JPS62168760A - Steering reaction controller - Google Patents

Abstract

PURPOSE:To provide improved controllability by using a vehicle model for deducing vehicle movement to deduce at least a quantity of motional state presented by the vehicle model in steering and adjust steering reaction on the basis of the deduced value. CONSTITUTION:On the basis of a vehicle model 107 modeled mathematically on a vehicle having desired motional performances is provided a deducing means 100 for deducing at least one of quantities of state presented by the vehicle model in steering to determine the desired value Tc of steering reaction of a steering wheel 106 by a determining means 101 on the basis of the deduced quantity M* of state. Also, is provided a deducing means 102 for deducing torque input to a steering system from a road surface by the use of the vehicle model 107 so that a determining means 103 determines the desired value Tps of assist torque from deduced input torque value T*L and said desired value Tc. And a power steering gear 105 is controllably driven by a drive controlling means 104 according to the desired value Tps.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering reaction force control device that controls a steering reaction force of a steering wheel in response to turning motion of a vehicle.

(Prior Art) In recent years, more and more vehicles are equipped with a power steering device. This power steering device works to assist steering by adding assist torque using a hydraulic booster or the like to the steering force of a steering wheel by a driver.

In addition to the conventional hydraulic power steering device, power steering devices include, for example, Japanese Patent Laid-Open No. 59-68
An electric power steering device as shown in No. 264 has also been proposed.

This electric power steering device has a configuration as shown in FIG.

A first steering shaft 2 is connected to the steering handle 1, and the first steering shaft 2 is connected to a second steering shaft 5 via a first universal joint 4.

A DC servo motor DM is attached to the second steering shaft 5 via a reduction gear 9.

Further, a steering torque sensor 8 is attached to the second steering shaft 5 to detect the torque (hereinafter referred to as "handle steering torque") applied to the steering handle l.

An eighth steering shaft 7 is connected to the second steering shaft 5 via a second universal joint 6. The tip of this eighth steering shaft 7 is connected to a rack-binion type gear box 8.
It is connected to the.

Note that the inclination rl of the first steering shaft 2 and the second steering shaft 5 and the inclination γ of the second steering shaft 5 and the eighth steering shaft 7 are set to be equal.

The gear box 8 is connected to a tie rod 17, which in turn is connected to a knuckle arm 16 of the wheel 12.

Then, the controller IO detects the detected value T of the steering torque of the steering wheel 1 detected by the steering torque sensor 8. is input as an electrical signal, and the detected value T of this steering torque is input. Assist torque Tyu corresponding to. will generate 5
Then, the drive current of the servo motor DM is controlled.

(Problems to be Solved by the Invention) However, in the conventional power steering device as described above, the main purpose is to reduce the burden of steering force on the steering wheel on the driver, and therefore, information on the turning motion of the vehicle is not used. Drivers who rely on the steering reaction force of the steering wheel feel dissatisfied with the fact that they are not able to obtain sufficient information.

In other words, when a driver turns the steering wheel, he or she generally feels a steering reaction force and also experiences changes in vehicle motion state quantities such as yaw rate and lateral acceleration.Based on these sensations, the driver determines the ease of driving. is being evaluated.

Additionally, drivers generally perform driving operations that emphasize the yaw rate of the vehicle in medium and low speed ranges, and the lateral acceleration in high speed ranges.

As described above, although the driver needs turning motion information such as yaw rate and lateral acceleration, this information must be obtained by the driver's senses.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes means shown in FIG.

The motion state quantity estimating means 100 is based on a vehicle model 107 that is a mathematical model of a vehicle having desired motion performance.
At least one motion state quantity exhibited by the vehicle model during steering is estimated.

Based on the estimated value CK of the motion state quantity estimated by the motion state quantity estimation means 100, the steering reaction force target value determining means 101
A target value T0 of the steering reaction force of the steering handle 106 is determined.

The road surface input torque estimating means 102 uses the vehicle model 10.
7 is used to estimate the torque input to the steering system from the road surface.

