JP2009280098A - Travel control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vehicle behavior control having a plurality of control modes capable of obtaining output characteristics adapted to vehicle behavior characteristics selected by vehicle behavior control without making calculation complicated in cruise control, and obtaining favorable drivability. <P>SOLUTION: A vehicle behavior control part 1 has three modes of : a normal mode for executing all of ABS control, anti-skid control, and traction control; a traction mode for executing the ABS control, the limited anti-skid control, and the traction control; and an off-mode for executing only the ABS control. A driver selects the mode by a mode switch 14. A cruise control part 2 has an upper limit guard value corresponding to each mode according to the mode switch 14, and sets output characteristics adapted to the mode of the vehicle behavior control during normal driving by limiting target vehicle speed with the upper limit guard value during the cruise control. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle travel control device equipped with an antilock brake system (hereinafter abbreviated as “ABS”), a vehicle behavior control function such as a side slip prevention control and a traction control, and a cruise control function.

  In recent years, various vehicle behavior control technologies such as ABS, side slip prevention control, and traction control have been installed in vehicles. In such vehicle behavior control, the control mode and A sensor with a freely selectable sensitivity has been proposed and put into practical use.

  For example, in Japanese Patent Laid-Open No. 6-99801, in a vehicle slip control device that performs brake traction control for controlling the braking force of a drive wheel so that the slip amount of the drive wheel becomes a target slip amount, The first mode in which the brake traction control is performed based on the difference between the driven wheel speed and the driven wheel speed, the second mode in which the brake traction control is performed based on the difference between the driving wheel speeds of the left and right driving wheels, and the third mode in which the brake traction control is not performed. A technique provided with a manual mode setting switch for alternatively setting a mode is disclosed.

Similarly, in the cruise control device, for example, in Japanese Patent Application Laid-Open No. 2003-343305, when the driving state can be selected according to the driver's preference, the control pattern can be selected and the eco-run mode is selected. In addition, there is disclosed a technology for realizing fuel efficiency reduction by regulating the increase amount of the throttle opening and the upper limit value of the engine speed.
JP-A-6-99801 JP 2003-343305 A

  By the way, in a technique in which a plurality of characteristics (modes) are set for vehicle behavior control as disclosed in Patent Document 1 described above, a plurality of control modes as disclosed in Patent Document 2 described above are used. When the cruise control technology having the above is applied, the cruise control intended by the driver is performed also in the cruise control. For example, even in the follow-up travel, the acceleration performance equivalent to the mode selected in the vehicle behavior control can be obtained. Therefore, good drivability can be obtained.

  However, in the technique disclosed in Patent Document 2, the driver independently selects the characteristic (mode) regardless of the selection in the vehicle behavior control, so that the driving by the vehicle behavior control and the cruise control is performed. There is a problem that cannot be adapted.

  In order to cope with this, it is conceivable that the characteristics corresponding to the mode selected by the vehicle behavior control are read at the time of the cruise control, and the cruise control is performed based on the characteristics, so that the adaptation is possible.

  However, vehicle behavior control is performed to generate a predetermined yaw moment in the vehicle or to maintain the wheel grip force at a predetermined level. There is a problem that it is difficult to do.

  The present invention has been made in view of the above circumstances, and for vehicle behavior control having a plurality of control modes, in cruise control, an output suitable for the vehicle behavior characteristics selected in the vehicle behavior control without complicating the calculation. It is an object of the present invention to provide a vehicle travel control device that can obtain characteristics and obtain good drivability.

  The present invention is a vehicle behavior control in which a specific vehicle behavior control characteristic is freely selectable by a selection means from among a plurality of vehicle behavior control characteristics, and a vehicle behavior is controlled by outputting a signal to at least one of a brake control means and an engine control means. Means, and a cruise control means for setting a target value for control of the host vehicle based on at least one of a preset target vehicle speed and a traveling state of a preceding vehicle, and performing travel control based on the target value for control, The cruise control means sets an upper limit guard value in the control target value corresponding to the specific vehicle behavior control characteristic selected by the selection means for each driving region of the cruise control of the cruise control means, The upper limit guard value and the control target value are compared for each operation region. When the control target value is higher than the upper limit guard value, the control target value is set with the upper limit guard value. It is characterized by a constant.

