JP4049991B2 - Suspension control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling a suspension provided in a vehicle such as an automobile, and more particularly to a method for controlling a suspension provided with an actuator that applies a force to a wheel in a vertical direction.
[0002]
[Prior art]
A suspension provided in a vehicle has a role of improving a ride comfort by absorbing an impact from a road surface on which a wheel contacts a ground, and generally includes a coil spring and a shock absorber for suppressing vibration of the coil spring. If the spring rate of the coil spring provided in the suspension is reduced and the spring is softened, the riding comfort tends to be good.
On the other hand, the vehicle's maneuverability is improved when the body rigidity is high.However, if the spring rate is reduced to improve the ride comfort, rolling tends to occur when the vehicle turns, and pitching occurs during acceleration / deceleration. It becomes easier, the maneuverability tends to decrease, and the rider cannot say that the ride comfort is good because the vehicle body tilts.
As described above, it is generally difficult to improve both the maneuverability and the ride comfort of the vehicle suspension, so whether to give priority to the ride comfort or the maneuverability according to the characteristics of the vehicle. It is often set to either.
[0003]
Conventionally, a stabilizer is known as one for increasing the roll rigidity of a vehicle body. The stabilizer has no function as a spring when the left and right wheels move in the same phase, but suppresses rolling by acting as a spring when the left and right wheels move in the opposite phase as in rolling. Since the stabilizer acts as a spring only when the left and right wheels move in opposite phases, rolling can be suppressed without increasing the spring rate of the coil spring.
[0004]
[Problems to be solved by the invention]
By the way, if the spring rate of the coil spring is reduced to improve riding comfort, rolling is likely to occur during turning, so the diameter of the stabilizer bar is increased or the length of the portion where the torsion occurs is shortened, etc. It is necessary to increase the reaction force generated by the stabilizer bar.
[0005]
However, if the reaction force generated by the stabilizer bar is increased, when the vehicle travels straight on a road surface with irregular irregularities, the result is that it is equivalent to increasing the spring rate of the coil spring, and the riding comfort tends to deteriorate. is there. In addition, the stabilizer only suppresses rolling and cannot obtain the effect of suppressing pitching or bouncing.
[0006]
The present invention has been made in view of such circumstances, and by controlling an actuator that applies a force to the wheels in the vertical direction according to the traveling state of the vehicle, the steering stability of the vehicle and the occupant An object of the present invention is to provide a suspension control method capable of improving the ride comfort of the vehicle.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, one actuator is provided on each of the left and right wheels of the vehicle (for example, the actuators 1L and 1R in the embodiment), and the wheels can receive a force in the vertical direction by the actuator. In addition, a first target value map in which the accelerator opening and the target value of the generated torque of the actuator are related, and a second target value in which the brake pedal force and the target value of the generated torque of the actuator are related A suspension control method comprising a map, wherein the control method is The force generated by the actuator is changed by multiplying the target value of the generated torque by a gain based on the vehicle speed (for example, step S64 in the embodiment). Control with priority on ride comfort (for example, skyhook control in the embodiment) The force generated by the actuator is changed by multiplying the target value of the generated torque by a gain based on the vehicle speed (for example, step S64 in the embodiment). When the control that gives priority to the suppression of rolling (for example, the rolling suppression control in the embodiment) is performed and the longitudinal acceleration of the vehicle is larger than a predetermined value even in the straight traveling state, the first and second target values Accelerator opening or brake obtained by referring to the map According to the pedal effort Control that prioritizes suppression of pitching based on the target value (for example, pitching suppression control in the embodiment) The target value of the control that gives priority to the suppression of the pitching is not multiplied by the gain based on the vehicle speed (for example, step S68 in the embodiment). It is characterized by that.
[0008]
According to the present invention, when the vehicle is traveling straight in a suspension in which one actuator is provided for each of the left and right wheels of the vehicle, and each of the left and right wheels can receive vertical force by the actuator. Controls that prioritize ride comfort for passengers and control that prioritizes rolling restraint during turning can reduce body vibration during straight travel and reduce body tilt during turning It is possible to improve the ride comfort of the occupant. Further, since the apparent spring rate can be increased only during turning, an effect that both improvement in steering stability and improvement in riding comfort can be obtained.
[0010]
Also, According to the present invention, when the longitudinal acceleration of the vehicle is larger than a predetermined value even in the straight traveling state, the control is given priority to the suppression of the pitching, so that the vehicle body tilts back and forth during acceleration / deceleration. Can be reduced, and the ride comfort of the passenger can be improved. In addition, since the apparent spring rate can be increased only during acceleration / deceleration, there is also an effect that both steering stability and riding comfort can be achieved.
