JP2008213684A - Vehicle traveling road determination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine the road surface state on which a vehicle travels. <P>SOLUTION: In the vehicle traveling road determination device, a presumption acceleration operation part 104 operates presumed acceleration Ge presumed to be generated on the vehicle based on an output of a drive source for traveling the vehicle. An actual acceleration operation part 105 calculates actual acceleration Gx actually generated on the vehicle. A road surface state determination part 106 corrects the presumed acceleration Ge according to the vehicle state for giving influence to a relationship of the presumed acceleration and the actual acceleration to obtain presumed acceleration Ga after correction, and compares the presumed acceleration Ga after correction with the actual acceleration Gx to determine the road surface state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle travel path determination device, and in particular, vehicle travel for determining a road surface state on which a vehicle is traveling based on acceleration actually generated in the vehicle or acceleration estimated to be generated. The present invention relates to a road discrimination device.

In the case of executing anti-skid control for increasing or decreasing the brake pressure based on the slip ratio of the wheels, it is preferable to accurately determine the state of the traveling road surface of the vehicle and execute anti-skid control corresponding to the traveling road of the vehicle. For this reason, for example, a vehicle anti-skid control device that determines that the travel path is a travel path with a high travel resistance when the deviation between the estimated wheel speed and the actual wheel speed is larger than a reference value has been proposed (for example, Patent Document 1). In addition, for example, an anti-skid control device that cancels the brake pressure increase / decrease process according to the sandy road when it is determined that the vehicle running road is not a sandy road has been proposed (for example, see Patent Document 2). Further, for example, when it is determined that the vehicle is traveling on a sandy road, a vehicle that re-determines whether the vehicle is in a sandy traveling state or a towing traveling state while the vehicle is decelerating or traveling at a high speed. A traveling state determination device has been proposed (see, for example, Patent Document 3). In addition, for example, a vehicle travel path discriminating apparatus that determines that the travel path of a vehicle is a sandy road when both the vehicle body acceleration and the wheel acceleration are below the driving force estimation acceleration has been proposed (for example, Patent Documents). 4).
JP 2005-138737 A JP 2006-335111 A JP 2006-335113 A JP 2006-335114 A

  The relationship between the estimated acceleration and the actual acceleration may change due to various factors such as the total distance traveled by the vehicle, the age of the vehicle, the type of fuel used, such as regular and high-octane, etc. is there. In the technique described in the above-mentioned patent document, even if the relationship between the estimated acceleration and the actual acceleration is changed due to such factors, it is possible to suppress erroneous determination that the traveling path of the vehicle is a sandy road. It is necessary to take measures such as expanding the area determined to be a normal road in advance. However, when such measures are taken, it is difficult to accurately determine the normal road and the sandy road.

  This invention is made | formed in view of such a subject, The objective is to determine the road surface state in which the vehicle is drive | working accurately.

  In order to solve the above problems, a vehicle travel path determination device according to an aspect of the present invention is an acceleration that calculates an estimated acceleration that is estimated to be generated in a vehicle based on an output of a drive source for driving the vehicle. An estimation means, an actual acceleration calculation means for calculating an actual acceleration actually generated in the vehicle, a road surface condition determination means for comparing the estimated acceleration and the actual acceleration to determine a road surface condition in which the vehicle is traveling, . The road surface state determination means determines a road surface state in which the vehicle is traveling according to a vehicle state that affects the relationship between the estimated acceleration and the actual acceleration.

  According to this aspect, even when the relationship between the estimated acceleration and the actual acceleration changes due to such a change in the vehicle state, the road surface state in which the vehicle is traveling can be accurately determined. For this reason, it is possible to suppress erroneous determination of the road surface state in which the vehicle is traveling, and to realize appropriate control in the control using the determination result of the road surface state such as anti-skid control.

  The road surface state determining means may correct the estimated acceleration according to the vehicle state, and determine the road surface state by comparing the corrected estimated acceleration with the actual acceleration. According to this aspect, even when the relationship between the estimated acceleration and the actual acceleration changes due to the change in the vehicle state, it is possible to determine the road surface state in consideration of the change. For this reason, the road surface state where the vehicle is traveling can be accurately determined.

  The road surface state determining means obtains a correction value by calculating a ratio between the average value of the estimated acceleration within a predetermined time and the average value of the actual acceleration within the predetermined time, and uses the acquired correction value. Thus, the estimated acceleration may be corrected.

  By calculating the ratio between the average value of the estimated acceleration and the average value of the actual acceleration, it is possible to clarify how the relationship between the estimated acceleration and the actual acceleration changes depending on the vehicle state. In addition, by calculating the ratio between the average values of the two, it is possible to calculate the relationship between the estimated acceleration and the actual acceleration more accurately. Therefore, according to this aspect, the estimated acceleration can be accurately corrected.

