JPS62173371A - Controller for reaction force against steering operation - Google Patents

Abstract

PURPOSE:To improve steering performance by generating information on rotary movement such as Yawrate or lateral acceleration, etc., in a steering handle control system. CONSTITUTION:Means 101 determines a target value of the reaction force against the steering operation of a steering handle 109, based on the estimated value of a movement state generated by a vehicle model 103 in its steering operation. At the same time, means 102 estimates the torque which is inputted to the steering system from the road surface using the vehicle model 103. Means 104 determines an assisting torque ratio which is the ratio of the calculated value of the assisted torque to said target value, based on said target value and said estimated torque value. Finally, means 105 determines the assisting torque exerted by a power steering device, by multiplying the assisting torque ratio with the detected value of the steering torque generated in the steering handle 109.

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, many vehicles are equipped with a power steering device in their steering device.This power steering device uses a hydraulic booster or the like to match the steering force of the steering wheel by the driver. It adds assist torque and works to assist steering.

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 (Z) is connected to the steering handle l, 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 a torque Tc applied to the steering handle 1 (hereinafter referred to as "handle steering torque").

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 and pinion type gear box 3.
It is connected to the.

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

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

The controller 10 then uses a 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 drive current IP of the servo motor DM is controlled so as to generate an assist torque TP8 corresponding to the detected steering torque (JLTc).

(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.

In addition, the driver generally performs driving operations while directly observing 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 depend on 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 amount estimating means 100 is based on a vehicle model 10B 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.

The steering reaction force target value determination means 101 determines the target value T of the steering reaction force of the steering handle 1-09 based on the estimated value M of the motion state quantity estimated by the motion state quantity estimation means 100.
Determine c.

The road surface input torque estimating means 102 uses the vehicle model 10.
13 to estimate the torque applied to the steering system from the road surface.

The assist torque ratio determining means 104 determines the power steering device it from the estimated value Tc of the torque to be applied during steering.
At the same time, the assist torque ratio KPS, which is the ratio of the assist torque calculated value to the steering reaction force target value TO, is determined.

The assist torque target value determining means 105 multiplies the detected value TO of the steering torque generated at the steering wheel 109 detected by the steering torque detecting means 106 by the assist torque ratio KPS, thereby determining the assist torque by the power steering device. make a decision.

The drive control means 107 controls the drive of the power steering device 108 in accordance with the determined assist torque target value TPS.

(Function) The present invention adjusts the steering reaction force of the steering wheel 109 according to the estimated value M* of the motion state fBt estimated by the motion state amount estimating means 100, thereby adjusting the yaw rate and the like as described above. It is now possible to generate turning motion information such as lateral acceleration to the steering wheel operation system.
It becomes possible to improve maneuverability.

Furthermore, 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 the amount of motion state is actually measured.

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.

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

However, when performing such feedback loop control, the power steering system W105 and the steering system are included in the loop, so the loop becomes too large. The servo control tends to become unstable because it is easily influenced by external factors such as

That is, the detected value Tc of the steering torque is set as the steering reaction force target value T.
When matching with O, it is conceivable that the detection value Tc is taken before or after the target value Tc.

The above phenomenon is likely to occur near the limit range where the linearity of the vehicle's dynamic characteristics is lost.

Therefore, the present invention provides a road surface human torque estimation means 102, an assist torque ratio determination means 104, an assist torque target value determination means 105, and a drive control means 107, and estimates the torque input from the road surface while estimating the actual steering reaction force. The assist torque ratio required to make the steering reaction force target value TO is determined, and the power steering device 1ffi 108 is feedforward controlled in accordance with this assist torque ratio KPs.

This prevents the control from becoming unstable as in the case of the feedback loop control described above.

In addition, since the motion characteristics of the vehicle model are fixed, if a change in the motion characteristics of the actual vehicle occurs, the steering reaction force is changed in accordance with the change in the actual motion characteristics. First, the assist torque ratio determining means 104 determines the assist torque ratio KPs, and the assist torque target value determining means 105 determines the assist torque ratio KP8.
The assist torque target value TPs is determined by multiplying the detected value Tc of the steering torque by the detected value Tc of the steering torque, and the determined value TP8 is supplied to the drive control means 107.

(Embodiment) FIG. 2 shows the configuration of an embodiment of the invention. In addition, in the figure, the same reference numerals are attached to the components of the conventional example shown in the above-mentioned @6 figure, and the explanation thereof will be omitted.

In this embodiment, the steering reaction force of the steering handle 1 is adjusted in accordance with the lateral acceleration α of the vehicle.