The assist torque determining means 10B determines the target value T of the steering reaction force. Then, from the estimated value TL* of the torque input to the steering system from the road surface estimated by the road surface input torque estimating means 102, a target value Tj8 of the assist torque by the power steering system R105 is determined.

The drive control means 104 controls the assist torque [[Tp
The drive of the power steering device 105 is controlled according to s.

(Operation) According to the present invention, the steering wheel 10 is
To adjust the steering reaction force of 8, as mentioned above,
Turning motion information such as yaw rate and lateral acceleration can be generated in the steering handle operation system, making it possible to improve maneuverability.

Additionally, by estimating the amount of motion state of the vehicle using the above vehicle model, it is possible to obtain a stable degree of motion state with less error than when actually measuring the amount of motion state. .

During a transient movement in which the vehicle turns at a rate of 1 in 1%, it is difficult to actually measure the amount of motion state, so it is effective to use a vehicle model as in the present invention.

By the way, in order to adjust the steering reaction force, this steering reaction force, that is, the steering torque T generated at the steering handle 106 is used. is detected by a torque sensor, and the detected value T of this steering torque. is the steering reaction force target value T. It is generally considered that a servo system constitutes a feedback loop that drives and controls the power steering device 105 so as to match the servo system.

However, when performing such feedback loop control, the power steering family [105] and the steering system are included in the loop, so the loop becomes large. The servo control tends to become unstable because it is easily influenced by external factors such as

That is, the detected value T of the steering torque. Steering reaction force target value T
When matching with 0, the detected value T. is the target value T.

It is possible that it vibrates before and after. In particular, the above phenomenon is likely to occur near the limit range where the linearity of the vehicle's motion characteristics is lost.

Therefore, in the present invention, the assist torque determining means 10B and the drive control means 104 adjust the steering reaction force to the steering reaction force target value T. The assist torque required to achieve this is determined, and this is set as the assist torque target value, and the power steering device 105 is set to the assist torque target value Tp.
sVc is controlled accordingly. That is, the power generated by the power steering device 1050 is set to the above-mentioned steering reaction force target value T.

By adopting feedforward control that is controlled in accordance with the above, it is possible to eliminate the inconveniences that occur in the case of feedback loop control as described above.

(Embodiment) FIG. 2 shows the configuration of an embodiment of the present invention. In this figure, the same components as those of the conventional example shown in FIG. 6 are designated by the same reference numerals, and the explanation thereof will be omitted.

In this embodiment, the steering reaction force of the steering wheel l is adjusted in accordance with the lateral acceleration α of the vehicle.

A controller 80 composed of a microcomputer or other electric circuit is in charge of adjusting this steering reaction force.

The controller 80 includes a first steering shaft 2
The detected value θ5 of the steering angle of the steering wheel l detected by the steering angle sensor 21 attached to the vehicle speed sensor 2
The detected value V of the vehicle speed detected in step 2 is input.

Then, the controller 30 receives each of the above input information θ5.
By performing a predetermined calculation based on (2), the drive current of the servo motor DM necessary for generating a steering reaction force according to the lateral acceleration α of the own force is output.

The controller 80 has a functional configuration as shown in FIG. 8.

The motion state quantity estimation unit 81 uses a mathematical model (hereinafter referred to as "vehicle model J") for simulating the motion state of own troops.
and estimates the lateral acceleration exhibited by the vehicle model when the steering angle θ8 and vehicle speed V are given to the vehicle model. The estimated value α8 of the lateral acceleration estimated at this time is a value corresponding to the lateral acceleration α actually occurring in the host vehicle.

The motion state quantity estimation unit 81 calculates the estimated lateral acceleration value α8 by the following calculation.

