Control device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-05
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025003716_13082026_PF_FP_ABST
Abstract
Description
Control device
[0001] The present invention relates to a control device. In particular, the present invention relates to a control device for a vehicle having an assist function.
[0002] In a bicycle, there are the following two driving scenarios. 1. Acceleration (including starting) and steady running (including gradual deceleration due to rolling resistance) 2. Deceleration by a braking deviceIn the scenario of 1, acceleration and steady running are made possible by the torque applied by the user to the bicycle pedals. In the scenario of 2, deceleration is made possible by the user operating a brake lever (braking device) mounted on the bicycle.
[0003] Patent Document 1 discloses a bicycle (electric assist bicycle) having an assist function. In the case of such a bicycle, the function required for 1 is a function of adding an assist torque corresponding to the torque applied by the user to the pedals by a motor. The function required for the deceleration of 2 is, for example, a function of adding a braking force using the motor.
[0004] Japanese Patent Application Laid-Open No. 2019-154199
[0005] Conventionally, a control device mounted on an electric assist bicycle sets a torque target value based on various information acquired from sensors mounted on the bicycle for the acceleration and steady running of 1, and performs output control of the motor using the torque target value.
[0006] In the case of an electric assist bicycle, it is possible to make the motor function as a braking device. Therefore, even in the case of 2, it is conceivable to set the torque target value of the motor for braking as in 1. That is, in the case of braking, the control device obtains the amount of work required to reduce the kinetic energy during the running of the bicycle, converts the amount of work into a torque value, and sets the torque value as the torque target value for the motor that functions as a braking device. However, the amount of work is related to various factors such as the total mass of the bicycle, the running speed, the slope angle of the road surface, air resistance, and rolling resistance. Therefore, it is difficult to obtain an appropriate amount of work according to the situation, and as a result, it is also difficult to calculate the target value of the torque.
[0007] To date, as described in Patent Document 1, control methods focusing on regenerative braking and its efficiency have been proposed. However, these methods only provide a limited amount of braking force incidentally during regeneration and are not sufficient to assist in the braking of a bicycle. It should be noted that vehicles with assist functions are not limited to bicycles; wheelchairs, trolleys, and the like are also known.
[0008] Therefore, the present invention aims to provide a control device that enables vehicle braking with simple control.
[0009] The present invention relates to a control device for a vehicle having a braking system. The control device includes an acquisition unit for acquiring driving parameters relating to the vehicle's driving speed or driving acceleration, a target value setting unit for setting a target value for braking the vehicle, and a driving control unit capable of performing braking assist control to control the braking system so that the driving parameters approach the target value. The driving control unit performs the braking assist control when predetermined conditions relating to the deceleration of the vehicle are met.
[0010] Figure 1 is a side view showing an example of a vehicle with an assist function. Figure 2 is a schematic diagram of the assist unit. Figure 3 is a block diagram of the assist unit. Figure 4 is a diagram showing the change in bicycle speed due to brake assist control. Figure 5 is an explanatory diagram of the first means for determining the target acceleration. Figure 6 is a diagram showing the change in target acceleration over time in the case of the first means. Figure 7 is an explanatory diagram of the second means for determining the target acceleration. Figure 8 is a diagram showing the change in target acceleration over time in the case of the second means. Figure 9 is a diagram showing the change in bicycle speed due to brake assist control. Figure 10 is a side view showing another example of an electric assist bicycle. Figure 11 is a side view showing another example of an electric assist bicycle.
[0011] <Outline of Embodiments of the Invention> Hereinafter, an outline of embodiments of the present invention will be listed and described. (1) A control device according to an embodiment of the present invention is a control device for a vehicle having a braking device. The control device includes an acquisition unit that acquires driving parameters relating to the driving speed or driving acceleration of the vehicle, a target value setting unit that sets a target value for braking the vehicle, and a driving control unit that can perform braking assist control to control the braking device so that the driving parameters approach the target value. The driving control unit performs the braking assist control when predetermined conditions relating to the deceleration of the vehicle are met.
[0012] According to the control device, when predetermined conditions related to vehicle deceleration are met, this triggers the execution of brake assist control. In other words, when the vehicle decelerates, the control device only needs to control the braking system so that the acquired driving parameters approach the target value, making it possible to brake the vehicle with simple control. Moreover, since the brake assist control is executed as a result of the vehicle decelerating (meeting the predetermined conditions), it is less likely to cause discomfort to the user.
[0013] (2) The control device in (1) above is a control device for a vehicle having a motor capable of performing driving assist. The control device has a torque setting unit that sets a target assist torque for driving assist based on input information relating to the torque that the user has given to the vehicle for driving. The driving control unit is capable of performing driving assist control that controls the motor using the target assist torque. When the predetermined conditions are met, the driving control unit transitions from driving assist control to braking assist control. In this case, driving assist for the vehicle is obtained by the motor of the vehicle, and the user's load is reduced when the vehicle is driven. When the predetermined conditions are met, the control performed by the control device transitions from driving assist control that provides driving assist to braking assist control for decelerating the vehicle.
[0014] (3) In the control device described in (1) or (2) above, the target value setting unit determines a negative target acceleration from the negative acceleration of the vehicle during deceleration, and sets the target value by calculation between the negative target acceleration and the driving parameters. In this case, the negative target acceleration is determined from the actual negative acceleration of the vehicle during deceleration. By calculation between the negative target acceleration and the driving parameters, a target value related to the vehicle's speed or acceleration can be easily set. Since the negative target acceleration is determined from the actual negative acceleration during deceleration, deceleration with less discomfort is possible.
