USE OF AN ELECTRIC PARKING BRAKE FOR INoperative CONDITIONS OF A VEHICLE POWERTRAIN

Abstract

Vehicle that includes: a powertrain; an electric parking brake; and a controller programmed to activate the electric parking brake in response to the powertrain transitioning to a de-energized state that inhibits the production of drive torque during an ignition cycle when a vehicle speed is less than a predetermined speed and in the presence of conditions that inhibit the powertrain transitioning to an de-energized state that enables the production of drive torque.

Description

TECHNICAL FIELD

[0001] This application generally relates to the operation of an electric parking brake in a vehicle. BACKGROUND

[0002] A vehicle typically includes a parking brake configured to apply braking force when the vehicle is parked. The parking brake may be integrated into the braking system and may apply braking force to a given axle. The parking brake is typically engaged by a driver using a foot pedal or lever. The foot pedal or lever is connected to a cable that engages and disengages the parking brake mechanism. A manually activated mechanism precludes the use of the parking brake for automated functions. DE 10 2005 036 217 A1 discloses a device for ensuring the standstill of a motor vehicle. DE 10 2014 118 627 A1 relates to a vehicle and method for controlling the automatic stopping and restarting of an internal combustion engine.From US 2016 / 0 001 781 A1 a system and method for reacting to the driver’s condition is known. SUMMARY

[0003] In some configurations, a vehicle includes a powertrain. The vehicle also includes an electric parking brake. The vehicle also includes a controller programmed to activate the electric parking brake in response to the powertrain transitioning to a de-energized state that inhibits the production of drive torque during an ignition cycle when a vehicle speed is less than a predetermined speed and in the presence of conditions that inhibit the powertrain transitioning to an de-energized state that enables the production of drive torque.

[0004] Some configurations may include one or more of the following features. In the vehicle, the powertrain includes an engine configured to produce drive torque. In the vehicle, the powertrain further includes an electric machine configured to rotate a crankshaft of the engine before the engine is capable of producing drive torque, and the conditions include the electric machine being unable to rotate the engine. In the vehicle, the conditions include the engine being in a stopped state. In the vehicle, the controller is further programmed to automatically start and automatically stop the engine.The vehicle may include a sensor configured to provide a signal indicative of the absence of a driver from an interior of the vehicle, and wherein the conditions include the signal indicative of the absence of the driver during an automatic stop of the engine. In the vehicle, the powertrain includes at least one electric machine configured to provide drive torque. In the vehicle, the powertrain includes a transmission configured to transmit the drive torque, and the conditions include the transmission being unable to transmit the drive torque. The vehicle may include a grade sensor, wherein the electric parking brake is further activated in response to a signal from the grade sensor indicating that the vehicle is on a grade exceeding a predetermined grade.The vehicle may include a display wherein the controller is further programmed to display a message indicating a status of the powertrain and a status of the electric parking brake.

[0005] In some configurations, a method of controlling a vehicle includes activating, by a controller, an electric parking brake in response to a transition of the powertrain to a de-energized state that inhibits production of drive torque when a speed of the vehicle is less than a predetermined speed and in the presence of conditions that inhibit transition of the powertrain to an de-energized state that enables production of drive torque during an ignition cycle.

[0006] Some configurations may include one or more of the following features. The method further comprises activating in response to sensing that the vehicle is on a grade greater than a predetermined grade. The method may include displaying, by the controller, a message indicative of a status of the powertrain and an activation status of the electric parking brake. The method may include sensing, by the controller, an absence of a driver from a vehicle interior and, in response to the absence of the driver, inhibiting transition of the powertrain to the engaged state.

[0007] In some configurations, a vehicle powertrain includes a controller programmed to request activation of an electric parking brake in response to the vehicle powertrain transitioning to a de-energized state that inhibits production of drive torque during an ignition cycle when a vehicle speed is less than a predetermined speed and in the presence of conditions that inhibit the vehicle powertrain transitioning to an engaged state that enables production of drive torque.

