JP4440279B2 - Vehicle behavior detection device - Google Patents

Description

  The present invention relates to a vehicle behavior detection device that detects an unstable behavior state (such as understeer) that occurs in a running vehicle.

  Conventionally, a vehicle state detection device that detects an unstable behavior state such as understeer generated in a traveling vehicle includes a reference alignment torque calculator that calculates a reference alignment torque corresponding to a reference road surface reaction torque, An alignment torque measuring device that detects an actual alignment torque corresponding to a road surface reaction force torque that the vehicle receives from the road surface, and an alignment torque deviation calculator that calculates an absolute value of a deviation between the actual alignment torque and the reference alignment torque as an alignment torque deviation; A vehicle behavior stability discriminator that compares the alignment torque deviation with a predetermined amount and determines that the vehicle behavior is unstable when the alignment torque deviation is greater than or equal to the predetermined amount, and includes a reference alignment torque and an actual alignment torque. Vehicle instability using the absolute value of deviation from It is determined (e.g., see Patent Document 1).

  Further, the vehicle state detection device described in Patent Document 1 is a torque / handle that calculates the rate of change between the actual alignment torque and the handle angle from the time change rate of the actual handle operating angle and the time change rate of the actual alignment torque. An angle calculator is provided, and the instability state of the running vehicle is determined using the rate of change between the actual alignment torque and the steering wheel angle.

JP 2003-341538 A

  In the conventional vehicle state detection device, in the case of Patent Document 1, in order to determine the unstable behavior state of the traveling vehicle, the absolute value of the deviation between the reference alignment torque and the actual alignment torque, or the actual alignment torque and the handle Because the rate of change with the angle is used, understeer is judged based on the deviation between the reference alignment torque and the actual alignment torque, or a simple unstable state estimated from the rate of change between the actual alignment torque and the handle angle. However, if the vehicle's instability is detected using the road surface reaction force torque that can be estimated from the driver's steering torque and the assist torque of the electric power steering device to detect the actual alignment torque, the road surface reaction force In the region where the torque is smaller than the friction torque of the steering mechanism, the estimated accuracy of the road reaction torque is There since decreased, there has been a problem that an erroneous detection (misjudgment) to understeer.

  In addition, understeer generated in the vehicle is different from that of conventional understeer depending on the difference in the friction coefficient μ of road surface such as dry asphalt (slippery road surface) and snowy road (slippery road surface). Since the vehicle state detection device does not consider the road surface friction coefficient μ, there is a problem of erroneously detecting understeer.

  The present invention has been made to solve the above-described problems, and is a vehicle behavior detection device capable of accurately detecting an unstable behavior state of a vehicle without erroneous determination regardless of the state of road surface reaction torque. The purpose is to obtain.

A vehicle behavior detection device according to the present invention detects a road surface reaction force torque detecting means that detects a road surface reaction torque received by a tire of a vehicle from a road surface, a steering angle detection means that detects a steering angle of the vehicle, and a vehicle speed of the vehicle. Based on vehicle speed detection means, reference road surface reaction force torque calculation means for calculating reference road surface reaction force torque from detected values of steering angle and vehicle speed, detection value of road surface reaction force torque and calculation value of reference road surface reaction force torque Vehicle behavior detection apparatus comprising vehicle behavior state detection means for detecting an unstable behavior state of the vehicle, and vehicle behavior detection prohibition means for prohibiting the output of the vehicle behavior state detection means based on the detected value of the road surface reaction force torque the provided, the vehicle behavior detection inhibiting means, compared with a preset threshold detection value of the road surface reaction torque, the road surface reaction force comparator determines whether the detection value is in an unstable range of the torque Wherein, the comparator, when it is determined that the detected value of the road surface reaction torque is in an unstable range, and generates a prohibiting flag for prohibiting the output of the vehicle behavior state detecting unit.

  According to this invention, the unstable behavior state of the vehicle can be accurately detected without erroneous determination.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram schematically showing the overall configuration of a typical vehicle steering apparatus to which Embodiment 1 of the present invention is applied.
In FIG. 1, a vehicle steering apparatus includes a steering wheel 1 that is steered by a driver of a vehicle, a steering shaft 2 that is connected to the steering wheel 1, a steering gear BOX 3 that is provided at the tip of the steering shaft 2, and a steering shaft. 2, a torque sensor 4 and a steering assist motor 5, a rack and pinion shaft 6 of a rack and pinion mechanism connected to a steering gear BOX 3, traveling wheels 7 connected to both ends of the rack and pinion shaft 6, And a control device 8 for driving the motor 5 based on the detection value of the torque sensor 4.