[0015] (4) In the control device described in (3), the target value setting unit sets the target value by performing the calculation while gradually changing the acceleration toward the determined negative target acceleration value. If the target value is set abruptly to a large value, the speed fluctuation will be large during deceleration. However, according to the above configuration, the target value is set while gradually changing. Therefore, even if the target value is set to a large value, the speed fluctuation during deceleration is mitigated.
[0016] (5) In the control device of (3) or (4) above, the target value setting unit determines the negative target acceleration by multiplying the negative acceleration of the vehicle during deceleration by a coefficient of 1 or greater than 1. When the coefficient is 1, a negative target acceleration equal to the actual negative acceleration of the vehicle during deceleration is determined. This makes it possible to decelerate the vehicle to the same extent as the actual negative acceleration of the vehicle during deceleration. When the coefficient is greater than 1, a negative acceleration with a larger absolute value than the actual negative acceleration of the vehicle during deceleration is determined as the negative target acceleration. This makes it possible to decelerate the vehicle with a negative acceleration greater than the actual negative acceleration of the vehicle during deceleration. The braking distance is shortened.
[0017] (6) In the control device described in (5), the coefficient is variable according to the negative acceleration of the vehicle during deceleration. When the vehicle brakes suddenly, that is, when the actual negative acceleration is large, the coefficient is increased, and the absolute value of the negative target acceleration increases through the multiplication. As a result, it becomes possible to shorten the braking distance.
[0018] (7) In the control device described in (5) above, the coefficient is variable according to the vehicle's posture. If the coefficient is set large when the vehicle is traveling downhill, and the absolute value of the negative target acceleration is set large by the multiplication, unintended deceleration will occur, and the user may make a driving error. In contrast, if the coefficient is variable according to the vehicle's posture, the absolute value of the negative target acceleration is adjusted (set to a smaller absolute value) according to that posture, and appropriate deceleration is performed. For example, as the vehicle's posture, the greater the forward tilt angle, the smaller the coefficient is set and the smaller the absolute value of the negative target acceleration becomes.
[0019] (8) In the control device described in (5) above, the coefficient is variable according to the turning state of the vehicle. If the coefficient is set to a large value when the turning state of the vehicle is tight, and the absolute value of the negative target acceleration is set to a large value by the multiplication, unintended deceleration will occur, and the user may make a driving error. In contrast, if the coefficient is variable according to the turning state of the vehicle, the negative target acceleration is adjusted according to the turning state (its absolute value is set to a small value), and appropriate deceleration is performed. For example, the smaller the yaw angular velocity or turning radius of the vehicle, the smaller the coefficient is set to and the smaller the absolute value of the negative target acceleration becomes.
[0020] (9) In any one of the control devices described in (1) to (8) above, the driving control unit is capable of performing the braking assist control until the vehicle's speed reaches a preset final speed target value, and the final speed target value is variable according to the vehicle's posture. When the vehicle is traveling on a flat road and decelerating, the final speed target value is set to, for example, zero. In this case, the vehicle can be stopped by the braking assist control. When the vehicle is traveling downhill and decelerating, the final speed target value is set to, for example, a speed value greater than zero. This allows the vehicle to continue traveling while being braked. When a value related to the vehicle's posture exceeds a threshold (for example, when the vehicle is traveling down a steep slope), it is preferable that the final speed target value be set to a larger value than when the value is below the threshold (for example, when the vehicle is traveling down a gentle slope). This prevents an unnaturally large deceleration on a steep downhill slope.
[0021] (10) In any one of the control devices described in (1) to (9) above, the predetermined condition includes at least one of the following: the brake control unit of the vehicle is operated, and the driving parameter decreases. When the user operates the brake control unit, this is triggered to execute the braking assist control. Alternatively, even if the user does not operate the brake control unit, if the vehicle decelerates and the driving parameter decreases, for example, to a threshold, this is triggered to execute the braking assist control.
[0022] (11) In a control device capable of performing the driving assist control, the driving control unit gradually transitions from the driving assist control to the braking assist control when the predetermined conditions are met. In this case, the transition from driving assist control to braking assist control is made without any sense of incongruity.
[0023] <Details of Embodiments of the Present Invention> [Vehicle Configuration] Figure 1 is a side view showing an example of a vehicle having an assist function. The vehicle shown in Figure 1 is an electric assist bicycle 10, in which the wheels rotate due to the pedaling force applied by the user (driver) to the pedal 14, and an assist force corresponding to the pedaling force is applied by the motor 21. Hereinafter, the electric assist bicycle 10 will be referred to as "bicycle 10" in the description. The bicycle 10 has a body frame 11 that forms the skeleton, and a front wheel 12 and a rear wheel 13 supported by the body frame 11.
[0024] The bicycle 10 has pedals 14, a crank 15, a first sprocket 16, a second sprocket 17, a chain 18 that spans the first sprocket 16 and the second sprocket 17, and a saddle 19 on which the user sits. The pedals 14 are connected to the first sprocket 16 via the crank 15. The first sprocket 16 is rotatably supported on a part of the frame 11. The second sprocket 17 is rotatable together with the rear wheel 13. The force applied by the user to the pedals 14 causes the first sprocket 16 to rotate, and this rotational force is transmitted to the rear wheel 13 via the chain 18 and the second sprocket 17, causing the bicycle 10 to move.