[0012]
According to the present invention, the force generated by the actuator is changed in accordance with the speed of the vehicle, so that at a low speed, a minute control operation is performed due to the influence of road surface unevenness and the like, and the ride comfort is reduced. The effect that it can prevent is acquired.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention achieves both steering stability and ride comfort by complementing the spring rate of the spring in the suspension with the torque generated by the actuator in accordance with the running state of the vehicle. At this time, the torque generated by the actuator is calculated based on the output of the sensor that detects the vehicle body state.
As a result, the present invention substantially increases the rigidity of the vehicle body according to the traveling state of the vehicle and relaxes the inclination of the vehicle body due to rolling or pitching, thereby obtaining stability of vehicle traveling and It is intended to improve comfort.
[0014]
Also, if the spring rate of the spring is set to a large value from the beginning in order to increase the rigidity of the vehicle body, the vehicle body will be directly subjected to impacts due to the road surface condition, for example, road surface unevenness, etc. when going straight, and the ride comfort will deteriorate. End up.
However, according to the present invention, the spring rate of the spring is set to a value that suppresses the impact due to the condition of the road surface when traveling straight, and the spring rate for obtaining the required vehicle body rigidity during cornering or acceleration / deceleration, and the spring rate of the spring Since the difference is supplemented by the torque generated by the actuator, the maneuverability and the ride comfort can be improved.
[0015]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a perspective view from the rear of the vehicle showing the configuration of the suspension on the rear (rear wheel) side of the automobile according to the first embodiment of the present invention.
In the left rear wheel suspension of this figure, the knuckle 6L that rotatably supports the wheel WL is supported so as to be vertically movable via an A-type upper arm 2L and a lower arm 3L. The upper arm 2L is connected to the upper portion of the knuckle 6L via a joint provided at the distal end, and is connected to the vehicle body B via a joint provided at the proximal end. The lower arm 3L is connected to the lower part of the knuckle 6L via a joint provided at the distal end, and is connected to the vehicle body B via a joint provided at the proximal end. The lower part of the spring 7L is supported at the center of the lower arm 3L, the upper part of the spring 7L is supported by the vehicle body B, and the actuator 1L is connected to the base end side of the lower arm 3L via the link 5L and the drive arm 4L. A shock absorber (not shown) is provided between the vehicle body B and the lower arm 3L. Here, the actuator 1L is composed of a speed reducer GL and a motor ML, and the torque generated by the motor ML is increased in accordance with the speed reduction ratio of the speed reducer GL and given to the lower arm 3L.
[0016]
Further, the configuration of the right rear wheel suspension is the same except that the subscripts of the constituent elements described above are changed from “L” to “R”.
The front portions of the knuckle 6L and the knuckle 6R are connected to each other by a stabilizer bar (not shown), and the vehicle body B and the rear portions of the knuckle 6L and the knuckle 6R are connected by a lateral link (not shown).
[0017]
With the above-described configuration, the lower arm 3L and the upper arm 2L connected to the knuckle 6L are connected to the vehicle body B by rolling the vehicle body B up and down with respect to the road surface by cornering in the left rear wheel suspension. Move up and down starting from the base. As a result, the spring 7L and the shock absorber connected to the lower arm 3L expand and contract in response to the vertical movement, and the vertical movement of the vehicle body B with respect to the road surface is buffered. At this time, when the actuator 1L is driven and the drive arm 4L is rotated about the rotation axis in the same direction as the rolling, the torque (N that moves up and down to the lower arm 3L connected to the drive arm 4L via the link 5L) M) is transmitted to complement the spring rate of the spring 7L.
[0018]
Similarly, the suspension of the right rear wheel performs the same operation as the operation of the suspension of the left rear wheel only by changing the subscript of the above-described component from “L” to “R”. Thereby, by controlling the actuators 1L and 1R provided on the wheel WL and the wheel WR in relation to each other, the spring rate of the springs 7L and 7R can be complemented, and the inclination of the vehicle body B due to rolling or pitching can be positive. Can be controlled.
[0019]
That is, when the spring 7L connected to the lower arm 3L expands and contracts in response to the vertical movement of the vehicle body B due to cornering or the like, the left rear wheel suspension shown in FIG. Is applied to the vehicle body B to correct the inclination of the vehicle body B.
Hereinafter, for the sake of explanation, the torques applied to the lower arms 3L and 3R by the actuators 1L and 1R rotating the drive arms are referred to as torques TTL and TTR, respectively.
[0020]
Here, a sensor for detecting the state of the vehicle body B will be described with reference to FIGS. FIG. 15 is an explanatory diagram showing the arrangement of stroke sensors attached to the vehicle body B in order to detect the stroke amount of the suspension shown in FIG. In this figure, symbols SL and SR are stroke sensors that detect and output a relative movement amount (stroke amount) between the vehicle body B and the lower arm 3L. The example shown in FIG. 15 is an example in which a stroke potentiometer is attached to the left rear wheel suspension as the stroke sensor SL. In the example shown here, the stroke sensor SL is attached to the vehicle body B and coupled to the upper arm 2L by a link. The suspension of the right rear wheel is an example using a rotary potentiometer as the stroke sensor SR, and detects the amount of movement of the upper arm 2R by the rotation angle. The stroke sensors SL and SR are not limited to stroke type and rotary type potentiometers, but can be any sensors that can detect the stroke amount of the suspension.