  According to the vehicle travel control device of the present invention, an output characteristic suitable for the vehicle behavior control selected in the vehicle behavior control without complicating the calculation in the cruise control, compared to the vehicle behavior control having a plurality of control modes. And good drivability can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 6 show an embodiment of the present invention, FIG. 1 is a functional block diagram showing the overall configuration of a vehicle travel control device, FIG. 2 is a functional block diagram of a cruise control unit, and FIG. 3 is a preceding inter-vehicle distance. FIG. 4 is an explanatory diagram of the inter-vehicle distance deviation map, and FIG. 5 is an explanatory diagram showing the relationship between the follow target vehicle speed and the acceleration guard value corresponding to each control mode. FIG. 6 and FIG. 6 are explanatory diagrams of each guard value set in the follow-up running and the constant speed running during cruise control.

  As shown in FIG. 1, a vehicle is mounted with a vehicle behavior control unit 1 as vehicle behavior control means and a cruise control unit 2 as cruise control means.

  The vehicle behavior control unit 1 is configured such that the yaw rate (actual yaw rate) γ from the yaw rate sensor 11 and the handle angle θH from the handle angle sensor 12 are four wheel speed sensors 13 (left front wheel speed sensor 13fl, right front wheel speed sensor 13fr). , Left rear wheel speed sensor 13rl, right rear wheel speed sensor 13rr), the four wheel speeds ωfl, ωfr, ωrl, ωrr are the vehicle behavior control modes selected by the driver from the mode changeover switch 14 as selection means. (In this embodiment, for example, any one of three modes of a normal mode, a traction mode, and an OFF mode) is input.

  The vehicle behavior control unit 1 controls the braking force at the time of braking to prevent the occurrence of a wheel lock state, and applies a braking force to the selected wheel to generate a yaw moment in the vehicle. Control function according to the selected vehicle behavior control mode based on the above signals, with the function of anti-slip control to prevent the skidding behavior of the vehicle and the function of traction control to prevent slipping of the drive wheels Is achieved.

  That is, all of these control functions are known. For example, the ABS function includes the speed of each wheel, acceleration / deceleration, and pseudo-calculated vehicle body speed (the brake pedal is depressed and the deceleration of the wheel speed is If it is greater than or equal to a predetermined value, it is determined that the brake is suddenly applied, the wheel speed at that time is set as an initial value, and thereafter, a value calculated by decelerating at a predetermined deceleration is calculated). Judging from the comparison with the wheel speed, the magnitude of the acceleration / deceleration of the wheel, etc., three hydraulic modes of pressure increasing, holding and pressure reducing are selected during the ABS operation. Specifically, when the difference between the pseudo-calculated vehicle body speed and the wheel speed increases to indicate a slip state, the braking pressure is reduced from the braking pressure as the ABS operation estimated pressure, and the reduced braking pressure is set to a predetermined value. The pressure is reduced again when the ABS operation estimated pressure is reached and the slip state is reached, and this is repeated. The selected predetermined brake control signal is sent to the brake control unit 21 as the brake control means. Output.

  Further, the function of the skid prevention control in the vehicle behavior control unit 1 is based on, for example, a steering angle θH and a vehicle speed V (for example, an average value of four-wheel wheel speeds ωfl, ωfr, ωrl, and ωrr) based on a vehicle motion model. A target yaw rate γt is calculated, and a deviation Δγ between the target yaw rate γt and the actual yaw rate γ is calculated to determine whether the vehicle has an understeer tendency or an oversteer tendency. In the case of an understeer tendency, a control signal is output to the brake control unit 21 so as to add a predetermined braking force corresponding to the yaw rate deviation Δγ to the rear inner wheel, while in the case of an oversteer tendency, the outer side of the turn A control signal is output to the brake control unit 21 so as to apply a predetermined braking force according to the yaw rate deviation Δγ to the front wheels. Further, in addition to the brake control, when an unnecessary driving force is generated, a control signal is output to the engine control unit 22 as an engine control means so as to reduce the engine torque corresponding to the driving force. .

  Further, the traction control function in the vehicle behavior control unit 1 executes, for example, the traction control proposed by the present applicant in Japanese Patent Application Laid-Open No. 8-207607. Specifically, the actual slip ratio of the four wheels is calculated from the signal of the wheel speed of the four wheels, and the target slip ratio of the front and rear wheels is determined according to the running state by a map search or the like. When at least one target slip ratio is exceeded, the traction control operation is determined. At the time of traction control operation, the target brake pressure of the four wheels is calculated separately based on the deviation between the slip ratio of the four wheels and the target slip ratio of the front and rear wheels, and an instruction signal for these target brake pressures is output to the brake control unit 21. . When the traction control is activated, the target slip amount is compared with the actual slip amount for the fastest rotating wheel, the engine target torque is reduced by the difference between the two and the engine target torque is determined. Is output to the engine control unit 22 together with the signal.