  The road surface state determining means may determine whether or not the road surface on which the vehicle is traveling is a normal road other than a sandy road, and may correct the estimated acceleration when determining that the road surface on which the vehicle is traveling is a normal road. . For example, when the vehicle is traveling on a sandy road, it is determined whether the change in the relationship between the estimated acceleration and the actual acceleration is due to driving on a sandy road or due to a change in the vehicle state. Is difficult. According to this aspect, when the estimated acceleration is corrected, the change in the relationship between the estimated acceleration and the actual acceleration can be roughly regarded as being due to a change in the vehicle state. Therefore, the estimated acceleration can be corrected easily and accurately.

  You may further provide the vehicle speed detection means which detects a vehicle speed, and the wheel acceleration detection means which detects the acceleration of a wheel. The road surface condition determining means may determine that the road surface on which the vehicle is traveling is a normal road when the detected vehicle speed is greater than a predetermined speed threshold and the detected wheel acceleration is smaller than the predetermined acceleration threshold. Good.

  When the vehicle is traveling on a sandy road, when the speed of the vehicle is increased, the amount that the wheel is submerged in the sand is reduced, and the wheel acceleration is increased. According to this aspect, it is possible to accurately determine whether the traveling path of the vehicle is a sandy road or a normal road using this.

  When it is determined over a predetermined time that the road surface on which the vehicle is traveling is a normal road, the road surface state determination means calculates the average value of the estimated acceleration within the predetermined time and the actual acceleration within the predetermined time. The correction value may be acquired by calculating a ratio with the average value of the two, and the estimated acceleration may be corrected using the acquired correction value.

  According to this aspect, since the estimated acceleration can be corrected using the estimated acceleration and the actual acceleration obtained when traveling on a normal road for a predetermined time, the road surface condition can be determined with higher accuracy. Can be realized.

  Even if the road surface state determination means determines the road surface state by comparing the corrected estimated acceleration with the actual acceleration until immediately before the ignition switch is turned off, the next time the ignition switch is turned on Alternatively, the road surface condition may be determined by comparing the uncorrected estimated acceleration with the actual acceleration.

  When the ignition switch is turned off, there is a possibility that the vehicle state such as the total weight of the occupants in the vehicle changes during the time it is turned on. According to this aspect, in consideration of such a case, when the ignition switch is turned on, the road surface state is determined without correcting the estimated acceleration, so that the road surface state immediately after the ignition switch is turned on is determined. Misjudgments can be suppressed.

  According to the present invention, it is possible to accurately determine the road surface state where the vehicle is traveling.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a vehicle to which a vehicle travel path determination device according to the present invention is applied. The vehicle 1 shown in the figure has wheels FL, FR, RL, and RR. Here, the wheel FR indicates the front right side, the wheel FL indicates the front left side, the wheel RR indicates the rear right side, and the wheel RL indicates the rear left side as viewed from the driver's seat. The vehicle 1 has an internal combustion engine 2 that is a gasoline engine or a diesel engine, a transaxle 4 that includes a transmission 3 that is an automatic transmission or a continuously variable transmission, and a transfer (not shown). That is, the vehicle 1 of the present embodiment is configured as a four-wheel drive vehicle such as an RV vehicle or a so-called pickup truck, and the front wheels FL and FR are provided with a transfer, a front differential (not shown), and drive shafts 5L and 5R. The power is transmitted from the internal combustion engine 2 through this. The output shaft 6 of the transaxle 4 is connected to a rear differential 7. The rear differential 7 is connected to rear wheels RL and RR via drive shafts 8L and 8R. In addition, it cannot be overemphasized that the vehicle 1 of this embodiment can be comprised as what is called a hybrid vehicle and an electric vehicle.

  The vehicle 1 also includes a braking device 10 including disc brake units 9FR, 9FL, 9RR, and 9RL provided for each of the wheels FR to RL. The braking device 10 is configured as an anti-skid control device (ABS) with a so-called EBD (Electronic Brake force Distribution). Each of the disc brake units 9FR to 9RL includes a brake disc 11 and a brake caliper 12, and each brake caliper 12 incorporates a wheel cylinder 41, 42, 43, or 44. Further, the wheel cylinders 41 to 44 of each brake caliper 12 are connected to the brake actuator 20 via independent hydraulic lines.

  The brake actuator 20 is connected to two output ports of the master cylinder 14, and a brake pedal 16 is connected to the master cylinder 14 via a booster 15. In the present embodiment, the brake pressure of the wheel cylinders 41 to 44 included in each brake caliper 12 can be set independently regardless of the hydraulic pressure supplied from the master cylinder 14. A master cylinder pressure sensor 13 is provided for the master cylinder 14, and a brake lamp switch 17 that is turned on when the pedal is depressed is provided for the brake pedal 16. Further, the wheels FR to RL are provided with a wheel speed sensor 18 that outputs a signal corresponding to each rotation speed, that is, the wheel speed.

