plate assembly 1 , from the front of the base supports 36 towards the centre of their respective base support 36. The pivot points 37 are located in line with the slots 38. Figure 14 also shows the pivot point 21 (partially obscured), which as described herein above pivotally engages with the linear actuator 8.

Figure 15 shows an inner arm 42 of the scissor arrangements 5. In this embodiment, the inner arm 42 extends across the operator enable pedal 100, so as to act as the inner arm of both of the scissor arrangements 5. In other embodiments separate inner arms may be provided. The inner arm 42 includes three pivot points 43, 44, 45. The pivot point 43 receives a pin or stub shaft that extends through the slot 38. The pivot point 44 engages with the outer arm 46 (see below). The pivot point 45 engages with the upper support 39 at the pivot point 40. The pivot points 43 to 45 are in line with each other. The inner arm 42 is stiffened both laterally and torsionally.

Figure 16 shows an outer arm 46 of the scissor arrangement 5. The outer arm 46 includes three pivot points 47, 48, 49. The pivot point 47 receives a pin or stub shaft that extends through the slot 41. The pivot point 48 engages with the inner arm 42. The pivot point 49 engages with the base support 36 at the pivot point 37. As is apparent from the dashed line drawn across the outer arm 46, the pivot points 47 to 49 are offset from each other, creating a 'bent' scissor arm.

Figure 17 shows the upper support 39. The slots 41 extend at an angle to the top plate 15 (not shown in Figure 17) of the upper assembly 2 from the front of the upper support 39 towards the centre of the upper support 39. As apparent from the dashed line in Figure 17, in this embodiment, the pivot points 40 are located in line with the slots 38. The pivot points 40 are therefore located further from the top plate 15 than the slot 38.

The mounting plate 19 (obscured in Figure 17, but visible in Figure 1 ) extends from the upper support 39 and the linear actuator 8 is pivotally mounted to the

mounting plate 19 so that its point of mounting is in line between the pivot points 40 of the upper support 39. Figure 18 shows the linear actuator 8, including apertures 43, 44 to pivotally engage with pins provided through the pivot 21 of the base plate assembly 1 and through the mounting plate 19 respectively. The upper support 39 is torsionally stiffened to reduce flexural deformation under off-centre loading conditions and also incorporates planar rigidity to retain key component alignment.

Referring now to Figures 14, 17 and 18, the central termination point of the slots 38 and the pivot 21 of the base plate assembly 1 are located in line with each other. This, in combination with the alignment of the pivot point 44 of the linear actuator 8 with the pivot points 40 of the upper assembly 2, means that as the operator enable pedal 100 is raised, the inner arm 42 moves inwards along the slot 38 of the base support 36 towards the central terminal point until it is aligned with the linear actuator 8. When it reaches this position of alignment, then the linear actuator 8 can not be extended further and the operator enable pedal 100 is at its maximum height. In this position there may be a clearance at the ends of the slots 38, 41 to avoid the pins or rollers of the scissor assembly 5 impacting the base support 36 and upper support 39.

To reduce drag loading as the operator enable pedal 100 is raised and lowered, rollers 50 (see Figure 1 ) may be provided on the pins that extend through the slots. Also, the outer arms 46 and inner arm 42 of the scissor assemblies 5 are assembled using shoulder bolts, with the shoulder extending through the pivot points 43-45 and 47-49, to help avoid clamping (jamming) of the scissor assemblies 5.

The combination of providing a bent arm in the scissor assemblies 5 (in this embodiment the outer arm 46), with an offset but aligned slot and pivot (in this embodiment provided in the upper assembly 2) allows, with appropriate selection of the angle of the bend and angle of the slot, the top plate 15 to be raised and lowered at a constant angle relative to the base plate assembly 1. If a steepening angle was required as the top plate 15 was lowered, then the upper assembly 1 could be redesigned so that each slot 41 runs parallel to the top plate 15, but is still below the level of the pivots 40.

Referring again to Figure 14, two auxiliary spring units 7 are provided on the base plate assembly 1. The auxiliary spring units 7 may have a similar construction to the spring assemblies 23-25, but may exclude the adjustment mechanism. The auxiliary spring units 7 are shown in their compressed position in Figure 14 and in their raised position in Figure 1. The auxiliary spring units 7 are compressed by the upper assembly 2 as the upper assembly 2 moves towards its lowest point, relative to the base plate assembly 1.

As the upper assembly 2 is lowered, the linear actuator 8 rotates closer to horizontal. Accordingly, the force required to be applied by the linear actuator 8 to raise the upper assembly 2 increases rapidly as the upper assembly 2 is lowered. The auxiliary spring units 7 provide a vertical force to augment the linear actuator's vertical load vector when the linear actuator 8 is working to raise the upper assembly 2 from its lowest position. This therefore reduces the force required to be applied by the linear actuator 8, which may allow use of a smaller powered actuator than otherwise would be required.