  The vehicle behavior control unit 1 has the ABS function, the skid prevention control function, and the traction control function described above, and can be switched to the following vehicle behavior control by selection of the driver by the mode switch 14. Done.

  When the normal mode is selected, the ABS function, the skid prevention control function, and the traction control function are executed as described above.

  When the traction mode is selected, the ABS function is maintained as described above, but other skid prevention control functions and traction control functions are executed with the output to the engine control unit 22 limited. The For this reason, vehicle behavior control suitable for when the driver desires sports driving or the like is performed.

  When the OFF mode is selected, the ABS function is maintained as described above, but other skid prevention control functions and traction control functions are turned off, such as deep snow roads and muddy roads. It is a mode that is selected during emergency exit.

  The cruise control unit 2 inputs a vehicle behavior control mode (in this embodiment, for example, any one of three modes of a normal mode, a traction mode, and an OFF mode) selected by the driver from the mode switch 14 described above. Then, the accelerator opening degree θACC is input from the accelerator opening sensor 15, and the engine speed Ne is input from the engine speed sensor 16. Further, from the cruise control operation switch 17, an inter-vehicle distance (hereinafter referred to as “set inter-vehicle distance”) from the preceding vehicle at the cruise control, in this embodiment, “long”, “medium”, and “short” A cruise control ON / OFF signal, a set vehicle speed setting signal (basically set by an increase / decrease with respect to the previous set vehicle speed), and the like. Further, from the preceding vehicle detection unit 18, preceding vehicle information (presence / absence of preceding vehicle capture, distance between the preceding vehicle and the host vehicle (hereinafter referred to as preceding vehicle distance), preceding vehicle speed, etc.) is input. For example, the preceding vehicle detection unit 18 performs image processing such as extracting a feature of a box pattern on a distance image from a stereo camera or the like, and exists in front of the host vehicle from a three-dimensional object. The preceding vehicle is detected by specifying an object that becomes an obstacle to the vehicle, and the distance between the preceding vehicles is obtained. Then, the time-dependent change in the distance between the preceding vehicles is calculated to calculate the relative speed of the preceding vehicle with respect to the own vehicle, and the relative speed of the preceding vehicle is added to the own vehicle speed (for example, the average value of the wheel speeds of the four wheels). By doing so, the preceding vehicle speed is obtained.

  Then, as will be described later, when cruise control is started, the cruise control unit 2 reads the preceding vehicle information from the preceding vehicle detection unit 18, and if the preceding vehicle is not captured, the set vehicle speed is set as the target vehicle speed. On the other hand, when the preceding vehicle is captured, the target vehicle speed is obtained from the difference between the preceding vehicle speed and the own vehicle speed, and the target throttle opening θαs corresponding to the target vehicle speed is obtained and output to the engine control unit 22. Further, the pseudo accelerator opening degree θha is obtained and a signal is output to the transmission control unit 23.

  The brake control unit 21 performs control related to the brake. The brake control unit 21 outputs a signal to a brake drive unit (not shown) in accordance with the amount of depression of the brake pedal and a signal from the vehicle behavior control unit 1, and the wheel of each wheel. The cylinders are configured to generate brake pressure independently of each other.

  The engine control unit 22 controls the operating state of the engine. On the input side, the engine speed Ne, the intake air amount Q, the accelerator opening θACC, the throttle opening θth, the engine water temperature Tw, etc. Sensors for detecting a driving state are connected, and further, a vehicle behavior control unit 1 and a cruise control unit 2 are connected.

  Further, on the output side of the engine control unit 22, an injector that injects a predetermined metered amount of fuel into the combustion chamber, and a throttle actuator (not shown) that opens and closes the throttle valve are provided in an electronically controlled throttle device. Etc.) are connected to the actuators for controlling the engine drive.

  And the engine control part 22 sets the fuel-injection timing with respect to an injector, and a fuel-injection pulse width (pulse time) based on the detection signal from each input sensors. Further, a throttle opening signal is output to a throttle actuator that drives the throttle valve to control the opening of the throttle valve. In addition, when the engine control unit 22 receives an engine torque decrease signal or an engine target torque signal from the vehicle behavior control unit 1, the engine control unit 22 has an engine whose throttle valve opening corresponds to the electronic control throttle device. Control is performed so as to reduce the torque or converge to the engine target torque. Further, when the cruise control is started by the cruise control unit 2, the target throttle opening θαs calculated by the cruise control unit 2 is read, and the throttle valve opening is set to the target throttle opening θαs with respect to the electronic control throttle device. Control to converge.

