JP2015067163A - Suspension control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular suspension control device capable of keeping a vehicle behavior in a stable state even if arithmetic abnormality occurs.SOLUTION: A controller 21 includes: a sprung speed calculation unit 23; a relative speed calculation unit 24; a ride control unit 25; a lateral-jerk estimation unit 27; an anti-roll control unit 28; a longitudinal-jerk estimation unit 30; an anti-dive/anti-squat control unit 31; and a current calculation unit 32, each of which performs floating-point computation to calculate a control variable X. An arithmetic result determination unit 34 of the controller 21 detects whether an arithmetic abnormality occurs to the floating-point computation. A degradation processing unit 35 of the controller 21 adjusts a command current I so that a damping force of a damper 6 is set to a hard side if the control variable X is a non-numerical number and a driver steering is underway.

Description

  The present invention relates to a suspension control device that is mounted on a vehicle such as a four-wheeled vehicle and includes a damping force adjusting type shock absorber.

  Generally, a vehicle such as an automobile is provided with a damping force adjustment type shock absorber between the vehicle body and each axle, and suspension control is configured to adjust the damping force characteristic by the shock absorber according to the damping force control command by the controller. The apparatus is mounted (for example, refer patent document 1). In this type of suspension control device according to the prior art, for example, a shock absorber so as to detect vibrations in the upward and downward directions of the vehicle body as a sprung speed or a sprung acceleration and to generate a damping force corresponding to the detected speed or the like. A damping force control command was output.

JP 2011-57219 A

  By the way, in the suspension control device according to the prior art, the controller that calculates the damping force control command based on the sprung speed or the like performs, for example, a fixed-point type arithmetic processing. For this reason, when calculating the sprung speed, the estimation error of the vehicle behavior is large, such as a large integration error, a large error in the rate of change of lateral jerk, or a large relative speed calculation error that requires high accuracy. There was a tendency that the control performance of the vehicle body behavior by the shock absorber was lowered.

  As a countermeasure, a floating point type arithmetic processing capable of high-precision arithmetic is conceivable. In this case, various abnormalities in the controller (for example, register abnormality, ROM abnormality, RAM abnormality, non-number, infinity, A calculation abnormality may occur due to an FPU abnormality or the like, and the target damping force or relative speed may become an abnormal value. As a result, suspension control is interrupted, the damping force suddenly becomes soft from hard, and the behavior of the vehicle may become unstable.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a suspension control device capable of maintaining the behavior of a vehicle in a stable state even when a calculation abnormality occurs. There is.

  In order to solve the above-described problems, the present invention provides a damping force adjustment type shock absorber that is interposed between a vehicle body and a wheel of a vehicle and whose damping force characteristics are variably controlled according to a damping force control command by a control means. In the suspension control apparatus, the control means includes a vehicle behavior detection means for detecting the behavior of the vehicle, a driver operation detection means for detecting an operation of the vehicle by a driver, and a detection result of the vehicle behavior detection means. In order to calculate the damping force control command based on the detection result of the driver operation detection means, a floating point arithmetic unit for performing a floating point arithmetic is provided, and the control means is configured such that the floating point arithmetic unit has a non-numeric value. In the case of calculation, when it is detected that the driver is operating, the damping force control command is set to the hardware side.

  According to the present invention, the behavior of the vehicle can be maintained in a stable state even when a calculation abnormality occurs.

It is a figure showing typically a suspension control device by an embodiment of the invention. It is a block diagram which shows the controller in FIG. It is a flowchart which shows the suspension control by the controller in FIG. It is a flowchart which shows the calculation result determination process in FIG. It is a flowchart which shows the control variable comparison process in FIG. It is explanatory drawing which shows the relationship between lateral jerk and the estimated value of controlled variable. It is explanatory drawing which shows the content of the degradation process. It is a state transition diagram showing the relationship between normal control and degradation processing. It is a characteristic diagram which shows an example of a time change of a steering angle, a calculation abnormality flag, and command current. It is explanatory drawing which shows the relationship between the relative speed by the comparative example, target damping force, and command current. It is a characteristic diagram which shows an example of the time change of the command current by a comparative example.

  Hereinafter, a suspension control device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where it is applied to a four-wheeled vehicle.

  The vehicle body 1 constitutes a vehicle body. Below the vehicle body 1, for example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 2) are provided. The wheels 2 include tires 3. At this time, the tire 3 acts as a spring that absorbs fine irregularities on the road surface.

  The suspension device 4 is provided between the vehicle body 1 and the wheel 2. The suspension device 4 includes a suspension spring 5 (hereinafter referred to as a spring 5) and a damping force adjustment type shock absorber (hereinafter referred to as a shock absorber 6) provided between the vehicle body 1 and the wheel 2 in parallel with the spring 5. ). FIG. 1 illustrates a case where a set of suspension devices 4 is provided between the vehicle body 1 and the wheels 2. However, for example, a total of four suspension devices 4 are individually provided between the four wheels 2 and the vehicle body 1, and only one of these is schematically illustrated in FIG. 1. .