The torque sensor 4 inputs the detected value of the steering torque Ts to the control device 8 as a steering torque detection signal Tsd.
The control device 8 calculates the applied voltage Vi to the motor 5 based on the steering torque detection signal Tsd. A current detection signal (motor current) Im and a voltage detection signal (voltage between motor terminals) Vm of the motor 5 are fed back to the control device 8.

The motor 5 is feedback-driven under the control of the control device 8 and assists the steering torque Ts applied from the handle 1 to the steering shaft 2.
As a result, the torque obtained by adding the steering torque Ts applied from the steering wheel 1 through the steering shaft 2 and the assist torque Tas applied from the motor 5 to the steering shaft 2 is amplified several times through the steering gear BOX 3. The traveling wheels 7 are driven via the rack and pinion shaft 6.

  A road surface reaction force torque Talign from the road surface is applied to the traveling wheels 7, a friction torque Tf from the steering gear BOX 3 is applied to the steering shaft 2, and a steering shaft reaction force is applied to the steering shaft 2. Tr is generated.

  The vehicle steering apparatus shown in FIG. 1 has a main function of generating an assist torque Tas corresponding to the driver's steering torque Ts, and the torque sensor 4 is a steering torque Ts when the driver steers the steering wheel 1. Is electrically transmitted to the control device 8 as a steering torque detection signal Tsd. The control device 8 calculates the applied voltage Vi for generating the assist torque Tas based on the state quantity (current detection signal Im and voltage detection signal Vm) of the motor 5 and the steering torque detection signal Tsd, and The applied voltage Vi is supplied to generate the assist torque Tas.

Next, detection processing by the vehicle behavior detection apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. Here, as an example, understeer will be described as an example of the unstable behavior state of the vehicle.
FIG. 2 is a functional block diagram showing the vehicle behavior detection device according to Embodiment 1 of the present invention, and shows a specific configuration example of the control device 8 in FIG.

  In FIG. 2, the control device 8 includes a microcomputer 20 that is a main part of the vehicle behavior detection device, a steering angle detection means 21 that detects the steering angle θ of the steering wheel 1 by the vehicle driver, and a vehicle speed Vs (vehicle traveling speed). ) And a road surface reaction force torque detection means 23 for detecting a road surface reaction torque Talign generated between the tire 7 of the vehicle and the road surface. The detection values (steering angle θ, vehicle speed Vs, road surface reaction force torque Talign) of the detection means 21 to 23 are input to the microcomputer 20.

The microcomputer 20 includes a standard road surface reaction torque calculation unit 24, a vehicle behavior detection prohibiting unit 25, and a vehicle behavior state detection unit 26.
The control device 8 and the microcomputer 20 have various functions related to the vehicle steering device (see FIG. 1) in addition to the configuration shown in FIG. 2, but here, the embodiment of the present invention is described. Only the configuration directly related to 1 is shown.

In the microcomputer 20, the reference road surface reaction torque calculating unit 24 calculates the reference road surface reaction torque Ta * based on the steering angle θ and the vehicle speed Vs, and inputs it to the vehicle behavior state detection unit 26.
The vehicle behavior detection prohibiting means 25 determines whether or not the vehicle behavior detection should be prohibited based on the road surface reaction force torque Talign, and if it is determined that the vehicle behavior detection should be prohibited, FLi) (referred to as “prohibition flag”) is input to the vehicle behavior state detection means 26.

  The vehicle behavior state detecting means 26 detects an understeer (unstable state) of the vehicle based on the reference road surface reaction force torque Ta * and the road surface reaction force torque Talign, and an understeer detection flag (hereinafter simply referred to as “detection flag”) FLG. When the prohibition flag FLi is input, detection of the unstable state of the vehicle (outputting the detection flag FLG) is prohibited.

  In addition, the detection value of each detection means 21-23, the calculation value of the norm road surface reaction force torque calculation means 24, the calculation result of the vehicle behavior detection prohibition means 25 (prohibition flag FLi), and the detection result of the vehicle behavior state detection means 26 ( The detection flag FLG) is stored in a memory (not shown) in the microcomputer 20.

