Smart regenerative braking control

A smart braking system for a vehicle is provided. The smart braking system selectively activates a braking system of the vehicle when the smart braking system detects a scenario in which it is likely that a constant vehicle speed, rather than an increasing vehicle speed, would be desired by a driver. In one example, a driver releases an accelerator while the vehicle is on a decline but the vehicle accelerates anyway. In this instance, the smart braking system records the speed of the vehicle when the accelerator is released and applies the braking system to maintain the speed of the vehicle at the recorded speed while the vehicle is on the decline. The smart braking system stops activating the braking system upon detecting that braking is no longer needed to slow down the vehicle.

FIELD OF INVENTION

The present disclosure relates to efficient use of energy for electric vehicles, and, more particularly, to a smart regenerative braking for an electric vehicle.

BACKGROUND

A modern vehicle is capable of sensing its environment. Numerous companies have improved algorithms to increase efficiency, comfort, and safety of driving. Further improvements in the field of vehicle control are desirable.

SUMMARY

The present disclosure is related to smart braking systems for vehicles. The smart braking system may be a vehicle control system or may be included within a vehicle control system configured to perform one or more vehicle control operations. In some aspects, the control system is configured to perform a smart braking control method. The smart braking control method includes detecting a triggering condition, recording a current speed of the vehicle, and activating a braking system of the vehicle to maintain the speed of the vehicle at the current speed. The smart braking control method may be performed when cruise control is not activated for the vehicle.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1is a schematic drawing of a vehicle10, according to an embodiment. The vehicle10includes an energy storage system12, a motor14(and can include more than just one motor), a braking system16, and a control system18. The energy storage system12includes a battery20that stores electrical energy. The motor14is operatively connected to the battery20and is configured to produce mechanical energy to move the vehicle10(e.g., via wheels22). The braking system16is configured to slow the vehicle10via one or more brakes24. Brakes24include one or more friction braking mechanisms and one or more regenerative braking mechanisms that restore energy to the energy storage system12by reducing speed of the vehicle10.

The control system18is operatively connected to the energy storage system12, the motor14, and the braking system16. The control system18may include a controller26that includes, for example, a processor, memory, I/O device(s), database, etc., and the like. The control system18may be or may be included in a vehicle on-board computer. The control system18is configured to control motor power, other internal systems (e.g., passenger comfort systems, external signaling systems, and the like), and to autonomously pilot the vehicle10. Autonomous piloting includes controlling speed and steering based on autonomous operation algorithms and on inputs received with input devices28(such as sensors or communication equipment like cameras, radar sensors, microphones, wireless communication equipment, accelerometers, geo-positioning devices that determine a global position of the vehicle from satellite signals, and other input sensors) that are considered to be a part of the control system18. The control system18may control the vehicle based on a position of the vehicle as determined by a geo-positioning system within input devices28.

The input devices28obtain a wide variety of information about the vehicle10and the surroundings of the vehicle10. For instance, the input devices28include sensors such as a speedometer, motor power sensors for sensing motor power, sensors for determining battery charge and power usage, and the like. The input devices28also include communication devices for obtaining information about road or environmental conditions. The communication devices communicate wirelessly with an external computer system30to obtain road information (e.g., the shape of the road, including incline or decline), traffic information (e.g., traffic density and/or locations of vehicles, weather information, and the like. The communication devices may also obtain, from external computer system30, road parameters that define the layout of the road, including position and dimensions of the road as well as grade (incline/decline) of the road. Some road parameters may be pre-stored in a storage device accessible to the control system18and within the vehicle10. The external computer system30may be implemented as a typical computer system and include components such as a hardware processor and a hardware memory for storing instructions to be executed by the processor. The instructions would be configured to perform the functionality described herein.

Cruise control is a technique in which speed of the vehicle is maintained at or near a selected speed (also called a “target speed”). To perform cruise control, the control system18performs one or more steps that control a speed of the vehicle10. For example, the control system18may selectively control the motor14to provide power to the vehicle10in order to accelerate to the target speed or to maintain the speed of the vehicle10at the target speed. In some embodiments, the control system18may also selectively slow the vehicle10(e.g., via the brakes24or by applying zero or negative torque (e.g., with regenerative braking) to an output shaft) to maintain the selected speed (e.g., when the vehicle travels downhill).