  Here, the shock absorber 6 of the suspension device 4 is configured using a damping force adjusting hydraulic shock absorber. The shock absorber 6 continuously adjusts the generated damping force characteristic (damping force characteristic) from a hard characteristic (hard characteristic) to a soft characteristic (soft characteristic). An actuator 7 composed of a valve, a solenoid or the like is attached. The shock absorber 6 is capable of adjusting the damping force characteristic according to the command current I by supplying a command current I as a damping force control command to the actuator 7.

  Note that the damping force adjusting actuator 7 may be capable of adjusting the damping force characteristic in two or more stages without being continuous. Further, the shock absorber 6 may be a pneumatic damper or an electromagnetic damper as long as the damping force can be switched.

  The sprung acceleration sensor 8 is provided on the vehicle body 1. Specifically, the sprung acceleration sensor 8 is attached to the vehicle body 1 at a position near the shock absorber 6, for example. The sprung acceleration sensor 8 detects the vibration acceleration in the upward and downward directions on the side of the vehicle body 1 that is the upper side of the so-called spring, and outputs a detection signal S2 to the controller 21 described later.

  The lateral acceleration sensor 9 is provided on the vehicle body 1 and detects left and right (lateral) acceleration acting on the vehicle body 1, that is, lateral acceleration Ay indicating the roll behavior of the vehicle. The lateral acceleration sensor 9 outputs the detection signal Sy to the controller 21.

  The longitudinal acceleration sensor 10 is provided in the vehicle body 1 and detects the acceleration in the forward and backward directions acting on the vehicle body 1, that is, the longitudinal acceleration indicating the pitching behavior of the vehicle. The longitudinal acceleration sensor 10 outputs the detection signal Sx to the controller 21. The longitudinal acceleration sensor 10 and the sprung acceleration sensor 8 and the lateral acceleration sensor 9 constitute vehicle behavior detecting means for detecting the behavior of the vehicle.

  The driver operation sensor 11 is a driver operation detection unit that detects a vehicle operation by a driver (driver). The driver operation sensor 11 detects, for example, a steering angle sensor that detects a steering angle according to a steering operation of a steering wheel, a throttle opening sensor that detects a throttle opening according to an accelerator operation, and a brake fluid pressure according to a brake operation. A brake fluid pressure sensor for detecting the vehicle speed, a vehicle speed sensor for detecting the vehicle speed, and the like. The driver operation sensor 11 outputs the detection signal Sd to the controller 21.

  The controller 21 is composed of a microcomputer, for example, and constitutes a control means together with the sensors 8 to 11 described above. The controller 21 outputs a command current I as a damping force control command based on the detection signals S2, Sx, Sy, Sd from the various sensors 8 to 11 and the like, and a buffer 6 responds to the command current I. Controls the generated damping force. The controller 21 has an input side connected to the sensors 8 to 11 and the like, and an output side connected to the actuator 7 and the like of the shock absorber 6. The controller 21 has a storage unit 21A composed of a ROM, a RAM, and the like, and the storage unit 21A stores a processing program and the like described later shown in FIGS.

  As shown in FIG. 2, the controller 21 includes a sprung acceleration calculation unit 22, a sprung speed calculation unit 23, a relative speed calculation unit 24, and a riding comfort control unit 25. Thus, the controller 21 calculates a control amount Ctrl_C for increasing the riding comfort of the vehicle.

  Specifically, the sprung acceleration calculation unit 22 calculates the sprung acceleration A2 based on the detection signal S2 from the sprung acceleration sensor 8. The sprung speed calculation unit 23 calculates the sprung speed V2 by, for example, integrating the sprung acceleration A2. The relative speed calculator 24 calculates a relative speed V21 between the sprung and unsprung parts based on the sprung acceleration A2 by various estimation calculations using, for example, an observer. The riding comfort control unit 25 calculates a control amount Ctrl_C for increasing the riding comfort of the vehicle based on the sprung speed V2 and the relative speed V21.

  The controller 21 also includes a lateral acceleration calculation unit 26, a lateral jerk estimation unit 27, an anti-roll control unit 28, a longitudinal acceleration calculation unit 29, a longitudinal jerk estimation unit 30, and an anti-dive squat control unit 31. The controller 21 calculates control amounts Ctrl_R and Ctrl_DS for improving the steering stability of the vehicle by these as the steering control.

  Specifically, the lateral acceleration calculation unit 26 calculates the lateral acceleration Ay based on the detection signal Sy from the lateral acceleration sensor 9. The lateral jerk estimation unit 27 estimates the lateral jerk Aya by calculating the time derivative of the lateral acceleration Ay. The anti-roll control unit 28 calculates a control amount Ctrl_R for suppressing the roll of the vehicle based on the lateral jerk Aya.