  FIG. 2 is a system diagram of the brake actuator 20 included in the braking device 10. As shown in the figure, the hydraulic circuit in the brake actuator 20 is configured as a diagonal system in which the system for the right front wheel FR and the left rear wheel RL and the system for the left front wheel FL and the right rear wheel RR are independent. The Thereby, even if some trouble is caused in one system, the function of the other system is reliably maintained.

  Normally open solenoid valves 31 and 37 are connected in parallel to one output port of the master cylinder 14, and a wheel cylinder 41 for the right front wheel FR is connected to the solenoid valve 31 via a hydraulic path. A wheel cylinder 44 for the left rear wheel RL is connected to 37 via a hydraulic path. A discharge port of the hydraulic pump 21 is connected between the electromagnetic valves 31 and 37 and the master cylinder 14. Further, normally open solenoid valves 33 and 35 are connected in parallel to the other output port of the master cylinder 14, and a wheel cylinder 42 for the left front wheel FL is connected to the solenoid valve 33 via a hydraulic path. A wheel cylinder 43 for the right rear wheel RR is connected to the electromagnetic valve 35 via a hydraulic path. A discharge port of the hydraulic pump 22 is connected between the electromagnetic valves 33 and 35 and the master cylinder 14. The hydraulic pumps 21 and 22 are driven by an electric motor 23, and when these hydraulic pumps 21 and 22 are operated, brake fluid whose pressure has been increased to a predetermined pressure is supplied to the wheel cylinders 41 to 44. The

  The wheel cylinder 41 is further connected with a normally closed solenoid valve 32, and the wheel cylinder 44 is further connected with a normally closed solenoid valve 38. The downstream ports of the electromagnetic valves 32 and 38 are connected to the reservoir 24 and are connected to the suction port of the hydraulic pump 21 via the check valve CV. A normally closed electromagnetic valve 34 is connected to the wheel cylinder 42, and a normally closed electromagnetic valve 36 is connected to the wheel cylinder 43. The downstream ports of the electromagnetic valves 34 and 36 are connected to the reservoir 25 and are connected to the suction port of the hydraulic pump 22 via the check valve CV. Each of the reservoirs 24 and 25 includes a piston and a spring, and accommodates brake fluid from the wheel cylinders 41 to 44 flowing through the electromagnetic valves 32 to 38.

  Each of the electromagnetic valves 31 to 38 is a two-port two-position electromagnetic switching valve provided with a solenoid coil. The solenoid valves 31 to 38 are set to the first position shown in FIG. 2 when the solenoid coil is not energized, whereby the wheel cylinders 41 to 44 communicate with the master cylinder 14. The solenoid valves 31 to 38 are set to the second position when the solenoid coil is energized, whereby the wheel cylinders 41 to 44 are disconnected from the master cylinder 14 and communicate with the reservoir 24 or 25. In FIG. 2, DP is a damper, CV is a check valve, OR is an orifice, and FT is a filter. The check valve CV allows the brake fluid to flow from the wheel cylinders 41 to 44 and the reservoirs 24 and 25 to the master cylinder 14 while blocking the flow in the opposite direction.

  Then, by controlling the energization state of the solenoid coils of the solenoid valves 31 to 38, the brake fluid pressure of the wheel cylinders 41 to 44 can be increased, reduced or held. That is, when the solenoid coils of the solenoid valves 31 to 38 are not energized, the brake fluid is supplied from the master cylinder 14 and the hydraulic pump 21 or 22 to the wheel cylinders 41 to 44, and thereby the brake fluid pressure of the wheel cylinders 41 to 44 is increased. Is increased. When the solenoid coils of the solenoid valves 31 to 38 are energized, the wheel cylinders 41 to 44 communicate with the reservoir 24 or 25, and the brake fluid pressure of the wheel cylinders 41 to 44 is reduced. Further, if the solenoid coils of the solenoid valves 31, 33, 35 and 37 are energized while the solenoid coils of the other solenoid valves 32, 34, 36 and 38 are de-energized, the brake fluid pressure of the wheel cylinders 41 to 44 is increased. Retained. The brake fluid pressure in the wheel cylinders 41 to 44 can be gradually increased (pulse increase) by adjusting the time interval between energization and non-energization of the solenoid coil.

  The brake actuator 20 configured as described above is controlled by an electronic control unit (hereinafter referred to as “ECU”) 100 as shown in FIGS. 1 and 2. That is, ECU 100 executes anti-skid control (hereinafter referred to as “ABS control”) for increasing or decreasing the brake pressure for applying a braking force to each wheel FR to RL based on the slip ratio of wheels FR to RL. The ECU 100 includes a CPU, a ROM, a RAM, an input / output interface, a storage device, and the like (not shown), and controls the energization state of the solenoid coils of the electromagnetic valves 31 to 38 constituting the brake actuator 20. The electric motor 23 of the hydraulic pumps 21 and 22 is also controlled by the ECU 100.

  FIG. 3 is a control block diagram of the braking device 10 provided in the vehicle 1. The ECU 100 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, and a RAM that is used as a work area for data storage and program execution. In FIG. It is depicted as a functional block realized by cooperation of hardware such as RAM and software. Therefore, these functional blocks can be realized in various forms by a combination of hardware and software.

