Brake system for vehicle and method of controlling brake system

Abstract

A vehicle brake system is configured to mix a brake request signal corresponding to the level of a brake request with a variable frequency and a variable amplitude (e.g., torque tickle) when generating a signal to control the brake. The brake system includes one or more brakes configured to apply braking to one or more vehicle wheels; a memory; and a processor configured to mix a brake request signal corresponding to the level of a brake request with a variable frequency and a variable amplitude to generate a signal to control one or more brakes, wherein the variable frequency is retrieved from one or more predetermined frequencies stored in the memory, and the variable amplitude is calculated based on the level of the brake request.

Description

Technology Field

[0001] The present disclosure generally relates to an apparatus and method for controlling a vehicle. More specifically, some embodiments of the present disclosure relate to a brake system for a vehicle and a method for controlling the brake system. Background Technology

[0002] An electromechanical brake (EMB) is a brake assembly operated by electrical energy. For example, an EMB system typically provides braking of a vehicle by using a motor to which power is selectively applied in response to a signal from an electronic control unit (ECU) or a detected press of a brake input means. Generally, an EMB system may include a rotor, a brake caliper, and brake pads on the opposing sides of the rotor. The brake caliper is slidably supported on pins secured to an anchor bracket attached to a non-rotatable component of the vehicle and includes one or more piston bores, each of which accommodates a piston movable along the piston axis during brake application and brake release. Brake pads are connected to one or more electrically actuated pistons for movement between a non-braking position and a braking position in which the brake pads are moved by frictional engagement with the opposing braking surfaces of the rotor. For example, when a vehicle operator presses the brake pedal, the actuator moves the piston to make contact with one brake pad and then moves one brake pad to make contact with one side of the rotor, while the other opposing brake pad is moved to make contact with the opposite side of the rotor.

[0003] As an example rather than a limitation, such an EMB system provides the desired braking in a substantially shorter amount of time than that provided by conventional hydraulic braking systems and allows individual wheels of the vehicle or other optionally movable assemblies to be selectively controlled, thereby improving the operational effectiveness of many strategies, such as anti-slip or anti-lock braking strategies or strategies commonly referred to as integrated vehicle dynamic strategies.

[0004] The following embodiments are described with respect to these and other general considerations. Additionally, while relatively specific problems have been discussed, it should be understood that the embodiments are not limited to solving specific problems identified in the background.

[0005] The features and advantages of the present disclosure will be more easily understood and made clear from the following detailed description, which should be read together with the accompanying drawings, and from the claims appended at the end of the detailed description.

[0006] Various embodiments of the present disclosure may provide a brake system configured to mix a brake request signal corresponding to the level of the brake request with a variable frequency and variable amplitude (e.g., torque tickle) when generating a signal to control the brake. Thus, the effect of friction that directly affects clamp accuracy may be reduced. Furthermore, the torque tickle added to the brake request signal can improve the brake clamp accuracy as well as the braking performance characteristics of the vehicle. In addition, the brake can be controlled precisely so as not to require a force feedback sensor, and vehicle clamp force accuracy targets can be met without a force feedback sensor.

[0007] According to some embodiments of the present disclosure, a brake system for a vehicle comprises one or more brakes for applying braking to one or more vehicle wheels; a memory; and a processor for mixing a brake request signal corresponding to a level of brake request with a variable frequency and a variable amplitude to generate a signal for controlling one or more brakes, wherein the variable frequency is retrieved from one or more predetermined frequencies stored in the memory, and the variable amplitude can be calculated based on the level of the brake request.

[0008] The memory may store one or more predetermined frequencies of torque tickles. The processor may receive a brake request signal corresponding to the level of the brake request, calculate the amplitude of the torque tickle based on the level of the brake request, retrieve the frequency of the torque tickle from the memory, and add a torque tickle signal having the calculated amplitude of the torque tickle and the retrieved frequency of the torque tickle to the brake request signal to generate a signal for controlling one or more brakes.

[0009] Torque tickle may include periodic vibration motion.

[0010] The processor counts the time for performing a torque tickle and can add a torque tickle signal to a brake request signal during the counted time for performing the torque tickle.

[0011] The processor may start counting the time to perform a torque tickle in response to the detection of a decrease in the level of the brake request.

[0012] The processor can reset the counted time for performing a torque tickle to a preset value in response to the detection of an increase in the level of the brake request.

[0013] The processor may add a torque tick signal having a calculated amplitude of a torque tick and a searched frequency of a torque tick to a brake request signal to generate a signal for controlling one or more brakes in response to the detection that the level of the brake request is reduced.

[0014] The amplitude of the torque tickle can be calculated to be proportional to the brake request.

[0015] One or more predetermined frequencies of the torque tickle stored in memory may be 20 Hz to 50 Hz.

