Brake pedal device

Abstract

To provide a brake pedal device that can be improved in accuracy of / in operation by an occupant.SOLUTION: A brake pedal device, whose foot-operated pedal 13 performs braking operation of a braking device of a vehicle 1, is configured to comprise a vibrating part 501 that vibrates the pedal and a vibration control part 500 that makes the vibrating part vibrate the pedal in a vibration waveform including at least either of a frequency component of 10 and 50 Hz and a frequency component of 100 and 300 Hz.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a brake pedal device for performing a braking operation of a vehicle such as an automobile.

Background Art

[0002] As a technology related to a pedal-type operation device of a vehicle such as an automobile, for example, in Patent Document 1, in order to notify a driver by vibrating an accelerator pedal and a brake pedal, a reaction force is added according to a stepping operation of a stepping surface member on which the driver performs a stepping operation. A vehicle pedal device is described, which includes a reaction force adding means, a vibration means for vibrating the stepping surface member, and a vibration control means for controlling the vibration frequency of the vibration, and controls the vibration frequency of the vibration based on the resonance frequency of the stepping surface member. In Patent Document 2, in order to present information without giving discomfort or a sense of strangeness to the driver, it is described that the accelerator pedal or the like is vibrated by a vibrator according to the dangerous state of the own vehicle. Further, in accordance with the tactile sensation characteristics of humans with respect to vibration, and so that a virtual motion phenomenon is perceived by the driver, vibrations are applied to a plurality of selected vibrators in a predetermined order with respect to the detected dangerous state, and warning information indicating the detected dangerous state is presented. In Patent Document 3, in order to obtain vehicle information from a brake pedal, in a vehicle brake device that generates a braking force electrically based on the operation of the brake pedal, a reaction force actuator that applies an arbitrarily adjustable pedal reaction force to the brake pedal is provided, and information transmission regarding the vehicle is performed through the brake pedal by adjusting the pedal reaction force.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

[0004] When the driver operates the brake pedal, they sense the reaction force (pedaling force) from the spring and brake fluid pressure, as well as the vehicle's deceleration and behavior, and make fine adjustments to the braking force accordingly. However, with human manipulation, the spatial resolution becomes coarser as the reaction force decreases, and the precision of the manipulation decreases. In response to this, one could consider increasing the reaction force to the brake operation by increasing the spring constant of the spring, but in this case, the operating force required for braking would increase, causing fatigue and discomfort to the driver. In view of the above-mentioned problems, the object of the present invention is to provide a brake pedal device that can improve the accuracy of operation by the occupant. [Means for solving the problem]

[0005] To solve the above-mentioned problems, the brake pedal device of the present invention is a brake pedal device in which the braking operation of the vehicle's braking system is performed by a foot-operated pedal, comprising: an excitation unit that excites the pedal; and an excitation control unit that causes the excitation unit to excite the pedal with an excitation waveform that includes at least one of a frequency component of 10 to 50 Hz and a frequency component of 100 to 300 Hz. The braking device comprises a friction brake and a regenerative braking system, and the vibration control unit increases the amplitude of the vibration waveform in accordance with the increase in the braking force sharing ratio of the regenerative braking system. It is characterized by the following. Human perception of operating force (reaction force) involves both proprioception and cutaneous sensation, and the reaction force is perceived through the response of corresponding receptors. In the initial stages of pedaling, where the reaction force is minute, cutaneous sensation becomes dominant. According to the present invention, by vibrating the pedal in at least one of the frequency ranges in which Pacinian corpuscles, receptors that control cutaneous sensation, are highly sensitive (100 to 300 Hz), and in the frequency range in which Meissner corpuscles, are highly sensitive (10 to 50 Hz), these receptors are stimulated, making it easier for the driver to feel the pressure changes received from the soles of their feet. In particular, this effect can be obtained more effectively by vibrating the pedal in the frequency range in which Pacinian corpuscles, which are considered to have the fastest response in cutaneous sensation, are highly sensitive. This improves the spatial resolution with which the driver perceives pedal input, enabling more precise pedal control. As a result, it can improve the ease of driving and smoothness of the vehicle. Furthermore, since there is no need to increase the pedal's reaction force itself (for example, by increasing the spring constant of the spring), driver fatigue will not worsen. In particular, in the case of so-called brake-by-wire systems, which do not have a mechanical connection between the brake pedal and the braking device, or in the case of regenerative braking using a motor generator, the transmission of vibrations from the road surface and vibrations caused by the sliding of friction materials to the pedal is reduced, unlike conventional hydraulic friction brakes, which transmit vibrations from the wheel cylinder located in the wheel hub to the pedal via hydraulic piping, master cylinder, etc. In this invention, even in such cases, the above-mentioned effects can be ensured by vibrating the pedal to stimulate the skin receptors. Furthermore, according to the present invention, when the braking force sharing ratio between friction brakes and regenerative braking switches, it is possible to suppress the change in contact feel (pressure to press) due to the difference in vibration characteristics of the pedal, which can cause difficulty in operation.