[0021]
That is, the stroke amount here is a value corresponding to the displacement amount of the springs 7L and 7R, so any sensor can be used as long as it can detect the displacement amounts of the springs 7L and 7R. For example, the left and right stroke amounts corresponding to the acceleration in the lateral direction of the vehicle body B are obtained in advance, and the stroke amount obtained in advance according to the acceleration detected by the acceleration sensor is obtained. Good.
[0022]
FIG. 16 is a schematic diagram when the vehicle is viewed from above. In this figure, symbol SA is a steering angle sensor that detects and outputs the steering angle and steering direction of the steering wheel 8. The output of the steering angle sensor SA outputs a numerical value with a sign. For example, when steering to the left, a positive numerical value corresponding to the steering angle is output, and when steering to the right, the steering angle is output. Outputs a negative value corresponding to. Reference numeral SB denotes an acceleration sensor that is attached to the position of the center of gravity of the vehicle body B and detects acceleration in the vertical direction of the vehicle body B (direction perpendicular to the road surface). Reference numeral SC denotes an acceleration sensor that is attached to the front position of the vehicle body B and detects and outputs the acceleration in the longitudinal direction of the vehicle body B. The symbol SD is an accelerator opening sensor that detects and outputs the accelerator opening. Symbol SE is a pedal force sensor that detects and outputs the pedal force of the brake pedal. Symbol SF is a vehicle speed sensor that detects and outputs the speed of the vehicle.
[0023]
The acceleration sensor that detects the vertical acceleration of the vehicle body B may be attached to the left and right rear damper mounts of the vehicle body B as indicated by reference numerals SBL and SBR. If the acceleration sensors for detecting the acceleration in the vertical direction are attached to the positions of the left and right suspensions, the state of the vehicle body B can be detected in more detail.
[0024]
The control of the actuators 1L and 1R and the detection of the outputs of the stroke sensors SL and SR, the steering angle sensor SA, the acceleration sensor SB, and the acceleration sensor SC are performed by a control unit (not shown). The control unit includes a CPU and a storage unit such as a memory, and the CPU controls the actuators 1L and 1R according to a program stored in the storage unit.
[0025]
Next, with reference to FIGS. 2 to 8, an operation in which the control unit controls the suspension shown in FIG. 1 will be described. FIG. 2 is a flowchart showing a main process of the suspension control operation. First, the control unit detects the current state of the vehicle body B, and calculates a target value necessary for performing control for suppressing rolling of the vehicle body B (step S1). The target value used in the following description is a target torque (TTL, TTR) generated by the actuators 1L, 1R and a rotation direction in which the torque is generated.
In addition, the process of step S1 is demonstrated in detail later with reference to FIGS.
[0026]
Next, the control unit detects the state of the vehicle body B and calculates a target value necessary for performing skyhook control for improving the ride comfort when the vehicle is in a straight traveling state (step S2). Skyhook control is control in which vibration on the sprung (vehicle body B) is controlled by an actuator based on the skyhook theory.
The process of step S2 will be described in detail later with reference to FIG.
[0027]
Next, the control unit detects the current state of the vehicle body B, and calculates a target value necessary for performing control for suppressing the pitching of the vehicle body B (step S3).
The process of step S3 will be described in detail later with reference to FIG.
[0028]
Next, the control unit determines the control mode according to the current state of the vehicle body B (step S4). In the determination of the control mode, depending on the state of the vehicle body B, it is appropriate to perform any of the above-described three controls (rolling suppression control, skyhook control, pitching suppression control) at the present time. It is to determine and determine whether there is.
Here, the reason why the target value for performing the three controls is always calculated is to respond quickly to a change in the state of the vehicle.
[0029]
Next, the control unit selects the target value calculated in Steps S1, S2, and S3 based on the control mode determination result, obtains the amount of current corresponding to the target value, and applies the motor ML and MR to (Step S5).
For example, when controlling the torques of the motors ML and MR by PWM (pulse width modulation) control, the control unit calculates the duty ratio between the “H” level and the “L” level width according to the target value in a certain period. Obtain and adjust the amount of current applied to the motors ML and MR.
[0030]
At this time, if the control unit wants to increase the current in order to increase the torque, it widens the width of the “H” level, narrows the width of the “L” level, and decreases the current in order to reduce the torque, The duty ratio is calculated so that the width of the “L” level is widened and the width of the “H” level is narrowed. The direction in which the torque is generated is controlled by reversing the direction of the current flowing through the motors ML and MR.