[0016] A signal for controlling one or more brakes may include a signal for controlling torque generated by one or more brakes.

[0017] The processor is configured to generate a torque tickle signal using the following equation:

[0018] Torque_Tickle = Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter)

[0019] Here, Torque_Tickle is the torque tickle to be added to the brake request signal, Torque_Tickle_Amplitude is the calculated amplitude of the torque tickle, Torque_Tickle_Frequency is the searched frequency of the torque tickle, and Timer_Counter is the counted time to perform the torque tickle.

[0020] According to specific embodiments of the present disclosure, a method for controlling a brake system for a vehicle may include receiving a brake request signal corresponding to a level of brake request, searching for a variable frequency to be mixed with the brake request signal corresponding to the level of brake request from one or more predetermined frequencies stored in memory, calculating a variable amplitude to be mixed with the brake request signal corresponding to the level of brake request based on the level of brake request, and mixing the brake request signal corresponding to the level of brake request with the searched variable frequency and the calculated variable amplitude to generate a signal for controlling one or more brakes configured to apply braking to one or more vehicle wheels.

[0021] The memory may store one or more predetermined frequencies of torque tickle. Calculating the variable amplitude includes calculating the amplitude of the torque tickle based on the level of the brake request, and retrieving the variable frequency includes retrieving the frequency of the torque tickle from one or more predetermined frequencies of the torque tickle stored in the memory, and mixing the brake request signal with the retrieved variable frequency and the calculated variable amplitude may include adding the torque tickle signal having the calculated amplitude of the torque tickle and the retrieved frequency of the torque tickle to the brake request signal to generate a signal for controlling one or more brakes.

[0022] Torque tickle may include periodic vibration motion.

[0023] The method may further include counting the time for performing a torque tickle and adding the torque tickle signal to the brake request signal during the counted time for performing the torque tickle.

[0024] The method may further include initiating a count of time for performing a torque tickle in response to the detection of a decrease in the level of the brake request.

[0025] The method may further include resetting the time for performing a torque tickle to a preset value in response to the detection of an increase in the level of the brake request.

[0026] The amplitude of the torque tickle can be calculated to be proportional to the brake request.

[0027] One or more predetermined frequencies of the torque tickle stored in memory may be 20 Hz to 50 Hz.

[0028] The method may further include generating a torque tickle signal using the following equation:

[0029] Torque_Tickle = Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter)

[0030] Here, Torque_Tickle is the torque tickle to be added to the brake request signal, Torque_Tickle_Amplitude is the calculated amplitude of the torque tickle, Torque_Tickle_Frequency is the searched frequency of the torque tickle, and Timer_Counter is the counted time to perform the torque tickle.

[0031] This summary is provided to introduce, in a simplified form, the selection of concepts further described in the detailed description. This summary is not intended to identify material or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Brief explanation of the drawing

[0032] FIG. 1 is a schematic diagram of a vehicle including a brake system according to one embodiment of the present disclosure. FIG. 2 is a block diagram of a controller of a brake system according to one embodiment of the present disclosure. FIG. 3 is a flowchart illustrating a method for controlling a brake system according to one embodiment of the present disclosure. FIG. 4 is a flowchart illustrating steps for counting time to perform a torque tickle according to one embodiment of the present disclosure. FIG. 5 is a graph illustrating an example of a signal in which a brake request signal and a torque tickle are mixed with the brake request signal according to one embodiment of the present disclosure. Figure 6 is a graph for illustrating hysteresis loops of a brake cycle with and without torque tickle. FIG. 7 is a cross-sectional view of a brake according to one embodiment of the present disclosure. Specific details for implementing the invention

[0033] Throughout the specification, the same reference numerals refer to the same components. This specification does not describe all elements of the embodiments, and general content in the art to which the disclosed invention pertains or content that overlaps between embodiments is omitted. The terms 'part, module, component, block' used in the specification may be implemented in software or hardware, and depending on the embodiments, a plurality of 'parts, modules, components, blocks' may be implemented as a single component, or a single 'part, module, component, block' may include a plurality of components.

[0034] Throughout the specification, when a part is described as being 'connected' to another part, this includes not only cases where they are directly connected but also cases where they are indirectly connected, and indirect connections include connections made via a wireless communication network.

[0035] Furthermore, when it is stated that a part 'includes' a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0036] Throughout the specification, when it is stated that a component is located 'on' another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0037] Terms such as "first," "second," etc., are used to distinguish one component from another, and the components are not limited by the aforementioned terms.

[0038] Singular expressions include plural expressions unless there is an obvious exception in the context.

[0039] In each step, identification codes are used for convenience of explanation and do not describe the order of the steps; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context.