Further, the reference road surface reaction torque calculation means 24 uses a technique referred to in the publicly known technology (for example, Japanese Patent Application Laid-Open No. 2005-324737) based on the running state quantity of the vehicle. (Ideal road surface reaction torque) may be calculated.
That is, from the map showing the relationship between the steering angle θ (steering wheel angle) and the vehicle speed Vs (vehicle traveling speed) and the reference road surface reaction torque Ta * (handle angle / traveling speed−reference road surface reaction torque Ta *). The standard road surface reaction torque Ta * can be calculated.

  Further, a map showing the relationship between the steering wheel angle and the vehicle traveling speed and the reference road surface reaction torque Ta * (the steering wheel angle / traveling speed−reference road surface reaction torque Ta *) may be stored in a memory in advance. Instead of the map, it may be obtained from an arithmetic expression for the vehicle speed.

Further, as the road surface reaction force torque detecting means 23, the configuration referred to in the above known technique (Japanese Patent Laid-Open No. 2005-324737) can be used. For example, the steering torque Ts by the driver and the electric power steering are used. The road surface reaction force torque Talign may be estimated and calculated from the assist torque Tas.
The same applies to the second and later embodiments described later.

The operation of the vehicle behavior detection apparatus according to Embodiment 1 of the present invention shown in FIG. 2 will be described below with reference to the flowchart of FIG.
In FIG. 3, when the program starts, first, the steering angle detection means 21 detects the steering angle θ, and stores the detected value of the steering angle θ in the memory (step S101).

  Similarly, the vehicle speed detection means 22 detects the vehicle speed Vs and stores the detected value of the vehicle speed Vs in the memory (step S102), and the road surface reaction force torque detection means 23 detects the road surface reaction force torque Talign, The detected value of the road surface reaction torque Talign is stored in the memory (step S103).

  Subsequently, the reference road surface reaction torque calculation means 24 in the microcomputer 20 calculates the steering angle θ and the vehicle speed Vs stored in the memory, the steering angle θ corresponding to the vehicle speed Vs stored in advance, and the road surface reaction force torque Talign. The standard road surface reaction torque Ta * is calculated from the constant KTa representing the rate of change, and the calculation result of the standard road surface reaction torque Ta * is stored in the memory (step S104).

  Specifically, the vehicle behavior state detection means 26 calculates the absolute value of the road surface reaction force torque deviation ΔTa (= Talign−Ta *) between the road surface reaction force torque Talign and the reference road surface reaction force torque Ta * to obtain the road surface reaction. When the absolute value of the force torque deviation ΔTa is larger than a predetermined value, an unstable state is detected, and the detection result is stored in the memory. And it is determined whether the detection result of a vehicle behavior state is an unstable state.

In step S105, if it is determined that the detection result of the vehicle behavior state is a stable state (that is, NO), the process returns to the start and the above process is repeated.
On the other hand, if it is determined in step S105 that the detection result of the vehicle behavior state is an unstable state (YES), the vehicle behavior detection prohibiting means 25 is based on the road surface reaction force torque Talign stored in the memory. It is calculated (determined) whether or not the detection should be prohibited. If it is determined that the detection should be prohibited, the prohibition flag FLi is output (step S106).

Subsequently, the vehicle behavior state detection unit 26 determines whether or not the prohibition flag FLi is not output (detection of the vehicle behavior state is permitted) based on the calculation result of the vehicle behavior detection prohibition unit 25 (step S106). (Step S107).
If it is determined in step S107 that the prohibition flag FLi has been output (i.e., NO), the detection of the vehicle behavior state is prohibited, so the process returns to the start and the above steps S101 to S106 are repeated.

  On the other hand, if it is determined in step S107 that the prohibition flag FLi has not been output (that is, YES), since the detection of the vehicle behavior state is permitted, the vehicle behavior state detection means 26 is generated on the front wheel of the vehicle. The detection flag FLG indicating that the vehicle is understeered (unstable state) due to saturation of the road surface reaction torque Talign to be output is output (step S108), and the program operation of FIG.

Next, specific processing by the vehicle behavior detection prohibiting unit 25 will be described with reference to FIG. FIG. 4 is a functional block diagram illustrating a configuration example of the vehicle behavior detection prohibiting unit 25.
In FIG. 4, the vehicle behavior detection prohibiting means 25 includes a comparator 27 that uses a preset first threshold Th1 as a comparison reference value.

