JPH04505299A - Rear wheel control method of power vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Rear wheel control method of power vehicle The invention relates to a method according to the preamble of claim 1.

In a method of this type known from DE 36 23 479 A1, a car Both mathematical reference models are calculated and related to the actual vehicle model. Rear wheel The steering angle of The change is made so that the difference from the evaluation value representing the symptom is reduced.

This known method uses a sensor to detect the steering angle and a sensor to detect the speed of the vehicle. It just requires a service.

Also, vehicle-specific movements, such as yawing speed, speed, and curve angular velocity. There is no need to provide sensors for detecting specific movement parameters. however, The reference model of the vehicle and the actual vehicle model are compared with each other, and one model is compared with the other. Why is it possible to use a process computer that causes a change towards a model of is also necessary.

The use of process computers complicates configuration and typically External obstacles to movement 1 For example, non-flatness of the running track or the influence of crosswinds Impossible to take disability into account. In addition, the process computer Since the device operates automatically, a problem arises in terms of operation time. For this reason, especially when steering suddenly Changing the rotation angle may cause the entire vehicle to become unstable.

An object of the present invention is to simplify the configuration as much as possible and obtain high running stability. Ru.

In order to solve the above problem, the present invention is characterized by the characteristic part of claim 1. It is something.

Changing the steering angle of the front wheels by controlling and adjusting the rear wheels according to the invention The rear wheels can react quickly and without feedback. at the beginning In the known method mentioned above, in steady state, the steering angle of the rear wheels is equal to the steering angle of the front wheels. However, unlike this, the present invention maintains a constant ratio with respect to the rear wheel angle. Due to the temporal deflection, the stability of a typical power vehicle with a steering gear that acts only on the front wheels This approximates the normal steering characteristics.

Therefore, problems associated with drivers becoming accustomed to four-wheel steering systems do not arise.

This advantage lies in particular in that rear wheel positioning is at least approximately independent of vehicle speed. It is extremely effective when needed. Load switching of a motor vehicle with a constant steering angle of the front wheels In the case of a last vehicle reaction, the rear wheels are the steering wheel. The angle (=0) remains unchanged or approaches its rest position. Therefore, this A powered vehicle that is steered in this way adjusts the position of the rear wheels only when a load change reaction occurs. It does not generate the inherent dynamics caused by the adjustment, thus simplifying the load change reaction of the vehicle. It can be resolved.

An advantageous embodiment of the invention is disclosed in claim 2. In this configuration According to Since it starts, it is possible to further improve driving dynamics.

Additionally, during the dead time, the rear wheels are reversibly deflected in the opposite direction to The generation of lateral force can be accelerated. In this way, the rear wheels are initially deflected in the opposite direction. In principle, the steering movement of deflecting in the same direction It is known from Publication No. 3479.

By controlling rear wheel deflection, curve angular speed, yawing speed, and floating angle can be controlled. It becomes possible to form it without excessive shake. To do this, move the rear wheels in the same direction. The maximum value of the rear wheel steering angle and the change in the rear wheel steering angle when adjusting the position of the vehicle are It is only necessary to m* according to the respective physical parameters of . In this case, the rear wheel control of the deflection is fully effective. Because with just this adjustment, The steering angle of the rear wheels can be quickly responded to changes in the steering angle of the wheels. This is because that.

Properly adjust the steering angle of the rear wheels with respect to its maximum value and its change as shown in step 2. This means that the PD2T2-transmission element is used to control the rear wheels depending on the control of the front wheels. This can be done with a particularly simple configuration. In this case, the steering angle of the rear wheels is It relies only on the temporal change in the steering angle of the wheels. The steady floating angle is 1 normal It accurately corresponds to the floating angle of the vehicle being steered, and is dynamically small. It has become. Again, by reversibly deflecting the rear wheels in steady state conditions, The float angle corresponds to that of a vehicle where only the front axle is normally steered. occurs and this floating angle is set without excessive deflection.

The steering angle required for the front wheels is also equal to that of a normal vehicle.

Furthermore, safety technology is also important. In an emergency situation, it is necessary to steer the rear wheels, or If the control device for that purpose stops, even if the front wheels are steadily deflected, the rear If the wheels reach the steering angle of 0 again, there is no particular problem. In case of an emergency, the rear wheels The steering angle is frozen in most cases. i.e. in case of an emergency, the steering angle of the rear wheels The degree is fixed at 0. From this point on, the vehicle behaves like a normal E vehicle.

According to another advantageous embodiment of the invention, a PDTI control is superimposed on the PD2T2 control. . PDT1 control is known in principle from German Patent Publication No. 3624457. It is. This publication reveals special advantages of this type of control. 2 By superimposing two controls, the disadvantages of each can be eliminated and the advantages of both controls can be realized. It can be utilized.