[0040] In the following detailed description, reference is made to the accompanying drawings, which form part of the disclosure and illustrate specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it should be understood that other embodiments may be used and structural, logical, and electrical variations may be made without departing from the spirit and scope of the invention. Accordingly, the following detailed description should not be taken in a limiting sense, and the scope of the invention is defined only by the appended claims and their equivalents. Similar numbers in the drawings refer to similar components, which should be evident from the context of use.

[0041] The operating principle and embodiments of the disclosed invention will be described below with reference to the attached drawings.

[0042] FIG. 1 is a schematic diagram of a vehicle including a brake system according to one embodiment of the present disclosure.

[0043] Referring to FIG. 1, the vehicle (100) may include a plurality of vehicle wheels. For example, the wheels of the vehicle (100) may include a front left (FL) wheel (101), a front right (FR) wheel (102), a rear left (RL) wheel (103), and a rear right (RR) wheel (104). The brake system may include brake assemblies (110), a controller (130), and one or more sensors (150).

[0044] The brake assemblies (110) may include a plurality of brakes (111, 112, 113, 114) operably coupled to each of the four vehicle wheels (101, 102, 103, 104). Each of the brakes (111, 112, 113, 114) may be configured to apply an individual braking force to each of the vehicle wheels (101, 102, 103, 104). For example, braking may be achieved by forcing the brake pads of the brakes onto the discs of the vehicle wheels. The brakes (111, 112, 113, 114) may be operated independently via a controller (130). One exemplary embodiment of a brake (111, 112, 113, 114) is illustrated in FIG. 7, which is included in U.S. Patent Application Publication No. 2013 / 0314222, which is assigned to the assignee of the present disclosure and thereby incorporated by reference in its entirety into the present disclosure. However, any type of brake may be applied to the present disclosure.

[0045] The operation of the brake assemblies (110) may involve the vehicle operator pressing the driver-operated brake pedal (120), which is detected by the brake pedal sensor (141). The brake pedal sensor (141) monitors the position, movement force, and / or state of the brake pedal (120) and provides the controller (130) with a brake request signal (also known as driver braking intent) indicating the level of a brake request, such as a requested brake torque.

[0046] Additionally, the controller (130) may generate a brake request signal to control the brake assemblies (110) according to control algorithms, software, or instructions stored in memory, which are not limited to, for example, autonomous driving software for automatically controlling the vehicle or assisting the vehicle operator, advanced driver assistance systems (ADAS), traction slip control, anti-lock brake control, electronic stability control, and any other algorithm or computer implementation system.

[0047] Various sensors (150) may be associated with a controller (130) and may be used alone or in various combinations depending on the conditions. The sensors may include any combination of components, devices, modules, systems, etc., for measuring wheel speed, wheel acceleration, vehicle speed, vehicle acceleration, friction brake torque, regenerative brake torque, tire pressure, vehicle mass, yaw, yaw rate, steering angle, road slope, weather conditions, or any other vehicle operation parameters that can be used to control the vehicle (100). One or more of the sensors may be embodied in hardware, software, firmware, or a combination thereof, and may be electronically coupled to the controller (130) via electronic connections, via other electronic components such as other devices, modules, and systems, via a vehicle communication bus or network, or via some other communication. Other sensors may be used to complement or verify the decisions of other sensors. For example, some sensors may be used to check image or radar signals, and vice versa.

[0048] The controller (130) may be programmed to perform various functions and control various outputs in response to information received from a plurality of sensors. The controller (130) is electrically connected to various elements of the vehicle (100), not limited to brake assemblies (110) including, for example, brakes (111, 112, 113, 114), sensors (150), and memory (135). The controller (130) is configured to receive various input signals, not limited to, for example, signals from a plurality of sensors installed within the vehicle (100). During the braking operation of the brake assembly (110), the controller (130) may continuously receive signals from the sensors (150) or receive telemetry information from the sensors (150) after a braking event occurs. The controller (130) is configured to output control signals to the brake assemblies (110) to control the brakes (111, 112, 113, 114).

