Patent Application
20050023071
The present invention relates to a system for controlling a motor vehicle, and particularly for operating the vehicle accelerator and brakes. This invention can be readily applied to vehicle control systems for physically impaired drivers.
A conventional motor vehicle, such as an automobile, is designed for a driver having full and substantially unrestricted use of all of their limbs. The standard vehicle controls include a rotary operating steering wheel, a depressible brake pedal, and a depressible accelerator pedal. Of course, it is known that the steering wheel is operated manually, while the brake and accelerator pedals are operated by the driver's feet. Current production vehicles assume that the driver has full use of his/her hands and feet in order to operate these vehicle controls.
Unfortunately, a significant percentage of the driving population does not have full use of all of their limbs. For instance, drivers with certain physical disabilities may be unable to use their legs to operate the brake and accelerator pedals. Although no production vehicles have been developed to account for physically-impaired drivers, a significant amount of effort has been expended in developing systems that can be integrated into an existing vehicle control system to accommodate this driving population. One such system is depicted and described in U.S. Pat. No. 4,722,416, which issued on Feb. 2, 1998 to one of the inventors of the present invention. A system embodying the teachings of the '416 patent has been sold by Ahnafield Corporation as its “Joystick Driving Control®” system. The basic components of this system are shown in
While the Joystick Driving Control® vehicle control system has been very successful in improving the freedom and mobility of the physically-impaired driver, there is always room for improvement. One problem faced by this and other vehicle control systems is that they require significant modification of the existing vehicle and are very difficult and time-consuming to install. Another difficulty faced by some driving control systems is the “fail-safe” mode of operation of the system. For instance, in some prior vehicle control systems, a failure of certain components of the system can compromise the ability of the driver to achieve a safe, controlled stop of the vehicle. The Joystick Driving Controls®system of the Ahnafield Corporation has implemented a fail-safe condition in which all actuators return to a neutral position so that there can be no inadvertent application of the accelerator. In addition, this system provides redundancy for the brake actuators so that the failure of one actuator does not leave the brake pedals inoperable. While the Joystick Driving Control® system has an impeccable safety record, there again is always room for improvement to insure the continued safety of the physically-impaired driver. Thus, there remains a need for improvements to vehicle control systems, particularly those intended for use by the physically-impaired driver.
To address this continuing need, the present invention provides a system for use by a physically impaired driver for controlling the brake pedal and accelerator pedal of a vehicle. In one embodiment, the system includes a manually manipulated hand controller, movable in a first direction to control the brake pedal and in a second direction to control the accelerator pedal. An actuator assembly includes a first actuator operably coupled to the brake pedal to depress the brake pedal when activated, and a second actuator operably coupled to the accelerator pedal to depress the accelerator pedal when activated. An electrical control system connects the hand controller to the actuator assembly and is operable to activate the first actuator when the hand controller is moved in the first direction and to activate the second actuator when the hand controller is moved in the second direction. In one feature of this embodiment, a housing is provided for supporting the actuator assembly, in which the housing is pivotably mounted to the vehicle above the brake pedal so that the actuator assembly pivots relative to the vehicle when the first actuator is activated to depress the brake pedal. The accelerator actuator is provided with a U-joint linkage to accommodate this pivoting movement of the actuator assembly.
The housing can include a mounting clamp configured to engage the steering column of the vehicle. This clamp can be affixed with only minimal modification to the vehicle dashboard. The housing also includes a hinge connecting the housing to the mounting clamp to accommodate the pivoting movement of the housing and actuator assembly when the first actuator operates on the vehicle brake pedal. In one feature of the invention, a support arm is provided for connecting the hand controller to the housing. The support arm holds the hand controller in a position that does not interfere with the wheelchair of a driver while orienting the hand controller for easy access by the driver. In one embodiment, a support arm extends from the mounting clamp for supporting the hand controller. Preferably, the housing includes exterior padding for the comfort of the driver.
In another feature of the invention, the actuator assembly includes a brake actuator system operably coupled to the brake pedal to depress the brake pedal when activated. The brake actuator system includes a primary electric motor and a secondary electric motor, operable independent of the primary electric motor. The secondary motor is preferably operable in the event of an emergency or the occurrence of a failure of the primary motor. A linkage assembly is provided for commonly coupling the primary and secondary electric motors to the brake pedal. In a preferred embodiment, each of the primary and secondary motors includes a rack and pinion arrangement for translating motor rotary motion to linear motion. A link extends from each rack to a common bracket engaged to the vehicle brake pedal or pedal arm.
