METHOD AND APPARATUS FOR PARKING BRAKES FOR A SELF-DRIVEN VEHICLE

Abstract

A parking brake apparatus is provided for a self-driving vehicle, which includes components of a parking brake system for applying a parking brake. The parking brake apparatus comprises a first controller arranged to provide one or more control signals to be applied to the parking brake system components to apply the parking brake in response to a signal requesting that the parking brake be applied. The parking brake apparatus also comprises a second controller arranged to provide one or more control signals to be applied to other components of the parking brake system to apply the parking brake in response to the unavailability of the first controller to apply the parking brake.

Description

METHOD AND APPARATUS FOR PARKING BRAKES FOR AN AUTONOMOUSLY DRIVABLE VEHICLE BACKGROUND OF THE TECHNIQUE [1] The present application relates to vehicle parking systems, and in particular is directed to a parking brake method and apparatus for an autonomously driven vehicle, such as for a parking system for an autonomously driven commercial truck. [2] Vehicle parking systems for commercial trucks are well known. One type of vehicle parking system for trucks is an electronic parking system in which the parking brake is automatically applied using a primary parking mechanism when certain criteria associated with the truck or the truck driver are met. In some electronic parking systems, a secondary parking mechanism is provided as a backup to apply the parking brake in case the primary parking mechanism fails to do so.These known secondary parking mechanisms require the truck driver to perform some manual action to activate the secondary parking mechanism after the truck driver is alerted that the primary parking mechanism has failed to apply the parking brake. [3] Known secondary parking mechanisms can be used on any type of truck, including self-driving trucks. However, in the case of a self-driving truck, some manual action by an occupant would still be necessary to activate the secondary parking mechanism if the primary parking mechanism were unable to apply the parking brake. Consequently, those skilled in the art continue research and development efforts in the field of vehicle parking systems, such as those for commercial trucks, which include a primary parking mechanism and may or may not include a secondary parking mechanism as a backup to the primary parking mechanism. BRIEF DESCRIPTION OF THE INVENTION [4] According to one embodiment, a parking brake apparatus is provided for a self-driving vehicle, having parking brake system components for applying a parking brake. The parking brake apparatus comprises a first controller arranged to provide one or more control signals to be applied to the parking brake system components to apply the parking brake in response to a signal requesting that the parking brake be applied. The parking brake apparatus also comprises a second controller arranged to provide one or more control signals to be applied to other parking brake system components to apply the parking brake in response to the unavailability of the first controller to apply the parking brake. [5] According to another embodiment, a parking brake apparatus is provided for a self-driving vehicle, having components of a parking brake system for applying a parking brake. The parking apparatus comprises a primary parking brake controller arranged to control one or more parking brake valves to enable one or more parking brake springs to apply the parking brake in response to a signal requesting the application of the parking brake.The parking brake apparatus also comprises means for, when the vehicle is driven autonomously and without requiring any manual action by an occupant of the autonomously driven vehicle, controlling one or more parking brake valves to allow one or more parking brake springs to apply the parking brake when the primary parking brake controller is unable to cause the parking brake to be applied. [6] Pursuant to another embodiment, a computer-implemented method is provided for an autonomously driven vehicle having a parking brake, a primary parking brake controller, and a secondary parking brake controller that is different from the primary parking brake controller. The computer-implemented method comprises detecting the unavailability of the primary parking brake controller to cause the parking brake to be applied. The method also comprises electronically, through the secondary parking brake controller, causing the parking brake to be applied in response to the unavailability of the primary parking brake controller. BRIEF DESCRIPTION OF THE DRAWINGS [7] FIGURE 1A is a schematic block diagram showing an example parking brake apparatus for an autonomously driven vehicle, and constructed in accordance with a modality. [8] FIGURE IB is a schematic block diagram similar to FIGURE 1A, and showing parts in different positions. [9] FIGURE 2 is a flowchart depicting an example computer-implemented method for operating a parking brake apparatus in accordance with a modality.

[10] FIGURE 3A is a schematic block diagram showing an example parking brake apparatus for an autonomously driven vehicle, and constructed in accordance with another modality.