[0049] The controller (130) may be, for example, a device using mechanical, hydraulic, pneumatic, or electronic technologies, and / or a microprocessor or computer, but is not limited thereto, which monitors and physically changes the operating conditions of a given dynamic system. In one example, the controller (130) may include an Allen Bradley brand programmable logic controller (PLC). The controller (130) may include one or more processors (e.g., 210 in FIG. 2) for performing calculations to process inputs and / or outputs. The controller (130) may include memory (e.g., 240 in FIG. 2) for storing preset or predetermined values ​​for controlling the brake system and values ​​processed by the processor, or for storing the results of previous processing. The controller (130) may also be configured to accept inputs and outputs from a plurality of input and output devices for receiving or transmitting values. Such devices include other computers, keyboards, mice, visual displays, industrial equipment, and systems or machinery of all types and sizes. For example, the controller (130) may control a network or network interface to perform various network communications upon request. The network interface may be part of the controller (130) or may be characterized as being separate from and remote from the controller (130). The controller (130) may be a single physical computing device having functions similar to a desktop computer or a laptop computer, or may consist of multiple devices of the same type, such as a group of servers operating as one device within a networked cluster, or a heterogeneous combination of different computing devices operating as a single controller and linked together by a communication network. The communication network connected to the controller (130) may also be connected to a wider network such as the Internet.Accordingly, the controller (130) may include one or more physical processors or other computing devices or circuits, and may also include any suitable type of memory. The controller (130) may also be a virtual computing platform having an unknown or varying number of physical processors and memories or memory devices. Accordingly, the controller (130) may be physically located within a single geographical location or may be physically spread across multiple locations widely scattered with multiple processors linked together by a communication network and operate as a single controller. Multiple controllers or computing devices may be configured to communicate with each other or with other devices via wired or wireless communication links to form a network. Network communications may pass through various controllers acting as network devices, such as switches, routers, firewalls, or other network devices or interfaces, before passing through other larger computer networks, such as the Internet. Communications may also be transmitted through the network, such as wireless data transmissions carried over transmission lines or electromagnetic waves through free space. Such communications include using WiFi or other wireless local area networks (WLAN) or cellular transmitters / receivers to transmit data.

[0050] The memory (135) stores characteristic data, information, values ​​(parameters, curves, maps, patterns, tables, and / or thresholds), for example, brake characteristic parameters for controlling each of the brakes (111, 112, 113, 114). The brake characteristic parameters may include parameters related to braking force and / or braking time for controlling each of the brakes (111, 112, 113, 114). For example, initial parameters are determined based on results having various parameters tested in an assumed test environment and are stored in the memory (135). The controller (130) may change the initial parameters by calibration operations. The memory (135) may be a standalone memory associated with the controller (130) as shown in FIG. 1, or it may be integrated within the controller (130) as shown in FIG. 2.

[0051] FIG. 2 is a block diagram of a controller of a brake system according to one embodiment of the present disclosure, and FIG. 3 is a flowchart illustrating a method for controlling a brake system according to one embodiment of the present disclosure.

[0052] The controller (130) of FIG. 1 may include a processor (210) and memory (240). However, the memory (240) may not be included in the controller (130). For example, the memory (240) of FIG. 2 may be implemented as the memory (135) of FIG. 1, which is a standalone memory associated with the controller (130). Alternatively, the memory (240) may be integrated into the processor (210).

[0053] The configurations and operations of the memory (240) of FIG. 2 may be identical or similar to those of the memory (135) of FIG. 1 described above. Identical descriptions of the memory (240) of FIG. 2 will be omitted.

[0054] The controller (130) may be a central controller as illustrated in FIG. 1, but the present disclosure is not limited thereto. Alternatively, the controller (130) may be implemented as a plurality of controllers having a storage medium and a suitable amount of programmable memory, which may store and execute one or more algorithms or methods to achieve control of the brakes (111, 112, 113, 114), and each brake (111, 112, 113, 114) may have a respective controller therein or may be operably connected to a respective controller controlling the corresponding brake. For example, each controller may be a controller located in an EMB unit at each corner of the vehicle (100). However, one or more controllers according to the present disclosure may be placed at any suitable location of the vehicle (100) and implemented in any suitable manner.

[0055] The processor (210) may be a computer processor in which data and signal processing logic and control are included on one or more integrated circuits. The processor (210) may include arithmetic, logic, and control circuits necessary to perform the functions of a central processing unit (CPU). The processor (210) may include, for example, a microprocessor having a large-scale integrated circuit (LSI) that includes a control program for controlling a brake system and a ROM in which various constants are stored, but is not limited thereto. The processor (210) may include a CPU for reading control programs from the ROM to execute necessary operations, and a RAM that temporarily stores various data related to operations executed within the CPU and allows the CPU to read the data stored therein. The processor (210) may include a clock generator that generates clock pulses in response to various operations being executed in the processor (210), and input-output devices for controlling various input-output signals to and from the processor (210).

[0056] In step 302, the processor (210) receives a brake request signal (IN). The brake request signal (IN) is generated to correspond to the level of the brake request. The brake request signal (IN) may indicate the brake torque required by the driver. Specifically, the brake request signal (IN) has a magnitude corresponding to the level of braking force input by the driver, which can be detected by the brake pedal sensor (141) of FIG. 1. Other techniques and methods may be used to generate the brake request signal (IN). For example, the brake request signal (IN) corresponding to the level of the brake request may be generated according to driving assistance or autonomous driving algorithms or software instructions for controlling the vehicle (100) and / or brake assemblies (110), such as autonomous driving software for automatically controlling the vehicle or assisting the vehicle operator, advanced driver assistance systems (ADAS), traction slip control, anti-lock brake control, electronic stability control, and any other algorithm or computer-implemented system.