In accordance with a further aspect of the invention, at least the primary brake motor is a reversible motor. The actuator assembly includes motor control circuitry that is operable in response to signals from the hand controller to activate the primary brake motor in a forward direction to depress the vehicle brake pedal. The motor control circuitry is also operable to direct the primary brake motor to operate in a reverse direction to release the brake pedal. The secondary brake motor can be similar controlled. In some embodiments, the secondary brake motor is operable in emergency braking conditions. In these embodiments, the secondary motor is capable of more rapid actuation of the brake pedal than the primary brake motor. In contrast, the primary brake motor is configured for more accurate actuation to permit partial activation of the brake, as may occur during normal driving conditions.
The actuator assembly also includes an accelerator actuator system that is operably coupled to the accelerator pedal to depress the accelerator pedal when activated. The electrical control system is also operable to activate the accelerator actuator when the hand controller is moved in the second direction. The accelerator actuator includes an electric motor that is connected to a rack gear through a free-wheeling clutch. When the clutch is energized, the accelerator motor extends the rack gear and associated linkage to depress the accelerator pedal. When the accelerator is to be deactivated, the clutch is deactivated—i.e., is permitted to freewheel—so that the return spring of the accelerator pedal itself pushes the accelerator linkage back to its neutral position.
In an embodiment of the invention, the actuator assembly includes a support plate that commonly supports the accelerator motor as well as the primary and secondary braking motors. The support plate is pivotably mounted to the vehicle above the brake pedal so that the support plate pivots relative to the vehicle when the brake actuator system is activated to depress the brake pedal.
In another aspect of the invention, the manually manipulated hand controller includes a joystick assembly mounted to the slide member wherein the joystick assembly includes a platform, a gripping post at a forward end of the platform and a pair of offset support posts at a rearward end of the platform. The gripping post is arranged to be grasped by the driver to move the joystick in the fore and aft direction when the driver's e forearm is resting on the platform. The pair of offset support posts flank the opposite sides of the forearm and provide a reaction surface for tilting the platform to activate the turn signal switches. The support post also held support and retain the driver's arm during operation of the joystick assembly to reduce the risk of inadvertent disengagement of the driver's hand from the joystick assembly.
The gripping platform is mounted to permit side-to-side tilting concurrently with fore and aft movement of the joystick assembly and slide member. The gripping platform includes means for preventing tilting of the platform in the fore-aft direction. In one embodiment, this means is in the form of fore and aft walls that engage a slide block on which the joystick is mounted. The walls are configured to permit side-to-side tilting.
A further feature of the inventive system contemplates that the slide member defines at least one wiring channel for receiving a plurality of electrical wires therethrough. The wires can be associated with the turn signal switches activated by tilting the joystick assembly. The wiring channels direct the wires from the switches through the slide member so that the plurality of wires can pass through the slide channel in the body of the hand controller without interfering with the sliding movement of the slide member within the slide channel.
In another embodiment of the invention, the manually manipulated hand controller includes a body defining a channel and an upward facing slot in communication with the channel. The slide member is disposed within the channel for sliding movement in a fore-aft direction. Means responsive to the position of the slide member within the channel can be provided for generating control signals indicative of the desired vehicle command—i.e., acceleration or braking. The joystick assembly mounted to the slide member through the channel and is manually manipulable to slide the slide member in the fore-aft direction within the channel. Preferably, a slide block connects the joystick assembly to the slide member, with the slide block traversing the upward facing slot.
In a feature of this embodiment, the slide block has a length that is less than the length of the slide member in the fore-aft direction. A top plate is disposed over the upward facing slot, with the top plate defining a housing slot in communication with the upward facing slot and a recess surrounding the housing slot. A larger slot cover is disposed within the recess and has a length that is less than a length of the recess. The larger slot cover also defines a first slot in communication with the housing slot, wherein the first slot has a length greater than the length of the slide block but less than the length of the housing slot. The assembly is completed by a smaller slot cover also disposed within the recess between the larger slot cover and the slide block. The smaller slot cover has a length less than the length of the larger slot cover but greater than the length of the first slot. The smaller slot cover further defines a second slot having a length slightly greater than the length of the slide block and greater than the length of the first slot, but less than the length of the larger slot cover. This combination of recess and slot covers provides a closure for the housing slot so that the slide member can slide within the body with minimal risk of introduction of dust and other contaminants into the slide channel that might foul the movement of the slide member or disturb the associated electrical components.