  Further, the longitudinal acceleration calculation unit 29 calculates the longitudinal acceleration Ax based on the detection signal Sx from the longitudinal acceleration sensor 10. The longitudinal jerk estimation unit 30 estimates the longitudinal jerk Axa by calculating the time derivative of the longitudinal acceleration Ax. The anti-dive / squat control unit 31 calculates a control amount Ctrl_DS for suppressing the dive or squat of the vehicle based on the lateral jerk Aya.

  The current calculation unit 32 of the controller 21 converts the control amounts Ctrl_C, Ctrl_R, and Ctrl_DS calculated by the riding comfort control unit 25, the anti-roll control unit 28, and the anti-dive / squat control unit 31 into a command current I. The current control unit 33 of the controller 21 performs output setting of the command current I serving as a damping force control command and outputs the command current I to the actuator 7 of the shock absorber 6.

  Here, in order to improve the control performance of the suspension device 4, the sprung speed calculation unit 23, the relative speed calculation unit 24, the lateral jerk estimation unit 27, and the longitudinal jerk estimation unit 30 need to perform calculation with high accuracy. There is. For this reason, the sprung speed calculation unit 23, the relative speed calculation unit 24, the lateral jerk estimation unit 27, and the longitudinal jerk estimation unit 30 perform a floating point calculation. Along with this, a ride comfort control unit 25, an anti-roll control unit 28, an anti-dive squat control unit 31 using the sprung speed V2, the relative speed V21, the lateral jerk Aya, and the longitudinal jerk Axa, which are the calculation results, The current calculation unit 32 also performs floating point calculations.

  That is, the sprung acceleration calculation unit 22, the sprung speed calculation unit 23, the relative speed calculation unit 24, the riding comfort control unit 25, the lateral acceleration calculation unit 26, the lateral jerk estimation unit 27, the anti-roll control unit 28, and the longitudinal acceleration calculation unit. 29, the longitudinal jerk estimation unit 30, the anti-dive squat control unit 31, and the current calculation unit 32 are each a floating point arithmetic unit. These floating-point arithmetic units perform various floating-point operations to calculate the command current I based on the detection results of the sprung acceleration sensor 8, the lateral acceleration sensor 9, the longitudinal acceleration sensor 10, and the driver operation sensor 11. Do. Accordingly, the sprung acceleration A2, lateral acceleration Ay, longitudinal acceleration Ax, sprung velocity V2, relative velocity V21, lateral jerk Aya, longitudinal jerk Axa, and control variables Ctrl_C, Ctrl_R, Ctrl_DS are all floating-point control variables. X.

  The controller 21 determines the correctness and validity of the control variable X calculated by the floating-point type arithmetic processing, and the command current I when the arithmetic result determination unit 34 determines that the calculation is abnormal. A degradation processing unit 35 for adjusting and generating an appropriate damping force is further provided. The output of the degradation processing unit 35 is multiplied by the command current I by the multiplier 36 and input to the current control unit 33.

  Therefore, when the calculation result determination unit 34 determines that the calculation is normal, the degradation processing unit 35 outputs a signal for inputting the command current I from the current calculation unit 32 to the current control unit 33 as it is. As a result, the controller 21 performs normal control, and the buffer 6 generates a damping force corresponding to the command current I from the current calculation unit 32. At this time, the generated damping force of the shock absorber 6 is controlled (adjusted) between hardware and software continuously or variably in multiple stages according to the command current I supplied to the actuator 7.

  On the other hand, when the calculation result determination unit 34 determines that the calculation is abnormal, the degradation processing unit 35 adjusts the command current I according to the presence / absence of the driver operation and the control of the damping force characteristic. Here, the degradation processing unit 35 detects the presence or absence of a driver operation based on the detection signal Sd from the driver operation sensor 11. Further, the degradation processing unit 35 detects the presence or absence of control of the damping force characteristic based on the feedback value Ifb of the command current I. As a result, the controller 21 performs a degradation process and causes the shock absorber 6 to generate a hard-side damping force or, for example, the same intermediate damping force as that of a passive hydraulic shock absorber.

  The suspension control apparatus according to the present embodiment has the above-described configuration. Next, processing for variably controlling the damping force characteristic of the shock absorber 6 using the controller 21 will be described.

  First, when the suspension control process shown in FIG. 3 is started upon receiving power supply accompanying the start of the vehicle engine, the controller 21 is initialized in step 1. Then, in step 2, it is determined whether or not a control cycle of, for example, about 5 to 10 ms has been reached, and the process waits until the control cycle is reached while determining “NO”. On the other hand, if “YES” is determined in step 2 and the control period is reached, the process proceeds to the next step 3 to drive the actuator 7 of the shock absorber 6.