[0057] The processor (210) counts the time to perform a torque tickle (step 305). The torque tickle may be a periodic vibrating motion. For example, the torque tickle is a continuous, fast, slight shaking motion. The torque tickle may have a variable amplitude and a variable frequency, which will be described in more detail later.

[0058] A detailed exemplary embodiment of step 305 is described in FIG. 4. FIG. 4 is a flowchart illustrating steps for counting time to perform a torque tickle according to one embodiment of the present disclosure. In the exemplary embodiment of FIG. 4, the processor (210) detects an increase and / or decrease in the level of a brake request signal (IN) (step 402). When the processor (210) detects that the level of the brake request signal (IN) is decreasing (step 405), the processor (210) begins counting time to perform a torque tickle (step 407). Time to perform a torque tickle may be counted until the decrease in the level of the brake request signal (IN) stops (e.g., when the level of the brake request does not increase or change). Then, when an increase in the level of the brake request is detected (step 410), the processor (210) resets the counted time to perform a torque tickle to a preset value, for example, not limited to zero (0) (step 412).

[0059] Accordingly, according to some exemplary embodiments of the present disclosure, a torque tickle may be mixed with a commanded brake torque only when the level of the brake request is decreasing, while the brake torque is applied to a vehicle wheel, such as a rotor, without a torque tickle during the increase in the level of the brake request.

[0060] Returning to FIGS. 2 and 3, the amplitude calculator (220) of the processor (210) calculates the variable amplitude of the torque tickle signal to be mixed with the brake request signal (IN) (step 307). The variable amplitude of the torque tickle signal can be calculated based on the level of the brake request. For example, the variable amplitude of the torque tickle signal can be proportional to the level of the brake request. The amplitude of the torque tickle can be calculated according to Equation (1):

[0061] Torque_Tickle_Amplitude = (Brake_Request) * (Dither_Gain) ...(1)

[0062] Here, Torque_Tickle_Amplitude is the amplitude of the torque tickle, Brake_Request is the level of the brake request, and Dither_Gain is an adjustable parameter (e.g., a parameter that is predetermined through experimental testing and / or subsequently changed by calibration actions).

[0063] The memory (240) is configured to store one or more predetermined or preset frequencies of the torque tickle signal. The predetermined or preset frequencies of the torque tickle signal may be adjustable parameters that are predetermined through experimental testing and / or subsequently changed by calibration operations. The predetermined or preset frequencies of the torque tickle signal may be set to 20 Hz to 50 Hz. A frequency range of 20 Hz to 50 Hz of the torque tickle signal can improve the accuracy of the brake clamp force for a brake request. In step 310, the processor (210) retrieves one of the predetermined frequencies of the torque tickle signal from the memory (240) to be mixed with the brake request signal (IN).

[0064] The brake control signal generator (260) of the processor (210) generates a signal (OUT) for controlling the brakes (111, 112, 113, 114) by mixing the brake request signal (IN) with a variable amplitude calculated by the amplitude calculator (220) of the processor (210) and a variable frequency retrieved from the memory (240) (step 312). For example, the signal (OUT) for controlling the brakes (111, 112, 113, 114) may be a signal for controlling the torque applied to the vehicle wheels (101, 102, 103, 104) by the brakes (111, 112, 113, 114). The brake control signal generator (260) of the processor (210) can add a torque tickle signal to the brake request signal (IN), having an amplitude calculated by the amplitude calculator (220) of the processor (210) in step 307 and a frequency retrieved from the memory (240) in step 310. For example, the torque tickle signal can be generated using Equation (2):

[0065] Torque_Tickle = Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter) ...(2)

[0066] Here, Torque_Tickle is a torque tickle to be added to the brake request signal, Torque_Tickle_Amplitude is the amplitude of the torque tickle calculated in step 307, Torque_Tickle_Frequency is the frequency of the torque tickle retrieved in step 310, and Timer_Counter is the time to perform the torque tickle counted in step 305.

[0067] The signal of the torque tickle generated using Equation (2) is added to the brake request signal (IN) to generate a signal (OUT) for controlling the brakes (111, 112, 113, 114). For example, the signal (OUT) for controlling the brakes (111, 112, 113, 114) may represent a brake torque generated by the actuator (700) of FIG. 7, which includes a motor (710) and a gear assembly (720). In this case, the signal for controlling the brakes (111, 112, 113, 114) may be generated according to Equation (3):

[0068] Actuator_Command = Commanded_Torque + Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter) ...(3)

[0069] Here, Actuator_Command is the torque generated by the brake actuator, Commanded_Torque is the commanded clamping force applied to the rotor of the vehicle wheel, Torque_Tickle_Amplitude is the amplitude of the torque tickle, Torque_Tickle_Frequency is the frequency of the torque tickle, and Timer_Counter is the counted time to perform the torque tickle.