[0025] The bicycle 10 has an assist unit 20 to provide an assist function. The assist unit 20 includes a controller unit 20A and an electric motor 21. The controller unit 20A is mounted on the frame 11 and, in the configuration shown in Figure 1, is located below the saddle 19 supported by the frame 11 and near the first sprocket 16. In the configuration shown in Figure 1, the motor 21 is located on the rear wheel 13 side of the frame 11.
[0026] The mounting position of the assist unit 20 can be changed. For example, both the controller unit 20A and the motor 21 may be located below the saddle 19 supported by the vehicle frame 11, near the first sprocket 16 (see Figure 10). Alternatively, the controller unit 20A may be provided at a first mounting position near the first sprocket 16, and the motor 21 may be provided at a second mounting position on the front wheel 12 side (see Figure 11).
[0027] In Figure 1, the bicycle 10 has a battery (secondary battery) 30. The battery 30 supplies power to each part of the assist unit 20. The motor 21 operates using the power from the battery 30. The motor 21 has a regenerative function and can recover electrical energy into the battery 30. The motor 21 also functions as a braking device. In other words, based on the control by the control device 23 of the bicycle 10 (braking assist control described later), driving power for braking is supplied to the motor 21, causing the motor 21 to generate braking force on the wheels (rear wheel 13 or front wheel 12).
[0028] Thus, the bicycle 10 has a motor 21 that performs braking by electromagnetic force as a first braking device. The bicycle 10 also has a brake lever (brake operating part) 41 and a sliding member 42 that brakes the wheels (rear wheel 13 and front wheel 12) by frictional force in response to the operation of the brake lever 41 as a second braking device. The brake lever 41 is provided adjacent to the handlebars 43. The magnitude of the braking force by the sliding member 42 changes according to the operating force of the brake lever 41 by the user.
[0029] Figure 2 is a schematic diagram of the assist unit 20. As described above, the assist unit 20 includes a controller unit 20A and a motor 21. The controller unit 20A includes a sensor unit 22 that detects various physical quantities and a control device 23.
[0030] Motor 21 is, for example, a brushless DC motor. Motor 21 functions to perform driving assist and braking assist. Specifically, motor 21 generates an assist force (assist torque) corresponding to the force applied by the user to pedal 14, and this assist force is applied indirectly or directly to the wheels (rear wheels 13 or front wheels 12) (driving assist). Motor 21 also generates a braking force (braking torque) based on a command signal generated by the control device 23, and this braking force is applied indirectly or directly to the wheels (rear wheels 13 or front wheels 12) (braking assist).
[0031] In the configuration shown in Figure 1, the rotation of the motor 21 is reduced by a reduction gear (not shown), and the torque of the motor 21 (assist torque or braking torque) is transmitted to the rear wheel 13, which then rotates or brakes the rear wheel 13. In the configuration shown in Figure 10, the rotation of the motor 21 is reduced by a reduction gear (not shown), and the torque of the motor 21 (assist torque or braking torque) is transmitted to the chain 18 and the second sprocket 17, which then rotates or brakes the rear wheel 13. In the case of the bicycle 10 shown in Figure 11, the motor 21 is mounted on the front wheel 12. Depending on the mounting position of the motor 21, the torque of the motor 21 is transmitted directly to either the rear wheel 13 or the front wheel 12.
[0032] In Figure 2, the control device 23 controls the motor 21. The control device 23 has a drive circuit 211 for driving the motor 21. The drive circuit 211 supplies drive power corresponding to the motor drive command value generated in the control device 23 from the battery 30 to the motor 21. The control device 23 further has an arithmetic processing unit having, for example, a CPU (Central Processing Unit), memory (storage unit), and circuits. The CPU performs arithmetic processing by executing a computer program stored in memory, and thus the control device 23 has multiple functional units. The control device 23 has an acquisition unit 231, a target value setting unit 232, a driving control unit 233, and a torque setting unit 234 as the functional units. The control device 23 has a storage unit 235 consisting of a memory for storing various information.
[0033] The sensor unit 22 includes a pedal torque sensor 222 and a speed sensor 223. The pedal torque sensor 222 detects the magnitude of the input torque applied by the user to the pedal 14. The pedal torque sensor 222 outputs a torque detection signal to the control device 23 corresponding to the magnitude of the detected input torque (pedal torque). The pedal torque sensor 222 is configured, for example, by a known torque sensor that utilizes the magnetostrictive effect. The pedal torque sensor 222 detects the pedal torque without mechanically contacting the shaft of the crank 15 (first sprocket 16). The control device 23 (acquisition unit 231) acquires the torque detection signal.
[0034] The speed sensor 223 only needs to be installed on a wheel (front wheel 12 or rear wheel 13). The speed sensor 223 detects the rotational speed of the wheel (for example, the rear wheel 13) and outputs a speed detection signal corresponding to that rotational speed. The rotational speed of the wheel corresponds to the riding speed of the bicycle 10. The speed sensor 223 is composed of a known rotation sensor such as a Hall element or a magnetic sensor. The speed sensor 223 directly detects the rotational speed of the wheel. The speed detection signal is output to the control device 23, and the control device 23 (acquisition unit 231) acquires the speed detection signal.