  The transmission control unit 23 performs shift control of the automatic transmission. A four-wheel wheel speed sensor 13, an inhibitor switch (not shown), the cruise control unit 2, and the like are connected to the input side. Wheel speeds ωfl, ωfr, ωrl, ωrr, select lever position, pseudo accelerator opening θha, and the like are input. Further, the transmission control unit 23 is connected to a control valve that performs shift control of the automatic transmission and a lockup actuator (not shown) that locks up the lockup clutch on the output side. The transmission control unit 23 determines the set range of the select lever based on the signal from the inhibitor switch. When the transmission control unit 23 is set to the D range, the vehicle speed and the accelerator opening (the pseudo accelerator opening θha is obtained from the cruise control unit 2). If it is output, the shift signal is output to the control valve in accordance with the shift pattern specified based on the pseudo accelerator opening degree θha) to perform shift control. This shift pattern is variably set corresponding to the mode (normal mode, traction mode, OFF mode) set by the mode changeover switch 14.

  Next, the cruise control process executed by the cruise control unit 2 will be described in more detail using the functional blocks shown in FIG. As shown in the figure, the cruise control unit 2 has functions for executing cruise control as a target vehicle speed calculation unit 2a, a follow target vehicle speed calculation unit 2b, a tracking flag calculation unit 2c, a control target vehicle speed calculation unit 2d, cruise control. Requested horsepower (hereinafter referred to as “cruccone required horsepower”) calculation unit 2e, cruise control request torque (hereinafter referred to as “crucone request torque”) calculation unit 2f, accelerator request torque calculation unit 2g, request torque selection calculation unit 2h, target A throttle opening calculation unit 2i and a pseudo accelerator opening calculation unit 2j are provided.

  Next, the cruise control process executed by each of the calculation units 2a to 2j will be described. When the driver turns on the cruise control operation switch 17 while the vehicle is running, cruise control is started, and the target vehicle speed calculation unit 2a uses the set vehicle speed Sst [Km / h] set by the cruise control operation switch 17 as the target vehicle speed St. Set as [Km / h].

Further, the follow target vehicle speed calculation unit 2b is obtained from the preceding vehicle information (the preceding inter-vehicle distance L, the preceding vehicle speed Sn [Km / h]) obtained by the preceding vehicle detection unit 18 as a signal from the four-wheel wheel speed sensor 13. Based on the own vehicle speed Si [Km / h] and the vehicle behavior control mode (any one of the normal mode, the traction mode, and the OFF mode) selected by the mode switch 14, the following target vehicle speed Sfo of the own vehicle with respect to the preceding vehicle is set. Calculated from the following equation (1).
Sfo ← Sn + Sα (1)
Here, Sα is the tracking response speed [Km / h], which corresponds to the difference (inter-vehicle distance deviation) ΔL (= L−Lo) between the preceding inter-vehicle distance L and the set inter-vehicle distance Lo set by the cruise control operation switch 17. Is set. That is, in follow-up traveling during cruise control, as shown in FIG. 3A, when the preceding inter-vehicle distance L is longer than the set inter-vehicle distance Lo (ΔL> 0), the host vehicle speed Si is accelerated to set the inter-vehicle distance. It is necessary to hold Lo. Conversely, as shown in FIG. 5B, when the preceding inter-vehicle distance L is shorter than the set inter-vehicle distance Lo (ΔL <0), it is necessary to reduce the host vehicle speed Si to ensure the set inter-vehicle distance Lo. Therefore, since ΔL = 0 when Lo = L, the tracking response speed Sα = 0 is set.

  The tracking response speed Sα is set for each mode of vehicle behavior control based on the inter-vehicle distance deviation ΔL with reference to the inter-vehicle distance deviation map shown in FIG. The characteristics of the inter-vehicle distance deviation map shown in FIG. 4 will be described.

  The tracking response speed Sα is a response strength when attempting to maintain the set inter-vehicle distance Lo, and is a non-linear characteristic that increases from the minus side to the plus side through the center value (ΔL = 0) with respect to the inter-vehicle distance deviation ΔL. have. In addition, the tracking response speed Sα in the OFF mode has a gradual rise characteristic compared to the tracking response speed Sα in the normal mode, while the tracking response speed Sα in the traction mode has a sharp rise characteristic. ing. As a result, the driver can obtain an acceleration feeling equivalent to a normal acceleration operation by the accelerator pedal operation.