[0070] Here, the Commanded_Torque of Equation (3) can be calculated using Equation (4):

[0071] Commanded_Torque = Brake_Request / (Gear_Ratio * System_Efficiency) ...(4)

[0072] Here, Commanded_Torque is the commanded clamping force, Brake_Request is the level of the brake request, Gear_Ratio is the gear ratio of the brake, and System Efficiency is the efficiency of the brake actuator.

[0073] Examples of brake request signals and signals for controlling the brake are illustrated in FIG. 5, wherein a torque tick with variable frequency and variable amplitude is mixed with the brake request signal. Line (510) represents the brake request signal (IN), and line (520) represents the signal (OUT) for controlling the brake (111, 112, 113, 114). When the brake request signal (IN) represented by line (510) is received, the processor (210) generates the signal (OUT) for controlling the brake (111, 112, 113, 114), represented by line (520), by mixing the torque tick with variable frequency and variable amplitude with the brake request signal (IN) in the manner described above. In the example illustrated in Fig. 5, the torque tickle is mixed with the brake request signal (IN) only when the level of the brake request is decreasing, but the torque tickle is not mixed with the brake request signal (IN) during the increase in the level of the brake request.

[0074] In step 315, the processor (210) outputs a signal (OUT) for controlling the brake (111, 112, 113, 114) generated in step 312 so that the controller (130) can control the brake (111, 112, 113, 114) using the signal (OUT) for controlling the brake (111, 112, 113, 114) for the time to perform a torque tickle, which is counted in step 305. The processor (210) can command the actuator (710) of the brake (111, 112, 113, 114) to cause the brake (111, 112, 113, 114) to generate a brake torque requested by the brake request received in step 302.

[0075] FIG. 6 illustrates that specific embodiments of the present disclosure, which generate a signal for controlling a brake by mixing a brake request signal corresponding to the level of the brake request with a variable frequency and a variable amplitude (e.g., torque tickle), can reduce system hysteresis and improve the accuracy of brake torque control relative to the original clamp force request. Line 610 indicates the application portion of a braking cycle in which the brake torque increases. As previously described, some embodiments of the present disclosure apply brake torque to a vehicle wheel, such as a rotor, without torque tickle during the increase in the level of the brake request. Line 620 indicates the hysteresis loop of the release portion of the braking cycle with torque tickle, line 630 indicates the braking cycle in which torque tickle begins to be performed in an intermediate cycle, and line 640 indicates the hysteresis loop of the release portion of the braking cycle without torque tickle. Line 620, representing the hysteresis loop of the release portion of the braking cycle having torque tickle, is located closer to line 610, representing the application portion of the braking cycle, than line 640, representing the hysteresis loop of the release portion of the braking cycle not having torque tickle. Thus, by mixing the torque tickle with the commanded brake torque, hysteresis during brake release can be reduced.

[0076] According to some embodiments of the present disclosure, when generating a signal to control the brake, by mixing a brake request signal corresponding to the level of the brake request with a variable frequency and variable amplitude (e.g., torque tickle), the effect of friction that directly affects clamp accuracy can be reduced. Thus, the torque tickle added to the brake request signal can improve the brake clamp accuracy as well as the braking performance characteristics of the vehicle.

[0077] Conventional brake systems require force feedback sensors and may therefore have delayed feedback due to the signals from the force feedback sensors. However, according to specific embodiments of the present disclosure, by adding a signal of a torque tickle having a variable frequency and variable amplitude to a brake request signal to generate a signal for controlling the brake, the brake system can accurately control the brake without requiring a force feedback sensor, and vehicle clamp force accuracy targets can be met without a force feedback sensor. Due to the elimination of force feedback sensors in the electric brake system of some embodiments of the present disclosure, the electrical architecture of the electric brake system can be simplified and the manufacturing cost of the vehicle's brake system can be reduced. Furthermore, due to the reduced latency when applying the clamp force relative to the clamp force capability, the system reliability and braking performance of the brake control system according to specific embodiments of the present disclosure can be improved.

[0078] As understood by a person skilled in the art, the embodiments of the present disclosure may be embodied as a system, method, or computer program product. Accordingly, the embodiments of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware embodiments which may generally all be referred to herein as “circuit,” “module,” or “system.” Furthermore, the embodiments of the present disclosure may take the form of a computer program product embodied within one or more computer-readable media(s) that embody computer-readable program code. The amplitude calculator (220) and the brake control signal generator (260) may be a hardware-based unit, a software-based unit, or a combination of hardware and software. A hardware-based unit may include embedded components such as chipsets, specialized circuits, and one or more memory devices, while a software-based unit may be part of program code or linked to program code containing specific programmed instructions, which may be loaded into memory. The amplitude calculator (220) and the brake control signal generator (260) may be designed to implement or execute one or more of the aforementioned specific functions or routines.