[0035] The sensor unit 22 has a sensor 221 for detecting angular velocity and acceleration acting on the bicycle 10. In this embodiment, the sensor 221 is composed of a known inertial measurement unit (IMU). Hereinafter, the sensor 221 will be referred to as the inertial measurement unit 221. The inertial measurement unit 221 has the functions of a three-axis angular velocity sensor and a three-axis acceleration sensor. The three axes are the vertical axis Z, the front-rear axis X, and the left-right axis Y, which are all orthogonal to each other. Figure 1 shows a three-axis orthogonal coordinate system with the vertical axis Z, the left-right axis Y, and the front-rear axis X. The direction of travel for a bicycle 10 moving in a straight line is forward, and the front-rear axis X is the axis along the direction of travel when moving in a straight line.
[0036] The inertial measuring device 221 has the functions of an acceleration sensor for detecting the acceleration (velocity) of the bicycle 10, an angular velocity sensor for detecting the yaw angular velocity of the bicycle 10, and an attitude sensor for detecting the inclination angle of the bicycle 10 in the direction of travel (i.e., the inclination angle of the road surface). The yaw angular velocity is the angular velocity about the vertical axis Z, and as shown in Figure 1, it is the angular velocity about the vertical axis Z1 of the bicycle 10. The axis Z1 is a straight line parallel to the vertical axis Z. The inertial measuring device 221 outputs a detection signal to the control device 23. The control device 23 (acquisition unit 231) acquires the detection signal.
[0037] The sensor unit 22 has a braking detection sensor 224 that detects the operation of the brake lever 41. The braking detection sensor 224 in this embodiment is a brake lever sensor that detects when the brake lever 41 is operated by the user. Hereinafter, the braking detection sensor 224 will be referred to as the brake lever sensor 224. The brake lever sensor 224 is provided near the brake lever 41. The brake lever sensor 224 detects when the user operates the brake lever 41. The brake lever sensor 224 has a function similar to an on / off detection sensor. The brake lever sensor 224 outputs a detection signal to the control device 23. The control device 23 (acquisition unit 231) acquires the detection signal.
[0038] [Regarding the control device 23] The bicycle 10 has a motor 21 capable of providing both riding assistance and braking assistance. The control device 23 is a device for controlling the riding and braking of such a bicycle 10. As described above (see Figure 2), the control device 23 has, as its functional units, an acquisition unit 231, a target value setting unit 232, a riding control unit 233, and a torque setting unit 234. The riding control unit 233 is a functional unit for both riding assistance and braking assistance. The acquisition unit 231 and the target value setting unit 232 are functional units for braking assistance. The torque setting unit 234 is a functional unit for riding assistance. Each functional unit will be described below. Figure 3 is a block diagram of the assist unit 20.
[0039] [About the Torque Setting Unit 234] The torque setting unit 234 acquires a torque detection signal from the pedal torque sensor 222 according to the magnitude of the pedal torque applied by the user, and sets a target assist torque, which is the target value of the assist torque. The target assist torque is also called the basic assist torque, and the torque setting unit 234 acquires the basic assist torque by calculation. The target assist torque (basic assist torque) is provided to the conversion processing unit (conversion processing circuit) 233D, which converts torque into motor current, via the control switching unit 233B of the driving control unit 233.
[0040] The memory (storage unit 235) of the control device 23 stores, for example, basic correspondence information that shows the correspondence between the torque detection signal and the target assist torque. When the torque setting unit 234 acquires the torque detection signal, it refers to the basic correspondence information to determine the target assist torque. For example, if the pedal torque is large, a large value for the target assist torque is set. In this way, the torque setting unit 234 acquires input information regarding the torque that the user gives to the bicycle 10 for riding, and sets the target assist torque for riding assistance based on that input information. The target assist torque is the assist torque that the motor 21 outputs when accelerating (including starting) and steady riding (including slight deceleration due to rolling resistance) the bicycle 10.
[0041] [About the acquisition unit 231] The acquisition unit 231 acquires driving parameters related to the speed or acceleration of the bicycle 10. There is a correspondence between the rotation of the motor 21 and the speed of the bicycle 10 (actual bicycle speed). Therefore, the acquisition unit 231 can acquire driving parameters based on the detected value of the rotation sensor 225 of the motor 21. Alternatively, driving parameters related to the speed of the bicycle 10 may be acquired from the speed sensor 223. Alternatively, driving parameters may be acquired by calculating the detected value for acceleration of the inertial measuring device 221.
[0042] [Regarding the target value setting unit 232] The target value setting unit 232 sets a target value for braking the bicycle 10. In other words, the target value setting unit 232 sets a target value corresponding to the driving parameter in order to make the motor 21 function as a braking device. The driving parameter is a value related to the driving speed or driving acceleration of the bicycle 10, and the target value is a value related to the driving speed or driving acceleration of the bicycle 10 that corresponds to that driving parameter. In this embodiment, the driving parameter is the driving speed, and the target value is the driving speed. An example of the means for setting the target value will be described below.
