Patent Description:
With the developments of electric drivelines for vehicles, new concepts for assisting the driver are emerging. One such concept is called "one pedal drive", which means that the use of the accelerator does not only control the positive propulsion torque provided to the wheels. With this concept, when the driver is releasing the accelerator, a regenerative torque is applied which causes braking of the vehicle.

An example of a prior art system is described in <CIT>. From this document it is suggested to initiate a regenerative braking mode in response to a reduction in the degree of actuation of the accelerator of the vehicle. The level of regenerative braking is modified in response to the application of a brake of the vehicle. During the braking event the depression and successive release of the brake pedal results in a corresponding rise and fall in the degree of braking force.

Different schemes for determining the regenerative torque have been suggested, but so far, all existing solutions are quite simple; meaning that the regenerative torque applied when the accelerator is released, is often non-satisfactory for optimal driving. There is thus a need for improved methods for controlling braking of a vehicle, especially by enabling improved adaptation while still requiring minimum driver input.

According to a first aspect of the invention, a computer-implemented method is provided. The method comprises receiving, by a processor device of a computer system, a signal corresponding to a release of an accelerator. The method also comprises receiving, by the processor device, a signal corresponding to a first tap on a brake pedal, the first tap comprising an initiated physical interaction with the brake pedal and a subsequent release of the physical interaction with the brake pedal, and determining, by the processor device, a second braking torque. The method further comprises applying the second braking torque as a response to the first tap on the brake pedal, and maintaining the applied braking torque after said tap on the brake pedal. The first aspect of the invention may seek to improve the energy efficiency of an associated vehicle. A technical benefit may include more energy efficient braking of the vehicle, a more simple braking interface for the driver, as well as improved driver comfort during operation of the vehicle.

According to the invention, receiving a signal corresponding to a tap on the brake pedal further comprises determining an action on the brake pedal by a pressure within a predetermined pressure threshold interval and for a time period within a predetermined time threshold interval. A technical benefit may include a distinct definition of the required trigger signal for additional braking, i.e. the tap, both in space and time.

In some examples, the requested braking torque is applied by a brake device being separate from the wheel brakes of the vehicle.

According to a second aspect of the invention a computer system is provided. The computer system comprises a processor device configured to perform the method of the first aspect.

In some examples, the method further comprises determining, by the processor device, a first braking torque after release of the accelerator, and applying the first braking torque as a response to the release of the accelerator. A technical benefit may include a facilitated interface for the driver to correct a default braking torque.

In some examples, the requested braking torque is higher than the first braking torque. A technical benefit may include increased safety by the driver initiating a higher braking torque only by tapping the brake pedal.

In some examples, the method further comprises determining, by the processor device, a vehicle speed being above a predetermined speed threshold before applying the requested braking torque. A technical benefit may include avoidance of unintentional or unnecessary increase in braking at low speed.

In some examples, the method further comprises: receiving, by the processor device, a signal corresponding to a second tap on the brake pedal, said second tap comprising an initiated physical interaction with the brake pedal and a subsequent release of the physical interaction with the brake pedal, determining, by the processor device, an updated braking torque, and updating the requested braking torque by applying the updated braking torque as a response to the second tap on the brake pedal. A technical benefit may include enabling a stepwise increase of the braking torque in a simplified manner.

In some examples, the method further comprises: receiving, by the processor device, a release signal, and releasing the requested braking torque as a response to said release signal. A technical benefit may include a maintained braking torque by a simple tap, and a facilitated process for releasing the requested braking torque.

In some examples, the method further comprises: releasing the first braking torque as a response to said release signal. A technical benefit may include a facilitated process for releasing also the first braking torque.

In some examples, the release signal corresponds to a depression of the accelerator. A technical benefit may include a simplified interface for the driver to abort the braking by pressing the accelerator.

In some examples, the release signal corresponds to determining a vehicle speed being below a predetermined speed threshold. A technical benefit may include an automatic abortion of the braking when the speed is sufficiently low.

In some examples, the requested braking torque and/or the first braking torque is a regenerative torque. A technical benefit may include that existing electric motors can be used for braking, and that the regenerative motion can be used to charge onboard batteries.

According to a second aspect of the invention, a vehicle is provided. The vehicle comprises the processor device to perform the method of the first aspect.

According to a third aspect of the invention, a computer program product is provided. The computer program product comprises code for performing, when executed by the processor device, the method of the first aspect.

According to a fourth aspect, a control system is provided. The control system comprises one or more control units configured to perform the method of the first aspect.

According to fifth aspect, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium comprises instructions, which when executed by the processor device, cause the processor device to perform the method of the first aspect.

Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the invention as described herein.

Aspects set forth below represent the necessary information to enable those skilled in the art to practice the invention.