[0006] In the present invention, the vibration control unit comprises a vehicle speed detection unit for detecting the vehicle speed and an operating speed detection unit for detecting the operating speed of the pedal, and the vibration control unit comprises a first gain adjustment unit for adjusting the gain of the vibration waveform in accordance with the change in vehicle speed, a second gain adjustment unit for adjusting the gain of the vibration waveform in accordance with the change in operating speed, and a gain selection unit for generating a plurality of gain values ​​of different magnitudes based on the gains adjusted by the first gain adjustment unit and the second gain adjustment unit, respectively, and the gain selection unit can be configured to select one gain value from the plurality of gain values ​​in accordance with the braking force sharing ratio between the friction brake and the regenerative braking.

[0007] In the present invention, the vehicle speed detection unit is provided to detect the vehicle speed, and the vibration control unit can be configured to increase the amplitude of the vibration waveform in accordance with the increase in the vehicle speed. According to this, even if the amplitude of vibrations transmitted from the road surface increases with increasing vehicle speed, the above-mentioned effect can be ensured by increasing the amplitude of the excitation waveform in accordance with this increase.

[0008] In the present invention, the operating speed detection unit is provided to detect the operating speed of the pedal, and the vibration control unit can be configured to increase the amplitude of the vibration waveform in accordance with the increase in the operating speed. According to this, by increasing the amplitude of the excitation waveform in accordance with the increasing pedal operating speed, it is possible to effectively improve the driver's perception of the reaction force when pressing and releasing the pedal. In particular, when the operating speed is fast, increasing the excitation amplitude emphasizes the feeling of reaction force (pressure), allowing the driver to perceive a change in accordance with the operating speed, and this can act as a damping term.

[0009] In the present invention, a vibration input detection unit is provided for detecting vibration input from the road surface, and the excitation control unit can be configured to increase the amplitude of the excitation waveform in accordance with the increase in the amplitude of the vibration input. According to this, even if vibrations transmitted from the road surface increase due to factors such as a rough road surface or tire pattern, the above-mentioned effects can be ensured by increasing the amplitude of the excitation waveform. Here, as the vibration input detection unit, for example, an acceleration sensor that detects the acceleration of the unsprung portion of the vehicle (the part that moves relative to the vehicle body in accordance with the stroke of the suspension system), or a torque sensor that detects the torque acting on the steering shaft in a power steering system can be used. Here, the vibration control unit can be configured to extract a specific frequency band of vibration input from the road surface (typically a band including 100 to 300 Hz) and increase the amplitude of the excitation waveform in accordance with the increase in amplitude in the extracted band. [Effects of the Invention]

[0010] As described above, the present invention provides a brake pedal device that can improve the accuracy of operation by the occupant. [Brief explanation of the drawing]

[0011] [Figure 1]It is a diagram schematically showing a system configuration of a vehicle having an embodiment of a brake pedal device to which the present invention is applied. [Figure 2] It is a schematic diagram showing a configuration of a pedal unit in an embodiment. [Figure 3] It is a diagram schematically showing a configuration of a vibrator control unit in an embodiment. [Figure 4] It is a diagram schematically showing an example of a vibration waveform in an embodiment. [Figure 5] It is a diagram schematically showing the timing of an electric pulse emitted by a receptor when the skin receives pressure. [Figure 6] It is a diagram showing a sensitivity distribution with respect to frequencies of Pacinian corpuscles and Meissner corpuscles. [Figure 7] It is a diagram schematically showing an example of gain adjustment in a first gain adjustment unit. [Figure 8] It is a diagram schematically showing an example of gain adjustment in a second gain adjustment unit. [Figure 9] It is a diagram schematically showing an example of an output history of an acceleration sensor. [Figure 10] It is a diagram schematically showing a method for calculating a torque amplitude in a vibration amplitude calculation unit. [Figure 11] It is a diagram schematically showing an example of gain adjustment in a third gain adjustment unit. [Figure 12] It is a diagram showing an example of a correlation between an operation amount and a reaction force of a brake pedal.

MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, an embodiment of a brake pedal device to which the present invention is applied will be described. The brake pedal device of the embodiment is, for example, an automobile such as a passenger car, and performs a brake operation of an electric vehicle having a regenerative brake. FIG. 1 is a diagram schematically showing a system configuration of a vehicle having the brake pedal device of the embodiment. In FIG. 1, solid lines indicate electrical connections, and broken lines indicate hydraulic transmission of brake fluid. Figure 2 is a schematic diagram showing the configuration of the pedal section in the embodiment.

[0013] Vehicle 1 includes a brake pedal 10 (see Figure 2), a brake control unit 100, a hydraulic control unit 200, a motor-generator control unit 300, a power steering control unit 400, a vibrator control unit 500, and the like. Each of these units comprises a microcontroller having an information processing unit such as a CPU, a storage unit such as RAM or ROM, an input / output interface, and a bus to connect them. Furthermore, each unit can communicate with one another, either via an in-vehicle LAN such as a CAN communication system, or directly.

[0014] The brake pedal 10 shown in Figure 2 is a foot-operated control unit used by the driver to perform braking operations. The brake pedal 10 includes a bracket 11, a lever portion 12, a tread portion 13, and the like. The bracket 11 is a base that supports the lever portion 12 so that it can rotate around a rotation axis along the vehicle width direction. The bracket 11 has a spring (not shown) that biases the lever portion 12 in the restoring direction (towards the initial position). The bracket 11 is attached to a toe board (not shown), which is a bulkhead located at the front of the passenger compartment. The lever portion 12 is a member that protrudes downward and diagonally backward from the bracket 11. The tread portion 13 is located at the tip of the lever portion 12 (the end opposite to the bracket 11 side) and is the part that comes into contact with the underside of the occupant's foot 14.

[0015] The brake control unit 100 coordinately controls the hydraulic friction brake and the regenerative braking system in response to the operation of the brake pedal 10. Furthermore, the brake control unit 100 has functions for anti-lock brake control and behavior stabilization control. Anti-lock brake control periodically reduces the braking force on a wheel when it detects wheel lock, which occurs when the wheel's rotation becomes stuck during braking. Vehicle stabilization control generates a yaw moment in the restoring direction by using the difference in braking force between the left and right wheels when understeer or oversteer occurs. The brake control unit 100 is connected to a vehicle speed sensor 101, an acceleration sensor 102, a brake pedal sensor 110, and a reaction force generating device 120. Furthermore, the brake system of vehicle 1 also includes a master cylinder 130.

[0016] The vehicle speed sensor 101 is mounted in a hub bearing housing (not shown) that rotatably supports the wheels and generates a vehicle speed signal corresponding to the rotational angular velocity of each wheel. The brake control unit 100 calculates the vehicle speed (vehicle speed) of vehicle 1 based on the output of the vehicle speed sensor 101.

[0017] The acceleration sensor 102 is located in the so-called unsprung portion of a suspension device (not shown) that supports the wheel so as to be able to stroke relative to the vehicle body. The acceleration sensor 102 detects the vertical acceleration of a component located on the lower side of a spring, such as a suspension arm or a hub bearing housing. The acceleration sensor 102 is a vibration input detection unit that detects vibration input from the road surface. Furthermore, the brake control unit 100 is equipped with a vehicle body longitudinal acceleration sensor, a vehicle body lateral acceleration sensor, a yaw rate sensor, and the like (not shown) for the purpose of the aforementioned behavior stabilization control.

[0018] The brake pedal sensor 110 has an encoder that detects the rotational angle position of the lever portion 12 of the brake pedal 10. Alternatively, instead of such an encoder, a rod-type potentiometer or a pressure gauge may be used to detect the amount of movement of the brake pedal 10. The brake pedal sensor 110 is located on the bracket 11. The brake control unit 100 detects the amount of forward movement (pressure) of the tread surface 13 from its initial position based on the output of the brake pedal sensor 110.