  The comparator 27 compares the road surface reaction force torque Talign with the first threshold value Th1, and when the road surface reaction force torque Talign is smaller than the first threshold value Th1, the prohibition flag FLi is generated to detect the vehicle behavior state. Input to means 26.

  Here, the first threshold Th1 is set according to the friction torque Tf at the steering shaft 2 (see FIG. 1) constituting the steering mechanism. For example, the friction torque of the steering shaft 2 is “2 [Nm]”. In the case of a vehicle, the first threshold Th1 may be set to “2 [Nm]”. In general, the friction torque Tf of the steering mechanism of the vehicle is 1 [Nm] to 3 [Nm]. Therefore, in the case of a vehicle in which measurement of the friction torque Tf is difficult, 1 [Nm] to 3 [Nm]. The first threshold value Th1 may be set to the friction torque value within the range.

Next, the operation of the vehicle behavior detection prohibiting means 25 shown in FIG. 4 will be described with reference to the flowchart of FIG.
In FIG. 5, the comparator 27 first determines whether or not the road surface reaction force torque Talign is smaller than the first threshold value Th1 by comparing the road surface reaction force torque Talign stored in the memory with the first threshold value Th1. Determination is made (step S201).

  If it is determined in step S201 that Talign ≧ Th1 (that is, NO), the process returns to the start. On the other hand, if it is determined that Talign <Th1 (that is, YES), the prohibition flag FLi is output (step S202). The program operation of FIG.

  As described above, according to the first embodiment of the present invention, the road surface reaction force torque detecting means 23 that detects the road surface reaction force torque Talign from the steering torque Ts of the driver and the assist torque Tas of the electric power steering device, A vehicle behavior detection prohibiting means 25 is provided in a vehicle behavior detection device comprising a vehicle behavior state detection means 26 for detecting an unstable state of a vehicle based on a reference road reaction force torque Ta * and a road surface reaction force torque Talign. Yes.

  The vehicle behavior detection prohibiting unit 25 compares the road surface reaction force torque Talign with the first threshold value Th1, and determines that the road surface reaction force torque Talign is smaller than the first threshold value Th1 (corresponding to the friction torque Tf of the steering mechanism). If it is, the understeer detection (output of the detection result) by the vehicle behavior state detection means 26 is prohibited.

  As a result, the detection of the vehicle behavior state is prohibited in the region where the road surface reaction force torque Talign is smaller than the friction torque Tf of the steering mechanism and the estimation accuracy of the road surface reaction force torque Talign is lowered. It is possible to prevent, and an accurate vehicle state can be detected.

Embodiment 2. FIG.
In the first embodiment (see FIGS. 4 and 5), detection of understeer is prohibited when the road surface reaction force torque Talign is smaller than the first threshold Th1, but as shown in FIGS. The detection of understeer may be prohibited when the road surface reaction force torque Talign is larger than the second threshold Th2.

  6 is a functional block diagram showing a configuration example of the vehicle behavior detection prohibiting means 25A according to Embodiment 2 of the present invention, and FIG. 7 is a flowchart showing the processing operation of the vehicle behavior detection prohibiting means 25A. The configuration not shown in FIG. 6 is omitted here because it is as shown in FIG. 1 and FIG.

In FIG. 6, the vehicle behavior detection prohibiting means 25A includes a comparator 27A that uses a preset second threshold Th2 as a comparison reference value.
The comparator 27A compares the road surface reaction force torque Talign with the second threshold value Th2, and if the road surface reaction force torque Talign is larger than the second threshold value Th2, the prohibition flag FLi is generated to detect the vehicle behavior state. Input to means 26.

  Here, the second threshold Th2 corresponds to the road surface reaction force torque value generated when the vehicle travels on a road with a high road surface reaction torque torque Talign (such as an asphalt road having a high road surface friction coefficient μ). The values obtained from experimental data are used.

Next, the processing operation of the vehicle behavior detection prohibiting means 25A shown in FIG. 6 will be described with reference to FIG.
In FIG. 7, step S201A is a determination process corresponding to step S201 described above (see FIG. 5), and step S202 is the same process as described above.