Hereinafter, for the sake of explanation, the current direction in which the torque TL is generated in the direction of extending the spring 7L by the actuator 1L is defined as (+), and the current direction in which the torque TL is generated in the direction of contracting the spring 7L by the actuator 1L is defined as (−). To do.
Similarly, the current direction in which the torque TR is generated in the direction of extending the spring 7R by the actuator 1R is defined as (+), and the current direction in which the torque TR is generated in the direction of contracting the spring by the actuator 1R is defined as (−).
[0031]
In FIG. 2, the processes of steps S1 to S3 are illustrated in order, but the calculation of the three target values may be performed simultaneously in parallel. By doing in this way, the period which performs control operation shown in Drawing 2 can be shortened.
[0032]
As described above, since suspension control is performed by selecting any one of rolling suppression control, skyhook control, and pitching suppression control according to the state of the vehicle body B, both driving stability and ride comfort of the occupant are achieved. It becomes possible to improve.
[0033]
Next, with reference to FIGS. 3-5, the operation | movement which calculates the target value in the case of performing rolling suppression control shown to step S1 of FIG. 2 is demonstrated. 3 to 5 are flowcharts showing a process for calculating a target value for the control unit to control the actuators 1L and 1R.
As a premise of the operation, when the driver gets into the vehicle and turns on the ignition switch, the control unit sets the measured values MDL and MDR (unit: mm) output from the stroke sensors SL and SR at this time, respectively. It memorize | stores in a memory | storage part as reference value DL and DR (unit mm).
And a control part starts the process of each flowchart shown to FIGS. 3-5 according to a program.
The processing of these flowcharts is repeated as a set of processing at regular time intervals (for example, every 10 msec), and the control of the generation of torques TTL and TTR to be generated by the actuators 1L and 1R, respectively, is obtained from the obtained results. Performed every hour.
[0034]
First, a target value calculation process based on the steering speed will be described with reference to FIG. By this process, torques TL and TR to be generated by the actuators 1L and 1R are obtained based on the steering speed.
First, the control unit reads the steering angle amount output by the steering angle sensor SA (step S11). Then, a control part determines a steering direction from the steering angle sensor SA output value (step S12). The steered direction here indicates whether the steering wheel 8 is steered in the left or right direction from the neutral position, and is “right”, “neutral”, or “left”.
[0035]
Next, the control unit performs a calculation for obtaining a change in the rudder angle amount over the predetermined time, that is, a rudder angular velocity (rad / s) as a differential value of the steer amount (step S13). Then, a control part determines the steering angular velocity direction which shows the direction of a steering angular velocity based on a steering angle sensor output value (step S14). This is for determining the steering state in detail according to the direction of the steering angular velocity. For example, the process of returning the steering wheel 8 to the neutral position from the state where the steering wheel 8 is turned to the left cannot be determined only by the steering direction, and therefore the direction of the steering angular speed is required.
[0036]
Next, a control part calculates | requires the target value according to the steering angular velocity calculated | required in step S13 with reference to the target value map memorize | stored in the memory | storage part. FIG. 11 is an example of a target value map that defines the relationship between the steering angular velocity and the torque generated by the actuators 1L and 1R. The control unit refers to the target value map, selects each torque TL, TR corresponding to the steering angular speed, and outputs it as a calculation result. This output is passed to a process (process shown in FIG. 5) described later.
[0037]
Next, the target value (YL, YR) calculation process based on the stroke amount will be described with reference to FIG. First, the control unit reads measured values MDL and MDR from the stroke sensors SL and SR, respectively (step S21). Then, the control unit calculates the difference between the measured value and the reference value, that is, the stroke amount (step S22).
That is, the control unit calculates the left rear wheel stroke amount ΔDL by the formula “MDL-DL”, and similarly calculates the right rear wheel stroke amount ΔDR by the formula “MDR-DR”. Store in the storage unit. By this calculation, the amount of change in stroke from the state where the ignition switch is turned on is obtained.
[0038]
Next, the control unit calculates the stroke difference ΔLR between the stroke amount ΔDL of the left rear wheel and the stroke amount ΔDR of the right rear wheel obtained in step S22 by using the expression “ΔDL−ΔDR” (step S23). ). Subsequently, the control unit determines the vehicle state based on the obtained stroke difference ΔLR (step S24). The control unit determines that the vehicle body B is “neutral” with respect to the road surface when the stroke difference ΔLR = 0, determines that the vehicle body B is “lower right” when the stroke amount ΔLR> 0, and when the stroke difference ΔLR <0. Judged as “down to the left”. This determination result is stored in the storage unit together with the stroke difference ΔLR as a vehicle state value.
[0039]
Next, the control unit calculates a target value by calculation based on the stroke difference ΔLR (step S25).