[0008] Some configurations may include one or more of the following features. In the vehicle powertrain, the controller is further programmed to, in response to requesting activation of the electric parking brake, request displaying a message indicating that the electric parking brake is activated and that transition of the vehicle powertrain to the engaged state is inhibited. In the vehicle powertrain, the controller is further programmed to receive a signal indicating a downgrade and request activation of the electric parking brake further in response to the signal indicating that the downgrade exceeds a predetermined grade. In the vehicle powertrain, the controller is further programmed to receive a signal indicating an absence of an operator of the vehicle and inhibit transition of the vehicle powertrain to the engaged state in response to the signal.For the vehicle powertrain, the conditions include conditions that inhibit engine restart. For the vehicle powertrain, the conditions include conditions that inhibit transmission of drive torque. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a possible vehicle configuration. Fig. Figure 2 is a diagram of a possible electric parking brake system. Fig. 3 is a diagram of a vehicle having a powertrain including an engine. Fig. Figure 4 is a diagram of a vehicle having a purely electric powertrain. Fig. Figure 5 is a diagram of a vehicle having a hybrid electric powertrain. Fig. Figure 6 is a block diagram of a possible control strategy for controlling the electric parking brake system. DETAILED DESCRIPTION

[0009] Embodiments of the present disclosure are described herein. It should be understood, however, that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to variously employ the present invention.It will be apparent to one of ordinary skill in the art that various features illustrated and described with reference to any of the figures may be combined with features illustrated in one or more other figures to create embodiments not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

[0010] Fig. 1 illustrates a block diagram of a vehicle 100. The vehicle 100 may include a powertrain 102 configured to provide drive torque to one or more drive wheels 104. The vehicle 100 may include any of a variety of powertrain configurations. The powertrain 102 may include an internal combustion engine (ICE) or a diesel engine. The powertrain 102 may include one or more electric machines. In some powertrain configurations, the electric machine may be configured to rotate the engine for starting purposes. In some powertrain configurations, the electric machine may be configured to provide drive torque to the drive wheels 104. In a hybrid powertrain, the electric machine may be configured to provide drive torque and start the engine.The vehicle 100 may have one or more non-driven wheels 106.

[0011] Fig. 3 illustrates an example block diagram of a conventional powertrain or mild hybrid configuration 300. The mild hybrid configuration 300 may include an engine 302 mechanically connected to a transmission 304. The transmission 304 may be connected to the drive wheels 104 to provide drive torque. The transmission 304 may be configured to adjust a gear ratio between the engine 304 and the drive wheels 104. The transmission 304 may be an automatic transmission having a fixed number of gears and shifting without driver intervention. The transmission 304 may be a manual transmission having fixed gears and shifting with driver intervention. The transmission 304 may be a continuously variable transmission (CVT) having a variable gear ratio between the engine and the drive wheels. The mild hybrid configuration 300 may include a starter / generator 306 (e.g.Electric machine). The starter / generator 306 may be electrically connected to a battery 308. The starter / generator 306 may be configured to rotate a crankshaft of the engine 304 to start the engine 304 and generate electrical power for the battery 308. In a conventional powertrain, the starter / generator may be separate electric machines—a starter and a generator.

[0012] Fig. 4 illustrates an example block diagram of a battery electric vehicle (BEV) powertrain. The BEV powertrain 400 may include an electric machine 406 configured to provide drive torque to the drive wheels 104. The electric machine 406 may be mechanically connected to a transmission housing 404 configured to provide a gear ratio between the electric machine and the drive wheels 104. The transmission housing 404 may be mechanically connected to the drive wheels 104. The transmission housing 404 may have a single gear ratio. The electric machine 406 may derive power from a traction battery 408. A power electronics module (not shown) may electrically connect the electric machine 406 to the traction battery 408.

[0013] Fig. 5 illustrates an exemplary block diagram of a full hybrid electric (HEV) powertrain 500 configuration. The HEV powertrain 500 may include a motor 502 mechanically connected to a hybrid transmission 504. The hybrid transmission 504 may be a power-split hybrid configuration including a planetary gear set and connected to one or more electric machines 506. The electric machines 506 may be electrically connected to a traction battery 508.