  The ECU 100 is connected to the master cylinder pressure sensor 13, the brake lamp switch 17, and the wheel speed sensors 18 of the wheels FR to RL. The master cylinder pressure sensor 13 detects the pressure of the brake oil in the master cylinder 14 and gives a signal indicating the detected value to the ECU 100. The brake lamp switch 17 is turned on when the brake pedal 16 is depressed by the driver, and gives a signal to that effect to the ECU 100. Each wheel speed sensor 18 gives the ECU 100 a signal indicating the rotation speed of the corresponding wheels FL to RR, that is, the wheel speed and the rotation direction.

  In addition, the ECU 100 is connected with a G sensor 45, a shift position sensor 46, an engine speed sensor 47, and a throttle opening sensor 48. The G sensor 45 is a so-called biaxial acceleration sensor that detects acceleration (acceleration / deceleration) in the front-rear direction of the vehicle 1, that is, the traveling direction, and acceleration in the lateral direction of the vehicle 1, that is, the width direction. G sensor 45 provides ECU 100 with a signal indicating acceleration in the longitudinal direction and lateral direction of the vehicle. Instead of the G sensor 45 that is a biaxial acceleration sensor, a sensor that detects only acceleration in the front-rear direction of the vehicle 1 and a sensor that detects only acceleration in the lateral direction of the vehicle 1 may be used.

  Shift position sensor 46 detects the shift range of transmission 3 set by the driver, and provides ECU 100 with a signal indicating the detected range. The engine speed sensor 47 detects the speed of the internal combustion engine 2 and gives a signal indicating the detected value to the ECU 100. The throttle opening sensor 48 detects the opening of a throttle valve (not shown) included in the internal combustion engine 2 (for example, an electronically controlled throttle valve), and gives a signal indicating the detected value to the ECU 100.

  As shown in FIG. 3, the ECU 100 includes a slip ratio acquisition unit 101, a brake pressure setting unit 102, a vehicle speed acquisition unit 103, an estimated acceleration calculation unit 104, an actual acceleration calculation unit 105, and a road surface condition determination unit 106. ing. The slip ratio acquisition unit 101 acquires the slip ratios of the wheels FR to RL. The brake pressure setting unit 102 sets the brake fluid pressure of the wheel cylinders 41 to 44 in accordance with the slip rates of the wheels FR to RL acquired by the slip rate acquisition unit 101, and applies the electromagnetic pressure to the electromagnetic valves 31 to 38 and the electric motor 23. Generate a control signal. The vehicle speed acquisition unit 103 acquires the vehicle body speed Vs as the speed of the vehicle 1 (vehicle body) and the wheel acceleration Dw as the rotational acceleration of each wheel based on the detection value of each wheel speed sensor 18.

  The estimated acceleration calculation unit 104 first drives the drive wheel based on the rotational speed of the internal combustion engine 2 detected by the engine speed sensor 47 and the gear ratio of the transmission 3 obtained based on the signal from the shift position sensor 46. The estimated wheel speed of each of the wheels FR to RL is obtained every predetermined sampling time. The estimated acceleration calculation unit 104 calculates the estimated wheel acceleration based on the calculated estimated wheel speed and the sampling time, and calculates the estimated wheel acceleration of the average value of the estimated wheel accelerations of the wheels FR to RL. . The estimated acceleration calculation unit 104 calculates the estimated acceleration Ge of the vehicle 1 using this estimated wheel acceleration. The actual acceleration calculation unit 105 calculates an actual acceleration Gx as an actual acceleration of the vehicle 1 based on a signal from the G sensor 45. The road surface state determination unit 106 determines the state of the road surface on which the vehicle 1 is traveling (hereinafter referred to as “traveling road”) based on the calculated estimated acceleration Ge and actual acceleration Gx. Thus, ECU 100 also functions as a vehicle travel path determination device that determines the travel path of the vehicle.

  When the vehicle 1 is traveling on a sandy road, it cannot be smoothly accelerated even when the same engine output is generated compared to when traveling on a normal road, and the actual acceleration Gx is greater than the estimated acceleration Ge. Is also greatly reduced. The road surface state determination unit 106 of the ECU 100 uses this to compare the estimated acceleration Ge and the actual acceleration Gx, so that the traveling path of the vehicle 1 is either a “normal road” or a “sand road”. Determine. In addition, a normal road shall mean the pavement road and flat road whose traveling resistance is smaller than a sandy road.