  Next, in step 4, in order to input the sensor value, the detection signal S2 corresponding to the vibration acceleration in the upward and downward direction of the sprung (vehicle body 1) side is read from the sprung acceleration sensor 8, and the vehicle body 1 is read from the lateral acceleration sensor 9. The detection signal Sy corresponding to the vibration acceleration in the left and right directions is read, the detection signal Sx corresponding to the vibration acceleration in the front and rear directions of the vehicle body 1 is read from the longitudinal acceleration sensor 10, and the steering angle and throttle are read from the driver operation sensor 11. A detection signal Sd corresponding to the opening degree, brake fluid pressure, vehicle speed, etc. is read.

  In the next step 5, the controller 21 performs a ride comfort control process based on, for example, the skyhook theory, and calculates a control amount Ctrl_C for increasing the ride comfort of the vehicle. Specifically, the control amount Ctrl_C is calculated from the sprung acceleration A2 by the sprung acceleration calculating unit 22, the sprung speed calculating unit 23, the relative speed calculating unit 24, and the riding comfort control unit 25 of the controller 21.

  In step 6, the controller 21 performs a steering control process, and calculates control amounts Ctrl_R and Ctrl_DS for improving the steering stability of the vehicle. Specifically, the lateral acceleration calculation unit 26, the lateral jerk estimation unit 27, and the anti-roll control unit 28 of the controller 21 calculate the control amount Ctrl_R for suppressing the roll of the vehicle from the lateral acceleration Ay. In addition, the control amount Ctrl_DS for suppressing the dive and squat of the vehicle is calculated from the longitudinal acceleration Ax by the longitudinal acceleration calculation unit 29, the longitudinal jerk estimation unit 30 and the anti-dive squat control unit 31 of the controller 21.

  In step 7, the calculation result determination unit 34 of the controller 21 determines the validity and validity of the control variable X calculated by the floating point type calculation process. Specifically, the calculation result determination unit 34 is the control variable X, which is the sprung acceleration A2, lateral acceleration Ay, longitudinal acceleration Ax, sprung speed V2, relative velocity V21, lateral jerk Aya, longitudinal jerk Axa, control. It is determined whether or not the quantities Ctrl_C, Ctrl_R, and Ctrl_DS are abnormal values such as non-numbers and infinity.

  In subsequent step 8, the degradation processing unit 35 of the controller 21 performs a degradation process on the calculation result determination unit 34 according to the determination result. Specifically, the degradation processing unit 35 outputs a signal for adjusting the command current I to the calculation result determination unit 34 based on the determination result.

  It should be noted that the initialization of the abnormal state during the degradation process is performed at the time when the vehicle is stable, and when the initialization is completed normally, the control process of the suspension device 4 is resumed.

  In step 9, the command current I corresponding to the controlled variables Ctrl_C, Ctrl_R, and Ctrl_DS is calculated by the current calculation unit 32 of the controller 21. In step 10, based on the degradation process in step 8 and the command current I calculated in step 9, the output of the command current I is set by the current control unit 33.

  The command current I is used to drive and control the actuator 7 of the shock absorber 6 in the next step 3 every time it reaches the control cycle determined as “YES” in step 2 that is not related to the control cycle. Used. Thereby, the damping force characteristic of the shock absorber 6 is continuously controlled by being variable between a hard characteristic (hard characteristic) and a soft characteristic (soft characteristic).

  Next, the calculation result determination process in FIG. 3 will be described with reference to FIG. In the calculation result determination process, a control variable comparison process is performed in step 21, and a control variable validity determination process is performed in step 22. When these processes are completed, the process returns.

  Specific processing contents by the control variable comparison processing in FIG. 4 will be described with reference to FIG. In the control variable comparison process, each control variable X is checked for occurrence or propagation of an infinite number or infinity for each control of ride comfort control, anti-roll control, and anti-dive squat control.

  Here, a case where the correctness of each control variable X is checked in the order of ride comfort control, anti-roll control, and anti-dive squat control will be described as an example. Note that the order of these controls may be changed as appropriate.

  In step 31, the values of the sprung acceleration A2, the sprung speed V2, the relative speed V21, and the control amount Ctrl_C defined by the floating point type used in the ride comfort control are compared. If “NO” is determined in the step 31, each value is different, so that the calculation result is determined to be normal and the process returns.

  On the other hand, if “YES” is determined in step 31, any one of the sprung acceleration A 2, the sprung speed V 2, the relative speed V 21, and the control amount Ctrl_C is equal. There is a possibility. For this reason, the process proceeds to step 32, and a validity check is performed for each control variable X.

  In step 32, four arithmetic operations using only the control variable X are performed. Specifically, as shown in the following formula 1, subtraction by the same control variable X is performed, and it is confirmed whether or not it becomes 0 (zero) which is a predicted value in a valid case.