ψ−jdt... (1)■
A S ÷ y dt ... (2) βF = Z - (Vy + LF ÷) / V ... (8) βR
−(vyLR↓)/V... (4) OF
-eKFHβF -・-(51C
H= KR・βR... (6) ¥-(2LFCF -2LRCR) / I,
... (7) α”-(20F+2OR)/M
... (8)■ −α −■・÷
... (9) Here, Nose: Yaw rate of the vehicle model v2 Yaw angular acceleration of the interior model ■ = Lateral velocity of the vehicle model * : Lateral translational acceleration of the vehicle model LF: Between the front axis and center of gravity of the vehicle model Distance LR: Distance between the rear axle of the vehicle model and the center of gravity βF = Front wheel sideslip angle βR of the vehicle model Double sideways slip angle of the vehicle model CF: Front wheel cornering force of the vehicle model CR2 Rear wheel cornering force of the vehicle model eKF2 Vehicle model front wheel equivalent cornering power KR: Vehicle model rear wheel cornering power ■7. : Yaw inertia M of the vehicle model: Body mass N of the vehicle model = Steering gear ratio of the vehicle model.

In addition, this motion state amount estimating section 81 also outputs a front wheel cornering force estimated value C to be given to the assist torque determining section 88.
Find F*. This is the formula (7) above.

It is obtained by eliminating the rear wheel cornering force CR from (8). That is, Cy * - Ding L (' LRa '' ten I z '?
) ''' (10) However, L is the wheelbase of the vehicle model, and L = Ly +
It is LH.

The estimated lateral acceleration value α8 thus obtained is provided to the steering reaction force target value determination unit 82. The steering reaction force target value determination unit 82 multiplies the given lateral acceleration α8 by a preset proportionality constant K, and sets this value as the steering reaction force target value T. shall be. That is, α9 to T −
... (11). For this proportionality constant, a value that provides the most appropriate correlation between the lateral acceleration and the steering reaction force is determined in advance through experiments and calculations, and this value is set in the controller 80.

The assist torque determination unit 88 determines the steering reaction force target value T.

The assist torque target value Tps is determined from the front wheel cornering force estimated value CF and the front wheel cornering force estimated value CF. This assist torque target value T,8 is calculated by the following arithmetic expression.

Here, 2ξCi is the torque input to the steering system from the road surface (hereinafter referred to as "road surface input torque TI, J")
Since it is difficult to actually measure it, it is determined from the estimated front wheel cornering force CF and the vehicle specifications. That is, the road surface human torque T is estimated using the vehicle model.

Now, using the steering system model shown in Fig. 4 and considering the balance and unity of the steering system torque, we get: T+T = -TR... (18) CpS N TR = 2ξCF*...・ (1
4) Here, is the torsional torque of the column system, TR is the torsional torque of the rack system, and ξ is the trail.

Therefore, by substituting equation (14) into equation (18), the above (
12) Equation is obtained.

The assist torque target value lower s determined in this way is input to the motor control unit 84 and mechanically amplified to a predetermined gain to become the current target value. , is converted to The drive current is the assist torque target value T.
The current value is controlled to a value necessary to generate assist torque Tps equal to ps.

Note that it is also possible to configure the motion state amount estimating section 81, the steering reaction force target value determining section 82, and the assist torque determining section 8B with an arithmetic circuit using a microcomputer. The above calculation is performed according to the flowchart shown in FIG.

In step 42, the calculation performed by the motion state quantity estimating section 81 is executed, in step 48, the calculation performed by the steering reaction force target value determination section 82 is executed, and in step 44, the calculation performed by the above-mentioned steering reaction force target value determination section 82 is executed. The calculation performed by the torque determination unit 88 is executed.

In the above embodiment, the present invention is applied to a vehicle equipped with an electric power steering, but the present invention can also be applied to a vehicle equipped with a hydraulic power steering.

Further, in the above embodiment, an example was shown in which the steering reaction force is adjusted in accordance with the estimated value α of the lateral acceleration obtained using the vehicle model, but the present invention is not limited to this, and can be applied to other motion states. amount,
For example, the yaw rate, lateral speed, etc. can be estimated using a vehicle model, and the steering reaction force can be adjusted in accordance with the estimated values.