[0043] The target value setting unit 232 first obtains a negative target acceleration from the actual negative acceleration at the start of deceleration of the bicycle 10. To this end, when a detection signal is output from the brake lever sensor 224, the target value setting unit 232 acquires the actual negative acceleration of the bicycle 10 at that timing. There is a correspondence relationship between the rotation of the motor 21 and the traveling speed (actual bicycle speed) of the bicycle 10. Therefore, the actual negative acceleration is acquired by calculating the rotational speed obtained from the detection value of the rotation sensor 225 of the motor 21. Alternatively, the actual negative acceleration may be acquired from the inertial measurement device 221.
[0044] In the case of this embodiment, the acquired actual negative acceleration is set as the negative target acceleration. FIG. 4 is a diagram showing the speed change of the bicycle 10 by the braking assist control. The bicycle 10 is traveling at 10 km / h, and at time t1, the brake lever 41 is operated, and the bicycle 10 starts to decelerate. The target value setting unit 232 acquires the actual negative acceleration “−5 km / h / s” at the start of the deceleration and sets it as the negative target acceleration “−5 km / h / s”.
[0045] Next, the target value setting unit 232 sets a target value by calculating the acquired negative target acceleration and the acquired traveling parameter. For example, since the acquired traveling parameter (traveling speed) is 10 km / h and the target acceleration is −5 km / h / s, the target value setting unit 232 sets the target value 0.1 second later to 9.5 km / h. Then, 0.1 second later, when the traveling speed of the bicycle 10 becomes 9.5 km / h and it is acquired as a traveling parameter, since the target acceleration is −5 km / h / s, the target value setting unit 232 sets (updates) the target value 0.1 second later at the next control timing to 9.0 km / h. Thus, the target value setting unit 232 obtains a negative target acceleration from the actual negative acceleration during deceleration of the bicycle 10, and sets a target value by calculating the negative target acceleration and the traveling parameter.
[0046] [Regarding the Travel Control Unit 233] The travel control unit 233 has a control switching unit 233B (see FIG. 3). The control switching unit 233B has a function of switching between travel assist for acceleration or steady travel and braking assist for deceleration by a braking device. Here, the braking device is the motor 21. When the control switching unit 233B satisfies a predetermined condition regarding the deceleration of the bicycle 10, it executes braking assist control by the motor 21 functioning as a braking device.
[0047] In the case of this embodiment, the predetermined condition is the condition that the brake lever 41 has been operated. That is, when the control switching unit 233B receives a detection signal from the brake lever sensor 224, it selects braking assist control and causes the travel control unit 233 to function for braking assist.
[0048] On the other hand, when the predetermined condition regarding the deceleration of the bicycle 10 is not satisfied, the control switching unit 233B executes travel assist control for acceleration or steady travel. That is, the control switching unit 233B selects travel assist control in a state where it does not receive the detection signal of the brake lever sensor 224 and causes the travel control unit 233 to function for travel assist.
[0049] The travel control unit 233 has a first processing unit 233A that obtains a value of torque for braking (torque command value). The first processing unit 233A executes braking assist control for controlling the motor 21, which is a braking device, so that the acquired travel parameters approach the target value. Note that the target value is a value set by the target value setting unit 232.
[0050] The first processing unit 233A obtains the torque command value for braking according to a prescribed algorithm. For example, in the case of the example shown in FIG. 4, for the bicycle 10 traveling at 10 km / h, a torque command value is obtained that causes the motor 21 to generate a braking force for the travel parameter (travel speed) acquired 0.1 seconds after the time t1 when the brake lever 41 is operated to become the target value of 9.5 km / h. The torque command value is obtained based on, for example, setting information indicating the correspondence between the braking force and the torque command value stored in the storage unit 235.
[0051] When braking assist is selected by the control switching unit 233B, as shown in Figure 3, the torque command value obtained by the first processing unit 233A is converted into a motor current command value by the conversion processing unit 233D. The driving control unit 233 has a second processing unit 233C. The second processing unit 233C generates a motor drive command value from the motor current command value, and this motor drive command value is output to the drive circuit 211. Based on this motor drive command value, the drive circuit 211 supplies a drive current to the motor 21, driving the motor 21 and generating a braking force. As a result, the bicycle 10 is braked. Consequently, 0.1 seconds after time t1, the speed of the bicycle 10 becomes 9.5 km / h. Then, as described above, the target value setting unit 232 sets (updates) the target value for the next control timing, which is 0.1 seconds later (0.2 seconds after time t1), to 9.0 km / h.
[0052] The control process described above, which includes the first processing unit 233A determining the torque command value and the motor 21 generating braking force, is feedback control, as shown in Figure 3. In other words, while the bicycle 10 is being braked by the motor 21, the first processing unit 233A determines the torque command value for braking as described above, as braking assist control to control the motor 21 so that the acquired driving parameters approach the next target value (for example, the target value after 0.2 seconds). Similarly thereafter, since braking assist is selected by the control switching unit 233B, the motor 21 is driven to generate braking force based on the torque command value, thereby braking the bicycle 10. As a result, the bicycle 10 is gradually decelerated (see Figure 4). Although the driving parameters are acquired as decreasing values, in this embodiment, the target acceleration for setting the target value is the initially set value "-5 km / h / second" and is used continuously.
[0053] [Regarding the control device 23 of this embodiment] As described above, when predetermined conditions related to the deceleration of the bicycle 10 are met, the control device 23 uses this as a trigger to execute braking assist control. In other words, when the bicycle 10 decelerates due to the user's operation of the brake lever 41, the control device 23 controls the motor 21 so that the acquired driving parameters approach the target value. The control device 23 can perform braking assist for the bicycle 10 with such simple control. Moreover, since the braking assist is executed as a result of the bicycle 10 decelerating (satisfying the predetermined conditions), it is less likely to cause discomfort to the user.