  However, for example, the total travel distance of the vehicle 1 is increased, or the acceleration actually generated in the vehicle 1 is reduced even when the engine is operated at the same throttle opening degree because the vehicle 1 has passed through the years from the time of manufacture. I will do it. In such a case, even when the vehicle 1 is traveling on a normal road, as shown in FIG. 4, the relationship between the time t during the traveling of the vehicle 1 and the acceleration G is relative to the estimated acceleration Ge. The actual acceleration Gx decreases. Further, for example, when the estimated acceleration calculation unit 104 that calculates the estimated acceleration Ge on the assumption that high-octane gasoline is used is incorporated in the ECU 100, when the regular gasoline is used in the vehicle 1, Even when the weight of the vehicle 1 is large, such as when an occupant is on board or a heavy load is placed on the vehicle, the actual acceleration Gx may be lower than the estimated acceleration Ge. As described above, when the traveling path of the vehicle 1 is determined in a state where the relationship between the estimated acceleration Ge and the actual acceleration Gx is changed, it is erroneously determined that the traveling path of the vehicle 1 is a sandy road even though it is a normal road. There is a high possibility that it will end.

  For this reason, the road surface state determination unit 106 according to the embodiment determines the road surface state in which the vehicle 1 is traveling according to these vehicle states that affect the relationship between the estimated acceleration Ge and the actual acceleration Gx. Hereinafter, the procedure for determining the traveling path of the vehicle 1 will be described in detail with reference to FIGS. 5 and 6.

  FIG. 5 is a flowchart showing a learning control processing procedure for obtaining an average error rate K for correcting the estimated acceleration Ge in accordance with the vehicle state. In the process shown in this flowchart, for example, an accelerator pedal (not shown) is depressed by the driver until an ignition switch (not shown) provided in the vehicle 1 is turned on until it is turned off. It is repeatedly executed at predetermined time intervals when the vehicle 1 is accelerating.

  The relationship between the estimated acceleration Ge and the actual acceleration Gx not only changes depending on the vehicle state, but also changes when the vehicle 1 enters the sandy road from the normal road. Therefore, when the vehicle 1 is traveling on the sandy road, whether the change in the relationship between the estimated acceleration Ge and the actual acceleration Gx is due to the vehicle 1 traveling on the sandy road, It becomes difficult to determine whether it is due to changes in the vehicle state such as weight. Therefore, in order to appropriately correct the estimated acceleration Ge, the learning control for obtaining the average error rate K needs to be performed when the vehicle 1 is traveling on a normal road. Here, when the vehicle 1 is traveling on a sandy road, the wheel acceleration Dw is increased because the amount of the wheel dive in the sand is reduced. For this reason, when the vehicle body speed Vs of the vehicle 1 is larger than the predetermined speed and the wheel acceleration Dw is smaller than the predetermined acceleration, it can be considered that the vehicle 1 is traveling on a normal road.

Therefore, the road surface state determination unit 106 first determines whether or not the vehicle body speed Vs acquired by the vehicle speed acquisition unit 103 is equal to or higher than the threshold speed Vth (S10). When it is determined that the vehicle body speed Vs is equal to or higher than the threshold speed Vth (Y in S10), the road surface state determination unit 106 next determines whether or not the wheel acceleration Dw is equal to or lower than the threshold acceleration Dth (S12). The threshold speed Vth and the threshold acceleration Dth are those stored in the ROM of the ECU 100. In this embodiment, the threshold speed Vth is set to 50 km / h, and the threshold acceleration Dth is 1.0 G (9.8 m). / S ² ).

  When it is determined that the vehicle body speed Vs is equal to or greater than the threshold speed Vth and the wheel acceleration Dw is equal to or less than the threshold acceleration Dth (Y in S12), the vehicle 1 is traveling on a normal road and learning control for acquiring the average error rate K is performed. Since it is considered that it can be implemented, the road surface state determination unit 106 next determines whether or not to clear the learning control cancellation condition in S16 to S20.

  For example, even when any of the wheels is spinning, there is a possibility that the relationship between the estimated acceleration Ge and the actual acceleration Gx is affected. Therefore, it is not preferable to perform learning control when the wheel is spinning. Therefore, the road surface state determination unit 106 first determines whether or not the wheel is spinning by comparing the rotation speeds of the wheels calculated from the detection values of the wheel speed sensor 18 as cancellation conditions for the learning control. Determine (S14).

  Further, immediately after the shift change, the actual acceleration Gx may vary due to the shift shock. For this reason, when it is determined that there is no wheel spin (Y in S14), the road surface state determination unit 106 determines whether or not 2 seconds have elapsed after the shift change as a learning control cancel condition (S16). Here, the road surface state determination unit 106 uses the detection result of the shift position sensor 46 to turn on the timer when the shift range change is detected and measure the time from when the shift range is changed. Yes. The road surface state determination unit 106 determines whether or not 2 seconds have elapsed after the shift change by determining whether or not the count of the timer is 2 seconds or more.