[0014] The powertrain components (e.g., engine, transmission, electric machines, power electronics modules, traction battery) may each include a controller configured to control and monitor the associated powertrain component. Under certain conditions, the powertrain component may be unable to operate. Such conditions may be caused by fault conditions or routine maintenance issues. For example, there may be no fuel left to operate the engine. The associated controller may include circuitry and control logic for detecting conditions under which the associated powertrain component is unable to operate.

[0015] With reference again to Fig. 1, during an ignition cycle, the powertrain 102 may be expected to provide drive torque to the drive wheels 104 of the vehicle 100 upon driver request. An ignition cycle may be considered a period of time from an on-demand event (ignition key on) to a off-demand event (ignition key off). Alternatively, the ignition cycle may be the period of time during which the vehicle is in a drive state. Under normal operating conditions, the powertrain 102 may be able to provide drive torque upon request during an ignition cycle. Under abnormal conditions, it is possible that the powertrain 102 may not be able to provide drive torque upon request due to some abnormal condition. For example, the engine may fail to start when requested.

[0016] The vehicle 100 may include one or more brake modules 108. The brake modules 108 may be configured to apply torque to the wheels to resist wheel rotation. The brake modules 108 may be configured as disc brakes or drum brakes, or any combination thereof. The brake modules 108 may include a parking brake function. The parking brake function may include a mechanism configured to maintain a brake application to the wheels. The parking brake function may be applied to a subset of all wheels. In some configurations, the parking brake function may be applied to all wheels. In a mechanical parking brake system, the brake mechanism may be activated by a cable attached to a lever or pedal within an interior of the vehicle 100.In an electric parking brake (EFB) configuration, the parking brake function can be activated electrically using a motor.

[0017] The vehicle 100 may include at least one controller 120. The controller 120 may include a processor for executing instructions. The controller 120 may include volatile and non-volatile memory for storing data and programs. Although illustrated as a single module, the controller 120 may include multiple controllers communicating over a vehicle network.

[0018] The vehicle 100 may include one or more occupancy sensors 110. The occupancy sensors 110 may be configured to detect the presence or absence of a driver and / or passengers within a vehicle interior. For example, the occupancy sensor 110 may include a door sensor that provides a signal indicating that a door of the vehicle is in an open state. The driver may be assumed to have exited the vehicle if the door is detected in an open state with the ignition on. The occupancy sensor 110 may include a weight sensor in a seat of the vehicle that is configured to provide a signal indicating a weight resting on the seat (e.g., a driver or passenger). Driver presence may be detected if the weight exceeds a predetermined threshold.The controller 120 may communicate with other controllers in the vehicle via a communications network.

[0019] The vehicle 100 may include a speed sensor 112 configured to output a signal indicative of the speed of the vehicle 100. The speed sensor 112 may be one or more wheel speed sensors connected to one or more of the wheels 104, 106. The speed sensor 112 may be an output shaft speed sensor connected to an output shaft of the driveline 102.

[0020] The vehicle 100 may include a grade sensor 114 configured to output a signal indicative of a grade or slope on which the vehicle 100 is located. The grade sensor 114 may be a longitudinal accelerometer that provides a signal that varies with the grade.

[0021] The vehicle 100 may include a display module 116 configured to display various status and operational information to the vehicle occupants. The display module 116 may include a display screen configured to display text messages to the occupants. The display module 116 may include lamps or lights to indicate the status in a binary format. The display module 116 may include a message or light that conveys the operational status of the powertrain 102. For example, a powertrain status light may illuminate when the powertrain 102 is prevented from providing torque to the drive wheels 104.

[0022] The vehicle 100 may include an EFB switch 118 configured to activate and deactivate the EFB system. The EFB switch 118 may be located near the driver to enable activation and deactivation of the parking brake. The EFB switch 118 may be electrically connected to the controller 120. The controller 120 may include circuitry for receiving the EFB switch signal and be programmed to determine the status of the EFB switch 118. The controller 120 may debounce the signal from the EFB switch 118 to minimize noise pollution. The EFB switch 118 may be configured to have multiple positions. For example, in a first position, the parking brake may be released to allow vehicle movement. In a second position, the parking brake may be applied to prevent vehicle movement. In some configurations, the EFB switch 118 may be a pushbutton.The controller 120 may be programmed to toggle the parking brake position in response to a pushbutton press. For example, when the vehicle 100 is parked, the driver may press the EFB switch 118 to activate the EFB.