[0054] In this embodiment, as described above, the negative target acceleration is determined from the actual negative acceleration of the bicycle 10 during deceleration. Then, by calculating the negative target acceleration and the driving parameters, target values corresponding to the driving parameters can be easily set. Since the negative target acceleration is determined from the actual negative acceleration during deceleration, deceleration with minimal discomfort is possible.
[0055] [Regarding the Target Value Setting Unit 232] The functions of the Target Value Setting Unit 232 will be explained further. Figure 5 is an explanatory diagram of the first means by which the Target Value Setting Unit 232 determines the target acceleration. In the case of the first means, the brake lever 41 is operated at time t1, the Target Value Setting Unit 232 acquires the actual negative acceleration "-5 km / h / second", sets the target acceleration to "-5 km / h / second", and uses that target acceleration as is to set a target value corresponding to the driving parameters. Then, as described above, the motor 21 is controlled so that the acquired driving parameters approach the target value.
[0056] Figure 6 shows the time change (jerk) of the target acceleration in the case of the first means described above. As shown in Figure 6, the jerk at time t1 (tn) is large. Note that at time tn, the vehicle speed, which is a driving parameter, becomes zero, and the target acceleration is set to zero.
[0057] Figure 7 is an explanatory diagram of a second method by which the target value setting unit 232 determines the target acceleration. In the case of the second method, the brake lever 41 is operated at time t1, and the target value setting unit 232 obtains the actual negative acceleration "-5 km / h / second" and sets the target acceleration to "-5 km / h / second". In the case of the second method, after time t1, the target value setting unit 232 sets the target value while gradually changing the acceleration toward the target acceleration value "-5 km / h / second".
[0058] For example, if a target acceleration of "-5 km / h / second" is determined, the time Δt required to reach that target acceleration is predetermined. From the start of deceleration (time t1), the absolute value of the acceleration is gradually increased during that time Δt. At the point when time Δt has elapsed (time t2), the target acceleration reaches the set value of "-5 km / h / second".
[0059] Thus, in the second method, the target value setting unit 232 sets the target value by performing calculations while gradually changing the acceleration toward the calculated negative target acceleration value. As in the first method shown in Figure 5, if the target value is set abruptly to a large value, the velocity fluctuation (jerk) becomes large during deceleration (see Figure 6). In contrast, according to the second method shown in Figure 7, the target value is set while gradually changing in a manner that increases. Therefore, even if the target value is set to a large value, as shown in Figure 8, the velocity fluctuation (jerk) during deceleration is mitigated, and the discomfort given to the user is reduced.
[0060] Furthermore, in the second method shown in Figure 7, in addition to the timing when the bicycle 10 starts to decelerate (time t1), the target value is also set by performing calculations while gradually changing the absolute value of the target acceleration in a manner that decreases when the bicycle 10 comes to a stop. As a result, even when the bicycle 10 comes to a stop, the speed fluctuation is mitigated, and the discomfort felt by the user is reduced.
[0061] Another function of the target value setting unit 232 will now be described. As described above, the target value setting unit 232 determines the negative target acceleration based on the negative acceleration of the bicycle 10 when it is decelerating (when deceleration begins). In this case, the target value setting unit 232 sets the negative target acceleration to a value obtained by multiplying the negative acceleration of the bicycle 10 when it is decelerating (when deceleration begins) by a coefficient. The coefficient is "1" or "a value greater than 1".
[0062] When the coefficient is "1", the actual negative acceleration "-5 km / h / sec" immediately after time t1 (see Figure 4) is set as the target acceleration. Therefore, in Figure 4, the target value has a linear relationship shown by the dashed line, and the bicycle 10 is braked by changing its speed along that dashed line. When the coefficient is a value greater than "1", a target acceleration greater than the actual negative acceleration "-5 km / h / sec" immediately after time t1 (see Figure 4) is set. For example, when the coefficient is "1.2", the target acceleration is set to "-6 km / h / sec". Therefore, in Figure 4, the target value has a linear relationship shown by the solid line, and the bicycle 10 is braked by changing its speed along that solid line. As a result, the braking distance of the bicycle 10 is shortened compared to when the coefficient is "1".
[0063] In this way, the target value setting unit 232 can determine the negative target acceleration by multiplying the negative acceleration of the bicycle 10 during deceleration (at the start of deceleration) by a coefficient of 1 or greater than 1. If the coefficient is "1", it is possible to decelerate the bicycle 10 to about the same extent as the actual negative acceleration of the bicycle 10 during deceleration. If the coefficient is a value greater than "1", it becomes possible to decelerate the bicycle 10 with a negative acceleration greater than the actual negative acceleration of the bicycle 10 during deceleration, and the braking distance is shortened.
[0064] The coefficient may be a fixed value or a variable value. <In the case of a variable value (part 1)> The coefficient is variable according to the actual negative acceleration when the bicycle 10 is decelerating. For example, when the bicycle 10 is braking suddenly, that is, the larger the absolute value of the actual negative acceleration, the larger the coefficient becomes. As a result, the absolute value of the negative target acceleration becomes larger, and it becomes possible to shorten the braking distance.