In general, a method is described which is aimed to improve energy efficiency of vehicles. In addition, the described method may provide a more simple interface for controlling driving, especially with regards to manually affecting automatic braking of the vehicle.

<FIG> is an exemplary side view of a vehicle <NUM> according to one example. The vehicle <NUM>, in <FIG> represented as a truck, comprises ordinary components as are well known in the art, such as a chassis <NUM>, a plurality of wheel axles <NUM>, <NUM>, a propulsion unit <NUM> and an associated driveline <NUM>. Preferably, the vehicle <NUM> is an electric vehicle which means that the propulsion unit <NUM> comprises one or more electrical motors with associated equipment such as batteries, power electronics, etc..

Although the vehicle <NUM> is illustrated as a truck, it should be realized that other types of vehicles may be equally considered for the purpose of the herein described method such as busses, construction equipment, passenger cars, etc..

In <FIG> further details of the vehicle <NUM> are shown, exemplifying components used for implementing the method described further below.

An accelerator <NUM>, in the form of a pedal, is used by the driver to control propulsion of the vehicle <NUM>. A brake pedal <NUM> is further provided which is used by the driver to control braking of the wheels 13a, 13b of the vehicle <NUM>.

A computer system <NUM> is further provided. The computer system <NUM> comprises a processor device <NUM>, e.g. a control unit, which is in communication with the accelerator <NUM> and the brake pedal <NUM>. The processor device <NUM> is further in communication with a brake device <NUM>, <NUM>. In the shown example, the brake device <NUM> is preferably an electric propulsion unit <NUM> (in <FIG> illustrated as an electric motor with associated control circuitry); for braking, the electric propulsion unit <NUM> is configured to provide a regenerative torque to the vehicle <NUM>. Optionally, or in combination with the electric propulsion unit <NUM>, the vehicle <NUM> comprises a brake device <NUM> in the form of a retarder, such as an electrical or hydraulic retarder. Preferably, the brake device <NUM>, <NUM> is separate from the wheel brakes of the vehicle.

The computer system <NUM> is configured to enable so called "one pedal drive". This means the computer system <NUM> is configured to implement an automatic braking action on the vehicle <NUM> immediately when the driver releases the accelerator <NUM>. Such braking action is normally not effected by actuation of wheel brakes, but rather by activating a retardation for example by means of the retarder <NUM>, or by applying a regenerative torque by the electric propulsion unit <NUM>.

According to the present example, the computer system <NUM> is further configured to allow the driver to manually interact with the automatic braking procedure applied when releasing the accelerator <NUM>. This is done by the driver tapping the brake pedal <NUM>. Such tapping will be identified by the computer system <NUM>, e.g. by receiving a signal from a contact sensor <NUM> arranged on the brake pedal <NUM>, and a control signal will be transmitted to increase the braking torque. Typically, the tapping on the brake pedal <NUM> will not actuate the wheel brakes, but instead the braking torque already applied by the brake device <NUM>, <NUM> (may it be a separate retarder <NUM> and/or a regenerative torque from the electric propulsion unit <NUM>).

In <FIG> a general diagram of a method <NUM> according to an example is shown. The method <NUM> is performed by the computer system <NUM> receiving <NUM> a signal indicative of a driver's release of the accelerator <NUM>. Next, the method <NUM> determines <NUM> that the brake pedal <NUM> is tapped by the driver. When the brake pedal <NUM> is tapped, the method determines <NUM> a new requested braking torque. When the requested braking torque is determined, the method applies <NUM> the requested braking torque to the vehicle <NUM> and maintains <NUM> the applied braking torque after the brake pedal <NUM> has been tapped.

In order to further explain various examples of the method <NUM>, reference is made to <FIG>. The method <NUM> may preferably be implemented as a continuous control loop executed during driving of the vehicle <NUM>, as explained in the following.

At first, the method <NUM> determines <NUM> if the accelerator <NUM> is pressed (e.g. actuated), indicating that the driver is requesting propulsion of the vehicle <NUM>. If not, the method <NUM> returns for again checking if the accelerator <NUM> is actuated.

If it is determined that the accelerator <NUM> is pressed, the method <NUM> checks <NUM> if the accelerator <NUM> is released. This corresponds to the computer system <NUM> receiving a signal indicative of a driver's release of the accelerator <NUM>. If not, the method <NUM> may return to the initial state <NUM>.

If it is determined that the accelerator <NUM> is released, the method <NUM> determines <NUM> a first braking torque. The first braking torque is preferably automatically determined based on a plurality of parameters, such as vehicle speed, road inclination, etc. If the brake device <NUM> is a regenerative brake device <NUM>, also parameters like temperature and current charging level of onboard batteries may be considered.