  Further, as shown in the following equation (2), division by the same control variable X is performed, and it is confirmed whether or not 1 is a predicted value in a valid case.

  Further, as shown in the following equation (3), addition using the same control variable X is performed, and it is confirmed whether or not the value is twice the original control variable X, which is a predicted value in a valid case.

  Note that the four arithmetic operations for evaluating the validity of the control variable X are not limited to those described in Equations 1 to 3, and any four arithmetic operations combining addition, subtraction, multiplication, and division can be used.

  In step 33, it is determined whether or not the calculation result in step 32 matches the predicted value, that is, whether or not the left side and the right side of the formulas 1 to 3 match. When it is determined as “NO” in Step 33, it is considered that at least one of the control variables X used for the ride comfort control becomes a non-numerical value or an infinite value, and a calculation abnormality has occurred. Therefore, in step 34, an abnormality is set in the flag, and the process returns.

  If “YES” is determined in step 33, the control variable X (for example, sprung acceleration A 2) subjected to the four arithmetic operations is considered to be normal. Therefore, in step 35, all the control variables X for ride comfort control are determined. Determine whether the check is complete.

  If “NO” is determined in step 35, steps 32 and 33 are repeated, and four arithmetic operations are performed for the remaining control variables (for example, sprung speed V 2, relative speed V 21, control amount Ctrl_C). Check for correctness.

  On the other hand, if “YES” is determined in step 35, the control variables X (sprung acceleration A2, sprung speed V2, relative speed V21, control amount Ctrl_C) used for ride comfort control are considered to be normal. The process proceeds to step 36.

  In step 36, it is determined whether or not the control variable X has been checked for all controls. If "NO" is determined in the step 36, the processing after the step 31 is repeated, and the validity of the control variable X is checked for the remaining control. For example, when the validity check is completed for the control variable X (spring acceleration A2, sprung speed V2, relative speed V21, control amount Ctrl_C) used for ride comfort control, the control variable used for the remaining anti-roll control X (lateral acceleration Ay, lateral jerk Aya, control amount Ctrl_R) and control variables X used for anti-dive squat control (longitudinal acceleration Ax, longitudinal jerk Axa, control amount Ctrl_DS) are valid for each control variable X. Check the validity of each operation result.

  On the other hand, if “YES” is determined in the step 36, the control variable X has been checked for all the controls, and the process returns.

  Next, the control variable validity determination process in FIG. 4 will be described with reference to FIG. In the control variable comparison process in step 21, it is possible to determine the validity of whether the control variable X has become a non-numerical value or an infinite value. However, when the data is altered inside the RAM or ROM, this data You cannot check for alterations. Therefore, in the control variable validity determination process, the validity of the control variable X is determined from the relationship with the calculation result of the control variable X based on the control gain (for example, the control amount Ctrl_R).

  For example, in the anti-roll control, the control amount Ctrl_R is calculated by multiplying the change rate (lateral jerk Aya) of the lateral acceleration Ay by the control gain value. For this reason, as shown in FIG. 6, the upper limit value and lower limit value of the control variable X (control amount Ctrl_R) are derived using a linear map in which the estimation range varies for each control gain, and the control variable X (control amount Ctrl_R) is derived. ) Check the range. At this time, the horizontal axis of FIG. 6 indicates the absolute value of the lateral jerk Aya as an input signal, and the vertical axis of FIG. 6 indicates the control variable X (control amount Ctrl_R) calculated based on the control gain. .

  As shown in FIG. 6, for example, when the lateral jerk Aya becomes the lateral jerk Aya0, the estimated range R1 of the control variable X is large when the control gain is a large value, and when the control gain is small, the control variable X When the estimated range R2 becomes small and the control gain becomes an intermediate value, the estimated range R3 of the control variable X is a range between the estimated range R1 and the estimated range R2. When the control variable X is within the estimated range, it is determined that the calculation is normal. On the other hand, when the control variable X is out of the estimated range, it is determined that the calculation is abnormal, and the flag is set to abnormal. Thus, the validity of the control variable X can be determined using the fact that the estimation ranges R1 to R3 change according to the control gain.

  Also in the anti-dive squat control, the control amount Ctrl_DS is calculated by multiplying the rate of change of the longitudinal acceleration Ax (the longitudinal jerk Axa) by the control gain value. Therefore, an upper limit value and a lower limit value of the control variable X (control amount Ctrl_DS) are derived using a linear map (not shown) similar to that described above, and whether or not the control variable X (control amount Ctrl_DS) is within the estimation range. To check. When the control variable X is within the estimated range, it is determined that the calculation is normal. On the other hand, when the control variable X is out of the estimated range, it is determined that the calculation is abnormal, and the flag is set to abnormal.