[0079] Embodiments of the present disclosure may include or utilize a special-purpose or general-purpose computer comprising computer hardware, such as one or more processors and system memory, as discussed in more detail above, for example. Embodiments within the scope of the present disclosure also include physical and other computer-readable media for carrying or storing computer-executable instructions and / or data structures. Such computer-readable media may be any available media that can be accessed by a general-purpose or special-purpose computer system. Computer-readable media storing computer-executable instructions are computer storage media (devices). Computer-readable media carrying computer-executable instructions are transmission media. Accordingly, by example rather than limitation, embodiments of the present disclosure may include at least two distinctly different types of computer-readable media: computer storage media (devices) and transmission media.

[0080] Computer storage media (devices) include RAM, ROM, EEPROM, CD-ROM, solid-state drives (“SSDs”) (e.g., based on RAM), flash memory, phase change memory (“PCM”), other types of memory, other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other media that can be used to store desired program code means in the form of computer executable instructions or data structures and can be accessed by a general-purpose or special-purpose computer.

[0081] Furthermore, upon reaching various computer system components, means of program code in the form of computer-executable instructions or data structures can be automatically transferred from transmission media to computer storage media (devices) (or vice versa). For example, computer-executable instructions or data structures received via a network or data link may be buffered in RAM within a network interface module (e.g., "NIC") and then eventually transferred to computer system RAM and / or to less volatile computer storage media (devices) in the computer system. RAM may also include solid-state drives (SSDs or PCIx-based real-time memory hierarchy storage, e.g., FusionIO). Therefore, it should be understood that computer storage media (devices) may also (or even primarily) be included in computer system components utilizing transmission media.

[0082] Those skilled in the art will understand that the present disclosure may be implemented in network computing environments having many types of computer system configurations, including personal computers, desktop computers, laptop computers, message processors, handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile phones, PDAs, tablets, pagers, routers, switches, various storage devices, etc. The present disclosure may also be implemented in distributed system environments where local and remote computer systems are linked through a network (by hardwired data links, by wireless data links, or by a combination of hardwired and wireless data links) and both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

[0083] Embodiments of the present disclosure may also be implemented in cloud computing environments. In this description and in the claims below, “cloud computing” is defined as a model for enabling ubiquitous and convenient on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned through virtualization, released with minimal management effort or service provider interaction, and then scaled accordingly. The cloud model may consist of various characteristics (e.g., on-demand self-service, wide area network access, resource pooling, rapid elasticity, metering services, etc.), service models (e.g., Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure as a Service (IaaS), and deployment models (e.g., private cloud, community cloud, public cloud, hybrid cloud, etc.). The databases and servers described in this disclosure may be included in the cloud model.

[0084] Furthermore, where appropriate, the functions described herein may be performed by one or more of hardware, software, firmware, digital components, or analog components. For example, one or more application-specific integrated circuits (ASICs) may be programmed to perform one or more of the systems and procedures described herein. Specific terms are used throughout the specification and claims to refer to specific system components. As understood by a person skilled in the art, components may be referred to by different names. This disclosure is not intended to distinguish components that have different names but do not have different functions.

[0085] The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. As used herein, singular forms (indefinite articles (“a”), “an”) and definite article (“the”) are intended to include plural forms as well, unless the context otherwise clearly indicates. It will be further understood that the terms “include” and / or “comprising”, when used herein, designate the presence of specified features, integers, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, actions, elements, components, and / or groups thereof.

[0086] Although exemplary embodiments have been described in detail, it should be understood that various changes, substitutions, and modifications may be made herein without departing from the spirit and scope of the application as defined by the appended claims.

[0087] Furthermore, the scope of this application is not intended to be limited to specific embodiments of the processes, machines, manufactures, and material compositions, means, methods, and steps described in the specification. A person skilled in the art will readily understand from the disclosure that existing or subsequently developed processes, machines, manufactures, material compositions, means, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein may be utilized according to the embodiments and alternative embodiments. Accordingly, the appended claims are intended to include such processes, machines, manufactures, material compositions, means, methods, or steps within the scope of the claims.