A driver controls cruise control by setting a particular speed to maintain. The vehicle10then applies forwards or reverse torque to maintain that speed. The driver may use one or more cruise control input devices (included within input devices28) to enable and control the cruise control system. In one scheme, a first switch enables cruise control. Additional switches allow the target speed of cruise control to be set to the current speed of the vehicle10or allow the target speed to be increased or decreased. If no target speed exists, then even through cruise control may be enabled, the vehicle10does not control the vehicle10to match the target speed of the cruise control system. No target speed exists either when the cruise control is first enabled and no target speed has yet been set or when the driver activates the braking system (i.e., braking causes the cruise control system to stop controlling the vehicle10to maintain the target speed).

Cruise control is useful in certain scenarios but has limited use in certain situations. For example, cruise control typically cannot be enabled when the speed of a vehicle is less than a certain threshold (e.g., 25 miles per hour).

Therefore, a new technique for controlling speed of the vehicle10is provided herein. In the discussion of this technique provided below, wherever the vehicle10is described as performing certain control functions, it should be understood that appropriate control units within the vehicle10, such as the control system18, would perform the control functions. This new technique, referred to as “smart braking,” helps compensate for a situation in which a driver might expect the vehicle to maintain a particular speed, based on the inputs of the driver to the vehicle10, but the vehicle10accelerates instead. Such a situation typically occurs when the vehicle is on a decline. The force of gravity causes the vehicle10to accelerate to a greater degree than if the vehicle10were on less of a decline or were on no decline. Often in such situations, the vehicle10speeds up in such a way that the driver may be surprised by the speed of the vehicle10upon subsequently checking that speed.

Thus, smart braking selectively activates the braking system to decelerate the vehicle10to maintain the speed of the vehicle10at or near a “current speed” upon detecting a triggering condition. The triggering condition includes one or more of the following: detecting that the driver is not activating an accelerator (which may be included in input devices28and which comprises a device, such as a pedal, that allows the driver to cause the vehicle10to accelerate) to apply acceleration but that the vehicle10is accelerating anyway; detecting that the vehicle10is on a decline (via an accelerometer that detects that the vehicle is not level); or detecting that the vehicle10is experiencing more acceleration than “normal,” given the degree to which the accelerator is being activated. “Normal” acceleration may be determined by recording the history of the acceleration of the vehicle10correlated with the level to which the accelerator is activated and comparing the current level of acceleration and accelerator activation level to this history. The history may be recorded over a time period (e.g., the previous hour), over the entire current ride (e.g., since the vehicle10was powered on), or over the lifetime of the vehicle10. The current speed is the speed of the vehicle10when the vehicle10detected the triggering condition. Upon detecting the triggering condition, the vehicle10selectively activates the braking system to maintain the speed of the vehicle10at the current speed. In some embodiments, the vehicle10activates the braking system when the accelerator is not activated, but not when the accelerator is activated, even if the triggering condition occurs when the accelerator is activated. In other words, in some embodiments, if the triggering condition occurs while the accelerator is activated, then the vehicle10will record the current speed but waits until the accelerator is no longer activated to activate the braking system. In other embodiments, the only triggering condition is when the accelerator is deactivated. In such embodiments, the vehicle10detects that the accelerator is deactivated and the vehicle is accelerating anyway, and activates the braking system to maintain the vehicle at the speed that the vehicle10was at when the accelerator was deactivated.

Note that the smart braking technique does not involve automatically applying the accelerator. Only the brake is applied to maintain a particular speed. This is in contrast with cruise control, which applies both the brake and the accelerator.

The vehicle10may apply the smart braking technique during a smart braking mode and may refrain from applying the smart braking technique when the vehicle10is not in the smart braking mode. The smart braking mode may be always set such that the vehicle10always applies the smart braking technique. Alternatively, the driver may switch the smart braking mode on or off via a control included in the input devices28such that the driver can control when the vehicle10applies the smart braking technique. In some embodiments, the smart braking mode is not activated when cruise control is activated. In some embodiments, cruise control is not activated when the smart braking technique is activated.

Some examples of operation of the smart braking system are now provided. In one example, the smart braking mode is on. The driver drives the vehicle10on flat ground towards a decline in the road. Upon reaching the decline, the driver disengages the accelerator. The vehicle10detects that despite the accelerator being disengaged, the vehicle10is still accelerating. In response to detecting that the vehicle is accelerating while the accelerator is not activated, the vehicle activates the braking system to maintain the vehicle10at a current speed. The current speed may be the speed of the vehicle when the driver disengaged the accelerator or when the vehicle10detected that the vehicle10was still accelerating despite the accelerator being disengaged.