  Also in the ride comfort control, the target damping force can be calculated by multiplying the sprung speed V2 by the control gain value, and the control amount Ctrl_C can be calculated based on the target damping force and the relative speed V21. In this case, an upper limit value and a lower limit value of the target damping force that becomes the control variable X are derived using a linear map (not shown) similar to the above, and the control variable X (target damping force) is within the estimated range. You can check whether or not.

  In the control variable validity determination process, for example, when the input signal becomes infinite, the estimation range becomes infinite, and the validity of the control variable X cannot be determined. For this reason, in the present embodiment, various arithmetic abnormalities in the controller 21 are detected by combining with the control variable comparison processing in step 21 shown in FIG.

  Next, the degradation process in FIG. 3 will be described with reference to FIGS. FIG. 7 shows a case where a damping force corresponding to a passive hydraulic shock absorber is generated as the intermediate damping force.

  When it is determined that the calculation is abnormal by the calculation result determination process, that is, when an abnormality is set in the flag, the degradation process shown in FIG. 7 is performed. As shown in FIG. 8, when an abnormality in the calculation result is detected during the normal suspension apparatus 4 control process, the process shifts from the normal control to the degradation process. As shown in FIG. 7, for example, when the driver is operating the steering, brake, throttle, etc., the damping processing in the hard direction is performed by the degradation processing unit 35 of the controller 21 until the driver operation is completed. Set. After the driver operation is finished, the degradation processing unit 35 of the controller 21 gradually approaches the intermediate damping force (middle) determined in advance from the current damping force with an elapsed time of, for example, about several tens of ms to several hundreds of ms ( (See FIG. 9). At this time, the intermediate damping force corresponds to the same damping force as that of, for example, a passive hydraulic shock absorber. Thereby, the rapid fall of damping force can be suppressed. The intermediate damping force does not have to be an arithmetic average value between hardware and software, and may be biased toward the hardware side or between the hardware side and the software side.

  On the other hand, even when there is no driver operation, the current feedback value Ifb that is the value of the command current I output from the current control unit 33 of the controller 21 is monitored to detect whether or not the suspension device 4 is being controlled. As shown in FIG. 7, when the suspension device 4 is being controlled, this is detected based on the current feedback value Ifb, and gradually approaches the intermediate damping force from the current damping force. Thereby, the fluctuation | variation of a sudden damping force can be suppressed.

  If the vehicle stops during the degradation process, the work area is initialized. As shown in FIG. 8, when the vehicle is stopped and the initialization is normally completed, the normal control of the suspension device 4 is resumed.

  The suspension control device according to the embodiment executes the control processing as described above. Next, when an operation abnormality occurs in the operation of the suspension control device by the controller 21, the suspension control is performed using the previous calculation result. This will be described in comparison with a comparative example.

  For example, in Japanese Patent Application Laid-Open No. 2003-280891, floating point type data is used as a control variable used for engine control, and when a non-number or infinity is calculated as a control variable, control processing is continued using a default value. A configuration is disclosed. In the case of engine control, since engine fluctuations are small, it is considered that the control process can be continued even if the previous calculation result is substituted into the control variable in which the calculation abnormality has occurred. Considering this point, in the comparative example, when the control variable becomes non-numeric, the suspension control is performed by substituting the previous calculation result into the control variable.

  In ride comfort control, the target damping force is calculated by multiplying the sprung speed by a control gain. Then, for example, the damping force characteristic is adjusted based on the target damping force and the relative speed using the damping force characteristic calculation map shown in FIG.

  As shown in FIG. 10, in the ride comfort control according to the comparative example, when the extension-side target damping force DCVal_A and the extension-side relative speed V21_A are input, the command current Icnt_A employs a damping force in the hard direction. When the calculation is normally performed in the next control cycle, the compression-side target damping force DCVal_B and the compression-side relative speed V21_B are calculated, and the command current Icnt_B is assumed to employ a damping force in the hard direction. On the other hand, if the calculation result of the target damping force is determined to be abnormal, for example, due to non-number, infinity, RAM abnormality, or register abnormality, the previous value (the target damping force DCVal_A on the extension side) is the target damping force. Adopted. As described above, when the calculation abnormality occurs, if the positive and negative values of the target damping force are different between the previous time and the current time, the command current Icnt_B ′ employs a damping force in the soft direction, and an unintended reduction in the damping force occurs. .

  FIG. 11 shows a time chart of the command current when traveling on a lane change using the suspension control device according to the comparative example. FIG. 11A shows the time when the calculation is normally performed, and FIG. 11B shows the time when the calculation abnormality occurs during the control. As shown in FIG. 11, if a calculation abnormality occurs while outputting a damping force in the hard direction, a command current in the soft direction is generated, and the damping force of the suspension is reduced. For this reason, in a comparative example, there exists a problem that a control effect will deteriorate.