[11] FIGURE 3B is a schematic block diagram similar to FIGURE 3A, and showing parts in different positions. DETAILED DESCRIPTION

[12] This application relates to a parking brake apparatus for an autonomously driven vehicle such as a commercial truck. The specific construction of the parking brake apparatus may vary. It should be understood that the following disclosure provides a number of modalities or examples for implementing different features of various modalities. Specific examples of components and arrangements are described to simplify this disclosure. These are merely examples and are not intended to be exhaustive.

[13] With reference to FIGURE 1A, a schematic block diagram is illustrated showing an example parking brake apparatus 100 for an autonomously driven vehicle, and constructed in accordance with a modality. In FIGURE 1A, electrical line connections are shown as solid lines, pneumatic line connections are shown as dashed lines, and mechanical couplings are shown as double solid lines.

[14] The parking brake apparatus 100 includes a controller area network (CAN) bus 110 to which various vehicle devices connect to communicate with each other. The CAN bus 110 may be in a standardized serial communication format, such as SAE J1939, or in a proprietary format. It is conceivable that some or all of the vehicle devices may be hardwired for communication instead of using the CAN bus 110 for communication.

[15] Vehicle devices that can be connected to the CAN bus 110 include, but are not limited to, a first controller such as a primary parking brake controller 120, a second controller such as a redundant parking brake controller 160, and a third controller such as an automated driver controller 180. The primary parking brake controller 120 can provide the CAN bus 110 with a variety of signals, including configuration messages, diagnostic status, and brake-specific signals such as parking brake status and parking brake pressure. Similarly, the redundant parking brake controller 160 can provide the CAN bus 110 with a variety of signals, including configuration messages, diagnostic status, and brake-specific signals such as parking brake status and parking brake pressure.The automated driver controller 180 can provide the CAN bus 110 with a variety of signals, including configuration messages, diagnostic status, driving mode (i.e., autonomous, semi-autonomous, or driver-controlled), and the intended vehicle state (e.g., stop, move, park). The CAN bus 110 allows the primary parking brake controller 120, the redundant parking brake controller 160, and the automated driver controller 180 to communicate with each other.

[16] A primary compressed air supply 130 provides a source of compressed air in line 131 through a first normally open 3 / 2 solenoid valve 134 and then in line 135 to a first supply port 136 of a parking brake valve 138. As an example, the parking brake valve 138 may comprise such a valve available as part of the Bendix Intellipark® system, commercially available from Bendix Commercial Vehicle Systems LLC located in Elyria, Ohio. The first normally open 3 / 2 solenoid valve 134 is disposed between the primary compressed air supply 130 and the parking brake valve 138.Similarly, a secondary compressed air supply 140 provides a source of compressed air in line 141 through a second normally open 3 / 2 solenoid valve 144 and then in line 145 to a second supply port 146 of the parking brake valve 138. The second normally open 3 / 2 solenoid valve 144 is located between the secondary compressed air supply 140 and the parking brake valve 138. Each of the first and second normally open 3 / 2 solenoid valves 134 and 144 may comprise a Bendix AT-3™ solenoid valve, commercially available from Bendix Commercial Vehicle Systems LLC.

[17] Although the preceding description describes the use of a normally open 3 / 2 solenoid valve, it is conceivable that another type of valve could be used. For example, an anti-lock braking system (ABS) valve, such as a Bendix M-40™ modulator valve, commercially available from Bendix Commercial Vehicle Systems LLC, could be used. For the purpose of explanation, the use of normally open 3 / 2 solenoid valves will be described here.

[18] The primary parking brake controller 120 is in the form of an electronic controller unit arranged to monitor signals on the CAN bus 110 to provide one or more control signals to apply the parking brake based on control logic 122 stored in a data storage unit of the primary parking brake controller 120. The primary parking brake controller 120 provides one or more signals on lines 124, 125 to the first and second control ports 126, 127 of the parking brake valve 138 to control the delivery of compressed air (originating from the first and second compressed air supplies 130, 140) to the first and second delivery ports 128, 129 of the parking brake valve 138.