[0019] The reaction force generating device 120 generates a reaction force in the direction that returns the tread surface 13 to its initial position (the position where it is not pressed down) in response to a command from the brake control unit 100. The reaction force generating device 120 generates a reaction force on the tread surface 13, for example, using a drive power source such as an electric actuator, when regenerative braking is used.

[0020] The master cylinder 130 pressurizes the brake fluid, which is the working fluid for the friction brake, in response to the pressing motion of the tread surface 13 of the brake pedal 10. The brake fluid pressure generated by the master cylinder 130 is transmitted to the hydraulic control unit 200 via piping.

[0021] The hydraulic control unit (HCU) 200 is a hydraulic pressure control device that has the function of individually adjusting the brake fluid hydraulic pressure of the wheel cylinder 210 of each wheel. The hydraulic control unit 200 includes an electric pump for pressurizing the brake fluid, as well as pressure boosting valves, pressure reducing valves, and pressure holding valves for controlling the brake fluid pressure in each wheel cylinder.

[0022] The hydraulic control unit 200 is connected to the master cylinder 130, wheel cylinder 210, and other components via brake fluid piping. The brake fluid pressure generated by the master cylinder 130 is transmitted to the wheel cylinder 210 via the hydraulic control unit 200. The hydraulic control unit 200 has the function of overriding the brake fluid pressure generated by the master cylinder 130 to increase or decrease the brake fluid pressure of each wheel cylinder. The wheel cylinder 210 is provided on each wheel and, for example, presses the brake pad against the disc rotor, generating a frictional force (braking force) corresponding to the brake fluid pressure.

[0023] Furthermore, in the regenerative cooperative control of the brake control unit 100, if the control share ratio of regenerative braking occurs or increases, the hydraulic control unit 200 is equipped with a function to reduce or shut off the hydraulic pressure of the brake fluid transmitted from the master cylinder 130. In this case, in order to give the driver a feeling that simulates the use of a hydraulic friction brake, the brake control unit 100 uses the reaction force generating device 120 to generate a reaction force on the tread surface 14.

[0024] The motor-generator control unit 300 comprehensively controls the motor-generator 310 and its auxiliary equipment. The motor generator 310 is a rotating electric machine used as a power source for the vehicle 1. The motor-generator control unit 300 includes an inverter or the like for supplying power from a power source such as a traction battery to the motor-generator 310.

[0025] The motor generator 310 can be, for example, mounted on the vehicle body (sprung mass) and transmit driving force to the wheels via a differential, drive shaft, etc., but is not limited to this configuration; for example, it may be an in-wheel motor. The motor-generator control unit 300 switches between a drive mode in which the motor-generator 310 generates output torque and a regenerative power generation mode in which the motor-generator 310 performs regenerative power generation, absorbs torque transmitted from the wheels, and generates braking force.

[0026] In drive mode, the motor-generator control unit 300 controls the motor-generator 310 so that the actual torque it generates matches the required torque, which is set based on the amount of accelerator pedal operation (not shown). In regenerative power generation mode, the motor-generator control unit 300 controls the absorption torque in the motor-generator 310 according to the required braking force commanded by the brake control unit 100.

[0027] The power steering control unit 400 comprehensively controls an electric power steering system that provides assist force in response to the driver's steering input and steering force during automatic steering to a steering system (not shown) that steers the steering wheels (typically the front wheels) of the vehicle 1. The power steering control unit 400 is connected to a steering angle sensor 410, a torque sensor 420, a motor 430, and other components.

[0028] The steering angle sensor 410 is a sensor (steering angle detection unit) that detects the steering angle in the steering system. The torque sensor 420 is a sensor that detects the torque applied to the steering shaft to which a steering wheel (not shown) is connected, which is operated by the driver. The power steering control unit 400 controls the assist force according to the torque detected by the torque sensor 420. Motor 430 is an electric actuator that provides assist force and steering force to the steering system and generates rack thrust. The output of the motor 430 is controlled by the power steering control unit 400.