Once the first braking torque is determined, the method <NUM> continues by applying <NUM> the determined first braking torque to the vehicle <NUM>. This will cause a retardation of the vehicle <NUM>.

When it is determined to apply <NUM> a braking torque to the vehicle, the method <NUM> continues maintaining <NUM> the applied braking torque.

If the driver for some reason considers that the applied braking torque, experienced mainly by the resulting retardation of the vehicle <NUM>, is too low, the driver may tap the brake pedal <NUM>. Hence, during retardation caused by the applied first braking torque, the method <NUM> performs <NUM> a check if the brake pedal <NUM> is tapped by the driver. If not, the method <NUM> maintains <NUM> the current braking torque, i.e. the first braking torque.

It should be noted that the first braking torque does not need to be constant, but the determined first braking torque may be a dynamically changing braking torque based on any one or more of the plurality of driving parameters mentioned above. For example, the first braking torque may be a decaying function of vehicle speed (or any other suitable parameter), meaning that the first braking torque will decrease as the vehicle <NUM> retards. In other examples the first braking torque may be a progressive function of vehicle speed (or any other suitable parameter), meaning that the first braking torque will increase as the vehicle <NUM> retards. The first braking torque may in some examples be zero, meaning that the once the driver releases the accelerator <NUM>, the vehicle is rolling free.

If it is decided that the driver has tapped the brake pedal <NUM>, the method <NUM> performs <NUM> a check if the tapping is within predetermined tapping criteria. This is preferably performed in order to accurately distinguish a tap from a regular braking command, which normally involves distinct pressing of the brake pedal <NUM>. Hence, tapping is determined as being distinct from a normal pressing for actuating the wheel brakes. Typically, the tap comprises an initiated physical interaction with the brake pedal <NUM> and a subsequent release of the physical interaction with the brake pedal <NUM>.

A tap may be determined based on parameters such as pressure, time, and/or brake pedal <NUM> angle. For example, a tap is determined if the pressure is within a certain pressure interval (preferably being significantly less than required for normal braking using the wheel brakes) and/or within a certain time period (preferably being significantly less than required for normal braking using the wheel brakes). Further, a tap may be determined if there is a limited physical interaction with the brake pedal <NUM>, but the brake pedal <NUM> angle is zero, i.e. there is no physical movement of the brake pedal <NUM>.

Existing or dedicated sensors may be used to determine if the brake pedal <NUM> is tapped within the context of this example. The brake pedal <NUM> may e.g. be provided with a contact sensor <NUM> which is capable of detecting a physical interaction with the brake pedal <NUM>, as well as the time period for such physical interaction. If a separate brake pedal <NUM> angle sensor is provided for actuating the wheel brakes, a tap may be determined if the contact sensor <NUM> generates a signal indicative of the driver interacting with it, while at the same time the brake pedal <NUM> angle sensor is "silent", i.e. provides no actuation signal.

If the physical interaction is decided to fall outside the criteria for a valid tap, the method <NUM> continues by maintaining <NUM> the already applied braking torque.

On the other hand, if the check <NUM> for a valid tap is positive, the driver is requesting a change of the current braking torque. In such case, the method <NUM> continues by determining <NUM> a new, requested braking torque. The requested braking torque may be determined by various schemes. For example, the method <NUM> may determine that a tap should correspond to a predetermined increase of the braking torque, such as by a fixed amount or by a fixed percentage. The method <NUM> may, as an example, determine that a valid tap on the brake pedal <NUM> should increase the first braking torque by <NUM>% or by a fixed amount such as <NUM>. In other examples, the requested braking torque is determined based on one or more of a plurality of operation parameters such as such as vehicle speed, road inclination, the current braking torque, etc. Even if the first braking torque is zero, or a function of e.g. vehicle speed, the requested braking torque may be determined as an add-on to the first braking torque.

Either prior to or after the requested braking torque is determined <NUM>, the method <NUM> determines <NUM> if the current vehicle speed is above a predetermined threshold. By such check, the method <NUM> provides a safety measure not to increase the braking torque at too low speeds. If the current vehicle speed is below the threshold, which may be set to e.g. <NUM>/h, the method <NUM> continues to maintain <NUM> the current braking torque meaning that the tap by the driver will have no effect to the retardation.

If the current vehicle speed is above the threshold, the determined requested braking torque is applied <NUM> to the vehicle <NUM>. When it is determined to apply <NUM> the requested braking torque to the vehicle <NUM>, the method <NUM> continues maintaining <NUM> the applied braking torque.

At this stage <NUM>, the method <NUM> performs recurring checks <NUM> if the brake pedal <NUM> is once again tapped, which would trigger the same sequence <NUM>-<NUM> as previously explained. Hence, a driver may tap the brake pedal <NUM> a first time to initiate a first update of the braking torque, and subsequent taps on the brake pedal <NUM> to initiate further updates of the braking torque, whereby each tap on the brake pedal <NUM> will cause a corresponding change of the braking torque.