[19] The parking brake valve 138 is controlled by the parking brake controller 120's control logic 122 to vary the pneumatic pressure in line 142 to one or more chambers of the spring brake chambers 143 and also to vary the pneumatic pressure in line 152 to the trailer supply hose couplings 154. More specifically, when the vehicle's parking brake is applied, the primary parking brake controller 120 provides one or more signals on lines 124 and 125 to the parking brake valve 138 to expel air from one or more chambers of the spring brake chambers 143. The spring brake chambers 143 are operatively coupled via line 147 in a known manner to the parking brake springs 149. When air is expelled from the spring brake chambers 143 and the system air pressure drops to less than approximately 45 psi to 60 psi (310.From 26 kPa to 413.68 kPa), the parking brake springs 149 are activated to apply the vehicle parking brake, as is known. The structure and operation of the primary parking brake controller 120 and the parking brake valve 138 for controlling the operation of the spring brake chambers 143 and the parking brake springs 149 for applying the parking brake are conventional and, therefore, will not be described further.

[20] Simultaneously, the pneumatic pressure in line 142 to the one or more spring brake chambers 143 is varied to apply the parking brake, and the pneumatic pressure in line 152 to the trailer supply hose couplings 154 (which are connectable to a vehicle trailer parking brake) is varied to allow the trailer parking brake to be applied. The structure and operation of the primary parking brake controller 120 and the parking brake valve 138 for controlling the operation of a trailer parking brake by means of the trailer supply hose couplings 154 are conventional and, therefore, will not be described further.

[21] One or more pressure-to-voltage transducers are coupled to one or more corresponding parking brake components. Each pressure-to-voltage transducer provides a voltage indicative of the pressure associated with the corresponding parking brake component. More specifically, a first pressure-to-voltage transducer 171 senses the pressure on pneumatic line 142 and provides a corresponding voltage on electrical line 175 to the primary parking brake controller 120. A second pressure-to-voltage transducer 172 senses the pressure on pneumatic line 142 and provides a corresponding voltage on electrical line 176 to the redundant parking brake controller 160. A third pressure-to-voltage transducer 173 senses the pressure on pneumatic line 152 and provides a corresponding voltage on electrical line 177 to the primary parking brake controller 120.A fourth pressure-to-voltage transducer 174 detects the pressure on the pneumatic line 152 and provides a corresponding voltage on the electrical line 178 to the redundant parking brake controller 160.

[22] The redundant parking brake controller 160 is in the form of an electronic controller unit arranged to monitor signals on the CAN bus 110 to provide one or more control signals to apply the parking brake based on the control logic 162 stored in a data storage unit of the redundant parking brake controller 160. The redundant parking brake controller 160 provides a first control signal on line 164 to the first normally open 3 / 2 solenoid valve 134 and a second control signal on 165 to the second normally open 3 / 2 solenoid valve 142.

[23] The automated driver controller 180 is in the form of an electronic controller unit arranged to monitor signals on the CAN bus 110 indicating that the primary parking brake controller 120 is unavailable to apply the parking brake (or trailer parking brake). The automated driver controller 180 then provides one or more signals on the CAN bus 110 to activate the redundant parking brake controller 160 to apply the parking brake.

[24] Pursuant to one aspect of this disclosure, the redundant parking brake controller 160 and the automated driver controller 180 cooperate to provide a backup parking brake solution in the event of the primary parking brake controller 120 becoming unavailable to apply the parking brake. The automated driver controller 110 monitors the primary parking brake controller 120, detects the unavailability of the primary parking brake controller 120 to apply the parking brake, and activates the redundant parking brake controller 160 to apply the parking brake when the unavailability is detected.More specifically, the redundant parking brake controller 160 has control logic 162, and the automated driver controller 180 has control logic 182, which cooperates with the control logic 162 of the redundant parking brake controller 160 to provide the backup parking brake solution. Although shown separately, it is conceivable that the redundant parking brake controller 160 and the automated driver controller 180 could be combined into a single controller, and that control logic 162 and control logic 182 could be combined into a single control logic block.

[25] The first normally open 3 / 2 solenoid valve 134 and the second normally open 3 / 2 solenoid valve 144 are shown in FIGURE 1A in their de-energized positions. In their de-energized positions shown in FIGURE 1A, compressed air is supplied through the parking brake valve 138 to the spring brake chambers 143 and the trailer supply hose couplings 154. Both parking brakes (i.e., the truck tractor parking brake and the truck trailer parking brake) are released (i.e., not applied). When the primary parking brake controller 120 signals the parking brake valve 138 to apply the parking brakes, the compressed air in line 142 and the compressed air in line 152 are expelled to the atmosphere, allowing the parking brakes to be applied in the known manner.