[0029] The vibrator control unit 500 is an excitation control unit that supplies a drive current and voltage having a predetermined excitation waveform to the vibrator 501. The vibrator 501 is a vibration unit that vibrates the tread surface 13 of the brake pedal 10, etc. The oscillator 501 can, for example, have a configuration that includes a voice coil and a diaphragm that generate vibrations in response to fluctuations in the supplied voltage. For example, a small speaker can be used as the transducer 501. The transducer 501 is attached, for example, to the bracket 11 of the brake pedal 10. The vibrations from the transducer 501 are transmitted sequentially through the bracket 11, lever portion 12, and tread portion 13 to the foot 14.

[0030] Figure 3 is a schematic diagram showing the configuration of the oscillator control unit in the embodiment. The transducer control unit 500 includes a waveform generation unit 510, a first gain adjustment unit 520, a second gain adjustment unit 530, a road surface vibration monitoring unit 540, a vibration amplitude calculation unit 550, a third gain adjustment unit 560, a gain selection unit 570, and the like.

[0031] The waveform generation unit 510 generates the fundamental wave of the excitation waveform (without adjusting the gain, etc.), which is the voltage waveform of the drive power of the oscillator 501. Figure 4 is a schematic diagram showing an example of the excitation waveform in the embodiment. In Figure 4, the horizontal axis represents time, and the vertical axis represents voltage. As shown in Figure 4, the excitation waveform can be a square wave, for example, but is not limited to this and may be other waveforms.

[0032] In one embodiment, the frequency of the excitation waveform can be set to have a dominant frequency in the range of 100 to 300 Hz, for example. In this specification, the dominant frequency refers to a frequency whose amplitude is particularly large compared to the amplitudes of other frequencies. Generally, such a dominant frequency often coincides with the frequency with the largest amplitude among several eigenvalues ​​(natural frequencies). The reason is explained below.

[0033] The driver's foot 14, which touches the tread surface 13, has sensory receptors (tactile sensors) such as Merkel cells, Meissner corpuscles, and Pacinian corpuscles that acquire tactile sensations (skin sensation). Figure 5 schematically shows the timing of electrical pulses emitted by receptors when skin comes into contact with an object. In Figure 5, the horizontal axis represents time, and the vertical axis, from top to bottom, represents pressure and the electrical pulse generation state of Merkel cells, Meissner corpuscles, and Pacinian corpuscles.

[0034] Merkel cells respond relatively slowly and correspond to the DC component. Meissner bodies correspond to situations where a rate of change (velocity) of contact pressure is occurring. Since Meissner bodies always react when moving at high speeds, if a noise signal with a high sensitivity to Meissner bodies is used, it is thought that the driver will be more likely to perceive it as vibration. Pacinian corpuscles respond to moments of transient change and are considered to be the most sensitive of these receptors. Pacinian corpuscles are thought to be the dominant receptors that drivers use to sense the reaction force of micromanipulation.

[0035] Figure 6 shows the sensitivity distribution of Pacinian and Meissner corpuscles with respect to frequency. In Figure 6, the horizontal axis represents frequency, and the vertical axis represents amplitude above the threshold; a smaller value indicates better sensitivity. As shown in Figure 6, Pacinian bodies exhibit good sensitivity in the region around 100 to 300 Hz; therefore, in this embodiment, an excitation waveform having a dominant frequency within the 100 to 300 Hz frequency band is used.

[0036] The first gain adjustment unit 520 performs the first gain adjustment on the excitation waveform, as described below. The first gain adjustment involves changing the gain of the excitation waveform in accordance with the change in vehicle speed. The first gain adjustment is performed so that the level of vibration generated by the vibrator 501 is properly maintained, even if the level of vibration transmitted to the brake pedal 10 changes due to road surface vibrations or other factors in response to an increase in vehicle speed. Figure 7 is a schematic diagram showing an example of gain adjustment in the first gain adjustment section. In Figure 7, the horizontal axis represents vehicle speed, and the vertical axis represents the gain multiplied by the excitation waveform. The gain can be configured to increase, for example, in accordance with an increase in vehicle speed.