It is one object of the invention to provide a system that can be easily managed by a person having a physical disability that might otherwise prevent that person from operating a motor vehicle. One important object is to provide such a system that can provide that driver with the greatest ability to control the vehicle braking and acceleration.
A further object of the invention resides in features that make the system easy to retrofit to an existing vehicle, specifically with as little disruption to the driver-side area of the vehicle. Yet another object is accomplished by features that ensure stable and reliable actuation of the brake pedal, especially in an emergency braking condition.
These and other objects, as well as many benefits of the present invention, will become apparent upon consideration of the following written description, taken together with the accompanying figures.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.
The present invention contemplates a vehicles control system for integration into an existing vehicle. In particular, the vehicle control system 20 of the present invention interfaces with the vehicle brake pedal B and accelerator pedal A, as shown in
In the illustrated embodiment, the control system 20 is configured for controlling only the brake and accelerator pedals—i.e., the system does not provide an interface to control the steering of the vehicle. However, it is understood that the principles of the present invention can be integrated into a system that permits vehicle steering control other than through the steering wheel S itself. For instance, as disclosed in the aforementioned '416 patent, steering control can be implemented by providing 2-axis movement of the joystick controller. However, for the purposes of the present invention, the control system 20 is disclosed as operating only the brake and accelerator pedals.
As shown in
Details of the joystick 22 and control box 24 can be discerned from
The grip platform 40 is mounted to a rocker 44 that only permits side-to-side rocking movement. This rocking movement allows the driver to depress turn signal switches 48 mounted to opposite sides of a slide block 46. Thus, by rocking or wobbling the platform 40 to the left or to the right the driver can operate the vehicle turn signals.
The slide block 46 is mounted for linear sliding movement relative to the control box 24. Thus, the physically-impaired driver can move the grip platform 40 forward or backward to operate either the accelerator or the brake, respectively.
The control box 24 includes a cover that houses the internal components of the control box. For instance, controller circuitry 52 can be mounted within the cover 50, where the circuitry translates movement of the joystick controller 22 to specific control signals fed to the actuator mechanism 30 as described herein. The control box 24 further includes a controller housing 54 to which the cover 50 is mounted. Preferably, the controller housing 54 is in the form of a substantially rectangular block as can be discerned from
In one feature of the invention, the controller housing 54 supports a controller slide member 58 that is disposed within a slide channel 60. Preferably, the controller slide member 58 is generally cylindrical in configuration and has a diameter that is slightly less than a cylindrical diameter of the slide channel 60 (see
In accordance with a further aspect of the invention, the controller slide member 58 is provided with a tactile feedback and centering feature. In the preferred embodiment, this feature is provided by opposing springs that center the controller slide member 58 within the slide channel 60 when no pressure is applied to the grip platform 40. In addition, the opposing springs provide tactile feedback or resistance as the controller grip platform 40, and therefore the controller slide member 58, is moved further in the forward or backward directions.
Thus, in accordance with the illustrated embodiment, the controller housing 54 is provided with a pair of opposite spring channels 68, 69 that flank opposite sides of the slide channel 60, as best seen in
As can be appreciated from
Preferably, the two springs are configured so that they maintain some pressure against the engagement pins 79, 80, even when the pins reach their corresponding travel stops 76, 77. In other words, each of the springs 73, 74 preferably have a free length that is greater than the distance between the end of the corresponding spring stops 70, 72 and the corresponding travel stops 76, 77. In one aspect of the invention, the spring constants of the two springs 73, 74 can be adjusted to provide a different tactile feedback depending on the direction of movement of the grip platform 40. For instance, the spring 73 can be stiffer than the spring 74 so that forward movement (as designated by the arrow F in
In an alternative embodiment, the spring stops 70, 71 can be threaded, and the corresponding ends of the spring channels 68, 69 also threaded to permit threaded adjustment of the spring stops. In this manner, the spring stops 70, 71 can be threaded deeper into the corresponding spring channels 68, 69, to increase the resistive force generated by the corresponding springs 73, 74. The provision of threaded spring stops 70, 71 allows for more precise adjustment of the spring force resistance to forward or backward movement of the controller slide member 58, so that the joystick controller and control box 24 can be tailored to a particular driver's preference.