[0023] The brake modules 108 may be configured with an electric parking brake (EFB) 200 function. Fig. 2 illustrates one possible implementation of an electric parking brake (EFB) 200. The EFB 200 may include a motor 202 to actuate a piston 204 and a caliper 206 for disc brakes. A braking system may be a disc brake system and include a brake rotor 208. Brake pads 210 may be attached to each side of the brake rotor 208 such that the brake rotor 208 can move freely when the caliper 206 is not actuated. The brake piston 204 may be electrically actuated by an EFB motor 202. The EFB motor 202 may be connected to a drive spindle 212 through a gear train 214. The EFB motor 202 and / or the gear train 214 may be electrically connected to the controller 120 through a connector 218. The controller 120 may be programmed to control power distribution to the EFB motor 202.

[0024] The EFB 200 may be included in each brake module of a selected axle of the vehicle, for example, the rear wheels. Alternatively, all four wheels may have the EFB 200, or any combination of the drive wheels 104 and non-drive wheels 106 may be equipped with the EFB 200.

[0025] The controller 120 may be programmed to actuate the EFB motor 202 in response to driver activation of the EFB switch 118. Additionally, the controller 120 may be programmed to actuate the EFB motor 202 in response to a signal from another controller (e.g., vehicle powertrain controller) via the communication network. Upon receiving an actuation signal, the controller 120 may command the EFB 200 to actuate and lock the wheels.

[0026] The EFB 200's control system can be expanded to enable the EFB 200 to be used under different conditions. Such additional use can improve vehicle safety and reliability in certain situations.

[0027] In hybrid configurations where the engine can be automatically stopped and started, the EFB 200 can be activated under certain conditions. Under normal conditions, the engine can be automatically stopped if there is no drive torque request from the driver. If drive torque is then requested, an automatic engine start cycle can be initiated. However, under some conditions, automatic engine start may be unsuccessful. The engine may be unable to start automatically for several reasons. For example, a loss of battery power feeding the starter motor may result in the starter motor being unable to turn over the engine. In addition, a failing starter motor can also cause the engine to be unable to restart. Problems with the fuel system can also prevent the engine from restarting.For example, the fuel tank may be empty or a fuel line may be clogged.

[0028] When the primary power source of the powertrain 102 is unable to transition to a state to provide drive torque to the drive wheels 104, it may be beneficial to apply the EFB 200 to prevent vehicle movement. Under this condition, the controller 120 may be programmed to activate the EFB 200. Activation of the EFB 200 may be requested when a vehicle speed is less than a predetermined vehicle speed. This may prevent the EFB 200 from being activated under conditions in which the vehicle is moving to avoid unexpected deceleration. Under conditions in which the vehicle is stopped, the EFB 200 may be applied to prevent further vehicle movement.Other conditions may be met above the predetermined vehicle speed, and if the conditions are still met below the predetermined vehicle speed, the EFB 200 may be actuated when the vehicle speed drops below the predetermined vehicle speed. For example, a predetermined vehicle speed of 3 mph may be configured.

[0029] The controller 120 may detect when the powertrain 102 is unable to produce drive torque. The controller 120 may monitor various sensors and subsystems for proper operation. The controller 120 may monitor a status of the powertrain 102 to detect a transition from an engaged or running state (e.g., the powertrain 102 is capable of providing drive torque and / or actively providing drive torque) to an engaged or stopped state (e.g., the powertrain 102 is prevented from providing drive torque). In a mild hybrid vehicle, the engaged state may be identified to automatically start the engine, and the engaged state may be identified to automatically stop the engine.When the powertrain 102 is in the engaged state, the production of drive torque is possible.