Simultaneously, the method <NUM> performs a check <NUM> for a release signal. A release signal may for example correspond to a signal indicative of the driver again pressing the accelerator <NUM>. A release signal may also be generated if the vehicle speed decreases below a predetermined threshold. If no release signal is detected, the method <NUM> continues by returning to maintaining <NUM> the current braking torque.

If a release signal is issued, the method continues by releasing <NUM> the current braking torque. Upon such action, the method <NUM> returns to the initial stage <NUM> of checking <NUM> if the accelerator <NUM> is pressed.

The method <NUM> may further comprise processes for determining different tap schemes, and to apply a requested braking torque based on the different tap schemes. In one example, a single tap on the brake pedal <NUM> involves the same procedures as described above. The processor device <NUM> may be configured to associate other tap patterns, such as a fast double tap, with different braking torque requests. For example, a driver performing a double tap may cause the method <NUM> to apply an increased braking torque compared to a single tap. In other examples a double tap, performed after the first tap, may cause the method <NUM> to release the requested braking torque and return to the previously applied first braking torque.

<FIG> is a schematic diagram of a computer system <NUM> for implementing examples disclosed herein. The computer system <NUM> is adapted to execute instructions from a computer-readable medium to perform these and/or any of the functions or processing described herein. The computer system <NUM> may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the computer system <NUM> may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and/or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processor device, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc..

The computer system <NUM> may comprise at least one computing device or electronic device capable of including firmware, hardware, and/or executing software instructions to implement the functionality described herein. The computer system <NUM> may include a processor device <NUM> (may also be referred to as a control unit), a memory <NUM>, and a system bus <NUM>. The computer system <NUM> may include at least one computing device having the processor device <NUM>. The system bus <NUM> provides an interface for system components including, but not limited to, the memory <NUM> and the processor device <NUM>. The processor device <NUM> may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory <NUM>. The processor device <NUM> (e.g., control unit) may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor device may further include computer executable code that controls operation of the programmable device.

The system bus <NUM> may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and/or a local bus using any of a variety of bus architectures. The memory <NUM> may be one or more devices for storing data and/or computer code for completing or facilitating methods described herein. The memory <NUM> may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory <NUM> may be communicably connected to the processor device <NUM> (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory <NUM> may include non-volatile memory <NUM> (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory <NUM> (e.g., random-access memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with a processor device <NUM>. A basic input/output system (BIOS) <NUM> may be stored in the non-volatile memory <NUM> and can include the basic routines that help to transfer information between elements within the computer system <NUM>.

A number of modules can be implemented as software and/or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may be stored in the storage device <NUM> and/or in the volatile memory <NUM>, which may include an operating system <NUM> and/or one or more program modules <NUM>. All or a portion of the examples disclosed herein may be implemented as a computer program product <NUM> stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device <NUM>, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processor device <NUM> to carry out the steps described herein. Thus, the computer-readable program code can comprise software instructions for implementing the functionality of the examples described herein when executed by the processor device <NUM>. The processor device <NUM> may serve as a controller or control system for the computer system <NUM> that is to implement the functionality described herein.

The computer system <NUM> also may include an input device interface <NUM> (e.g., input device interface and/or output device interface). The input device interface <NUM> may be configured to receive input and selections to be communicated to the computer system <NUM> when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processor device <NUM> through the input device interface <NUM> coupled to the system bus <NUM> but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) <NUM> serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The computer system <NUM> may include an output device interface <NUM> configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system <NUM> may also include a communications interface <NUM> suitable for communicating with a network as appropriate or desired.

The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the invention.

For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present invention.

Claim 1:
A computer-implemented method (<NUM>), comprising:
receiving (<NUM>), by a processor device (<NUM>) of a computer system (<NUM>), a signal corresponding to a release of an accelerator (<NUM>),
receiving (<NUM>), by the processor device (<NUM>), a signal corresponding to a first tap on a brake pedal (<NUM>), comprising determining an action on the brake pedal (<NUM>) by a pressure within a predetermined pressure threshold interval and/or for a time period within a predetermined time threshold interval, wherein said first tap comprising an initiated physical interaction with the brake pedal (<NUM>) and a subsequent release of the physical interaction with the brake pedal (<NUM>),
determining (<NUM>), by the processor device (<NUM>), a requested braking torque,
applying (<NUM>) the requested braking torque as a response to the first tap on the brake pedal (<NUM>), and
maintaining (<NUM>) the applied braking torque after said tap on the brake pedal (<NUM>).