First, the comparator 27A determines whether or not the road surface reaction force torque Talign is larger than the second threshold value Th2 by comparing the road surface reaction force torque Talignn stored in the memory and the second threshold value Th2 (step S2). S201A).
In step S201A, if it is determined that Talign ≦ Th2 (ie, NO), the process returns to the start. If it is determined that Talign> Th2 (ie, YES), the prohibition flag FLi is output (step S202), and FIG. End program operation.

  As described above, according to the second embodiment of the present invention, the vehicle behavior detection prohibiting means 25A is provided in the vehicle behavior detecting device provided with the vehicle behavior state detecting means 26. If it is determined that the road surface reaction force torque Talign is greater than a second threshold Th2 (corresponding to a road surface reaction force torque value generated during traveling on a high μ road), detection of understeer is prohibited.

  As a result, when the vehicle is traveling on a high μ road such as an asphalt road and the road surface reaction force torque Talign is a large value (understeer is unlikely to occur), detection of the vehicle behavior state is prohibited. An erroneous determination can be prevented and an accurate vehicle state can be detected.

Embodiment 3 FIG.
In the first and second embodiments (FIGS. 4 to 7), the road surface reaction force torque Talign is used as a comparison object. However, as shown in FIGS. 8 and 9, the rate of change (time) of the road surface reaction force torque Talign is shown. The differential operation value) dTa / dt may be used as a comparison target.

  FIG. 8 is a functional block diagram showing a configuration example of the vehicle behavior detection prohibiting means 25B according to Embodiment 3 of the present invention, and FIG. 9 is a flowchart showing the processing operation of the vehicle behavior detection prohibiting means 25B. Since the configuration not shown in FIG. 8 is as shown in FIGS. 1 and 2, it is omitted here.

In FIG. 8, the vehicle behavior detection prohibiting means 25B calculates a comparator 27B having a preset third threshold Th3 as a comparison reference value, and a rate of change (time differential value) dTa / dt of the road surface reaction force torque Talign. Road surface reaction force torque change rate calculating means 28 is provided.
The comparator 27B compares the road surface reaction force torque change rate dTa / dt and the third threshold value Th3. If the road surface reaction force torque change rate dTa / dt is greater than the third threshold value Th3, the prohibition flag FLi Is input to the vehicle behavior state detection means 26.

  Here, the third threshold Th3 is set in consideration of the time change rate of the road surface reaction force torque Talign that is changing while the vehicle is running, and a value obtained from experimental data is used.

Next, the processing operation of the vehicle behavior detection prohibiting means 25B shown in FIG. 8 will be described with reference to FIG.
In FIG. 9, step S201B is a determination process corresponding to step S201A described above (see FIG. 7), and step S202 is the same process as described above.

In FIG. 9, first, the road surface reaction force torque change rate calculating means 28 differentiates the road surface reaction force torque Talign stored in the memory with respect to time, and stores the calculated value of the road surface reaction force torque change rate dTa / dt in the memory ( Step S200).
Next, the comparator 27B compares the road surface reaction force torque change rate (time differential value) dTa / dt with the third threshold value Th3, so that the road surface reaction force torque change rate dTa / dt is greater than the third threshold value Th3. Is also larger (step S201B).

  If it is determined in step S201B that dTa / dt ≦ Th3 (that is, NO), the process returns to the start, and if it is determined that dTa / dt> Th3 (that is, YES), a prohibition flag FLi is output (step S202). ), The program operation of FIG. 9 is terminated.

As described above, according to the third embodiment of the present invention, in the vehicle behavior detection device including the vehicle behavior state detection means 26, the vehicle behavior detection prohibiting means 25B is provided, and the road surface reaction force torque change rate dTa / dt is When it is larger than the third threshold Th3, detection of understeer is prohibited.
As a result, when the road surface reaction force torque change rate dTa / dt has a certain magnitude (the road surface reaction force torque Talign fluctuates relatively greatly), detection of understeer is prohibited. An erroneous determination (understeer misdetection) in a state where the reaction torque Talign is not saturated is avoided, and an accurate vehicle state can be detected.

Embodiment 4 FIG.
In the first to third embodiments, the reference road surface reaction torque Ta * and the road surface reaction force torque Talign based on the steering angle θ and the vehicle speed Vs are used as the input information to the vehicle behavior state detection unit 26. As shown in FIG. 10, the steering speed Vθ, the vehicle speed Vs, and the road surface reaction force torque change rate dTa / dt may be used.