To do this, it is necessary to calculate the rate at which the two controls affect the steering characteristics of the rear wheels. It only needs to be selected variably depending on the driving dynamics requirements of the vehicle. clear from basic considerations The obvious thing is that in the low speed range and the average speed range, i.e. 50 to 120 km /h speed, the influence of PDT1 control is dominant, while for higher speeds is that PD2T2 control gradually becomes dominant.

Therefore, in the low speed range and in the average speed range, in the ideal case the float angle should be completely adjusted. High running stability can be obtained. Faster range than this Within the range, the front wheel steering angle requirement is equal to the normal vehicle steering angle requirement. Obviously, running dynamics will be improved.

In this case, vehicles with PD2T2 control applied to the rear wheels have excellent controllability, and the steering Excellent obedience. Therefore, to achieve a steady arc, for example, usually Subjectively, the same steering angle must be given to the front wheels as in the case of a vehicle with Stabilize the steady running state quantity of a vehicle with PD2T2 control applied to the wheels so that there is no vibration. When set to , it gives a feeling of high safety. If the lateral acceleration is high or the friction characteristics In the limit range where the controllability is poor, the controllability of the vehicle is particularly good.

Next, embodiments of the present invention will be described using the accompanying drawings.

Figure 1 shows a jump in steering angle on the front axle in a vehicle steered in the normal manner. 5 graphs a) to C) showing the jumping response when it occurs; Figure 2 shows the jumping response of a vehicle with PD2T2 control applied to rear wheel steering, and Figure 1 A graph shown under the same conditions as in the case of Figure 3 shows Figures 1 and 2 of a vehicle in which PD2T2 control and PDT1 control are superimposed. The diagram corresponding to, Figure 4 is a graph of factors that determine PD2T2 control in Figure 2, It is.

The graph in Figure 1 shows that for a vehicle steered in the normal manner, speeds between 60 and This is a graph showing the jump response in the case of 240km/h with respect to time S. . We considered jumping at a speed of 30 km/h. In both cases, after the starting point At 0.5 seconds, a 1" steering angle jump is made on the front axle; It is assumed that the steering angle of l@ is maintained steadily. This assumption is shown in graph a) In this case, the arbitrarily selected curve ■ shows that when the speed is 120 km/h represents a jump in steering angle.

For vehicles steered in a conventional manner, the steering angle of the rear wheels is always equal to zero.

This is shown by parallel lines in graph b.

Graph C shows the yawing angular velocity. As is clear from this, this vehicle The parameters indicate excessive runout when the vehicle speed is high and then low runout. Show.

Asymptotically stabilizes to a steady value.

The same thing applies to the curve angular velocity shown in graph d and the floating angle shown in graph e. It also applies to The floating angle is relatively high speed of 150 to 180 km/h. It sometimes exhibits excessive runout and is therefore extremely problematic with respect to the overall controllability of the vehicle.

The graph in Figure 2 shows a vehicle with PD2T2 control applied to rear axle steering. Typical jump response and appropriately selected parameters dependent on running speed. It shows the data. Details are shown in Figure 4.

The front axle experiences a 1° steering angle jump at time 0.5 seconds at different speeds. (graph a), the steering angle of the rear axle (graph b) is The time jump, which has almost no relation to the running speed, is the same as the zero-order rear wheel, which shows the opposite characteristics. A deflection occurs, which reaches a maximum value and then returns to zero again. Therefore PD2T2 By appropriately selecting the control parameters (see Figure 4), the yawing angular velocity ( Graph c), curve angular velocity (graph d), and floating angle (graph e) should be adjusted to avoid excessive deflection. Can be set to In particular, as you can see from graph e, the floating angle is zero. increases uniformly to different terminal values, so this type of vehicle has high running stability. are doing. This terminal value depends on the running speed and can be compared with graph e in Figure 1. As you can easily see, it corresponds to that of a normal vehicle. However, usually Excessive vibrations at both yaw and curve angular speeds compared to This has not occurred.

FIG. 3 shows the superposition of PDT1 control and PD2T2 control. This weight Tatami is expressed by the following formula.

Here, swLaCMk (Place-Operator), k is 0 and 1 According to this formula, the weight factor (WIChl++a mouth faktor) between Therefore, the advantages of the two control methods described above can be combined. Important from this formula characteristics can be obtained. In other words, the transmission function of the yawing angular velocity is is equal to the transfer function with a stationary component obtained and modified corresponding to a normal vehicle. That is the characteristic.

The factor represents the degree of constant floating angle correction. Even if k is 0 For example, the floating angle correction is perfect. In this case, it is a pure PDTI transmission. k = 1 means that no steady floating angle correction is performed, in this case is PD2T2 transmission.