  Therefore, when the inter-vehicle distance deviation ΔL becomes a large value toward the plus side or minus side in the follow-up running, when the OFF mode is selected as the vehicle behavior control mode, the acceleration or deceleration is moderated as compared with the normal mode. Then, control is performed to slowly bring the preceding inter-vehicle distance L close to the set inter-vehicle distance Lo. On the other hand, when the traction mode is selected as the vehicle behavior control mode, the control to bring the preceding inter-vehicle distance L closer to the set inter-vehicle distance Lo by relatively abrupt acceleration or deceleration as compared with the normal mode. Done.

  At that time, an acceleration gradient is calculated from the change amount of the follow target vehicle speed Sfo, and the acceleration gradient is compared with the acceleration guard value gradient. When the acceleration gradient is larger than the acceleration guard value gradient as the first upper limit guard value, the follow target vehicle speed Sfo is limited by the acceleration guard value.

  The gradient of the acceleration guard value is set for each vehicle behavior control mode (normal mode, traction mode, OFF mode). As shown in FIG. 5, the gradient of the acceleration guard value in the normal mode is indicated by a thin line. On the other hand, the gradient of the acceleration guard value in the OFF mode indicated by the broken line is set gently, and the gradient of the acceleration guard value in the traction mode indicated by the alternate long and short dash line is set to be steep.

  As shown in the figure, for example, in follow-up traveling, when the preceding vehicle is accelerated as indicated by a two-dot chain line from a state where the preceding vehicle is traveling at a low speed at a constant speed, the following target vehicle speed Sfo calculated based on the equation (1) It is also accelerated with a certain gradient. In this case, the acceleration (gradient) of the tracking target vehicle speed Sfo indicated by the bold line in the figure is steeper than the acceleration guard value in the OFF mode indicated by the broken line and is gentler than the gradient of the acceleration guard value in the normal mode indicated by the thin line. In this case, when the traction mode or the normal mode is selected as the vehicle behavior control mode, the follow target vehicle speed Sfo calculated by the equation (1) is output as it is.

  On the other hand, when the OFF mode is selected as the vehicle behavior control mode, the acceleration (gradient) of the follow target vehicle speed Sfo calculated by the equation (1) is steeper than the gradient of the acceleration guard value in the OFF mode. Therefore, the acceleration (gradient) of the follow target vehicle speed Sfo is limited by the gradient of the acceleration guard value in the OFF mode.

  By the way, since this acceleration guard value is for restricting excessive acceleration during follow-up running, the follow-up target vehicle speed Sfo calculated by equation (1) does not exceed the acceleration guard value in normal follow-up running. . For example, when the OFF mode is selected as the vehicle behavior control mode, the tracking response speed Sα in the equation (1) shows a gradual change with respect to the inter-vehicle distance deviation ΔL, so the acceleration of the follow target vehicle speed Sfo The (gradient) does not become a steep slope as shown by a thick line in FIG. 5, but is accelerated with a gentler slope than the slope of the acceleration guard value in the OFF mode. When the preceding vehicle is not captured, the preceding vehicle speed Sn and the preceding inter-vehicle distance L are not detected, and therefore the follow target vehicle speed Sfo is not set.

  Further, the tracking flag calculation unit 2c reads the preceding vehicle capture signal from the preceding vehicle detection unit 18, sets the tracking flag Ffo when the preceding vehicle is captured (Ffo ← 1), and clears when the preceding vehicle is not captured. (Ffo ← 0).

  The control target vehicle speed calculation unit 2d includes the target vehicle speed St (set vehicle speed Sst) set by the target vehicle speed calculation unit 2a, the tracking target vehicle speed Sfo obtained by the tracking target vehicle speed calculation unit 2b, and the tracking flag set by the tracking flag calculation unit 2c. The value of Ffo is read to obtain the control target vehicle speed So, and a second upper limit guard value that restricts the upper limit of the control target vehicle speed So in each operation region is set. This second upper limit guard value is set for each driving region, and is set at the time of a transition to a constant speed driving and that set at the time of following driving.

  Specifically, when the tracking flag Ffo is cleared (Ffo = 0), that is, in the constant speed travel in which the preceding vehicle is not captured, the target vehicle speed St is prioritized, and the control target vehicle speed is set at the target vehicle speed St. So is set (So ← St). Further, when the tracking flag Ffo is set (Ffo = 1), that is, in the follow-up traveling in which the preceding vehicle is captured, the follow-up target vehicle speed Sfo is prioritized, and the control target vehicle speed So is set at the follow-up target vehicle speed Sfo. It is set (So ← Sfo). The upper limit of the follow target vehicle speed Sfo is the target vehicle speed St (set vehicle speed Sst).