[26] However, if the parking brakes are not applied in response to the primary parking brake controller 120 to do so, the redundant parking brake processor 160 and the automated driver controller 180 cooperate to energize the first normally open 3 / 2 solenoid valve 134 and the second normally open 3 / 2 solenoid valve 144 in order to move them to their energized positions shown in FIGURE IB.In their energized positions shown in FIGURE IB, the compressed air from the primary compressed air supply 130 and the compressed air from the secondary compressed air supply 140 are blocked by the first and second normally open 3 / 2 solenoid valves 134, 144 from reaching the parking brake valve 138. This allows the parking brakes to be applied when the primary parking brake controller 120 signals the parking brake valve 138 to do so. When the compressed air is blocked from reaching the spring brake chambers 143 and the trailer supply hose couplings 154, the parking brakes are applied.

[27] More specifically, program instructions of a secondary parking brake control algorithm associated with the redundant parking brake controller 160 control logic 162 and the automated driver controller 180 control logic 182 are executed to provide a backup for the primary parking brake controller 120 control logic 122 in the event that the parking brakes are not applied in response to the execution of program instructions of a primary parking brake control algorithm associated with the primary parking brake controller 120 control logic 122.

[28] The unavailability of the parking brakes to be applied can be due to several reasons. One reason may be that the primary parking brake controller 120 does not execute program instructions from the primary parking brake control algorithm to apply the parking brakes in response to a signal requesting their application. Another reason may be that one or more control signals from the primary parking brake controller 120 do not reach the parking brake components so that the parking brakes can be applied. Yet another reason may be due to the unresponsiveness of a portion of the parking brake valve 138 (for example, an internal relay valve of the parking brake valve 138).Another possible reason could be a loss of communication between certain vehicle components, including the parking brake system. Other reasons for the parking brakes not applying are also possible.

[29] With reference to FIGURE 2, a flowchart 200 represents an example computer-implemented method of operating a parking brake apparatus in accordance with a modality. The computer-implemented method is for an autonomously driven vehicle that has a parking brake, a primary parking brake controller, and a secondary parking brake controller that is different from the primary parking brake controller.

[30] In block 210, the process begins by detecting the unavailability of the primary parking brake controller to apply the parking brake. This detection can be performed by querying the primary parking brake controller's memory or a CAN bus for a signal indicating the parking brake's unavailability. Then, in block 220, the secondary parking brake controller responds by applying the parking brake in response to the primary parking brake controller's unavailability. For example, the secondary parking brake controller responds to the primary parking brake controller sending a signal indicating its unavailability.As another example, the secondary parking brake controller is responsive to the primary parking brake controller by simply not communicating at all when the secondary parking brake controller detects that the vehicle needs to be parked (for example, when the secondary parking brake controller receives a message from an automated driver controller indicating that the vehicle needs to be parked). The process then terminates.

[31] In some embodiments, the secondary parking brake controller causes the parking brake to be applied when the unavailability of the primary parking brake controller to cause the parking brake to be applied is due to the inability of the primary parking brake controller to provide one or more control signals to apply to one or more parking brake valves to allow one or more parking brake springs to apply the parking brake.

[32] In some embodiments, the secondary parking brake controller causes the parking brake to be applied when the unavailability of the primary parking brake controller to cause the parking brake to be applied is due to the inability of one or more control signals from the primary parking brake controller to reach one or more parking brake valves to allow one or more parking brake springs to apply the parking brake.

[33] In some embodiments, the secondary parking brake controller causes the parking brake to be applied when the unavailability of the primary parking brake controller to cause the parking brake to be applied is due to the lack of response from a parking brake valve of the parking brake system.

[34] In some embodiments, the unavailability of the primary parking brake controller to cause the parking brake to be applied is detected by the secondary parking brake controller receiving a signal from the primary parking brake controller indicating that the primary parking brake controller is unavailable.

[35] In some modalities, the unavailability of the primary parking brake controller to cause the parking brake to be applied is detected by the secondary parking brake controller receiving a signal from an autonomous driver controller indicating that the primary parking brake controller is unavailable.