  FIG. 10 is a functional block diagram showing a configuration example of the control device 8C according to the fourth embodiment of the present invention. Components similar to those described above (see FIGS. 2 and 8) are denoted by the same reference numerals as those described above. Detailed description is omitted. The steering mechanism not shown in FIG. 10 is omitted here because it is as shown in FIG.

  In FIG. 10, the control device 8C includes a steering speed detecting means 21C for detecting the steering speed Vθ of the driver, a vehicle speed detecting means 22 for detecting the vehicle speed Vs, and a road surface reaction force generated between the tire and the road surface. Road surface reaction force torque detecting means 23 for detecting torque Talign and a microcomputer 20C are provided.

The microcomputer 20C includes a vehicle behavior detection prohibiting unit 25, a vehicle behavior state detecting unit 26C, and a road surface reaction force torque change rate calculating unit 28C that calculates a road surface reaction force torque change rate dTa / dt.
The road surface reaction force torque change rate calculating means 28C performs a time differential operation on the road surface reaction force torque Talign to generate a road surface reaction force torque change rate (time differential value) dTa / dt and inputs it to the vehicle behavior state detection means 26C. .

As described above, the vehicle behavior detection prohibiting means 25 calculates (determines) whether or not the vehicle behavior detection should be prohibited based on the road surface reaction force torque Talign, and outputs the prohibition flag FLi when the vehicle behavior detection is prohibited.
The vehicle behavior state detection means 26C detects the vehicle behavior state based on the steering speed Vθ, the vehicle speed Vs, and the road surface reaction force torque change rate dTa / dt, and when the prohibition flag FLi is input, Prohibit output.

  Note that the steering speed detection means 21C applies, for example, the configuration referred to in the above-mentioned known technique (Japanese Patent Laid-Open No. 2005-324737), and the motor terminal voltage Vm and the motor of the brushed motor 5 (see FIG. 1). The steering speed Vθ can be easily calculated from the current Im without installing a special circuit element.

  Next, the operation of the vehicle behavior detection apparatus according to Embodiment 4 of the present invention shown in FIG. 10 will be described with reference to the flowchart of FIG. In FIG. 11, steps S102, S103, and S106 to S108 are the same processing as described above (see FIG. 3).

In FIG. 11, when the program starts, first, the steering speed detecting means 21C detects the steering speed Vθ and stores the detected value of the steering speed Vθ in the memory (step S101C).
In the same manner as described above, the vehicle speed detection means 22 and the road surface reaction force torque detection means 23 detect the vehicle speed Vs and the road surface reaction force torque Talign, and store the respective detection results in the memory (steps S102 and S103).

  Subsequently, the road surface reaction force torque change rate calculating means 28C performs time differentiation on the road surface reaction force torque Talign stored in the memory, and stores the calculated value of the road surface reaction force torque change rate dTa / dt in the memory (step S200C). .

  Next, the vehicle behavior state detection means 26C includes the steering speed Vθ and the vehicle speed Vs stored in the memory, the steering angle θ stored in the memory in advance, a constant KTa indicating the rate of change of the road surface reaction force torque, and the road surface reaction force. Based on the torque change rate (time differential value) dTa / dt, it is determined whether or not an unstable state is detected, and the detection result is stored in the memory (step S105C).

If it is determined in step S105C that the vehicle is in a stable state (that is, NO), the process returns to the start, and steps S101C to S103 and S200C are repeatedly executed.
On the other hand, if it is determined in step S105C that the vehicle behavior is unstable (that is, YES), the vehicle behavior detection prohibiting means 25 prohibits vehicle behavior detection based on the road surface reaction force torque Talign stored in the memory. Whether or not to do so is calculated, and when prohibiting vehicle behavior detection, a prohibition flag FLi is output (step S106).

  Next, the vehicle behavior state detection unit 26C determines whether or not the prohibition flag FLi is not output from the vehicle behavior detection prohibition unit 25 (detection is permitted) (step S107), and the prohibition flag FLi is output. If it is determined (that is, NO), vehicle behavior detection is prohibited, and the process returns to the start.