That is, the spring rate between the target spring rate JT (unit N (Newton) / mm) set corresponding to the vehicle type and the basic spring rate JS (unit N (Newton) / mm) of the spring 7L actually provided on the suspension. A value obtained by multiplying the difference ΔJ by the stroke difference ΔLR (mm) is the roll rigidity reaction force insufficient force FW.
Therefore, the control unit calculates based on the formula “(JT−JS) × ΔLR” to obtain the roll stiffness reaction force insufficient force FW.
Further, the torques TL and TR generated in the actuators 1L and 1R are torques necessary for complementing the spring rate difference ΔJ in which the basic spring rate JS is insufficient with respect to the target spring rate JT, and the roll rigidity obtained previously. The reaction force insufficient force FW is multiplied by the lever ratio DD (substantially the length of the drive arm 4L or 4R, unit cm).
[0040]
Therefore, the control unit calculates based on the formula “(FW × DD) / 2” and obtains torques YL and YR, respectively. Here, “FW × DD” is divided by “2” because the torque required for complementing the roll stiffness (the increase in the apparent spring rate) is complementarily set by the actuators 1L and 1R in the opposite directions. This is because control for generating the direction torque by “½” is performed.
[0041]
Next, the control unit attaches a polarity to the previously obtained (FW × DD / 2) depending on whether the vehicle state value is “downward to the right” or “downward to the left”, and torques YL, YR. Is calculated. Torques YL and YR obtained by this calculation become target values based on the stroke amount.
For example, when the driver steers to the right and the vehicle body B rolls to the left, the control unit applies torque TL (+ FW × DD / 2) for applying a reaction force in the direction in which the actuator 1L extends the spring 7L. On the other hand, a torque YR (−FW × DD / 2) for applying a reaction force in the direction in which the actuator 1R contracts the spring 6R is calculated. Hereinafter, for the sake of explanation, the torque in the direction of extending the spring is assumed to be (+) and the torque in the direction of contracting the spring is assumed to be (−).
[0042]
Next, the control unit determines whether or not the vehicle state can be regarded as “neutral” based on the vehicle state value and the stroke difference ΔLR (step S26). This determination is to determine whether the stroke difference ΔLR is not “0” but is an amount that can be regarded as almost “0”. If the stroke difference ΔLR is within a predetermined range, the stroke difference “ It is processed as “0”. Thereby, even if there is a minute stroke difference, the vehicle state can be regarded as “neutral”.
As a result of this determination, if it cannot be regarded as “neutral”, the control unit stores the values of the torques YL and YR obtained in step S25 in the storage unit, and ends the process.
On the other hand, when the vehicle state can be regarded as “neutral”, the control unit sets the vehicle state value to “neutral” and sets the torques YL and YR, which are target values based on the previously obtained stroke, to “0” ( Step S27), storing in the storage unit, and the process is terminated.
[0043]
Next, referring to FIG. 5, target values (torque) that are actually generated by actuators 1L and 1R using target values (TL and TR) based on the steering angular velocity and target values (YL and YR) based on the stroke amount are used. Processing for obtaining (TTL, TTR) will be described.
First, the control unit determines whether or not the vehicle state value is “neutral” (step S31). If the determination result is “neutral”, the process proceeds to step S34, and the vehicle state is “neutral”. Otherwise, the process proceeds to step S32.
[0044]
Next, based on the vehicle state value and the steering angular speed direction, the control unit matches the roll direction of the vehicle body B (either the left-down direction RL or the right-down direction RR shown in FIG. 1) with the steering angular speed direction. It is determined whether or not to perform (step S32). Normally, the vehicle body B rolls in a direction opposite to the rudder angle by centrifugal force generated during turning. However, when fast steering is performed, the roll is generated with a certain delay from the start of the steering angle, so the steering angular speed direction and the roll direction may coincide.
As a result of this determination, if the roll direction and the rudder angular velocity direction match, only the target value based on the stroke amount is output.
That is, the control unit outputs torques YL and YR obtained from the stroke difference LR as target values of torques TTL and TTR.
[0045]
On the other hand, when the roll direction and the steering angular velocity direction do not match, the target value based on the steering angular velocity and the target value based on the stroke amount are added and output (step S34).
That is, the control unit calculates the torque TTL generated in the actuator 1L based on the expression “YL + TL”, calculates the torque TTR generated in the actuator 1R based on the expression “YR + TR”, and determines the torque TTL obtained by this calculation. , TTR is output as target value torque.
[0046]
Next, with reference to FIG. 6, the operation for calculating the target value when the skyhook control shown in step S2 of FIG. 2 is performed will be described.
First, the control unit reads the vertical acceleration GB, which is the output of the acceleration sensor SB that detects the vertical acceleration of the vehicle body B (step S41). Subsequently, the control unit calculates a cancel value for canceling the DC offset included in the vertical acceleration GB (step S42). The cancel value DC (k) is calculated by the following equation: DC (k) = (0.75 / (0.75 + T)) · (DC (k−1) + GB (k) −GB (k−1). Here, T is the sampling time, GB is the vertical acceleration, k is the latest value, and k-1 is the value used in the previous calculation process.