[36] In some forms, the method is performed by a processor that has a memory that executes one or more instruction programs that are tangibly embedded in a processor-readable program storage medium.

[37] The program instructions to enable the secondary parking brake controller (e.g., the redundant parking brake controller 160 together with the automated driver controller 180 shown in FIGURES 1A and 1B) to perform the operating steps in accordance with flowchart 200 shown in FIGURE 2 can be integrated into the controllers' internal memory. Alternatively, or additionally, the program instructions can be stored in memory external to the controllers. For example, the program instructions can be stored in the internal memory of an electronic controller unit other than the vehicle's. Any number of electronic controller units can be used. Furthermore, any type of electronic controller unit can be used.Suitable electronic control units for use in vehicles are known and, therefore, have not been described. Consequently, the program instructions in this disclosure may be stored on program storage media associated with one or more vehicle electronic control units. The program instructions may be stored on any type of program storage media, including, but not limited to, external hard drives, flash drives, and compact discs. The program instructions may be reprogrammed depending on the characteristics of the particular electronic control unit.

[38] A second embodiment of a parking brake apparatus is illustrated in FIGURES 3A and 3B. Because the embodiment illustrated in FIGURES 3A and 3B is generally similar to the embodiment illustrated in FIGURES 1A and 1B, similar numbers are used to designate similar components, the suffix letter 'a' being associated with the embodiment in FIGURES 3A and 3B to avoid confusion.

[39] The parking brake apparatus 100a comprises the primary parking brake controller 120a, the redundant parking brake controller 160a, and the automated driver controller 180a. The primary parking brake controller 120a controls the operation of the parking brake valve 138a and the spring brake chambers 143a in a similar manner to how the primary parking brake controller 120 controls the parking brake valve 138 and the spring brake chambers 143 as described above in the embodiment of FIGURES 1A and 1B.

[40] Similarly, the redundant parking brake controller 160a controls the operation of the first and second normally open 3 / 2 solenoid valves 134a, 144a in a manner similar to how the redundant parking brake controller 160 controls the operation of the first and second normally open 3 / 2 solenoid valves 134, 144 as described above in the mode of FIGURES 1A and 1B. The automated driver controller 180a communicates with the primary parking brake controller 120a and the redundant parking brake controller 160a in the same manner as the automated driver controller 180 communicates with the primary parking brake controller 120 and the redundant parking brake controller 160 as described above in the mode of FIGURES 1A and 1B.

[41] In the embodiment of FIGURES 3A and 3B, a first relay valve 310 is arranged between the first normally open 3 / 2 solenoid valve 134a and the parking brake valve 138a. Similarly, a second relay valve 320 is arranged between the second normally open 3 / 2 solenoid valve 144a and the parking brake valve 138a.

[42] Compressed air is supplied from primary compressed air supply 130a in line 131a to the first normally open 3 / 2 solenoid valve 134a and then in line 312 to the control port 313 of the first relay valve 310. Pneumatic line 315 interconnects the delivery port 314 of the first relay valve 310 and the supply port 136a of the parking brake valve 138a. Compressed air is also supplied from primary compressed air supply 130a in line 316 to the supply port 318 of the first relay valve 310.

[43] Compressed air is supplied from secondary compressed air supply 140a in line 141a to the second normally open 3 / 2 solenoid valve 144a and then in line 322 to the control port 323 of the second relay valve 320. Pneumatic line 325 interconnects the delivery port 324 of the second relay valve 320 and the supply port 146a of the parking brake valve 138a. Compressed air is also supplied from secondary compressed air supply 140a in line 326 to the supply port 328 of the second relay valve 320.

[44] In the event that the primary parking brake controller 120a is not available to cause the parking brake to be applied, the redundant parking brake controller 160a and the automated driver controller 180a cooperate to energize the first and second normally open 3 / 2 solenoid valves 134a, 144a to move them from their de-energized positions shown in FIGURE 3A to their energized positions shown in FIGURE 3B to apply the parking brake in the same manner as described above in the mode of FIGURES 1A and 1B.However, in the configuration shown in FIGURES 3A and 3B, the use of the first and second relay valves 310, 320 together with the first and second normally open 3 / 2 solenoid valves 134a, 144a increases the compressed air flow capacity to the parking brake valve 138a to apply the parking brake while reducing the electrical power required to energize the first and second normally open 3 / 2 solenoid valves 134a, 144a.