  In contrast, in the present embodiment, the calculation result determination process and the degradation process shown in FIGS. 3 to 7 are performed. In the calculation result determination process, the correctness and validity of the control variable X calculated by each processing unit is confirmed, and if it is determined that the calculation is abnormal, a degradation process is performed. If the vehicle stops during the degradation process, the work area is initialized. The abnormal state is initialized when the vehicle is stable and the suspension control process is resumed when the initialization is completed normally.

  FIG. 9 shows a time chart of the command current according to the present embodiment. In the comparative example, the damping force is switched in the soft direction when the calculation abnormality is detected. However, in this embodiment, even if the calculation abnormality is detected, the damping force in the hardware direction is continued until the driver's operation is completed, which is not intended. It turns out that the fall of damping force can be prevented.

  Thus, according to the present embodiment, the controller 21 responds to the vehicle behavior such as the sprung speed V2, the lateral jerk Aya, the longitudinal jerk Axa, etc. by the floating point type arithmetic processing capable of high-precision computation. Control variable X is calculated. For this reason, the estimation error of the vehicle behavior can be reduced, and the control performance of the vehicle body behavior by the shock absorber 6 can be enhanced.

  Further, when the controller 21 calculates a non-numeric value by a floating point type arithmetic processing, when it is detected that the driver is operating, the controller 21 sets the command current I so that the damping force of the shock absorber 6 is on the hardware side. adjust. For this reason, even when a non-numeric value is calculated for the control variable X, the damping force on the hardware side can be generated by the shock absorber 6 when the driver is operating. As a result, it is possible to prevent control abnormality of the damping force characteristic due to calculation abnormality, for example, when traveling on a road surface where the sprung greatly fluctuates, or when traveling on a road surface where the unsprung fluctuates Even when a sudden turn, a sudden start, or a sudden stop, the stability of the vehicle body 1 can be ensured.

  Further, when the control variable X is calculated as a non-numerical value, the driver 21 is not operated, and the damping force characteristic of the shock absorber 6 is not controlled, the damping force of the shock absorber 6 is determined as a predetermined intermediate damping force. The command current I is adjusted so that Further, the controller 21 calculates a non-number for the control variable X, when there is no driver operation, and when the damping force characteristic of the shock absorber 6 is being controlled, the damping force of the shock absorber 6 is intermediately attenuated from the current damping force. The command current I is adjusted so that the force gradually changes.

  Therefore, even when a non-numeric value is calculated for the control variable X, if there is no driver operation and the damping force characteristic is not controlled, the same damping force as that of, for example, a passive hydraulic shock absorber is generated as an intermediate damping force. be able to. At this time, since the switching to the intermediate damping force is performed inside the controller 21, the damping force can be switched with high responsiveness.

  Even when a non-numeric value is calculated for the control variable X, when there is no driver operation and the damping force characteristic is being controlled, the current damping force is gradually changed to an intermediate damping force. For this reason, it is possible to change the current damping force to the same damping force as that of, for example, a passive hydraulic shock absorber while suppressing a sudden change in the damping force, and to ensure the stability of the vehicle.

  Furthermore, when the vehicle stops, the controller 21 initializes the work area and initializes the control variable X that is floating point type data. Therefore, the control variable X can be initialized while the vehicle is stable, and normal control processing can be resumed while suppressing a rapid change in damping force.

  In the embodiment described above, the relative speed V21 is obtained based on the sprung acceleration A2, but the relative speed V21 may be obtained based on the sprung acceleration A2 and the unsprung acceleration A1. In this case, the unsprung acceleration sensor for detecting the unsprung acceleration A1 also constitutes the vehicle behavior detecting means.

  In the above-described embodiment, the suspension device 4 is configured to include the shock absorber 6 including a so-called semi-active damper and a damping force adjusting hydraulic shock absorber. However, the present invention is not limited to this, and a configuration using a pressure cylinder capable of adjusting the wheel load by increasing or decreasing the internal pressure by supplying or discharging fluid, such as an active suspension of pneumatic pressure or hydraulic pressure, may be used. Good. Further, the present invention can be applied not only to a suspension device using a fluid but also to a ball screw type or electromagnetic type active suspension.

  In the embodiment, the case where the damping force characteristic becomes soft when the command current I becomes small and the damping force characteristic becomes hard when the command current I becomes large has been described as an example. However, the present invention is not limited to this. For example, the damping force characteristic may be hard when the command current I is small, and the damping force characteristic may be soft when the command current I is large.

  Furthermore, in the above-described embodiment, the case where the present invention is applied to the controller 21 that controls the shock absorber 6 of the suspension device 4 based on the Skyhook theory has been described as an example. However, the buffer is based on H∞ control or modern control theory. The vessel may be controlled. Moreover, you may apply to the buffer which performs roll feedback control or pitch feedback control.