As shown in
As also indicated above, the slide block 46 supports the rocker 44. As can be seen in
The rocker 44 also defines a body 83 that is integral with the side walls 82. The body defines a bolt recess 92 that allows the rocker 44 to be bolted to the slide block 46. In a preferred embodiment, the rocker and slide block are also bolted to the controller slide member 58, as shown in
Since the rocker 44 must be permitted to rock from side to side as depicted by the direction arrow R in
The control system 20, and particularly the control box 24 of the present invention, contemplates unique features associated with the slide block 46. In particular, the slide block 46 includes a body 94 from which extends a slide extension 96. The slide extension is configured to fit through the housing slot 62 (
As shown in
As depicted in
The top cover 110 is configured to sit generally coextensively with the top plate 56. The top cover 110 defines a slot 112 that has a length and width substantially equal to the length and width of the slot 62. It is of course understood that the slide block 46 also extends through the slot 112 and reciprocates within that slot as well as within the slot 62. Sandwiched between the top cover 110 and the top plate 56 are a pair of slot covers 114 and 118. The smaller slot cover 114 defines a slot 115 that has a length and width slightly larger than the length of the slide block 46. The larger slot cover 118 also defines a slot 119 that is larger in dimension than the slot 115 in the smaller slot cover 114, but is smaller than the slots 62 and 112.
The two slot covers 114 and 118 cooperate with each other to, in effect, provide a seal between the inside of the control box 24 and the environment outside the box. Thus, the two slot covers 114, 118 are free to slide back and forth within the housing recess 64 and are free to slide relative to each other. The largest slot cover 118 substantially covers the housing slot 62 in the controller housing 54. The smaller slot cover 114 covers a substantial portion of the slot 119 in the larger slot cover 118. Thus, the two slot covers 114, 118 provided overlapping coverage to minimize the chance of dust and dirt passing through the slot 62 and infecting the inner workings of the control box 24.
The tapered ends 65 of the housing recess 64 act as a sort of particle ejector. In other words, when dirt and dust does manage to pass through the top cover 110 and into the recess 64, movement of the larger slot cover 118 along the tapered ends 65 of the recess 64 has a tendency to push or eject dirt and dust particles from the recess. In this way, the combination of the slot covers 114, 118 with the tapered 65 help achieve a self-cleaning action for the control box 24.
Referring back to
In one embodiment, the rack 125 includes teeth 126 that mesh with a sensor gear 128 of a movement sensor 127 that is supported by the controller circuitry 52, as shown in
With either embodiment, i.e., the rack gear 125 or 200, the direction and angular magnitude of rotation of the sensor gear 128 is translated by appropriate circuitry within the controller circuitry 52 into control signals. The control signals pass through control signal wires 130 to the actuator mechanism 30 to control the actuators as described wherein. It is understood that other forms of position and/or movement detectors or transducers may be used to translate the longitudinal movement of the grip platform 41 to signals indicative of a braking or an acceleration command from the vehicle operator.
More particularly, the controller circuitry 52 can include electronics and/or software that translate the clockwise or counter-clockwise rotation of the sensor gear 128 into an acceleration or a braking signal. In a specific embodiment, clockwise rotation of the sensor gear 128 corresponding to forward movement of the controller slide member 58 corresponds to an operator acceleration command. Conversely, counter-clockwise rotation of the sensor gear 128 can correspond to a braking command. Movement of the controller slide member 58 to either its forward or backward limits will cause the sensor gear 128 to move to it fullest clock wise or counter-clockwise angular extent. The circuitry and/or software within the control circuitry 52 can translate that movement into an appropriate command to fully depress the accelerator pedal A or the brake pedal B. With respect to the full stroke backward movements of the controller slide member 58 (and of course the joystick controller 22), can be calibrated to define an emergency braking condition.