[45] It should be evident that the above description describes a backup parking brake system for a primary parking brake system of an autonomously driven vehicle that may or may not have a human driver occupying the autonomously driven vehicle. If a human driver is occupying the autonomously driven vehicle, the human driver is not an integral part of the backup parking brake system (i.e., no manual action by the human driver is required to activate the backup parking brake system in the event of the primary parking brake system's unavailability to apply the parking brake).Consequently, the backup parking brake system causes the parking brake to be applied when the main parking brake system is unable to apply the parking brake, such as when a control signal is unable to reach a parking brake valve or when a parking brake valve does not respond.

[46] It should also be evident that the parking brake control algorithms associated with the parking brake apparatus 100 of FIGURES 1A and 1B and the parking brake apparatus 100a of FIGURES 3A and 3B are integrated into a practical application of implementing a low-cost backup parking brake mechanism for autonomously driven vehicles. The backup parking brake mechanism is low-cost because implementation requires the addition of essentially only a pair of normally open 3 / 2 solenoid valves and a pair of controllers (or only a single controller if the redundant parking brake controller and the automated driver controller are combined).

[47] Several advantages result from providing a self-driving vehicle with the parking brake apparatus 100 described above of FIGURES 1A and 1B (and the parking brake apparatus 100a of FIGURES 3A and 3B) to provide the backup parking brake mechanism.

[48] ​​One advantage is that even if the main parking brake system is unavailable, the service brake pressure can be retained (i.e., it does not need to be released to the atmosphere) so that the service brake can continue to hold the vehicle if necessary. This eliminates the need to release compressed air or to shut down the vehicle's engine.

[49] Another advantage is that because the first and second normally open 3 / 2 solenoid valves 134, 144 are controlled by one controller (i.e., the redundant parking brake controller 160), there is no need to coordinate solenoid valve diagnostics between two controllers. This simplifies the design of the parking brake system and facilitates troubleshooting when maintenance of the parking brake mechanisms is required.

[50] Yet another advantage is that, because two pressure-to-voltage transducers 171, 172 are coupled to the pneumatic line 142 to the spring brake chambers 143, an independent indication of the air pressure in the spring brake chambers 143 is provided. Similarly, because two pressure-to-voltage transducers 173, 174 are coupled to the pneumatic line 154 to the trailer supply hose couplings 154, an independent indication of the air pressure at the trailer supply hose couplings 154 is provided. This is advantageous because additional information can be used to meet further functional safety requirements of the system.

[51] Furthermore, although the above description describes the use of pressure-to-voltage transducers 171, 172, 173, and 174, it is conceivable that other types of transducers, such as wheel-speed-to-voltage transducers (i.e., wheel-speed detectors), could be used. As an example, with the use of wheel-speed detectors (either alone or in conjunction with pressure-to-voltage transducers), it is possible to monitor the following sequence of events: (1) the vehicle is stationary with the parking brake released, (2) the vehicle is stationary with the main parking brake system indicating that the parking brake is engaged, and (3) the vehicle is moving with the main parking brake system indicating that the parking brake is engaged.Observing this sequence of events indicates a roll away from the parking space rather than a roll due to the unavailability or inability of the parking brake to be applied when needed. If this occurs, the automated driver 180 controller could use the service brake to stop the vehicle or use the backup parking brake system to attempt to park the vehicle while continuing to monitor the wheel speed sensors to determine if the vehicle remains stationary.

[52] Aspects of the disclosed modalities can be implemented in software, hardware, firmware, or a combination thereof. The various elements of the system, either individually or in combination, can be implemented as a computer program product tangibly materialized on a machine-readable storage device for execution by a processor. Several stages of the modalities can be performed by a computer processor executing a program tangibly materialized on a computer-readable medium to perform functions by operating on input and generating output. The computer-readable medium can be, for example, memory, a portable medium such as a compact disc or a flash drive, such that a computer program incorporating aspects of the disclosed modalities can be loaded onto a computer.