[0037] The second gain adjustment unit 530 performs a second gain adjustment on the excitation waveform after the first gain adjustment, as described below. The second gain adjustment adjusts the gain according to the operating speed of the brake pedal 10. The operating speed of the brake pedal 10 (angular velocity of rotation of the tread surface 13) can be determined, for example, by the rate of change per unit time of the hydraulic pressure generated by the master cylinder 130, or by the time derivative of the amount of operation (depression amount) of the brake pedal 10 detected by the brake pedal sensor 110.

[0038] Figure 8 is a schematic diagram showing an example of gain adjustment in the second gain adjustment section. In Figure 8, the horizontal axis represents the pedal operating speed (for example, the angular velocity of the tread surface 13), and the vertical axis represents the gain multiplied by the excitation waveform. The gain can be configured to increase, for example, in accordance with an increase in pedal operation speed. Here, the rate of increase in gain with respect to pedal operation speed is set to be larger in the region of low pedal operation speed compared to the region of high operation speed, and to gradually decrease as the pedal operation speed increases.

[0039] The road surface vibration monitoring unit 540 has the function of monitoring the output of the acceleration sensor 102 and retaining its history over a predetermined period of time. Figure 9 is a schematic diagram showing an example of the output history of an accelerometer. In Figure 9, the horizontal axis represents time, and the vertical axis represents the detected value of the acceleration sensor 102 (vertical acceleration of the unsprung mass). Data regarding the output history of the acceleration sensor 102 is provided to the vibration amplitude calculation unit 550.

[0040] The vibration amplitude calculation unit 550 applies a bandpass filter to the output of the acceleration sensor 102 provided by the road surface vibration monitoring unit 540 to extract components in a specific frequency range, and then calculates the vibration amplitude in that frequency range. Figure 10 schematically shows the method for calculating vibration amplitude in the vibration amplitude calculation unit. In Figure 10, the horizontal axis represents frequency, and the vertical axis represents the detected value from the acceleration sensor 102. A bandpass filter can be configured to extract a portion of the frequency band (for example, around 250 Hz) that is included in the 100 to 300 Hz band. The vibration amplitude A in the extracted frequency band (for example, the average value of the frequency band) is provided to the third gain adjustment unit 560.

[0041] The third gain adjustment unit 560 performs a third gain adjustment on the noise signal after the second gain adjustment, as described below. The third gain adjustment unit 560 performs a third gain adjustment based on the outputs of the road surface vibration monitoring unit 540 and the vibration amplitude calculation unit 550.

[0042] Figure 11 is a schematic diagram showing an example of gain adjustment in the third gain adjustment section. In Figure 11, the horizontal axis represents the torque amplitude calculated by the vibration amplitude calculation unit 550, and the vertical axis represents the gain multiplied by the excitation waveform. As shown in Figure 11, the third gain adjustment unit 560 increases the gain in response to an increase in the vibration amplitude from the road surface. In the third gain adjustment unit 560, if the excitation amplitude added from the vibrator 501 is ΔA and the vibration amplitude from the road surface obtained from the vibration amplitude calculation unit 650 is A, then ΔA / A can be considered to be the Weber ratio W. Therefore, by adjusting the gain so that the Weber ratio W becomes a predetermined value, it is believed that a stable effect can be obtained according to the Weber-Fechner law.

[0043] The gain selection unit 570 generates multiple gain values ​​of progressively different magnitudes based on the multiplication of the gains set by the first gain adjustment unit 520, the second gain adjustment unit 530, and the third gain adjustment unit 560, and selects one gain value from the multiple gain values ​​according to the control sharing ratio (braking force ratio) between friction brakes and regenerative braking set by the brake control unit 100. The gain selection unit 570 selects a larger gain in accordance with the increase in the control share ratio of regenerative braking.

[0044] The following describes the effect of vibration by the vibrator 501 in the brake pedal device of this embodiment. Figure 12 shows an example of the correlation between the amount of brake pedal operation and the reaction force. In Figure 12, the horizontal axis represents the amount of operation of the brake pedal 10, and the vertical axis represents the reaction force acting on the occupant's foot 14. In Figure 12, as shown by the solid line, if the reaction force rises linearly with respect to the operating force, and the rate of increase of the reaction force relative to the increase in the operating force is relatively small, the reaction force becomes minute in the region where the amount of operation of the brake pedal 10 is small. As a result, the area on which pressure is transmitted to the sole of the driver's foot becomes minute, making it difficult for the driver to accurately perceive the reaction force.