  Further, during braking and during electronic control of braking force such as VSC (Vehicle Stability Control) and TRC (Traction Control), the vehicle 1 is decelerating and the relationship between the estimated acceleration Ge and the actual acceleration Gx cannot be accurately grasped. It is not preferable to implement learning control. For this reason, when it is determined that two seconds have elapsed after the shift change (Y in S16), the road surface state determination unit 106 uses the detection result of the brake lamp switch 17 or the master cylinder pressure sensor 13 as a cancellation condition for learning control. Thus, it is determined whether or not the vehicle 1 is being braked. (S18) When the vehicle 1 is not being braked (Y in S18), the road surface state determination unit 106 determines whether or not the vehicle 1 is under braking control such as VSC or TRC as a learning control cancellation condition. The determination is made by referring to the flag (S20). When the braking control is being performed, these automatic control execution flags are turned on.

  If the cancellation condition of all learning controls is cleared, not during braking control such as VSC or TRC (Y in S20), the road surface state determination unit 106 has already turned on the timer that measures the elapsed time of learning control. It is determined whether or not (S22). When the timer is still off (N in S22), the road surface state determination unit 106 turns on the timer and starts measuring the elapsed time of learning control (S28). At the same time, each of the estimated acceleration calculation unit 104 and the actual acceleration calculation unit 105 calculates the estimated acceleration Ge and the actual acceleration Gx for each predetermined sampling period, and the road surface state determination unit 106 calculates the calculated estimated acceleration Ge. The actual acceleration Gx is sequentially stored and stored in a storage unit such as a RAM (S30).

  When the timer is already turned on (Y in S22), the road surface state determination unit 106 determines whether or not the learning control is performed for 2 seconds or more using the measured value of the timer (S24). When it is determined that 2 seconds have not yet elapsed since the start of the learning control (N in S24), it is assumed that the accumulation of the estimated acceleration Ge and the actual acceleration Gx for obtaining the accurate average error rate K is insufficient, and the road surface The state determination unit 106 once ends the process in this flowchart.

  When it is determined that 2 seconds have elapsed since the start of the learning control (Y in S24), the road surface state determination unit 106 uses the accumulated estimated acceleration Ge and actual acceleration Gx to store the learning period of 2 seconds. The average value of the estimated acceleration Ge and the average value of the actual acceleration Gx are calculated. The road surface state determination unit 106 divides the average value of the estimated acceleration Ge by the average value of the actual acceleration Gx, that is, the average error rate K = (average value of the estimated acceleration Ge in the learning period) / (actual acceleration in the learning period). The average error rate K is obtained by calculating with the equation (average value of Gx) (S26). The road surface state determination unit 106 stores the acquired average error rate K in a storage unit such as a RAM. When the average error rate K is 1 and the average error rate K is less than 1, the road surface condition determination unit 106 sets the value of the average error rate K to 1 and is mistaken for a sandy road. Setting the average error rate K in the determination direction is suppressed. In the present embodiment, the average error rate K is normally a value of 1 to 1.2.

  When it is determined that the vehicle body speed Vs is smaller than the threshold speed Vth (N in S10) and when it is determined that the wheel acceleration Dw is smaller than the threshold acceleration Dth (N in S12), the vehicle 1 is traveling on a normal road. Therefore, it is not preferable to perform learning control. Further, when there is a wheel that is spinning (N in S14), when 2 seconds have not elapsed since the shift change (N in S16), in the case of braking (N in S18), and in the case of braking control (N Even when the learning control cancellation condition is satisfied, such as N) in S20, it is not preferable to perform the learning control.

  Therefore, the road surface state determination unit 106 determines whether or not the timer for measuring the elapsed time of learning control is on in these cases (S32). When the timer is on (Y in S32), the learning control is started, so the road surface state determination unit 106 turns off the timer to stop the learning control and measures the elapsed time of the learning control. The process is stopped (S34), and data indicating each of the estimated acceleration Ge and the actual acceleration Gx accumulated in the storage unit is deleted (S36). If the timer is off (N in S32), learning control is not being performed, so the road surface state determination unit 106 once ends the processing in this flowchart.

  FIG. 6 is a flowchart showing a determination procedure of the traveling path of the vehicle 1 by the road surface condition determination unit 106. The processing in this flowchart starts at a predetermined timing such as when anti-skid control of the vehicle 1 is performed.

  When the predetermined determination timing of the travel path of the vehicle 1 is reached, the estimated acceleration calculation unit 104 calculates the estimated acceleration Ge (S40), and the actual acceleration calculation unit 105 calculates the actual acceleration Gx (S42). Next, the road surface state determination unit 106 performs learning control to acquire the average error rate K, and determines whether or not the estimated acceleration Ge should be corrected by determining whether or not the average error rate K has already been acquired. Determine (S44).

  When the average error rate K is not acquired and it is not necessary to correct the estimated acceleration Ge (N in S44), the road surface state determination unit 106 determines that the value obtained by subtracting the actual acceleration Gx from the estimated acceleration Ge is the first determination threshold value. It is determined whether it is A1 or more (S54). When the calculated value is equal to or greater than the first determination threshold A1 (Y in S54), the road surface state determination unit 106 determines that the traveling path of the vehicle 1 is a sandy road (S50), and the calculated value is based on the first determination threshold A1. If it is smaller (N in S54), the traveling path of the vehicle 1 is determined to be a normal path (S52).