[53] Although the present invention has been illustrated by the description of system components and example processes, and although the various processes and components have been described in detail, the applicant does not intend to restrict or limit the scope of the appended claims in any way to such detail. Further modifications will also readily appear to those skilled in the art. Accordingly, the invention in its broader aspects is not limited to the specific details, implementations, or illustrative examples shown and described. Consequently, deviations from such details may be made without departing from the spirit or scope of the applicant's overall inventive concept.

Claims

1. A parking brake apparatus for a self-driving vehicle having parking brake system components for applying a parking brake, the parking brake apparatus comprising: a first controller arranged to provide one or more control signals to be applied to the parking brake system components to apply the parking brake in response to a signal requesting that the parking brake be applied; and a second controller arranged to provide one or more control signals to be applied to other parking brake system components to apply the parking brake in response to the unavailability of the first controller to cause the parking brake to be applied.

2. A parking brake apparatus for an autonomously driven vehicle according to claim 1, wherein (i) the first controller is arranged to execute program instructions of a primary parking brake control algorithm to apply the parking brake in response to the signal requesting that the parking brake be applied, and (ii) the second controller is arranged to execute program instructions of a secondary parking brake control algorithm to apply the parking brake in response to the unavailability of the first controller to execute program instructions of the primary parking brake control algorithm to apply the parking brake in response to the signal requesting that the parking brake be applied.

3. A parking brake apparatus for an autonomously driven vehicle according to claim 1, wherein (i) the first controller is arranged to execute program instructions of a primary parking brake control algorithm to apply the parking brake in response to the signal requesting that the parking brake be applied, and (ii) the second controller is arranged to execute program instructions of a secondary parking brake control algorithm to apply the parking brake in response to the inability of one or more control signals from the first controller to reach the parking brake system components.

4. A parking brake apparatus for an autonomously driven vehicle according to claim 1, wherein (i) the first controller is arranged to execute program instructions of a primary parking brake control algorithm to apply the parking brake in response to the signal requesting that the parking brake be applied, and (ii) the second controller is arranged to execute program instructions of a secondary parking brake control algorithm to apply the parking brake in response to the unresponsiveness of a parking brake valve of the parking brake system.

5. A parking brake apparatus for a self-driving vehicle according to claim 1, further comprising: a parking brake valve controllable by the first controller; a first normally open 3 / 2 solenoid valve disposed between a primary compressed air supply and the parking brake valve; and a second normally open 3 / 2 solenoid valve disposed between a secondary compressed air supply and the parking brake valve; wherein the second controller is arranged to provide a first control signal to the first normally open 3 / 2 solenoid valve, and a second control signal to the second normally open 3 / 2 solenoid valve.

6. A parking brake apparatus for a self-driving vehicle according to claim 5, further comprising: a first relay valve arranged between the first normally open 3 / 2 solenoid valve and the parking brake valve; and a second relay valve arranged between the second normally open 3 / 2 solenoid valve and the parking brake valve.

7. A parking brake apparatus for an autonomously driven vehicle according to claim 1, further comprising: a third controller arranged to (i) monitor the first controller, (ii) detect the unavailability of the first controller to cause the parking brake to be applied, and (iii) activate the second controller to provide one or more control signals to be applied to the parking brake system components to apply the parking brake in response to the detection of the unavailability of the first controller to cause the parking brake to be applied.

8. A parking brake apparatus for an autonomously driven vehicle according to claim 7, wherein the second controller and the third controller comprise a single controller.

9. A parking brake apparatus for an autonomously driven vehicle according to claim 7, further comprising: a controller area network (CAN) bus enabling the first, second, and third controllers to communicate with each other.

10. A parking brake apparatus for a self-driving vehicle according to claim 1, further comprising: one or more pressure-to-voltage transducers coupled to one or more corresponding components of the parking brake system, wherein each pressure-to-voltage transducer provides a voltage indicative of the pressure associated with the corresponding component of the parking brake system.

11. A parking brake apparatus for an autonomously driven vehicle having parking brake system components for applying a parking brake, the parking apparatus comprising: a primary parking brake controller arranged to control one or more parking brake valves to permit one or more parking brake springs to apply the parking brake in response to a signal requesting that the parking brake be applied; and means for, when the vehicle is driven autonomously and without requiring any manual action by an occupant of the autonomously driven vehicle, controlling the one or more parking brake valves to permit the one or more parking brake springs to apply the parking brake when the primary parking brake controller is unable to cause the parking brake to be applied.