On the other hand, if it is determined in step S107 that the prohibition flag FLi has not been output (that is, YES), vehicle behavior detection is permitted, so that the vehicle is saturated by the saturation of the road surface reaction force torque Talign generated on the front wheels of the vehicle. Is output in an unstable state (understeer) (step S108), and the program operation of FIG. 11 is terminated.
Note that the specific configuration and operation of the vehicle behavior detection prohibiting means 25 are the same as those in the first to third embodiments (see FIGS. 4 to 9), and thus the description thereof is omitted here.

  As described above, according to the fourth embodiment of the present invention, the steering speed detection means 21C for detecting the steering speed Vθ of the driver, the vehicle speed detection means 22 for detecting the vehicle speed Vs, and the steering torque Ts of the driver. A road surface reaction force torque detecting means 23 for detecting the road surface reaction force torque Talign from the assist torque Tas of the electric power steering device; a road surface reaction force torque change rate calculating means 28C for calculating the road surface reaction force torque change rate dTa / dt; The vehicle behavior detection prohibiting means 25 comprises a vehicle behavior state detecting means 26C including a vehicle behavior state detecting means 26C for detecting an unstable state of the vehicle based on the road surface reaction force torque change rate dTa / dt, the steering speed Vθ, and the vehicle speed Vs. Is provided.

  The vehicle behavior detection prohibiting means 25 is configured, for example, as in the first embodiment (FIGS. 4 and 5) described above, and prohibits detection of understeer when the road surface reaction torque Talign is smaller than the first threshold Th1. The prohibition flag FLi to be output is output.

As a result, detection of understeer is prohibited in a region where the road surface reaction force torque Talign is smaller than the friction torque Tf of the steering mechanism and the estimation accuracy is lowered, so that erroneous determination can be prevented.
Further, compared to the first embodiment described above, the steering angle detection means 21 (see FIG. 2) for detecting the steering angle θ of the driver is not necessary, so that an accurate vehicle state can be detected with a simple configuration and low cost. can do.

  Further, the vehicle behavior detection prohibiting means 25 is configured, for example, as in the above-described second embodiment (FIGS. 6 and 7), and the prohibition flag FLi when the road surface reaction force torque Talign is larger than the second threshold Th2. Is output.

As a result, detection of understeer is prohibited on a high μ road where the road surface reaction torque Talign is a large value, and erroneous determination on a high μ road where understeer is unlikely to occur can be prevented.
Further, as compared with the above-described second embodiment, the steering angle detecting means 21 (see FIG. 2) is not required, so that an accurate vehicle state can be detected with a simple configuration and low cost.

  Furthermore, the vehicle behavior detection prohibiting means 25 is configured, for example, as in the above-described third embodiment (FIGS. 8 and 9), and the road surface reaction force torque change rate dTa / dt is greater than the third threshold Th3. Understeer detection is prohibited.

As a result, understeer detection is prohibited when the road surface reaction force torque change rate dTa / dt is somewhat large (the road surface reaction force torque Talign is fluctuating), thereby preventing erroneous determination of erroneously detecting understeer. can do.
Further, as compared with the above-described third embodiment, the steering angle detection means 21 (see FIG. 2) is not required, so that an accurate vehicle state can be detected with a simple configuration and low cost.

1 is a block configuration diagram schematically showing the overall configuration of a typical vehicle steering device to which a vehicle behavior detection device according to Embodiment 1 of the present invention is applied. FIG. It is a functional block diagram which shows the specific structural example of the vehicle behavior detection apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the vehicle behavior detection apparatus which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows the structural example of the vehicle behavior detection prohibition means which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the vehicle behavior detection prohibition means which concerns on Embodiment 1 of this invention. It is a functional block diagram which shows the structural example of the vehicle behavior detection prohibition means which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the vehicle behavior detection prohibition means which concerns on Embodiment 2 of this invention. It is a functional block diagram which shows the structural example of the vehicle behavior detection prohibition means which concerns on Embodiment 3 of this invention. It is a flowchart which shows operation | movement of the vehicle behavior detection prohibition means which concerns on Embodiment 3 of this invention. It is a functional block diagram which shows the specific structural example of the vehicle behavior detection apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows operation | movement of the vehicle behavior detection apparatus which concerns on Embodiment 4 of this invention.