[0047]
Next, the control unit calculates the sprung (vehicle body B) speed y (k) (step S43). This speed y (k) is calculated by the equation y (k) = (1 / (1.3 + T)) · (1.3y (k−1) + T · DC (k)). Here, T is the sampling time, and DC is the cancel value calculated in step S42. Further, k means the latest value, and k-1 means the value used in the previous calculation process.
[0048]
Next, the control unit determines the operation direction of the actuators 1L and 1R based on the value of the speed y (k) calculated in step S43 (step S44). The determination of the operation direction is a direction in which the actuators 1L and 1R are contracted if the sprung speed y (k) is a positive value, and a direction in which the actuator 1L and 1R is extended if the value is negative.
[0049]
Next, the control unit calculates torques TTL and TTR as target values based on the value of sprung speed y (k) (step S45).
The target values TTL and TTR are calculated by the equation TTL, TTR = | y (k) | · C · K. Here, C is a damping coefficient, and K is a torque constant.
[0050]
Next, with reference to FIG. 7, an operation for calculating a target value when the pitching suppression control shown in step S3 of FIG. 2 is performed will be described.
First, the control unit reads the longitudinal acceleration GC, which is the output value of the acceleration sensor SC that detects the longitudinal acceleration of the vehicle body B (step S51). And a control part determines the direction of the reaction force which the actuators 1L and 1R generate | occur | produce based on the longitudinal acceleration GC read (step S52). The direction of the reaction force is determined by determining whether the vehicle is accelerating or decelerating based on the value of the longitudinal acceleration GC. When the vehicle is accelerating, the load moves backward, so the rear wheel springs 7L and 7R contract. On the other hand, since the load moves forward during deceleration, the rear wheel springs 7L and 7R extend. Therefore, when it is determined that acceleration is being performed, the direction in which the reaction force is generated is the direction in which the springs 7L and 7R are extended. On the other hand, when it is determined that deceleration is in progress, the direction in which the reaction force is generated is the direction in which the springs 7L and 7R are contracted. And
[0051]
Next, the control unit calculates the amount of movement of the load moved by acceleration / deceleration (step S53). The load movement amount ΔW is calculated by the equation: ΔW = (1/2) · (hg / L) · W · Xg. Here, hg is the height of the center of gravity of the vehicle, L is the wheelbase of the vehicle, W is the vehicle weight, and Xg is the absolute value of the longitudinal acceleration GC. Subsequently, the control unit calculates and outputs a target value TTL per actuator (step S54). Since the reaction force of the load movement amount ΔW has only to be generated in the same direction simultaneously by the two actuators 1L, 1R, the target value torques TTL, TTR are obtained by the equation of TTL, TTR = ΔW / 2.
[0052]
Next, with reference to FIG. 8, the operation for performing the control mode determination shown in step S4 of FIG. 2 will be described.
First, the control unit reads a sensor output value (step S61). The sensor output value read here reads the output value acquired and stored in the storage unit during the processing operation for obtaining the target value described above. Then, the control unit determines whether or not the absolute value of the rudder angle is greater than 5 (°) (step S62). If the result of this determination is greater than 5 (°), it is determined that the vehicle is turning, and a target value for rolling suppression control is selected (step S63).
[0053]
Next, the control unit multiplies the selected target value by the gain obtained based on the current vehicle speed (step S64). The gain multiplied by the target value is obtained with reference to a gain map that defines the relationship between the vehicle speed and the gain shown in FIG. As shown in FIG. 12, in the gain map, the X axis is the vehicle speed, the Y axis is the gain, and the gain is a value between “0” and “1”. In the example shown here, the gain is “0” when the vehicle speed is 0 to 10 (Km / h), the gain is “1” when the vehicle speed is 20 (Km / h) or more, and 10 to 20 (Km / h). Between, linear interpolation is performed.
Therefore, when the vehicle speed is 0 to 10 (Km / h), the control by the actuators 1L and 1R is not performed, and when the vehicle speed is 20 (Km / h) or more, the control is performed according to the target value set in step S63. means.
Thus, by multiplying the target value by the gain, it becomes possible to change the target value in accordance with the speed of the vehicle. Therefore, at low speeds of 10 (Km / h) or less, due to road surface unevenness. Due to the influence, a minute control operation is performed, and it is possible to prevent the ride comfort from being lowered.
[0054]
Next, in step S62, when the absolute value of the steering angle is 5 (°) or less, the control unit determines whether or not the absolute value of the steering angular velocity is greater than 0.5 (rad / s) (step S62). S65). If the absolute value of the steering angular speed is greater than 0.5 (rad / s) as a result of this determination, it is determined that there is a high possibility of rolling because the steering angle is small but the steering angular speed is fast, and the process proceeds to step S63. The process described above is performed.