[0045] In contrast, as shown by the dashed line in Figure 12, if the rate of increase of the reaction force relative to the increase in the operating force is made relatively large, the reaction force can be increased even in the region where the amount of operation of the brake pedal 10 is small, which is advantageous in terms of operability in such a region. However, in this case, the force required to operate the brake pedal 10 becomes greater, raising concerns that it may lead to driver fatigue. Therefore, as shown by the dashed line in Figure 12, it is also possible to increase the rate of increase of the reaction force in relation to the increase in the operating force only in the region where the amount of manipulation is relatively small, and reduce the rate of increase in other regions. However, in this case, the linearity of the reaction force with respect to the amount of input is compromised, raising concerns that the driver may feel unnaturalness or find it difficult to drive.

[0046] In contrast, according to this embodiment, by vibrating the tread surface 13 of the brake pedal 10 with an excitation waveform having a dominant frequency in the 100 to 300 Hz frequency band, in which Pacinian corpuscles are highly sensitive, it is possible to stimulate the receptors in the occupant's foot 14 and enhance the pressure received by the foot 14 from the tread surface 13 without increasing the actual reaction force of the brake pedal 10. As a result, even with a brake pedal 10 that has relatively little reaction force and is less likely to cause fatigue, the driver can improve the spatial resolution when sensing the amount of movement of the brake pedal 10, and operate the brake pedal 10 precisely.

[0047] According to the embodiment described above, the following effects can be obtained. (1) By vibrating the tread surface 13 of the brake pedal 10 in a frequency band in which Pacinian corpuscles, which are receptors that control skin sensation, are particularly sensitive to Pacinian corpuscles, these receptors are stimulated, making it easier for the driver to feel the pressure changes received through the soles of their feet 14. This improves the spatial resolution with which the driver perceives the amount of pressure applied to the brake pedal 10, enabling more precise braking. As a result, the ease of driving and smoothness of the vehicle 1 can be improved. Furthermore, since there is no need to increase the reaction force of the brake pedal 10 itself (for example, by increasing the spring constant of the spring), driver fatigue will not worsen. In particular, in the case of regenerative braking where the transmission of brake fluid hydraulic pressure between the master cylinder 130 connected to the brake pedal 10 and the wheel cylinder 210 of the friction brake is interrupted, the transmission of vibrations from the road surface and vibrations caused by the sliding of the friction material from the wheel cylinder 210 to the brake pedal 10 via hydraulic piping, the master cylinder 130, etc. is reduced. In this embodiment, even in such cases, the above-mentioned effects can be ensured by vibrating the brake pedal 10 to stimulate the skin receptors. (2) By increasing the amplitude of the excitation waveform in accordance with the increase in the braking force sharing ratio of the regenerative braking system, it is possible to suppress the change in contact feel (pressure to press) due to the difference in vibration characteristics of the pedal when switching between the control sharing ratio of the friction brake and the regenerative braking system, which can make operation difficult. (3) As the amplitude of vibrations transmitted from the road surface increases with increasing vehicle speed, the above-mentioned effects can be ensured by increasing the amplitude of the excitation waveform. (4) By increasing the amplitude of the excitation waveform in accordance with the operating speed of the brake pedal 10, the driver's perception of the reaction force when pressing down and releasing the brake pedal 10 can be effectively improved. In particular, when the operating speed is fast, increasing the excitation amplitude emphasizes the feeling of reaction force (pressure), allowing the driver to perceive a change in accordance with the operating speed, and this can act as a damping term. (5) By increasing the amplitude of the excitation waveform in response to an increase in the amplitude of vibration input from the road surface, the above-mentioned effects can be ensured even when vibrations transmitted from the road surface increase due to, for example, a rough road surface or tire pattern shape.