[0030] Under normal conditions, the powertrain 102 may transition between the on and off states as the demand for drive torque changes. Under some conditions, the powertrain 102 may be unable to transition from the off state to the on state. In some cases, a failing component may inhibit the transition of the powertrain 102 to the on state. The controller 120 may be programmed to detect when transitions to the on state are inhibited.

[0031] In a vehicle where the engine is the sole power source, an engine-off condition may cause the engine to stop (e.g., enter a powered-off state). Since an ICE-only configuration may not be configured to automatically stop and start the engine, it may not be possible to automatically transition back to the powered-on state without driver intervention. In such cases, a return of the powertrain to a running or powered-on state without driver intervention is inhibited. The controller 120 may request activation of the EFB 200 in response to detecting an engine-off condition. To correct the condition, the driver may turn on the key / ignition to initiate a new ignition cycle. The EFB 200 may prevent movement of the vehicle 100 during the engine-off condition.

[0032] The EFB 200 may be actuated when the powertrain 102 has inhibited the production of drive torque during a firing cycle without being able to re-enable drive torque production. After the powertrain 120 has lost the ability to re-enable drive torque production, the safest state of the vehicle 100 may be a parked state. Manual operation of the EFB 200 to deactivate the EFB 200 may be enabled to permit movement of the vehicle 100 (e.g., towing).

[0033] In a hybrid vehicle (mild hybrid and / or full hybrid) that can automatically transition between the on and off states, normal transitions should not affect the operation of the EFB 200. Only those conditions in which the powertrain has transitioned to a off state without the possibility of returning to the on state can trigger the activation of the EFB 200. The hybrid powertrain can still provide drive torque via the electric machines if the engine is prevented from providing drive torque. However, the electric machines can only provide drive torque as long as the traction battery has a sufficient state of charge. In a hybrid vehicle, the application of the EFB 200 can be delayed until the electric machines are prevented from providing drive torque.

[0034] In a BEV powertrain configuration, conditions for applying the EFB 200 may include a traction battery state of charge falling below a threshold at which drive torque can no longer be provided. An additional condition may include an electric machine temperature exceeding a predetermined temperature. Such a temperature condition may prevent thermal overload of the electric machine. Further, any condition where torque production is inhibited may cause activation of the EFB 200. Such conditions may include battery, power electronics, and electric machine fault conditions.

[0035] Other conditions that may inhibit the transition of the powertrain 102 to the on state may include sensor problems. An accelerator pedal may have one or more sensors for providing signals indicative of a position of the accelerator pedal. The one or more sensors may be compared to determine the accuracy of the accelerator pedal command. If the one or more sensor values do not agree regarding the accelerator pedal position, the transition of the powertrain to the on state may be inhibited. Other powertrain sensors may prevent transitions to an on state and may be monitored to activate the EFB 200.

[0036] Once the EFB 200 is activated, it can remain activated until the next ignition cycle. In some configurations, the EFB 200 can remain activated until the driver manually deactivates the EFB 200 using the EFB switch 118.

[0037] Operating the EFB 200 when drive torque production is inhibited can improve vehicle safety. The vehicle 100 can be held in a stopped state to prevent movement while the driveline cannot provide torque. For example, if torque inhibition occurs on a downhill grade, the vehicle 100 may roll backward or forward due to the lack of torque. Applying the EFB 200 under this condition can prevent vehicle movement and improve safety.

[0038] Fig.6 illustrates a block diagram of possible control logic for implementing the described methods. The various control blocks illustrated may implement functions and features as previously described. The control blocks may be implemented by instructions programmed into the controller 120. A first control block 600 may be configured to determine certain enabling conditions for activating the EFB 200. The enabling conditions may include firing in a running state, vehicle speed being less than a speed threshold, and a grade exceeding a predetermined grade. Other enabling conditions are possible. The first control block 600 may output a first signal 602 indicating whether EFB activation is enabled.

[0039] A second control block 604 may be configured to detect when the powertrain is in a power-off state. The second control block 604 may receive inputs such as the powertrain status and an engine start / stop status. The powertrain status signal may include the operating state of the powertrain and whether or not it is in a state to provide drive torque. The second control block 604 may detect when the powertrain is in a power-off state and output a second signal 606 indicative of the powertrain power-off state. For example, the powertrain 102 may be in a power-off state during an automatic engine stop or an engine off state.