Thus, the controller circuitry 52 generates the control signals along the signal wires 130 that are fed to the actuator mechanism 30. In a preferred embodiment, the control wires 130 can pass through the hollow interior of the support arm 26. The control wires provide the acceleration/braking control signals to motor control circuitry 135 disposed within the actuator mechanism 30. As depicted in
Turning to
In addition, as shown in
The drive link 144, 154 interface with the brake pedal B through the brake pedal arm BR as shown in
In addition, the present invention contemplates a unique manner for supporting the actuator mechanism 30 to insure that the driving force generated by the primary and secondary brake assemblies is always perpendicular to the brake pedal arm BR, even as the arm BR is itself pivoted as the brake pedal B is depressed. This beneficial feature is accomplished through the mount 28 that is utilized to mount both the support arm 26 and the actuator mechanism 30. More specifically, the mount 28 is adapted to engage the vehicle steering column underneath the dashboard D as shown in
The steering column mount 28 is preferably formed as a pair of clamp halves 185, 186. The two halves are configured to define a steering column opening 187 when the halves are bolted together. With this steering column mount 28 configured as shown in
In prior remote braking systems, the brake actuator includes a roller that contacts the brake pedal so the roller translates along the width of the pedal as it is depressed. With this prior approach, the line of action of the actuator force changes, thereby decreasing the mechanical advantage for the actuator. Moreover, the roller is susceptible to slipping off the brake pedal if the roller travels too much. The present invention eliminates these problems by providing the steering column mount 28 with a hinge 190 that is fixed to the underside of the mount, and preferably to the underside of the clamp half 185. The hinge plate 190 can include a number of screw holes 191 that allow the hinge plate to be fastened to the actuator housing 192 (
In an alternative embodiment, the hinge plate 190 of
Returning to
As with the primary and secondary brake assemblies, the accelerator assembly includes a rack gear 164 that is a meshed engagement with the drive spindle 163. The rack gear 164 terminates in a U-joint 166 that mounts to the drive link 168. Thus, the U-joint 166 permits multiple degrees of freedom of movement to account for actuation of the accelerator assembly. In addition, this U-joint allows the accelerator pedal actuator to accommodate the pivoting of the actuator housing 192 that occurs when the brake pedal is depressed, as described above. With this configuration, the independence between the brake actuators and the accelerator actuator can be maintained while the overall size of the actuator system 138 can be kept to a minimum.
Preferably, the link 168 includes a link adjustment feature 169 that permits fine adjustment of the length of the accelerator drive link 168 upon installation, namely by adjusting the relative position of the link halves 168a, 168b. The drive end of the link 168 forms a clevis 170 that can engage the accelerator pedal A linkage by way of a link bracket at 178 and bolt 179, as shown in
In the preferred embodiment, the free-wheeling clutch 162 essentially disconnects the drive link 168 from the motor 161 when power is shut off to the motor and clutch. In other words, when the joystick controller 22 (and ultimately the controller slide member 58) are not moved forward, but are instead at the neutral position as depicted in
On the other hand, the primary and secondary brake assemblies do not permit a free-wheeling movement. In other words, the brake motors 141, 151 do not incorporate a clutch between the motor and the drive spindle 142. When power is terminated to either of the motors, the motors are held in whatever position they hold at the time power is terminated, which means that the rack gear 143, 153 are also held in their particular position. Ultimately, if the drive motors are fixed in position, then the drive links 144. 154 are fixed in position, which means that if the brake pedal B was depressed when the power to the brake assembly motors is terminated, then the brake will be maintained depressed. This is an important failsafe feature that permits release of the brake should electrical power to the actuator system 138 be interrupted for any reason.
The brakes are released, and more particularly, the primary and secondary brake motors 141, 151 are reversed, when the joystick controller 22 is moved to its neutral position, or forward of the neutral position. When the joystick is returned to its neutral position after a braking maneuver has been completed, this return movement is sensed by the control circuitry 52 which sends a signal to the motor control circuitry 135 to reverse the direction of the brake motors 141, 151. The motors are then reversed and the drive racks 143, 153 are retracted to release the brake pedal B. In one embodiment of the invention, proximity sensors or limit switches can be used to sense when the drive racks are at the limits of their stroke. In other words, when the brake motors 141, 151 are driven in reverse, a limit switch can be tripped by movement of the drive racks 143, 153 to prompt the motor control circuitry 135 to issue a motor stop command. Likewise, limit switches positioned at the limit of forward movement of the drive racks, corresponding to completely depressing the brake pedal B, can send a signal to the motor control circuitry to issue a motor stop command.
In addition to or in lieu of limit switches, the barking and steering rack gears can be monitored by position encoders. In one embodiment, a position encoder 159 can mesh with the rack gear 143 for the primary brake assembly 140. Likewise, a position encoder 172 can mesh with the rack gear 164 for the accelerator assembly 160. The position encoders can provide signals to the microprocessor 135 indicative of the stroke of the corresponding rack gear. When the rack gear reaches the limit of its extension or retraction travel, the microprocessor can issue an appropriate stop or return command to the corresponding motor 151 or 161.
In a more preferred embodiment of the invention, a limit switch can be used to sense a return of the brake motors to the neutral (non-braking) position, but an open-loop control system is used to determine when to stop the brake motors during a braking maneuver. In prior systems, a closed loop control system provides a positive limit to movement of the braking controls. These closed loop systems cannot account for mechanical variations in the operation of the vehicle brakes. For instance, over time, the brake pads wear, which means that the brake pedal B must be depressed farther. A closed loop system cannot account for this variation. On the other hand, the open loop control of the present invention accounts for this variation by, in essence, sensing the increase in resistance that occurs when the brake pedal is at or near its fully depressed position.