Control of this steering reaction force is controlled by the controller A-280, which is composed of a microcomputer or other cardiopulmonary circuit.

This controller 80 has a detected value Tc of the steering torque of the steering wheel l detected by a steering torque sensor 8 attached to the steering shaft 5 of PAz, and a steering angle sensor 21 attached to the first steering shaft 2. A detected value θ8 of the steering angle of the steering handle 1 and a detected value V of the vehicle speed detected by the vehicle speed sensor 22 are input.

Then, the controller 80 controls each of the above-mentioned human power information IEITs.
. , θ8. By performing a predetermined calculation based on (2), the drive flow Ip of the servo motor DM necessary to generate a steering reaction force according to the lateral acceleration α of the own force is output.

The controller 30 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") for simulating the motion state of own troops.
and estimates the lateral acceleration exhibited by the vehicle model when the steering angle θS and vehicle speed V are given to the vehicle model. The estimated value α'' of the lateral acceleration estimated at this time is a value corresponding to the lateral acceleration α actually occurring in the own army.

The motion state Of estimation unit 81 calculates the estimated lateral acceleration value α7 by the following calculation.

Meeting = door dt ... (1) vy
= fvy at...(2
)βR=-(vy-LR?)/■...(4)OF=
eKF-βF-(5)OR
= KR・βR...(6) ψ = (2LFOF -2LRCR) / IZ
...(7) α"= (2C!F+ 2OR)/
M...(8)vy=α−■−÷
...(9) Here, Yaw rate ψ of the two-vehicle model: Yaw angular acceleration of the vehicle model ■ Directional speed Q of the two-vehicle model Q: Translational acceleration in the inertial direction of the vehicle model ■ LF: Front axis of the vehicle model Distance between centers of gravity LR: ELI1
Distance β between the rear axle and center of gravity of the 17i model, dual vehicle model front axle side slip angle βR: Vehicle model rear wheel groove slip angle CF: Tan Ryosenryo model wheel cornering force ○R: Vehicle model rear wheel cornering force 8KF : Front wheel equivalent cornering power KR of the vehicle model, Rear wheel cornering power of the vehicle model Z: Yaw inertia M of the vehicle model: 4L constitution ratio N of the 4-car model: Steering gear ratio of the vehicle model.

In addition, this motion state amount estimating unit 81 calculates an estimated front wheel cornering force value C〆 to be applied to the assist torque ratio determining product 38. This is the formula (7) above.

It is obtained by eliminating the rear wheel cornering force OR from (8). That is, 1 OF=7. (MLRα ÷ engineering zψ) −(
1o) However, L is the wheelbase of the vehicle model,
L”LF+LR.

The estimated lateral acceleration α" obtained in this way is given to the steering reaction force target value determination unit 82. This steering reaction force target value determination unit 32 uses a preset ratio measurement value to the given lateral acceleration α". %KY and set this value as the steering reaction force target value TO. That is, TO: α car
...(11). For this proportionality constant, a value that provides the most appropriate correlation between the f-angular acceleration and the steering reaction force is determined in advance by actual measurements or calculations, and this value is set in the controller 80.

The assist torque ratio determination section 88 determines the above-mentioned steering reaction force target value T.
. and the @if m cornering force estimated value Oy
'', the assist torque ratio KPS is determined.

This assist torque ratio KPs is calculated by the following equation.

Here, 2ξC7 is the torque input from the road surface into the steering system (hereinafter referred to as [road surface input torque T, J)]
Since it is difficult to actually measure, it is determined from the above estimated front wheel cornering force "OF" and the vehicle specifications. That is,
The road surface input torque TL will be estimated using the above vehicle model.

Further, T* is a calculated value of assist torque calculated when the steering reaction force target value C and corner S ring force estimated value CF* act.

Now, if we consider the balance of torque in the steering system using the steering system model shown in Figure 4, we get Tc + Tps -, TR"° (1B) TR22ξG
F“...(14) Here, TG
is the torsional torque of the column system, TR is the torsional torque of the rack system, ξ is the trail, and TP8 is the assist torque. Therefore, the assist torque ratio KPS obtained in this way is converted from equation (14) to (18)% by the steering torque detection value T in the assist torque determining section 84. The assist torque target value TPs is determined. This assist torque target value TPs is sent to the motor control section 85.

The assist torque determination unit 84 is arranged so that the steering reaction force target value C obtained using the vehicle model can be adjusted in accordance with the change in the actual vehicle movement characteristics when the movement characteristics of the vehicle change. The assist torque target value TPS is determined as follows.