[0065] <In the case of variable values (part 2)> The coefficient is variable according to the posture of the bicycle 10. The posture is, for example, the forward-leaning posture of the bicycle 10. In other words, when the bicycle 10 is traveling downhill, the posture corresponds to the inclination angle of the slope. The inclination angle can be obtained from the detection result of the inertial measuring device 221. Here, if the coefficient is set large when the bicycle 10 is traveling downhill, and the absolute value of the negative target acceleration is set large through multiplication, it will result in unintended deceleration, and the user may make a mistake in driving operation.
[0066] In contrast, if the coefficient is variable according to the posture of the bicycle 10, the absolute value of the negative target acceleration is adjusted according to that posture (i.e., the absolute value is set to be smaller), and appropriate deceleration is performed. The larger the forward lean angle, the smaller the coefficient is set to be, and as a result, the absolute value of the negative target acceleration becomes smaller. This allows the bicycle 10 to decelerate in accordance with the slope angle of the downhill when traveling downhill, improving safety.
[0067] <In the case of variable values (part 3)> The coefficient is variable according to the turning state of the bicycle 10. The turning state is the yaw angular velocity acting on the bicycle 10, or the turning radius of the turning bicycle 10. The yaw angular velocity is acquired by the inertial measuring device 221. The yaw angular velocity is the angular velocity about the vertical axis Z, and as shown in Figure 1, it is the angular velocity about the vertical axis Z1 of the bicycle 10. In addition, for example, a sensor for detecting the steering angle of the handlebars 43 is provided at the base of the handlebars 43 of the bicycle 10, and the turning radius is acquired based on the value detected by that sensor.
[0068] Here, if the coefficient is set large when the bicycle 10 is making a tight turn, and the absolute value of the negative target acceleration is set large by the aforementioned multiplication, unintended deceleration will occur, and the user may make a mistake in operating the bicycle. In contrast, if the coefficient is variable according to the turning state of the bicycle 10, the negative target acceleration is adjusted according to the turning state (its absolute value is set small), and appropriate deceleration is performed. For example, the smaller the yaw angular velocity or turning radius of the bicycle 10, the smaller the coefficient is set, and as a result, the absolute value of the negative target acceleration becomes smaller. This prevents unintended deceleration when the bicycle 10 is turning, improving safety.
[0069] [Regarding the Driving Control Unit 233] Figure 9 shows the change in speed of the bicycle 10 due to braking assist control. The Driving Control Unit 233 can perform braking assist control until the speed of the bicycle 10 reaches a preset final speed target value. The final speed target value is a value for the speed of the bicycle 10 and is set by the Driving Control Unit 233. For example, when stopping the bicycle 10, the final speed target value Ve1 is zero, as shown by the solid line in Figure 9.
[0070] The final speed target value is variable depending on the posture of the bicycle 10. The posture is, for example, the forward-leaning posture of the bicycle 10. In other words, when the bicycle 10 is traveling down a slope, the posture corresponds to the inclination angle of the slope. This inclination angle can be obtained by the inertial measuring device 221. Based on the detection results of the inertial measuring device 221, the driving control unit 233 can determine whether the bicycle 10 is traveling on a flat road, down a slope, or up a slope.
[0071] Therefore, when bicycle 10 is traveling on a flat road and decelerating, the final speed target value Ve1 is set to zero, as shown by the solid line in Figure 9. In this case, it becomes possible to stop bicycle 10 by braking assist control. When bicycle 10 is traveling downhill and decelerating, the final speed target value Ve2 is set to a speed value greater than zero, as shown by the dashed line in Figure 9. This makes it possible for bicycle 10 to continue traveling while being braked.
[0072] The final speed target value Ve2, shown by the dashed line in Figure 9, is the value set when the bicycle 10 is traveling down a gentle slope and decelerating. In contrast, when the bicycle 10 is traveling down a steep slope and decelerating, that is, when the value related to the posture of the bicycle 10 exceeds the threshold and decelerates, the final speed target value Ve3 is set to a larger value, as shown by the double dashed line in Figure 9. When the value related to the posture of the bicycle 10 exceeds the threshold, the final speed target value is set to a larger value than when the value related to the posture (inclination angle) is below the threshold. This prevents excessive braking on steep downhill slopes and avoids creating an unnatural, large deceleration.
[0073] The transition in control between driving assist for acceleration or steady driving and braking assist control for braking will be explained. As described above, the torque setting unit 234 acquires a torque detection signal from the pedal torque sensor 222 according to the magnitude of the pedal torque by the user and sets a target assist torque which is the target assist torque value. The control switching unit 233B, without receiving a signal from the brake lever sensor 224, selects driving assist control and makes the driving control unit 233 function for driving assist.
[0074] When braking assist control is not selected, the driving control unit 233 executes driving assist control to control the motor 21 using the set target assist torque. In other words, when driving assist control is selected, as shown in Figure 3, the target assist torque value set by the torque setting unit 234 is converted into a motor current command value by the conversion processing unit 233D. The second processing unit 233C generates a motor drive command value from the motor current command value. The motor drive command value is output to the drive circuit 211. As a result, the motor 21 is driven in a manner that generates torque corresponding to the motor drive command value, and this torque is used to accelerate or maintain steady-state driving of the bicycle 10. This braking assist control is feedback control. The motor 21 driven by the driving assist control provides driving assist to the bicycle 10, reducing the user's load when riding the bicycle 10.