  When the target vehicle speed So for control is set at the follow target vehicle speed Sfo, when the preceding vehicle is accelerated, the acceleration (gradient) of the follow target vehicle speed Sfo is determined in the vehicle behavior control mode in the follow target vehicle speed calculation unit 2b. It is regulated by the acceleration guard value set for each (normal mode, traction mode, OFF mode).

  Therefore, as shown in FIG. 6, in the follow-up acceleration that accelerates following the acceleration operation of the preceding vehicle, the follow-up target vehicle speed Sfo does not generate an acceleration that is greater than the acceleration guard value set in the follow-up target vehicle speed calculation unit 2b. However, if the following target vehicle speed Sfo of the wrong acceleration is output from the following target vehicle speed calculation unit 2b, the acceleration is abrupt. Similarly, the maximum value of the follow target vehicle speed Sfo is the set vehicle speed Sst, but there may be a case where the follow target vehicle speed Sfo is set to an erroneous value equal to or higher than the set vehicle speed Sst, that is, the target vehicle speed St.

  Therefore, as shown in FIG. 6, in the follow-up running in which the tracking flag Ffo is set (Ffo = 1), the follow-up target vehicle speed Sfo that is set when the vehicle is accelerated following the acceleration operation of the preceding vehicle is regulated. The following acceleration guard value is set. Further, a set vehicle speed guard value that restricts the upper limit value of the follow target vehicle speed Sfo is set.

  The following acceleration guard value is set for each vehicle behavior control mode (normal mode, traction mode, OFF mode). The follow-up acceleration guard value has a role as a safety function, and the gradient thereof is set for each vehicle behavior control mode (normal mode, traction mode, OFF mode) set by the follow-up target vehicle speed calculation unit 2b. It is set at a steeper slope than the acceleration guard value. Further, the set vehicle speed guard value is set by the set vehicle speed Sst that is the maximum vehicle speed during cruise control, that is, the target vehicle speed St.

  Further, when the tracking flag Ffo is cleared (Ffo ← 0), that is, when the constant speed running is started, the constant speed running start guard value is first set. This constant speed travel start guard value is set to a value decelerated by the set speed ΔSg from the current host vehicle speed Si. The set speed ΔSg is a fixed value (for example, 5 [Km / h]) in the present embodiment, but may be a variable value set based on the host vehicle speed Si at the start of constant speed running. This constant speed running start guard value is maintained for a set time, and then the constant speed return acceleration guard value is set. This constant speed return acceleration guard value regulates the acceleration (gradient) when returning the host vehicle speed Si to the target vehicle speed St, and is set for each vehicle behavior control mode (normal mode, traction mode, OFF mode). The constant speed return acceleration guard value set when the OFF mode is selected is 80, for example, compared to the gradient of the constant speed return acceleration guard value set when the normal mode is selected. It is set with a gentle slope of [%]. The gradient of the constant speed return acceleration guard value set when the traction mode is selected is, for example, 110% of the constant speed return acceleration guard value set when the normal mode is selected. It is set with a steep slope.

  The control target vehicle speed calculation unit 2d first refers to the value of the tracking flag Ffo, and sets the control target vehicle speed So at the target vehicle speed St obtained by the target vehicle speed calculation unit 2a during constant speed travel of Ffo = 0. (So ← St). Further, at the time of follow-up traveling with Ffo = 1, the control target vehicle speed So is set with the follow-up target vehicle speed Sfo obtained by the follow-up target vehicle speed calculation unit 2b (So ← Sfo). During follow-up driving, the control target vehicle speed So is compared with the follow-up acceleration guard value and the set vehicle speed guard value. When the control target vehicle speed So exceeds the follow-up acceleration guard value, this control target vehicle speed So The vehicle speed So is set by the following acceleration guard value. As a result, even if the following target vehicle speed Sfo of erroneous acceleration is output from the following target vehicle speed calculation unit 2b, the target vehicle speed So for rapid acceleration is not set. Further, when the control target vehicle speed So exceeds the set vehicle speed guard value, the control target vehicle speed So is regulated by the set vehicle speed guard value, so a vehicle speed equal to or higher than the set vehicle speed Sst is set as the control target vehicle speed So. It will not be done.

  On the other hand, when shifting from follow-up running to constant speed running, first, a constant speed running start guard value is set. Since the constant speed travel start guard value is set to a value decelerated by the set speed ΔSg from the current host vehicle speed Si, the control target vehicle speed So is always set to the constant speed travel start guard at the start of constant speed travel. Set by value. As a result, even when the preceding vehicle is lost for a moment and is captured again at the start of constant speed running, the driver does not feel the vehicle jumping out and good drivability can be obtained.