[0040] A third control block 608 may be configured to detect when powertrain transitions to the on state are inhibited. The third control block 608 may receive inputs such as powertrain status, engine start / stop status, fault conditions, and occupancy signals. The inputs may be processed, and a third signal 610 may be output to indicate whether transitions to the on state are inhibited. For example, the occupancy sensor may indicate driver absence (e.g., the driver exited the vehicle without turning off the ignition) or a fault condition is present that prevents the transition to the on state.

[0041] The first signal 602, the second signal 606, and the third signal 610 may be input to an AND function 612. The AND function 612 may output an EFB enable signal 614. The EFB enable signal 614 may be true if all input signals to the AND function 612 are true. The EFB enable signal 614 may be input to an EFB control block 616 and a display control block 618. The EFB control block 616 may enable the EFB 200 in response to the EFB enable signal 614 transitioning to a true value. EFB enablement may proceed until the EFB enable signal transitions to false. In response to the EFB enable signal 614 transitioning to true, the display control block 618 may activate one or more visual indicators to warn the driver that the EFB 200 is enabled and the transition of the powertrain to an on state is inhibited.

[0042] The processes, methods, or algorithms disclosed herein may be deliverable to or implemented by a processing device, controller, or computer, which may include any pre-existing programmable electronic control unit or a dedicated electronic control unit. Likewise, the processes, methods, or algorithms may be stored as data and instructions executable by a controller or computer in many forms, including, but not limited to, information permanently stored on non-writable storage media, such as read-only devices, and information modifiably stored on writable storage media, such as floppy disks, magnetic tapes, compact discs, RAM devices, and other magnetic and optical media.The processes, methods, or algorithms may also be implemented in a software executable object. Alternatively, the processes, methods, or algorithms may be implemented in whole or in part using suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0043] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The terms used in the description are for the purpose of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of the various embodiments may be combined to form further embodiments of the disclosure that may not have been explicitly described or illustrated. Although various embodiments may have been described as providing advantages over other embodiments or prior art implementations with respect to one or more desired characteristics.are preferable to these, those of ordinary skill in the art will understand that compromises may be made with respect to one or more features or characteristics to achieve required properties of the overall system, which depend on the specific application and implementation. These features may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Thus, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for certain applications.

Claims

[1] Vehicle comprising: a powertrain; an electric parking brake; and a controller programmed to activate the electric parking brake in response to the powertrain transitioning to a de-energized state that inhibits the production of drive torque during an ignition cycle when a vehicle speed is less than a predetermined speed and in the presence of conditions that inhibit the powertrain transitioning to an de-energized state that enables the production of drive torque. [2] The vehicle of claim 1, wherein the powertrain includes a motor configured to produce drive torque. [3] The vehicle of claim 2, wherein the powertrain further comprises an electric machine configured to rotate a crankshaft of the engine before the engine is capable of producing the drive torque, and wherein the conditions include the electric machine being unable to rotate the engine. [4] The vehicle of claim 2, wherein the conditions include the engine being in a stopped state. [5] The vehicle of claim 2, wherein the controller is further programmed to automatically start and automatically stop the engine. [6] The vehicle of claim 5, further comprising a sensor configured to provide a signal indicative of the absence of a driver from an interior of the vehicle, and wherein the electric parking brake is further activated in response to the signal indicative of the absence of the driver during an automatic stop of the engine. [7] The vehicle of claim 1, wherein the powertrain includes at least one electric machine configured to provide drive torque. [8] The vehicle of claim 1, wherein the powertrain includes a transmission configured to transmit the drive torque, and wherein the conditions include the transmission being unable to transmit the drive torque. [9] The vehicle of claim 1, further comprising a grade sensor, wherein the electric parking brake is further activated in response to a signal from the grade sensor indicating that the vehicle is on a grade exceeding a predetermined grade. [10] The vehicle of claim 1, further comprising a display, wherein the controller is further programmed to display a message indicative of a powertrain status and an electric parking brake status.

Images