On the other hand, when the absolute value of the rudder angular velocity is 0.5 (rad / s) or less, the control unit further determines that the absolute value of the longitudinal acceleration is 2 (m / s). ² ) Is determined (step S66). As a result of this determination, the absolute value of the longitudinal acceleration is 2 (m / s ² In the following cases, the control unit selects a target value for skyhook control (step S67), proceeds to step S64, and multiplies the obtained target value by a gain based on the vehicle speed. As a result of the determination in step S66, the absolute value of the longitudinal acceleration is 2 (m / s ² If greater than (), the control unit selects a target value for pitching suppression control (step S68). When the target value for the pitching suppression control is selected, the control unit does not perform gain multiplication based on the vehicle speed (step S64). This is because whether or not the longitudinal acceleration at which pitching is likely to occur is greater than or equal to a predetermined value and the pitching suppression control is determined based on the absolute value of the longitudinal acceleration, the gain based on the vehicle speed is determined. This is because no multiplication is required.
[0055]
Thus, based on the output value of the sensor provided in the vehicle, the state of the vehicle body B is determined based on whether or not a predetermined condition is satisfied. As a result of the determination, it is determined that the vehicle is in a turning state. In this case, since the control for suppressing the rolling is performed on the suspension, it is possible to obtain the same effect as if the spring rate of the suspension is increased only during turning.
In addition, as a result of the determination, when it is determined that the vehicle is in a straight traveling state, the suspension is mainly controlled to suppress bouncing to improve the ride comfort. It is possible to obtain the same effect as when the spring rate is reduced.
Furthermore, as a result of determination, when it is determined that the vehicle is in a straight traveling state and is in an acceleration / deceleration state, control is mainly performed to suppress pitching, so that it is equivalent to increasing the suspension spring rate only during acceleration / deceleration. An effect can be obtained.
[0056]
<Second Embodiment>
Next, a second embodiment will be described with reference to FIGS.
FIG. 9 is a flowchart showing a processing operation for calculating the target value without using the output of the longitudinal acceleration sensor in the process of calculating the target value used for the pitching suppression control shown in FIG. FIG. 10 is a diagram illustrating only a portion in which the control mode determination process shown in FIG. 8 is different when the target value is obtained by the process shown in FIG.
First, the control unit reads the output value of the accelerator opening sensor SD (step S71). Subsequently, the control unit reads the output value of the pedal force sensor SE (step S72). Then, the control unit determines whether or not there is an output from the accelerator opening sensor SD (step S73). As a result of the determination, when there is an output from the accelerator opening sensor SD, the control unit obtains a target value corresponding to the accelerator opening with reference to the target value map (step S74). FIG. 13 shows a target value map for obtaining a target value corresponding to the accelerator opening.
[0057]
As a result of the determination in step S73, when there is no output from the accelerator opening sensor SD, the control unit determines whether there is an output from the pedal effort sensor SE (step S75). As a result of this determination, when there is an output from the pedal effort sensor SE, the control unit obtains a target value corresponding to the brake depression force with reference to the target value map (step S76). FIG. 14 shows a target value map for obtaining a target value corresponding to the brake depression force.
On the other hand, when there is no output from the pedal force sensor SE, the control unit sets the target value to “0” (step S77).
[0058]
Next, a control mode determination process in the second embodiment will be described with reference to FIG. FIG. 10 is a flowchart illustrating only processing portions corresponding to steps S65 to S68 shown in FIG. In this figure, the operations in steps S65, S67, and S68 are the same as the processing shown in FIG. The process shown in FIG. 10 is different from FIG. 8 in that steps S66A and S66B are provided instead of step S66.
[0059]
In step S65, when the rudder angular velocity absolute value is 0.5 (rad / s) or less, the control unit determines whether the accelerator opening is 10 (°) or less (step S66A). As a result of the determination, if the accelerator opening is larger than 10 (°), the process proceeds to step S68. If the accelerator opening is 10 (°) or less, the control unit determines whether the pedal effort is 20 (N, Newton) or less. It is determined whether or not (step S66B). As a result of this determination, if the pedal effort is greater than 20 (N), the process proceeds to step S68, and if the pedal effort is 20 (N) or less, the process proceeds to step S67.
[0060]
As described above, acceleration / deceleration is determined by the accelerator opening and the brake pedaling force without using the longitudinal acceleration sensor, so that it is possible to remove disturbance from the road surface and disturbance due to the road surface gradient. As a result, the state determination process can be simplified, and fine control can be performed.
[0061]
In the above description, the example in which the actuators 1L and 1R are provided on the rear wheels of the automobile has been described. However, the above-described control may be performed by providing the actuators for the suspension of the front wheels in the same manner. . Furthermore, it is possible to control each of the four wheels by providing actuators for all the suspensions of the rear wheels and the front wheels.