  Further, after the shift to the constant speed running, when the own vehicle speed Si is returned to the target vehicle speed St, the constant speed return acceleration guard value is set. Therefore, the control target vehicle speed So is gradually regulated by the constant speed return acceleration guard value. Increased speed. When the target vehicle speed So for control is suddenly set to the target vehicle speed St (set vehicle speed Sst) when switching from the follow-up travel to the constant speed travel, if the deviation between the own vehicle speed Si and the target vehicle speed St is large, the vehicle accelerates rapidly. However, in this embodiment, since the acceleration gradient is regulated by the constant speed return acceleration guard value, there is no sudden acceleration, and this constant speed return acceleration guard value is the vehicle behavior control mode. Since it is set for each (normal mode, traction mode, OFF mode), good drivability can be obtained.

  Then, the control target vehicle speed So is read by the cruise control request horsepower (hereinafter referred to as “cruccone request horsepower”) calculation unit 2e. The cruise control required horsepower calculation unit 2e is based on the speed difference ΔS (= So−Si) between the control target vehicle speed So and the host vehicle speed Si, and the cruise control request horsepower HPs for causing the host vehicle speed Si to reach the control target vehicle speed So. Is obtained by a calculation formula or a table search.

  The cruise control required horsepower HPs is read by the cruise control required torque calculation unit 2f. The cruise control required torque calculation unit 2f obtains the cruise control required torque Tcs from the calculation formula based on the cruise control required horsepower HPs and the engine speed Ne (Tcs = k · (HPs / Ne), where k is a coefficient).

  On the other hand, during the cruise control, the accelerator required torque calculation unit 2g is based on the accelerator opening θACC that is the amount of depression of the accelerator pedal detected by the accelerator opening sensor 15 and the engine speed Ne from the engine speed sensor 16. Accelerator required torque Tacs is obtained by referring to a predetermined characteristic map of accelerator opening θACC, engine speed Ne, and engine torque Tacs.

  The required torque selection calculation unit 2h compares the cruise control required torque Tcs and the accelerator required torque Tacs, and sets the higher one as the required torque Ts. Therefore, in the state where the driver releases the accelerator pedal, the cruise control required torque Tcs is set as the required torque Ts (Ts ← Tcs). On the other hand, when the driver depresses the accelerator pedal and the accelerator request torque Tacs higher than the cruise control request torque Tcs is output, the cruise control is temporarily suspended, and the accelerator request torque Tacs is set as the request torque Ts (Ts ← Tacs).

  This cruise control required torque Tcs is determined during acceleration / deceleration operation without referring to the characteristic map of the accelerator opening θACC, engine speed Ne, and engine torque set in advance, which is referred to during normal operation that is performed by operating the accelerator pedal. Since the above-mentioned characteristics are only restricted using the first and second upper limit guard values described above, the calculation is not complicated, and the upper limit guard value corresponds to the vehicle behavior control mode selected by the driver. Since it is set, it can be adapted to the engine output characteristics during normal operation, and good drivability can be obtained.

  Further, the required torque selection calculation unit 2h compares the required torque Ts with the third upper limit guard value. If the required torque Ts exceeds the third upper limit guard value, the required torque Ts is set to the third upper limit guard value. Set with the upper guard value. The third upper limit guard value is set to the maximum torque when the accelerator pedal is fully depressed. In normal operation where the accelerator pedal is operated, the throttle valve opening does not open much more than when the accelerator pedal is fully depressed, but in cruise control, the throttle valve opening is set from the required torque. Therefore, the throttle valve can be opened larger than when the accelerator pedal is fully depressed. However, in the present embodiment, since the required torque Ts is regulated by the third upper limit guard value, the throttle opening does not open larger than when the accelerator pedal is fully depressed. Since the third upper limit guard value can be set arbitrarily, a value lower than the maximum torque when the accelerator pedal is fully depressed, for example, 80 [%] of the maximum torque when the accelerator pedal is fully depressed. It is also possible to set the degree.

  Then, the required torque Ts is read into the target throttle opening calculation unit 2i and the pseudo accelerator opening calculation unit 2j.

  Based on the required torque Ts, the target throttle opening calculator 2i calculates a target throttle opening θαs corresponding to the required torque Ts and outputs it to the engine control unit 22.

  On the other hand, the pseudo accelerator opening calculation unit 2j refers to a characteristic map of the accelerator opening θACC, the engine speed Ne, and the engine torque set in advance based on the required torque Ts and the engine speed Ne, and opens the pseudo accelerator opening. The degree θha is calculated by back calculation and output to the transmission control unit 23.