Claims

Claim 1 A brake system comprising: one or more brakes for applying braking to one or more vehicle wheels; a memory; and a processor for mixing a brake request signal corresponding to a level of brake request with a variable frequency and a variable amplitude to generate a signal for controlling the one or more brakes, wherein the variable frequency is retrieved from one or more predetermined frequencies stored in the memory, and the variable amplitude mixed with the brake request signal is calculated based on the level of the brake request, and wherein the processor counts a time for performing a torque tickle in response to the detection of the level of the brake request, and during the counted time for performing the torque tickle, adds a torque tickle signal to the brake request signal. Claim 2 A brake system according to claim 1, wherein the memory stores one or more predetermined frequencies of the torque tickle; and the processor receives the brake request signal corresponding to the level of the brake request, calculates the amplitude of the torque tickle based on the level of the brake request, retrieves the frequency of the torque tickle from the memory, and adds the torque tickle signal having the calculated amplitude of the torque tickle and the retrieved frequency of the torque tickle to the brake request signal to generate a signal for controlling the one or more brakes. Claim 3 In paragraph 2, the torque tickle comprises a periodic vibration motion, in a brake system. Claim 4 delete Claim 5 A brake system according to claim 1, wherein the processor counts the time for performing the torque tickle in response to the detection of a decrease in the level of the brake request. Claim 6 A brake system according to claim 1, wherein the processor resets the counted time for performing the torque tickle to a preset value in response to the detection of an increase in the level of the brake request. Claim 7 A brake system according to paragraph 2, wherein the processor adds a torque tick signal having a calculated amplitude of the torque tick and a searched frequency of the torque tick to the brake request signal in response to a detection that the level of the brake request is reduced, for generating a signal to control the one or more brakes. Claim 8 A brake system according to paragraph 2, wherein the amplitude of the torque tickle is calculated to be proportional to the brake request. Claim 9 A brake system according to paragraph 2, wherein one or more predetermined frequencies of torque tickles stored in the memory are 20Hz to 50Hz. Claim 10 A brake system according to claim 1, wherein the signal for controlling one or more brakes includes a signal for controlling torque generated by one or more brakes. Claim 11 In paragraph 2, the processor is configured to generate the torque tickle signal using the following equation: Torque_Tickle = Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter), where Torque_Tickle is the torque tickle to be added to the brake request signal, Torque_Tickle_Amplitude is the calculated amplitude of the torque tickle, Torque_Tickle_Frequency is the searched frequency of the torque tickle, and Timer_Counter is the counted time for performing the torque tickle, a brake system. Claim 12 A method for controlling a brake system, comprising: receiving a brake request signal corresponding to a level of a brake request; searching for a variable frequency to be mixed with the brake request signal corresponding to the level of the brake request from one or more predetermined frequencies stored in memory; calculating a variable amplitude to be mixed with the brake request signal based on the level of the brake request; and mixing the brake request signal corresponding to the level of the brake request with the searched variable frequency and the calculated variable amplitude to generate a signal for controlling one or more brakes configured to apply braking to one or more vehicle wheels, and further comprising, in response to the detection of the level of the brake request, counting a time for performing a torque tickle, and adding a torque tickle signal to the brake request signal during the counted time for performing the torque tickle. Claim 13 A method for controlling a brake system according to claim 12, wherein the memory stores one or more predetermined frequencies of the torque tickle, calculating the variable amplitude includes calculating the amplitude of the torque tickle based on the level of the brake request, retrieving the variable frequency includes retrieving the frequency of the torque tickle from one or more predetermined frequencies of the torque tickle stored in the memory, and mixing the brake request signal with the retrieved variable frequency and the calculated variable amplitude includes adding a torque tickle signal having the calculated amplitude of the torque tickle and the retrieved frequency of the torque tickle to the brake request signal to generate a signal for controlling the one or more brakes. Claim 14 In claim 13, the above torque tickle is a control method of a brake system comprising periodic vibration motion. Claim 15 delete Claim 16 A method for controlling a brake system according to claim 12, further comprising counting the time for performing the torque tickle in response to the detection of a decrease in the level of the brake request. Claim 17 A method for controlling a brake system according to claim 12, further comprising resetting the time for performing the torque tickle to a preset value in response to the detection of an increase in the level of the brake request. Claim 18 A method for controlling a brake system according to claim 13, wherein the amplitude of the torque tickle is proportional to the brake request. Claim 19 A method for controlling a brake system according to claim 13, wherein one or more predetermined frequencies of the torque tickle stored in the memory are 20 Hz to 50 Hz. Claim 20 A method for controlling a brake system according to claim 13, further comprising generating the torque tickle signal using the following formula: Torque_Tickle = Torque_Tickle_Amplitude * sin(2π * Torque_Tickle_Frequency * Timer_Counter), wherein Torque_Tickle is a torque tickle to be added to the brake request signal, Torque_Tickle_Amplitude is the calculated amplitude of the torque tickle, Torque_Tickle_Frequency is the searched frequency of the torque tickle, and Timer_Counter is the counted time for performing the torque tickle.

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