In another example, the vehicle10is approaching a decline in the road. When the vehicle10arrives at the decline, the vehicle10detects that the vehicle10is accelerating to a greater degree than “normal,” where “normal” acceleration is determined based on the history of acceleration versus accelerator activation level for the vehicle10. This detection occurs despite the driver activating the accelerator to some degree greater than zero activation. In an example, the vehicle10may determine that the vehicle10is accelerating to a greater degree than normal by examining the average historical acceleration of the vehicle10for the current degree to which the accelerator is being activated and determining that the current acceleration of the vehicle10is above a threshold percentage (e.g., 110%, 125%) of that average. In response to detecting that the vehicle10is accelerating to a greater degree than normal, the vehicle10records the current speed of the vehicle and activates the braking system to maintain the vehicle10at that current speed.

In some examples, the vehicle10resets the current speed, such that no current speed is set for the smart braking application, upon detecting a reset condition. The reset condition may include one or more of the vehicle10detecting that the vehicle10is decelerating without the braking system activated or that the vehicle10is accelerating under a threshold amount below an average amount of acceleration for the level of accelerator activation. Resetting the current speed allows a new speed to be recorded as the current speed when the vehicle10again detects a triggering condition.

FIGS. 2A-2Cillustrate examples of the smart braking technique. InFIG. 2A, a vehicle10is driving on a flat section202of road. At some point, the driver releases the accelerator206and then the vehicle10arrives at a decline204. The vehicle10detects a triggering condition, records a current speed, and, inFIG. 2B, activates the braking system to maintain the vehicle10at the current speed. InFIG. 2C, the vehicle10detects a reset condition and resets the current speed so that the current speed can be set to something different upon again detecting a triggering condition.

The smart braking technique is used when cruise control is off. More specifically, if cruise control is set, the vehicle10maintains a particular speed regardless of whether the triggering conditions above are detected. Additionally, the smart braking technique may cease to be applied when braking is no longer needed. For example, the vehicle10may detect that the vehicle10is decelerating despite no braking being applied. In that scenario, the vehicle10would stop applying the smart braking technique.

FIG. 3is a flow diagram of a method300for operating a vehicle10in smart braking mode, according to an example. Although described with respect to the system shown and described with respect toFIGS. 1 and 2A-2C, it should be understood that any system configured to perform the method, in any technically feasible order, falls within the scope of the present disclosure.

As shown, the method300begins at step302, where the vehicle10detects a triggering condition. The triggering condition includes at least one of detecting that the driver is not activating the accelerator but that the vehicle10is accelerating anyway, detecting that the vehicle10is on a decline, or detecting that the vehicle is experiencing more acceleration than normal, given the degree to which the accelerator is being activated.

At step304, the vehicle10records the current speed. This current speed is the speed of the vehicle10at the time of recording. The purpose of recording this speed is so that the vehicle10can apply brakes to maintain the speed. Note that this smart braking technique does not involve automatically applying the accelerator. Only the brake is applied to maintain a particular speed.

At step306, the vehicle10activates the braking system to maintain the recorded speed. The braking system applies a friction brake and/or a regenerative brake to cause the vehicle to maintain speed at or near the recorded speed.

Steps308and310are optional. At step308, the vehicle10detects a reset condition. The reset condition includes one of the vehicle10detecting that the vehicle is decelerating without the braking system activated or that the vehicle is accelerating under a threshold amount below a “normal” amount of accelerating. In response to such detection, at step310, the vehicle10resets the current speed and stops applying the braking technique. The vehicle10may again apply the braking technique responsive to detecting another triggering condition.

The disclosed embodiments provide techniques for controlling a braking system of a vehicle to prevent undesirable acceleration that may occur, for example, when the vehicle is on a decline. Often, drivers may activate an accelerator to approximately the same degree regardless of slope of the road. Alternatively, drivers may realize that there is a decline in the road and may release the accelerator, but the vehicle may accelerate anyway due to the decline. Thus, when a vehicle is driving over a declining road, the vehicle may accelerate to a greater speed than desired by the driver. The techniques provided herein activate the braking system to reduce the acceleration of the vehicle to prevent such unwanted acceleration.

Having thus described the presently preferred embodiments in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiments and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.