  When the average error rate K has already been acquired and it is determined that the estimated acceleration Ge should be corrected (Y in S44), the road surface state determination unit 106 determines that (corrected estimated acceleration Ga = estimated acceleration Ge / average error rate K). ) To correct the estimated acceleration Ge to obtain a corrected estimated acceleration Ga (S46).

  FIG. 7 shows the relationship between the estimated acceleration Ge, the corrected estimated acceleration Ga, and the actual acceleration Gx when the estimated acceleration Ge is corrected to the corrected estimated acceleration Ga at time t1. Before correction, when the actual acceleration Gx is lower than the estimated acceleration Ge on the normal road due to various factors described above, the estimated acceleration Ge is divided by the acquired average error rate K to be corrected to the corrected estimated acceleration Ga. Thus, the corrected estimated acceleration Ga can be brought close to the actual acceleration Gx. For this reason, it is possible to accurately determine whether the traveling road is a sandy road or a normal road by using the relationship between the corrected estimated acceleration Ga and the actual acceleration Gx that change depending on the state of the traveling road.

  Returning to FIG. When the corrected estimated acceleration Ga is acquired, the road surface state determination unit 106 determines whether or not the value obtained by subtracting the actual acceleration Gx from the corrected estimated acceleration Ga is not the estimated acceleration Ge as in S54, or more. Determination is made (S48). When the calculated value is equal to or greater than the second determination threshold A2 (Y in S48), the road surface state determination unit 106 determines that the traveling path of the vehicle 1 is a sandy road (S50), and the calculated value is based on the second determination threshold A2. If it is smaller (N in S48), the traveling path of the vehicle 1 is determined to be a normal path (S52). When the road surface state determination unit 106 determines that the travel path of the vehicle 1 is a sandy road, the road surface state determination unit 106 sets the travel road flag to a value indicating the sandy road, and when the road surface of the vehicle 1 determines that the travel path is a normal road, The flag is set to a value indicating a normal road.

  When an ignition switch (not shown) of the vehicle 1 is turned on and learning control for acquiring the average error rate K is not performed, the road surface state determination unit 106 determines the number of passengers of the vehicle 1 and the load to be loaded. It is difficult to grasp the vehicle state that affects the relationship between the estimated acceleration Ge and the actual acceleration Gx, such as the weight of the vehicle. Therefore, when the estimated acceleration Ge is not corrected, the road surface state determination unit 106 sets the first determination threshold value A1 so that the normal road determination area determined as a normal road becomes wide as shown in FIG. Used to determine the state of the travel path of the vehicle 1. Thereby, it is possible to suppress erroneous determination that the vehicle 1 is determined to be a sandy road even though the vehicle 1 is traveling on a normal road.

  However, before the estimated acceleration Ge is corrected, since the normal road determination area is set wide, there is a possibility that the vehicle 1 is determined to be a normal road even though the vehicle 1 is traveling on a sandy road. There is. On the other hand, when the estimated acceleration Ge is corrected, the traveling road can be accurately determined in a situation where there is little disturbance. Therefore, as shown in FIG. The need for an increase is also considered low. For this reason, when correcting the estimated acceleration Ge, the road surface state determination unit 106 sets the second determination threshold A2 so that the sandy road determination area determined as the sandy road becomes wider, as shown in FIG. Used to determine the state of the travel path of the vehicle 1. This makes it possible to accurately determine the travel path of the vehicle 1.

  As described above, when the road surface state determination unit 106 determines the traveling road of the vehicle 1 and the traveling road flag is set to a value indicating a sandy road or a normal road, the brake pressure setting unit 102 of the ECU 100 performs the ABS control. At the timing to be executed, the brake hydraulic pressures of the wheel cylinders 41 to 44 are set according to the travel path of the vehicle 1 indicated by these flags and the slip rates of the wheels FR to RL acquired by the slip rate acquisition unit 101. Then, control signals to the electromagnetic valves 31 to 38 and the electric motor 23 are generated. That is, in the vehicle 1, the ABS control for rough roads is performed when the travel road is a rough road, the ABS control for sandy land is performed when the travel path is a sand road, and the travel path is a normal road. The ABS control for the normal road is executed.

  Even if the road surface state determination unit 106 determines the road surface state by comparing the corrected estimated acceleration Ga and the actual acceleration Gx until immediately before the ignition switch is turned off, the road surface state determination unit 106 turns on the ignition switch next time. When this is done, the acquired average error rate K is cleared, and the road surface condition is determined by comparing the uncorrected estimated acceleration Ge with the actual acceleration Gx. Once the ignition switch is turned off, there is a possibility that the number of passengers and the weight of the load have changed between the time when the ignition switch is turned on. For this reason, erroneous determination of the travel path of the vehicle 1 due to such a change in the vehicle state is performed by determining the travel path of the vehicle 1 using the estimated acceleration Ge that is not corrected when the ignition switch is turned on. Can be suppressed.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art. Embodiments described may also fall within the scope of the present invention. Here are some examples.