[0048] (modified version) The present invention is not limited to the embodiments described above, and various modifications and changes are possible, all of which fall within the technical scope of the present invention. (1) The brake pedal device, brake device, and vehicle configuration are not limited to the embodiments described above and can be modified as appropriate. (2) In this embodiment, the brake fluid pressure of the hydraulic friction brake is generated by a master cylinder that is linked to the brake pedal, but the present invention is not limited to this and can also be applied to vehicles with a so-called brake-by-wire system in which the brake fluid pressure is generated by an actuator alone. (3) In the embodiments, the vehicle was, for example, an electric vehicle such as a battery EV that uses only an electric motor generator as a power source for driving. However, the present invention can also be applied to vehicles that use only an internal combustion engine as a power source for driving and whose service brakes used during driving are only friction brakes such as hydraulic or electric brakes. It can also be applied to engine-electric hybrid vehicles (HEVs). (4) In this embodiment, vibrations from the road surface are detected based on the acceleration of the unsprung portion of the suspension device, but the method for detecting vibrations from the road surface is not limited to this and can be changed as appropriate. For example, a vibration pickup may be installed in the brake fluid piping (brake line) connected to the wheel cylinder located in the unsprung portion. Alternatively, vibrations from the road surface may be detected based on the output of the torque sensor of the power steering system. (5) In this embodiment, a square wave is used as the excitation waveform, but it is not limited to this, and other waveforms of noise signals such as sine waves, triangular waves, and random waves may be used. Also, the gain adjustment method is not limited to the configuration of this embodiment and can be changed as appropriate. (6) The specific configuration of the vibrator (excitation unit), the principle of excitation, and the installation location are not limited to this embodiment and can be changed as appropriate. (7) The configuration of the brake pedal in the embodiment is an example, and the present invention can be applied to other forms of brake pedals. For example, the present invention can be applied to so-called organ-type brake pedals in which a pivot shaft for rotating the tread is provided below the tread. [Explanation of symbols]

[0049] 1 Vehicle 10 Brake pedal 11 Bracket 12 Lever part 13 Tread surface 14 Foot 100 Brake control unit 101 Vehicle speed sensor 102 Acceleration sensor 110 Brake pedal sensor 120 Reaction force generating device 130 Master cylinder 200 Hydraulic Control Unit 210 Wheel Cylinder 300 Motor Generator Control Unit 310 Motor Generator 400 Power steering control unit 410 Steering angle sensor 420 Torque sensor 430 Motor 500 Transducer control unit 501 Transducer 510 Waveform generation unit 520 First gain adjustment unit 530 Second gain adjustment unit 540 Road surface vibration monitor unit 550 Vibration amplitude calculation unit 560 Third gain adjustment unit 570 Gain Selection Section

Claims

1. A brake pedal device in which the braking system of a vehicle is operated by a foot-operated pedal, A vibration unit that vibrates the pedal, The vibration unit includes a vibration control unit that vibrates the pedal with a vibration waveform that includes at least one of a frequency component of 10 to 50 Hz and a frequency component of 100 to 300 Hz, Equipped with, The braking system comprises a friction brake and a regenerative braking system. The vibration control unit increases the amplitude of the vibration waveform in accordance with the increase in the braking force sharing ratio of the regenerative braking system. A brake pedal device characterized by the following.

2. A vehicle speed detection unit for detecting the vehicle speed of the aforementioned vehicle, An operating speed detection unit for detecting the operating speed of the pedal, Equipped with, The vibration control unit, A first gain adjustment unit adjusts the gain of the excitation waveform in accordance with the change in vehicle speed, A second gain adjustment unit adjusts the gain of the excitation waveform in accordance with the change in the operating speed, A gain selection unit generates multiple gain values ​​of different magnitudes based on the gains adjusted by the first gain adjustment unit and the second gain adjustment unit, respectively. It has, The gain selection unit selects one gain value from the plurality of gain values ​​according to the braking force sharing ratio between the friction brake and the regenerative braking. The brake pedal device according to claim 1, characterized by the following:

3. The vehicle speed detection unit is provided to detect the vehicle speed of the aforementioned vehicle, The vibration control unit increases the amplitude of the vibration waveform in accordance with the increase in vehicle speed. A brake pedal device according to claim 1 or claim 2, characterized by the above.

4. The system includes an operating speed detection unit that detects the operating speed of the pedal, The vibration control unit increases the amplitude of the vibration waveform in accordance with the increase in the operating speed. A brake pedal device according to any one of claims 1 to 3, characterized by the above.

5. It is equipped with a vibration input detection unit that detects vibration input from the road surface, The vibration control unit increases the amplitude of the vibration waveform in response to an increase in the amplitude of the vibration input. A brake pedal device according to any one of claims 1 to 4, characterized by the above.

Images