Furthermore, the steering reaction force can be adjusted not only by making it correspond to one motion state quantity, but also by making it correspond to the estimated value of two or more motion state quantities. In this case, weighting is applied to the estimated values of the motion state quantity obtained by 2 or more,
It is also possible to increase the weight of the estimated value of the motion state quantity, in which the association with the steering reaction force should be particularly emphasized.

Furthermore, the present invention was previously disclosed in Japanese Patent Application No. 60-505 by the applicant.
In combination with the vehicle motion state amount estimation device proposed in No. 58, the motion characteristics of the vehicle model are made to match the actual vehicle motion characteristics by feeding back the detected value of the actual motion state amount. It is also possible to perform corrections sequentially.

In this way, it becomes possible to control the correspondence between the change in the amount of motion state and the steering reaction force with higher accuracy.

(Effects of the Invention) As described in detail above, the present invention uses a vehicle model that estimates vehicle motion to estimate at least one motion state quantity that the vehicle model exhibits during steering, and also estimates this motion state quantity. By adjusting the steering reaction force of the steering wheel in accordance with the estimated value of , it is possible to generate turning motion information such as yaw rate and lateral acceleration to the steering wheel operation system, improving maneuverability. becomes possible.

Further, by estimating the amount of motion state of the vehicle using the vehicle model, it is possible to obtain a stable amount of motion state with fewer errors than when actually measuring the amount of motion state. In particular, when the vehicle is in a transient turning motion, it is difficult to actually measure the amount of motion state, so it is effective to use a vehicle model as in the present invention.

Furthermore, the present invention estimates the torque input to the steering system from the road surface using the vehicle model, and uses this estimated value to realize the steering reaction force target value. By using feedforward control, which calculates the assist torque target value from , and controls the power generated by the power steering system according to this assist torque target value, the steering system, which has many unstable elements, can be controlled more easily than by feedback control. , can be controlled more stably.

Furthermore, since the present invention does not require a torque sensor that is required to detect and feed back actual steering torque when performing feedback control, it is also possible to reduce costs.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 8 is a block diagram showing the configuration of the controller in Fig. 2, and Fig. 4 is a model of the steering system. Fig. 5 is a flowchart showing the processing executed when the controller in Fig. 2 is configured using a microcomputer; Fig. 6 is the configuration of a conventional electric power steering device. It is a diagram. 100... Motion state quantity estimating means 101... Steering reaction force target value determining means 102... Road surface input torque estimating means 108... Assist torque determining means 104... Drive control means 105... Power steering Device 106...Steering handle 107...Vehicle model...Steering handle 2...First steering shaft 5...Second steering shaft 9...Reducer 21...Steering angle sensor 2
2...Vehicle speed sensor 80...Controller 81...
Motion state quantity estimating unit 82...Steering reaction force target value determining unit 88...Assist torque determining unit 84...Motor control unit r1,...Steering torque To...Steering reaction force target value θ5...・Steering angle V...Vehicle speed α8・
...Estimated lateral acceleration Tps...Assist torque T
,...Road surface input torque CF*...Front wheel cornering force estimated value Tyu.・
...Assist torque target value Fig. 1 Fig. 2

Claims (1)

[Claims] 1. In a steering reaction force control device for controlling the steering reaction force of a steering wheel of a vehicle equipped with a power steering device, based on a vehicle model that is a mathematical model of a vehicle having desired motion performance, a motion state quantity estimating means for estimating at least one motion state quantity exhibited by the vehicle model during steering; and a motion state quantity estimating means for estimating at least one motion state quantity that the vehicle model exhibits during steering; Steering reaction force target value determining means for determining a target value of force; road surface input torque estimating means for estimating torque input to the steering system from the road surface using the vehicle model; assist torque determining means for determining a target value of assist torque by the power steering device from an estimated value of torque input to the steering system from the road surface; and drive of the power steering device in accordance with the target value of the assist torque. What is claimed is: 1. A steering reaction force control device comprising: a drive control means for controlling a steering reaction force;