  Next, the invention included in each of the embodiments will be described. According to the present invention, the control means includes a vehicle behavior detection means for detecting the behavior of the vehicle, a driver operation detection means for detecting an operation of the vehicle by a driver, a detection result of the vehicle behavior detection means, and the driver In order to calculate the damping force control command based on the detection result of the operation detection means, a floating point arithmetic unit that performs a floating point arithmetic operation is provided, and the control means calculates a non-numeric value by the floating point arithmetic unit. In this case, the damping force control command is set to the hardware side when it is detected that the driver is operating.

  For this reason, even when the floating point arithmetic unit calculates a non-number, the damping force on the hardware side can be generated by the damping force adjusting buffer when the driver is operating. As a result, it is possible to prevent control abnormality of the damping force characteristic due to calculation abnormality, for example, when traveling on a road surface where the sprung greatly fluctuates, or when traveling on a road surface where the unsprung fluctuates Even when a sudden turn, a sudden start, or a sudden stop, the stability of the vehicle body can be ensured.

  According to the present invention, the control means calculates the damping force when the floating point arithmetic unit calculates a non-number, when there is no driver operation, and the damping force characteristic of the damping force adjusting shock absorber is not controlled. The damping force control command is adjusted so that the damping force of the adjustable shock absorber is an intermediate damping force between hardware and software, the floating point calculator calculates a non-numerical value, no driver operation, and the When the damping force characteristic of the damping force adjusting shock absorber is under control, the damping force control command is issued so that the damping force of the damping force adjusting shock absorber gradually changes from the current damping force to the intermediate damping force. It was set as the structure adjusted.

  For this reason, even when the floating point arithmetic unit calculates a non-number, when there is no driver operation and the damping force characteristic is not controlled, the same damping force as that of, for example, a passive hydraulic shock absorber is generated as an intermediate damping force. be able to. At this time, since the switching to the intermediate damping force is performed inside the control means, the damping force can be switched with high responsiveness. Even when the floating point arithmetic unit calculates a non-number, when there is no driver operation and the damping force characteristic is being controlled, the current damping force is gradually changed to the intermediate damping force. For this reason, it is possible to change the current damping force to the same damping force as that of, for example, a passive hydraulic shock absorber while suppressing a sudden change in the damping force, and to ensure the stability of the vehicle.

  According to the present invention, the control means initializes a calculation result of the floating point arithmetic unit when the vehicle stops. For this reason, the calculation result of the floating point arithmetic unit can be initialized while the vehicle is stable, and normal control processing can be resumed while suppressing a sudden change in damping force.

DESCRIPTION OF SYMBOLS 1 Car body 2 Wheel 4 Suspension device 6 Damping force adjustment type shock absorber 7 Actuator 8 Sprung acceleration sensor 9 Lateral acceleration sensor 10 Longitudinal acceleration sensor 11 Driver operation sensor (driver operation detection means)
21 controller 22 sprung acceleration calculation unit 23 sprung speed calculation unit 24 relative speed calculation unit 25 riding comfort control unit 26 lateral acceleration calculation unit 27 lateral jerk estimation unit 28 anti-roll control unit 29 longitudinal acceleration calculation unit 30 longitudinal jerk estimation unit 31 Anti-dive / squat control unit 32 Current calculation unit 33 Current control unit 34 Operation result determination unit 35 Degradation processing unit 36 Multiplier

Claims (3)

In a suspension control device including a damping force adjusting type shock absorber that is interposed between a vehicle body and a wheel of a vehicle and whose damping force characteristic is variably controlled according to a damping force control command by a control unit,
The control means includes
Vehicle behavior detecting means for detecting the behavior of the vehicle;
Driver operation detecting means for detecting operation of the vehicle by the driver;
A floating-point arithmetic unit that performs a floating-point operation in order to calculate the damping force control command based on the detection result of the vehicle behavior detection unit and the detection result of the driver operation detection unit;
The suspension control device according to claim 1, wherein when the floating point arithmetic unit calculates a non-numeric value, the control means sets the damping force control command to a hardware side when detecting that the driver is operating. The control means calculates the damping of the damping force adjusting shock absorber when the floating point arithmetic unit calculates a non-number, when there is no driver operation, and the damping force characteristic of the damping force adjusting shock absorber is not controlled. Adjust the damping force control command so that the force is an intermediate damping force between hard and soft,
When the floating point arithmetic unit calculates a non-number, there is no driver operation, and the damping force characteristic of the damping force adjusting shock absorber is under control, the damping force of the damping force adjusting shock absorber is the current damping The suspension control device according to claim 1, wherein the damping force control command is adjusted so that the force gradually changes from a force to the intermediate damping force.   The suspension control device according to claim 1 or 2, wherein the control means initializes a calculation result of the floating point arithmetic unit when the vehicle stops.

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