  In a modification, the estimated acceleration calculation unit 104 calculates the estimated wheel acceleration as described above. The road surface state determination unit 106 determines whether the traveling road of the vehicle 1 is a sand road or a normal road by comparing the calculated estimated wheel acceleration and the wheel acceleration Dw that is the actual wheel acceleration. Further, the road surface state determination unit 106 performs similar learning control, calculates a ratio between the average value of the estimated wheel acceleration accumulated during the learning period and the average value of the accumulated wheel acceleration Dw, and calculates an average error rate. Acquire K. The road surface state determination unit 106 corrects the estimated wheel acceleration using the average error rate K, and compares the corrected estimated wheel acceleration and the wheel acceleration Dw to determine the road surface state. In this way, it is possible to determine the travel path of the vehicle 1 noting the acceleration of the vehicle 1 but focusing on the acceleration of the wheels.

1 is a schematic configuration diagram illustrating a vehicle to which a vehicle travel path determination device according to the present invention is applied. It is a systematic diagram of the brake actuator contained in a braking device. It is a control block diagram of the braking device provided in the vehicle. It is a figure which shows the state by which the real acceleration Gx became low with respect to the estimated acceleration Ge. It is a flowchart which shows the process sequence of the learning control which acquires the average error rate K for correct | amending the estimated acceleration Ge according to the change of a vehicle state. It is a flowchart which shows the determination procedure of the traveling path of the vehicle by a road surface state determination part. It is a figure which shows the relationship between the estimated acceleration Ge, the corrected estimated acceleration Ga, and the actual acceleration Gx when the estimated acceleration Ge is corrected at the time t1 to obtain the corrected estimated acceleration Ga. (A) is a figure which shows the relationship between the normal road determination area | region and sandy road determination area | region before correct | amending estimated acceleration Ge, (b) is the normal road determination area | region and sandy ground after correcting estimated acceleration Ge. It is a figure which shows the relationship with a road determination area | region.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Vehicle, 2 Internal combustion engine, 13 Master cylinder pressure sensor, 17 Brake lamp switch, 18 Wheel speed sensor, 20 Brake actuator, 45 G sensor, 46 Shift position sensor, 47 Engine speed sensor, 48 Throttle opening sensor, 100 ECU 101 slip ratio acquisition unit, 102 brake pressure setting unit, 103 vehicle speed acquisition unit, 104 estimated acceleration calculation unit, 105 actual acceleration calculation unit, 106 road surface state determination unit.

Claims (7)

Acceleration estimating means for calculating an estimated acceleration estimated to be generated in the vehicle based on an output of a driving source for running the vehicle;
An actual acceleration calculating means for calculating an actual acceleration actually generated in the vehicle;
Road surface condition determining means for comparing the estimated acceleration and the actual acceleration to determine the road surface state on which the vehicle is traveling,
The road surface state determining means determines a road surface state in which the vehicle is traveling according to a vehicle state that affects the relationship between the estimated acceleration and the actual acceleration.   2. The vehicle according to claim 1, wherein the road surface state determination unit corrects the estimated acceleration according to the vehicle state, and determines the road surface state by comparing the corrected estimated acceleration with an actual acceleration. Traveling path discrimination device.   The road surface state determining means obtains a correction value by calculating a ratio between an average value of estimated acceleration within a predetermined time and an average value of actual acceleration within the predetermined time, and uses the acquired correction value. The vehicle travel path determination device according to claim 2, wherein the estimated acceleration is corrected.   The road surface condition determining means determines whether or not the road surface on which the vehicle is traveling is a normal road other than a sandy road, and corrects the estimated acceleration when the road surface on which the vehicle is traveling is determined to be a normal road. The vehicle travel path determination device according to claim 2, wherein Vehicle speed detecting means for detecting the vehicle speed;
Wheel acceleration detection means for detecting wheel acceleration, and
The road surface state determining means determines that the road surface on which the vehicle is traveling is a normal road when the detected vehicle speed is greater than a predetermined speed threshold value and the detected wheel acceleration is smaller than the predetermined acceleration threshold value. The vehicle travel path determination device according to claim 4.   The road surface state determining means, when it is determined over a predetermined time that the road surface on which the vehicle is traveling is a normal road, the average value of the estimated acceleration within the predetermined time and the actual value within the predetermined time. 6. The vehicle travel path determination device according to claim 4, wherein a correction value is acquired by calculating a ratio with an average value of acceleration, and the estimated acceleration is corrected using the acquired correction value.   Even if the road surface state determination means determines the road surface state by comparing the corrected estimated acceleration and the actual acceleration until immediately before the ignition switch is turned off, the next time the ignition switch is turned on. 7. The vehicle traveling road discriminating apparatus according to claim 2, wherein the road surface condition is determined by comparing the estimated acceleration that has not been corrected and the actual acceleration.

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