Although the auxiliary spring units 7 act to resist lowering of the upper assembly 2 to its lowest point, the linear actuator 8 need only overcome the difference between the upward force applied by the auxiliary spring units 7 (and friction) and the downward force applied by gravity acting on the upper assembly 2. Therefore, the auxiliary spring units 7 can apply an upwards force greater than the force resulting from the weight of the upper assembly 2. The auxiliary spring units 7 also act to buffer the end of travel movement of the upper assembly 2 when it reaches its bottom position.

Installation of the operator enable pedal

Figure 19 shows one embodiment of a mechanical and electrical mount for the operator enable pedal 100. An arm 51 extends from the back wall of the alcove of the train where the operator enable pedal 100 is to be installed. The arm 51 is pivotally engaged to the alcove and the operator enable pedal 100 an also includes a pivot 52 at a mid-point of the arm. The arm 51 therefore folds up and extends to move the

operator enable pedal 100 into and out of the alcove respectively. The arm 51 is rigid so as to support the weight of the operator enable pedal 100 when it is moved away from the surface on which it is mounted, which as described previously herein may be inclined for example at about 10 degrees from horizontal.

Power is provided to the pedal terminal board 11 from the train's dc power supply via a power cable located within a cable sheath 53. The cable sheath 53 also contains cables to carry the signals from the pedal terminal board 11 that indicate driver presence and driver responsiveness.

The electrical connection between the operator enable pedal 100 and the train's power supply and safety management system may be though a bayonet fitting (not shown), so that no site terminations are required. The operator enable pedal 100 includes a mounting block (also not shown) to which the arm 51 is mechanically secured, for example through bolting, sliding a tongue into a slot, or otherwise.

Figure 20 shows an enlarged view of a fixing tongue 14. The base assembly 1 may include four fixing tongues 14, each of which may be located so as to be accessible through the top of the operator enable pedal 100 when the pedal 4 is in its open position as shown in Figure 2. The fixing tongues 14 each include a tongue 54, which can deflect from the plane of the base assembly 1. The tongues 54 may facilitate mounting to surfaces that have variations from planar without applying stress to the base plate assembly 1.

On each tongue 54 is provided a disc 55, which is rotatable through 360 degrees and includes a slot 56. The slot 56 extends from the centre of the rotatable disc 55 to near its periphery. Therefore, by rotating the disc 55 and placing a bolt (or other fixing means) in the appropriate location in the slot 56, the bolt can be put in a relatively wide range of position in comparison to if a simple aperture were provided in the base plate assembly 1. This may be useful, for example, where there are preformed holes in the alcove of the train due to the prior mounting of a different pedal in the alcove.

Circuitry

Figure 21 shows in block diagram form, the circuitry of the operator enable pedal 100. The wiring and specific electrical components selected are a matter for design choice, taking into consideration the requirement to avoid chafing of cables, possible requirements regarding switch bounce and any limitations on the supply power and output signals.

A power and ground signal is received at the pedal terminal board 11 fro the train power supply. This may be a 120 V dc signal. This is received by the power supply 9, which steps down the voltage to, for example, a 24 V dc signal for supply to the motor controller 10, linear actuator 8 and sensors 27-29. The sensor 28 and 29 are arranged in series with their output connected to the presence signal output on the pedal terminal board 11. The output of the sensor 27 is connected to the responsiveness signal output on the pedal terminal board 11. The sensors 27-29 will typically operate on dedicated circuitry to ensure functionality in all operating situations, even when the train power supply is interrupted. Accordingly, the power supply for the sensors may differ from that shown in Figure 21.

Figure 17 also shows a height controller 57, which may be the previously discussed dial that the driver operates to raise and lower the operator enable pedal 100.

Where in the foregoing description reference has been made to integers having known equivalents, then those equivalents are hereby incorporated herein as if individually set forth.

Those skilled in the relevant arts will appreciate that modifications and additions to the embodiments of the present invention may be made without departing from the scope of the present invention.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual

features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Index of reference numerals

Base plate assembly 26 Slot

Upper assembly 27-29 Sensors

Rubber mat 30 Sensor block

Pedal 31 Cambered entrancea Upper surface 32 Adjustment bolt

Scissor arrangement 33 Hole

Bellows 34 Base platform

Auxiliary spring unit 35 Fixed shafts

Linear actuator 36 Base support

Power supply 37 Pivot point 0 Motor controller 38 Slot 1 Pedal terminal board 39 Upper support 2 Load module 40 Pivot point 3 Sensor module 41 Slot 4 Fixing tongues 42 Inner arm 5 Top plate 43-45 Pivot points 6 Brush seal 46 Outer arm 7 Edge frame 47-49 Pivot points 8 Shaped tongue 50 Roller 8A-C Triggers 51 Arm 8D Extension 52 Pivot 9 Mounting plate 53 Cable sheath 0 Telescoping shaft 54 Tongue 1 Pivot 55 Disc 2 Stop 56 Slot 3-25 Spring assemblies 57 Height controller3a Spring 100 Operator enable pedal