  Thus, according to the present embodiment, the target vehicle speed during acceleration is regulated by the guard value set for each vehicle behavior control mode selected by the driver. The driver can be given an acceleration feeling that matches the mode characteristics of the vehicle behavior control selected by the driver during driving, and good drivability can be obtained. In cruise control, the target vehicle speed is only regulated by a guard value, so that it is not necessary to separately provide a map that matches a mode map that is referred to during normal operation, and control is facilitated.

  In the present embodiment, the target regulated by the guard value is set as the target vehicle speed. However, the acceleration generated by the acceleration value of the host vehicle is provided, and the acceleration generated in the host vehicle by the guard value is detected. However, the same effect can be obtained.

  Furthermore, in this embodiment, after the tracking flag is set, when the tracking flag is cleared, it shifts to constant speed traveling control and has a guard value different from that in the following traveling control, but there is no preceding vehicle. While it is not fixed, the guard value during constant speed traveling control is set to a value smaller than the guard value during follow-up traveling control, and safety is improved by preventing sudden acceleration when the absence of the preceding vehicle is not confirmed. On the other hand, when the absence of the preceding vehicle is confirmed, the guard value at the constant speed driving control is set to a value larger than the guard value at the following driving control, thereby accelerating according to the driver's intention. Therefore, the operability is improved.

  It should be noted that the above-described guard values can be further adapted to the engine output characteristics during normal operation by operating the accelerator pedal by finely adjusting the guard values individually.

  In the present embodiment, the vehicle behavior control unit 1 is selected from the three modes of the normal mode, the traction mode, and the OFF mode as described above, but is selected from four or more modes or two modes. It goes without saying that the present invention can be applied even if it has such specifications. Furthermore, the normal mode, the traction mode, and the OFF mode of the vehicle behavior control are merely examples. For example, the control timing (the operation sensitivity of the skid prevention control function or the traction control function) is changed. A plurality of these selectable modes may be provided in combination.

Functional block diagram showing the configuration of the entire vehicle travel control device Functional block diagram of the cruise control unit Explanatory drawing of a state where the preceding inter-vehicle distance is longer than the set inter-vehicle distance and a short state Illustration of the distance deviation map Explanatory drawing showing the relationship between the following target vehicle speed and the acceleration guard value corresponding to each control mode Explanatory drawing of each guard value set in follow-up driving and constant speed driving during cruise control

Explanation of symbols

1 Vehicle behavior control unit (vehicle behavior control means)
2 Cruise control unit (cruise control means)
2a target vehicle speed calculation unit 2b tracking target vehicle speed calculation unit 2c tracking flag calculation unit 2d control target vehicle speed calculation unit 2e cruise control required horsepower calculation unit 2f cruise control required torque calculation unit 2g accelerator required torque calculation unit 2h required torque selection calculation unit 2i target throttle Opening calculation unit 2j Pseudo accelerator opening calculation unit 11 Yaw rate sensor 12 Handle angle sensor 13 Four-wheel wheel speed sensor 14 Mode switch (selection means)
DESCRIPTION OF SYMBOLS 15 Accelerator opening degree sensor 16 Engine speed sensor 17 Cruise control operation switch 18 Leading vehicle detection part 21 Brake control part (brake control means)
22 Engine control unit (engine control means)
23 Transmission control unit

Claims (3)

A vehicle behavior control means for controlling a vehicle behavior by outputting a signal to at least one of a brake control means and an engine control means, wherein a specific vehicle behavior control characteristic can be freely selected by a selection means from a plurality of vehicle behavior control characteristics;
A cruise control means for setting a target value for control of the host vehicle based on at least one of a preset target vehicle speed and a driving state of a preceding vehicle, and performing travel control based on the control target value;
The cruise control means sets an upper limit guard value in the control target value corresponding to the specific vehicle behavior control characteristic selected by the selection means for each driving region of the cruise control of the cruise control means, An upper limit guard value and the control target value are compared for each operation region, and when the control target value is higher than the upper limit guard value, the control target value is set with the upper limit guard value. A vehicle travel control device.   2. The vehicle travel control apparatus according to claim 1, wherein the control target value is at least one of a vehicle speed and an acceleration / deceleration.   The vehicle behavior control means controls the braking force at the time of braking to prevent the occurrence of a locked state of the wheel, and provides the braking force to the selected wheel to generate the yaw moment in the vehicle. The vehicle travel control device according to claim 1, wherein the vehicle travel control device has a side slip prevention control function for preventing a side slip behavior of the vehicle and a traction control function for preventing a drive wheel from slipping.

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