[0062]
As described above, it is determined whether the vehicle is in a turning state or a straight traveling state according to the state of the vehicle. If the vehicle is in a turning state, the left and right wheels are controlled in opposite phases, thereby rolling. When the vehicle is in a straight-running state, the same phase control is performed on the left and right wheels to mainly suppress bouncing, thereby improving steering stability and passenger comfort. Is possible.
[0063]
In addition, even in a straight-ahead state, during acceleration / deceleration, the left / right in-phase control is mainly used to suppress pitching, and during acceleration, the force to lift the rear of the vehicle is applied to the road surface as a reaction force. As a result, the ground contact weight is increased, the grip force of the tire can be increased, and acceleration can be performed efficiently. Further, since the sinking behind the vehicle can be reduced during deceleration, it is possible to reduce changes in the behavior of the vehicle.
[0064]
【The invention's effect】
As described above, according to the first aspect of the present invention, in the suspension in which one actuator is provided on each of the left and right wheels of the vehicle, and each of the left and right wheels can receive a vertical force by the actuator. In addition, when the vehicle is traveling straight, control is given priority to the rider's ride comfort, and control is given priority to restraining the roll when turning, thus reducing vibration of the vehicle body when traveling straight. Thus, when turning, the tilt of the vehicle body can be reduced and the ride comfort of the occupant can be improved. Further, since the apparent spring rate can be increased only during turning, an effect that both improvement in steering stability and improvement in riding comfort can be obtained.
[0065]
Also, This According to the invention, even when the vehicle is traveling straight, when the longitudinal acceleration of the vehicle is larger than a predetermined value, the control that gives priority to the suppression of pitching is performed, so that the vehicle body tilts back and forth during acceleration / deceleration. Can be reduced, and the ride comfort of the passenger can be improved. In addition, since the apparent spring rate can be increased only during acceleration / deceleration, there is also an effect that both steering stability and riding comfort can be achieved.
[0066]
Also, This According to the invention, since the force generated by the actuator is changed in accordance with the speed of the vehicle, a minute control operation is performed at the low speed due to the unevenness of the road surface and the ride comfort is lowered. The effect that it can prevent is acquired.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a suspension according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a main process for controlling the suspension shown in FIG. 1;
FIG. 3 is a flowchart showing detailed processing of step S1 shown in FIG.
FIG. 4 is a flowchart showing detailed processing of step S1 shown in FIG.
FIG. 5 is a flowchart showing detailed processing of step S1 shown in FIG.
6 is a flowchart showing detailed processing in step S2 shown in FIG.
FIG. 7 is a flowchart showing detailed processing in step S3 shown in FIG.
FIG. 8 is a flowchart showing a detailed process of step S4 shown in FIG.
FIG. 9 is a flowchart showing a detailed process of step S3 shown in FIG.
FIG. 10 is a flowchart showing detailed processing of step S4 shown in FIG.
FIG. 11 is an explanatory diagram showing an example of a target value map.
FIG. 12 is an explanatory diagram showing an example of a gain map for obtaining a gain multiplied by a target value.
FIG. 13 is an explanatory diagram showing an example of a target value map.
FIG. 14 is an explanatory diagram showing an example of a target value map.
15 is an explanatory diagram showing the arrangement of sensors for detecting the state of the vehicle body B. FIG.
FIG. 16 is an explanatory diagram showing the arrangement of sensors for detecting the state of the vehicle body B.
[Explanation of symbols]
1L, 1R Actuator
2L, 2R upper arm
3L, 3R Lower arm
4L, 4R drive arm
5L, 5R link
6L, 6R knuckle
7L, 7R Spring
GL, GR reducer
ML, MR motor
WL, WR wheel

Claims (1)

One actuator is provided for each of the left and right wheels of the vehicle, and in order to allow each of the left and right wheels to receive a vertical force by this actuator, the relationship between the accelerator opening and the target value of the generated torque of the actuator is related. A suspension control method comprising: a first target value map attached; and a second target value map in which a brake pedal force and a target value of the generated torque of the actuator are related to each other,
The control method is:
When traveling straight ahead, by multiplying the target value of the generated torque by a gain based on the vehicle speed, change the force generated by the actuator to give priority to riding comfort,
At the time of turning, by multiplying the target value of the generated torque by a gain based on the vehicle speed, the force generated by the actuator is changed to give priority to suppression of rolling,
Even when the vehicle is running straight, when the longitudinal acceleration of the vehicle is larger than a predetermined value, the target value corresponding to the accelerator opening or the brake pedal force obtained by referring to the first and second target value maps is set. There rows priority control pitching suppression based,
The suspension control method according to claim 1, wherein the target value of control giving priority to suppression of pitching is not multiplied by a gain based on a vehicle speed .

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