Explanation of symbols

  1 steering wheel, 2 steering shaft, 8, 8C control device, 20, 20C microcomputer, 21 steering angle detection means, 21C steering speed detection means, 22 vehicle speed detection means, 23 road surface reaction force torque detection means, 24 reference road surface reaction torque calculation Means, 25, 25A, 25B Vehicle behavior detection prohibiting means, 26, 26C Vehicle behavior state detecting means, 27, 27A, 27B, 27C Comparator, 28, 28C Road surface reaction force torque change rate calculating means, FLi prohibition flag (vehicle behavior) State detection prohibition flag), FLG detection flag (understeer detection flag), Talign road surface reaction torque, Ta * standard road surface reaction torque, dTa / dt road surface reaction torque change rate, Tas assist torque, Tf friction torque, Ts operation torque , Th1 first threshold, Th2 second threshold, Th3 third threshold Vs vehicle speed, Vθ steering speed.

Claims (8)

Road surface reaction force torque detecting means for detecting road surface reaction force torque received by the vehicle tire from the road surface;
Steering angle detection means for detecting the steering angle of the vehicle;
Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
Reference road surface reaction torque calculation means for calculating a reference road surface reaction torque from the detected values of the steering angle and the vehicle speed;
In a vehicle behavior detection device comprising: vehicle behavior state detection means for detecting an unstable behavior state of the vehicle based on the detected value of the road surface reaction force torque and the calculated value of the reference road surface reaction torque.
Vehicle behavior detection prohibiting means for prohibiting the output of the vehicle behavior state detecting means based on the detected value of the road reaction force torque ,
The vehicle behavior detection prohibiting unit compares the detection value of the road surface reaction force torque with a preset threshold value and determines whether or not the detection value of the road surface reaction force torque is in an unstable range. Including
The comparator generates a prohibition flag for prohibiting the output of the vehicle behavior state detection means when it is determined that the detected value of the road surface reaction force torque is in an unstable range. Behavior detection device.   The vehicle behavior detection prohibiting means prohibits the output of the vehicle behavior state detecting means when the detected value of the road surface reaction force torque is smaller than a preset first threshold value. The vehicle behavior detection device according to 1.   The vehicle behavior detection prohibiting means prohibits the output of the vehicle behavior state detecting means when the detected value of the road surface reaction force torque is larger than a preset second threshold value. The vehicle behavior detection device according to 1. The vehicle behavior detection prohibiting means includes road surface reaction force torque change rate calculating means for calculating a change rate of the road surface reaction force torque from a detected value of the road surface reaction force torque,
2. The vehicle behavior according to claim 1, wherein when the calculated value of the road surface reaction force torque change rate is larger than a preset third threshold, the output of the vehicle behavior state detection unit is prohibited. Detection device. Road surface reaction force torque detecting means for detecting road surface reaction force torque received by the vehicle tire from the road surface;
Road surface reaction force torque change rate calculating means for calculating a rate of change of the road surface reaction force torque from the detected value of the road surface reaction force torque;
Steering speed detecting means for detecting the steering speed of the vehicle;
Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
Vehicle behavior state detection means for detecting an unstable behavior state of the vehicle based on a calculated value of the road surface reaction force torque change rate, a detected value of the steering speed, and a detected value of the vehicle speed;
In a vehicle behavior detection device comprising:
Vehicle behavior detection prohibiting means for prohibiting the output of the vehicle behavior state detecting means based on the detected value of the road reaction force torque ,
The vehicle behavior detection prohibiting unit compares the detection value of the road surface reaction force torque with a preset threshold value and determines whether or not the detection value of the road surface reaction force torque is in an unstable range. Including
The comparator generates a prohibition flag for prohibiting the output of the vehicle behavior state detection means when it is determined that the detected value of the road surface reaction force torque is in an unstable range. Behavior detection device.   The vehicle behavior detection prohibiting means prohibits the output of the vehicle behavior state detecting means when the detected value of the road surface reaction force torque is smaller than a preset first threshold value. 5. The vehicle behavior detection device according to 5.   The vehicle behavior detection prohibiting means prohibits the output of the vehicle behavior state detecting means when the detected value of the road surface reaction force torque is larger than a preset second threshold value. 5. The vehicle behavior detection device according to 5.   The vehicle behavior detection prohibiting means prohibits the output of the vehicle behavior state detecting means when the calculated value of the road surface reaction force torque change rate is larger than a preset third threshold value. The vehicle behavior detection device according to claim 5.

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