That is, the assist torque ratio KPS is calculated using the above formula (12).
As shown in , this value is determined by the steering reaction force target value Tc and the estimated value T♂ of the road surface human torque;
Both c are estimated values obtained using the vehicle model, and KPS is the assist torque ratio determined based on these estimated values, so in addition to equation (12), some actual changes in vehicle dynamic characteristics are You have to enter the information. Therefore, the actual steering torque detection value TO detected by the steering torque sensor 8 is multiplied by the assist torque ratio determined by the above formula (12), and the target value T of the assist torque when the actual steering torque TO acts is calculated. , 8 is determined by the assist torque determining section 34.

Therefore, the assist torque determination unit 84 performs the following calculation to determine the assist torque target value 〒,8.

TPS: KPS°TC゛-(to) This is the result of calculating the ratio *KPs of the assist torque calculation value TPS'' to the steering torque target value below, and multiplying the actual steering torque TO by this ratio.

The assist torque target inclination value lower PS determined in this way is input to the motor control unit 85 and mechanically amplified to a predetermined gain to become the fifth target value value. It is converted to Dynamic Driving Work. This drive current is controlled to a current value necessary to generate an assist torque TPs equal to the assist torque target value TPs.

Note that the motion state amount estimating section 31, the steering reaction force target value determining section 82, the assist torque ratio determining section 83, and the assist torque determining section 34 may be configured with an arithmetic circuit using a microcomputer. In this case, the above calculation is performed according to the flowchart shown in FIG.

In step 42, the calculation performed in the motion state bond estimation i 81 is executed, in step 8, the calculation performed in the steering reaction force target value determining section 82 is executed, and in step 44
In steps 45 and 45, the calculation performed by the assist torque ratio determining section 88 is executed, and in step 47, the calculation performed by the assist torque determining section 34 is executed.

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

Further, in the above embodiment, an example was shown in which the steering reaction force is adjusted in accordance with the estimated value α9 of the 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 whose correlation with the steering reaction force should be particularly emphasized.

(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 becomes possible to improve.

In addition, by estimating the vehicle's motion state and nodding using the above vehicle model, the motion state D is more stable and has fewer errors than when the motion state quantity is actually measured.
i can be obtained. In particular, it is difficult to actually measure the state of motion at during turning transient motion of the vehicle, 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 ratio of the assist torque calculated value to The steering system can be controlled more stably than in the case of feedback control.

Further, the present invention provides an estimated value of the amount of motion state obtained using a vehicle model by determining the target value of the assist torque using the assist torque ratio based on the estimated value and the detected value of the actual steering torque. Compared to the case where the target value of the assist torque is determined only by the above method, the target value of the assist torque can be immediately determined in accordance with changes in the actual dynamic characteristics of the vehicle.

Therefore, if the actual vehicle dynamic characteristics change due to changes in the coefficient of road friction, etc., the vehicle model dynamic characteristics will deviate from the actual vehicle dynamic characteristics. It can be kept small by determining the value.

[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 process executed after the controller c+-ra in Fig. 2 is completed s1 using a microcomputer. 1 is a configuration diagram of a power steering device according to the present invention. 100... Motion state quantity estimating means 101... Steering reaction force target value determining means 102... Road surface human torque estimating means 10B... Vehicle model 104... Assist torque ratio determining means 105... Assist torque Eyes (vote value control means 10B...steering torque detection means 107...drive control means 108...power steering device 109...steering shaft...steering handle 2...first steering shaft 5... ...Second steering shaft 8...Steering torque sensor 9...Reducer 21...
Steering angle sensor z2...Vehicle speed sensor 30...Controller 31...Motion state quantity estimation unit 32...
- Steering reaction force target value determination unit 33...assist torque ratio determination unit 34...assist torque determination unit 85...motor control unit To...steering torque T. ...Steering reaction force target value θ8...Steering angle V...Vehicle speed α1...
・Estimated lateral acceleration value TPs...Assist torque TL
...Road surface human torque CF*...Front wheel cornering force estimated value TPs.
...Assist torque target value KPs...Assist torque ratio Fig. 2 Fig. 3 Tc

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; A steering torque detecting means detects a calculated assist torque by the power steering device from the steering reaction force target value and an estimated value of torque input from the road surface to the steering system, and calculates the calculated value of the assist torque by the power steering device. assist torque ratio determining means for determining an assist torque ratio that is a ratio to the steering reaction force target value; and multiplying the detected value of the steering torque detected by the steering torque detecting means by the assist torque ratio. Assist torque target value determining means for determining a target value of assist torque by the power steering device; and controlling drive of the power steering device in accordance with the target value of assist torque determined by the assist torque target value determining means. A steering reaction force control device comprising: drive control means.