Thus, in one embodiment of the invention, the motor control circuitry 135 uses feedback on the current delivered to the motors 141, 151 to determine when to stop the motors at the end of a braking stroke. When the brake assembly 140 is actuated to depress the brake pedal B near its mechanical limit, the braking system exerts greater resistance to continued movement of the pedal, and consequently of the drive links 144, 154 of the brake assembly. As the motor torque increases to meet this increased load, the motor current increases. The motor control circuitry can sense this increase in current, either as a function of time or magnitude, to determine that the brake pedal is fully depressed. The motor control circuitry 135 then issues a motor stop command because the brake pedal has reached the mechanical limit of its stroke.
In another aspect of the motor control circuitry 135, the motor current is constantly monitored to determine if a problem exists in the braking or acceleration motors. If the current delivered to any motor is too low, an open circuit may exist. If the current delivered to the motor is too high, a short may exist in the motor. In either case, the function of the actuator mechanism 30 is compromised. The motor control circuitry 135, or microprocessor, can transmit a warning signal or illuminate an enunciator light to call attention to the condition.
In one feature of the invention, the drive components of the actuator system 138 are mounted on a common support plate 196 that forms part of the actuator housing 192. Thus, the primary and secondary brake motors 141, 151 and the accelerator motor 161 are mounted on this support plate. Moreover, the rack gears 143, 153 and 164 are slidably supported on the plate 196. This common support characteristic reduces the size of the envelop occupied by the actuator system 138 and minimizes the incursion into the driver's space behind the steering wheel S.
In specific embodiments of the invention, the motors in the actuator system 138 are precision DC motors. The accelerator motor 161 can be a 90 watt, 15V motor, with a no load speed of 7070 rpm and a maximum continuous torque of 77.7 mNm. Preferably, the accelerator motor is geared down at a ratio of 74:1 to rotate the drive spindle 163. In the specific embodiments, the primary brake motor 141 can be a 150 watt, 12V motor with a no load speed of 6920 rpm and a maximum continuous torque of 98.7 mNm. The primary brake motor can be geared down at a ratio of 156:1 to rotate the spindle 142. The secondary brake motor 151 can be similar to the primary motor.
In an alternative embodiment, the secondary brake motor can be a 150 watt, 48V motor with a no load speed of 7850 rpm and a maximum torque of 201 mNm. This alternative motor is geared down at a ratio of 43:1. In this embodiment, the secondary brake motor 151 operates as an emergency braking motor that is activated when the joystick is “pegged”. In other words, in an emergency braking condition, the joystick is pulled back as far and as quickly as possible. The control circuitry 52 can be configured to sense this rapid movement and issue an appropriate signal to the motor control circuitry.
However, in a preferred embodiment, a limit switch is positioned relative to the rack gear 125 so that when the rack gear is moved to its farthest extent by the joystick, the limit switch is actuated. When this limit switch is actuated, a signal is sent to the motor control circuitry to activate the secondary brake motor 151, which then quickly depresses the brake pedal for an emergency braking maneuver. In this alternative embodiment, the secondary brake motor is not normally activated, with the primary brake motor 141 absorbing the braking function of the system.
In one embodiment of the invention shown in
As shown in
The switch 220 includes an electrical connector 222 that can mate with a wiring harness forming part of the control signal wires 130 (
At the other end of the spectrum, a second limit switch 230 can be constructed like the switch 220 just described. This second switch includes a follower element 238 that contacts the rack gear 200 when the gear is at the farthest right extent of its stroke. This position of the rack gear 200 corresponds to an emergency braking command when the vehicle operator has pushed the grip platform 40 of the joystick fully forward. Referring again to
In the preferred embodiment of the invention, the electrical system of the control system 10 is connected to the vehicle electrical system. Preferably, this electrical connection is accomplished from the motor control circuitry 135, in the actuator mechanism 30 mounted to the steering column, to the vehicle fuse box. The electrical components within the control box 24 for the joystick 22 can be supplied with power from the motor control circuitry, rather than independently from the vehicle electrical system. In one embodiment, the actuator mechanism 30 can include a back-up power supply, such as a battery, mounted within the actuator housing 192. This battery back-up can thus supply electricity to the control circuitry to permit activation of the brake assemblies 140, 150 even after a loss of vehicle power.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.