[0075] Then, when the driving control unit 233 satisfies predetermined conditions related to the deceleration of the bicycle 10, it switches from driving assist control to braking assist control for decelerating the bicycle 10. In this embodiment, the predetermined condition is that the brake lever 41 is operated. When the driving control unit 233 (control switching unit 233B) satisfies the predetermined conditions, it may immediately switch the control mode to stop driving assist control and execute braking assist control, or it may gradually switch the control mode from driving assist control to braking assist control. For example, the control switching unit 233B may gradually switch the control mode by changing the ratio between driving assist control and braking assist control. In other words, the control mode may be gradually switched by changing the ratio between the target assist torque for acceleration or steady driving and the torque (torque command value) for braking.
[0076] In this way, when the driving control unit 233 (control switching unit 233B) satisfies the predetermined conditions, it gradually transitions from driving assist control to braking assist control, thereby allowing a seamless transition from driving assist control to braking assist control. Alternatively, when the driving control unit 233 (control switching unit 233B) satisfies the predetermined conditions, it may reduce the ratio of driving assist control and transition to a control mode in which driving assist control is performed while braking assist control is performed in parallel. In other words, when the driving control unit 233 converts the torque value to a motor current command value, the torque value may include both the target assist torque set by the torque setting unit 234 and the torque for braking (torque command value) set by the first processing unit 233A.
[0077] In the above embodiment, the predetermined condition is that the brake operating unit (brake lever 41) of the bicycle 10 is operated. In this case, when the user operates the brake lever 41, this acts as a trigger and braking assist control is executed.
[0078] The predetermined state may be any other condition, and may be a decrease in the driving parameters. In other words, the predetermined state may be a decrease in the driving parameters that exceeds a threshold. In this case, even if the user does not operate the brake lever 41, if the driving parameters decrease by the bicycle 10 due to deceleration, this will trigger the execution of braking assist control. When starting or accelerating while holding the brake lever 41, it is desirable that driving assist control takes precedence over braking assist control. Therefore, in this case, it is preferable that the predetermined condition is a condition related to a decrease in the driving parameters.
[0079] The predetermined conditions may include at least one of the following: the brake operating unit (brake lever 41) has been operated, and a decrease in driving parameters. The predetermined conditions may also be based on pedal torque or pedal rotation speed. In other words, the predetermined conditions may be that the pedal torque or pedal rotation speed has fallen below a threshold.
[0080] In the above embodiment, the vehicle with the assist function was described as a bicycle 10, but the vehicle with the assist function may also be a wheelchair or a trolley, etc. The control device of such a vehicle performs the driving assist control and braking assist control as described in the above embodiment.
[0081] [Other] The embodiments described above are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the embodiments, and includes all modifications within the scope of equivalence to the configurations described in the claims.
[0082] 10 Electric assist bicycle (vehicle) 21 Motor (braking device) 23 Control device 41 Brake lever (brake operation part) 231 Acquisition unit 232 Target value setting unit 233 Driving control unit 234 Torque setting unit Ve1 Final speed target value Ve2 Final speed target value Ve3 Final speed target value
Claims
1. A control device for a vehicle having a braking system, comprising: an acquisition unit for acquiring driving parameters relating to the vehicle's driving speed or driving acceleration; a target value setting unit for setting a target value for braking the vehicle; and a driving control unit capable of performing braking assist control for controlling the braking system so that the driving parameters approach the target value, wherein the driving control unit performs the braking assist control when predetermined conditions relating to the deceleration of the vehicle are met.
2. A control device for a vehicle having a motor capable of performing driving assist, comprising a torque setting unit that sets a target assist torque for the driving assist based on input information relating to torque given to the vehicle by the user for driving, the driving control unit is capable of performing driving assist control that controls the motor using the target assist torque, and the driving control unit transitions from the driving assist control to the braking assist control when the predetermined conditions are met, according to claim 1.
3. The control device according to claim 1 or 2, wherein the target value setting unit determines a negative target acceleration from the negative acceleration during deceleration of the vehicle, and sets the target value by calculation between the negative target acceleration and the driving parameters.
4. The control device according to claim 3, wherein the target value setting unit sets the target value by performing the calculation while gradually changing the acceleration toward the determined negative target acceleration value.
5. The control device according to claim 3, wherein the target value setting unit determines the negative target acceleration as a value obtained by multiplying the negative acceleration during deceleration of the vehicle by a coefficient of 1 or more than 1.
6. The control device according to claim 5, wherein the coefficient is variable according to the negative acceleration during deceleration of the vehicle.
7. The control device according to claim 5, wherein the coefficient is variable according to the attitude of the vehicle.
8. The control device according to claim 5, wherein the coefficient is variable according to the turning state of the vehicle.
9. The control device according to claim 1 or 2, wherein the driving control unit can perform the braking assist control until the vehicle's driving speed reaches a preset final speed target value, and the final speed target value is variable according to the vehicle's attitude.
10. The control device according to claim 1 or claim 2, wherein the predetermined condition includes at least one of the following: the brake operating unit of the vehicle being operated, and a decrease in the driving parameter.
11. The control device according to claim 2, wherein the driving control unit gradually transitions from the driving assist control to the braking assist control when the predetermined conditions are met.