12. A parking brake apparatus for a self-driving vehicle according to claim 11, wherein the means include a redundant parking brake controller arranged to control one or more parking brake valves to allow one or more parking brake springs to apply the parking brake when the primary parking brake controller is unable to cause the parking brake to be applied.

13. A parking brake apparatus for an autonomously driven vehicle according to claim 12, wherein the means include an autonomous driver controller arranged to (i) monitor the primary parking brake controller, (ii) detect when the primary parking brake controller is unable to respond to the signal requesting that the parking brake be applied, and (iii) activate the redundant parking brake controller to control one or more parking brake valves to allow one or more parking brake springs to apply the parking brake when the primary parking brake controller is detected to be unable to cause the parking brake to be applied.

14. A parking brake apparatus for an autonomously driven vehicle according to claim 12, wherein the means include an autonomous driver controller arranged to (i) monitor the primary parking brake controller, (ii) detect when one or more control signals from the primary parking brake controller are unable to reach one or more components of the parking brake system, and (iii) activate the redundant parking brake controller to control one or more parking brake valves to allow one or more parking brake springs to apply the parking brake when it is detected that one or more control signals from the primary parking brake controller are unable to reach one or more components of the parking brake system.

15. A parking brake apparatus for an autonomously driven vehicle according to claim 12, wherein the means include an autonomous driver controller arranged to (i) monitor the primary parking brake controller, (ii) detect when a portion of a parking brake valve of the parking brake system is unresponsive, and (iii) activate the redundant parking brake controller to control one or more parking brake valves to allow one or more parking brake springs to apply the parking brake when unresponsiveness of the parking brake valve portion of the parking brake system is detected.

16. A computer-implemented method for an autonomously driven vehicle having a parking brake, a primary parking brake controller, and a secondary parking brake controller that is different from the primary parking brake controller, the computer-implemented method comprising: detecting the unavailability of the primary parking brake controller to cause the parking brake to be applied; and electronically by the secondary parking brake controller, causing the parking brake to be applied in response to the unavailability of the primary parking brake controller.

17. A computer-implemented method according to claim 16, wherein electronically by the secondary parking brake controller, the parking brake is applied in response to the unavailability of the primary parking brake controller, includes: electronically by the secondary parking brake controller, the parking brake is applied when the unavailability of the primary parking brake controller to apply the parking brake is due to the inability of the primary parking brake controller to provide one or more control signals to apply to one or more parking brake valves to enable one or more parking brake springs to apply the parking brake.

18. A computer-implemented method according to claim 16, wherein electronically by the secondary parking brake controller, the parking brake is applied in response to the unavailability of the primary parking brake controller, includes: electronically by the secondary parking brake controller, the parking brake is applied when the unavailability of the primary parking brake controller to apply the parking brake is due to the inability of one or more control signals from the primary parking brake controller to reach one or more parking brake valves to enable one or more parking brake springs to apply the parking brake.

19. A computer-implemented method according to claim 16, wherein electronically by the secondary parking brake controller, the parking brake is applied in response to the unavailability of the primary parking brake controller, includes: electronically by the secondary parking brake controller, the parking brake is applied when the unavailability of the primary parking brake controller to apply the parking brake is due to the non-response of a parking brake valve of the parking brake system.

20. A computer-implemented method according to claim 16, wherein detecting the unavailability of the primary parking brake controller to cause the parking brake to be applied includes: electronically by the secondary parking brake controller, receiving a signal from the primary parking brake controller indicating that the primary parking brake controller is unavailable.

21. A computer-implemented method according to claim 16, wherein detecting the unavailability of the primary parking brake controller to cause the parking brake to be applied includes: electronically by the secondary parking brake controller, receiving a signal from an autonomous driver controller indicating that the primary parking brake controller is unavailable.

22. A computer-implemented method according to claim 16, wherein the method is performed by means of a processor having a memory that executes one or more instruction programs that are tangibly incorporated in a processor-readable program storage medium.

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