The characteristics when the two control methods are superimposed in this way are shown in graphs C to i in Figure 3. In this case, the value of the factor is v = 60k depending on the traveling speed. Use = 0 when m/h to = 1 when v = 240km/h. Ta.

Here, the floating angle is smaller than the PD2T2 control in Figure 2, and the yaw It can be seen that the curve angular velocity and curve angular velocity are somewhat small. This is the steady state This is because the steering angle of the rear wheels obtained from PDT1 control for the case remains. be. By adapting the factor k, stable course characteristics without excessive deflection can be achieved. It is possible to influence the steady-state characteristics of the vehicle without deteriorating it.

Figure 4 shows that the parameters for PD2T2 control depend on vehicle speed. This is a graph showing. In graphs a to e, these parameters are determined experimentally. is shown for a vehicle model. Steering angle 2δ of the front axle and steering angle of the rear axle The transmission function of the leap angle δ1 is expressed by the following differential equation.

This differential equation has four vehicle-specific parameters; T1 and T2 delay time Reinforcement faucet for steering angular velocity ctor D3 Compensation for steering angle acceleration strong factor These parameters are related to vehicle speed as shown in graphs 4a to 4e. It is in.

The above differential equation does not contain a stationary component, i.e. a turn of the rear axle will result in a change of course. If you fix the rear handle, it will always return to its original intermediate position.

Due to the delay times T1 and T2, the steering angular velocity 6. and steering angular acceleration6. depends on Adjustment movements are delayed and carried out smoothly. The delay effect increases as vehicle speed increases. It gets bigger. This is because the sum and product of both parameters T and T2 become large.

Parameter indicating that the steering angle of the rear axle depends on the steering angular velocity D2 is positive at vehicle speeds above 1100k/h and gradually increases. There is.

Therefore, if the steering angle process is rapid, the rear axles will turn in the same direction.

The dependence of the steering angle of the rear axle on the steering angular velocity has a dependence on the steering angular acceleration. are superimposed. The dependence on the steering angular acceleration is given by the parameter D3. Ru.

This parameter is negative throughout the vehicle speed range. Therefore, the first A very rapid change in steering angle in the range will result in a reverse steering movement on the rear axle. . This is because a relatively large steering angular acceleration occurs on the rear axle. this place In this case, the smooth delay effect of the time constant T2 is dominant, so this short turn in the opposite direction increases as vehicle speed increases.

If the front wheels are at a steady steering angle different from zero.

Due to the lack of a proportional component, the steering angle of the rear wheels approaches the value 0 asymptotically and thus If the steering characteristics of a normal vehicle approach and the rear wheel steering stops, as described above, High driving safety.

The scope of the claims 1. Steering means for the front and rear wheels that are mechanically uncoupled and depending on the deflection of the front wheels. and a transmission member for adjusting the position of the steering means for the rear wheels. A method for controlling according to the deflection of the front wheels, in which the rear wheels are controlled in the direction of the front wheels for a short period of time. Said method comprising reversibly deflecting in the opposite direction and then in the direction of the front wheels. In, The position of the rear wheel is adjusted without feedback, and the front wheel is at a steady state different from zero. It is characterized by decreasing the value to zero after reaching the maximum value when the steering angle is at a certain angle. how to.

2. Measure the position adjustment of the rear wheels in the same direction from the start of the steering movement of the front wheels, and determine the vehicle speed. 2. A method according to claim 1, characterized in that it is carried out after a time-dependent dead time.

3. Rear wheel position W! The maximum value of the steering angle of the rear wheels when I is in the same direction, and this Changes in the steering angle of the rear wheels before and after reaching the maximum value are calculated using curve angular velocity and yaw speed. -Select the flying speed and floating angle so that there is no excessive deflection at all times. The method according to claim 1 or 2, characterized in that:

4. Use PD2T2 transmission member to control the rear wheels depending on the control of the front wheels 4. A method according to claim 1, characterized in that:

5. According to claim 4, the PDT1 control is superimposed on the PD2T2 control. How to put it on.

6. When the vehicle is running at a low speed, PDTI control is dominant and the vehicle is running at a low speed. A claim characterized in that PD2T2 control is dominant when the speed is high. The method described in 5.

Daisemi-Akihiro fi11S base@- trace gk history Factor pl Hi 1L I Release 1. IIQ Io Copy of ms amendment letter Translation) Submission form (Article 184 s of the Patent Act>m Exit-w August 30, 1991 Day

Claims (5)

[Claims] 1. Steering means for the front and rear wheels that are mechanically uncoupled and depending on the deflection of the front wheels. and a transmission member for adjusting the position of the steering means for the rear wheels. A method for controlling according to the deflection of the front wheels, in which the rear wheels are controlled in the direction of the front wheels for a short period of time. Said method comprising reversibly deflecting in the opposite direction and then in the direction of the front wheels. In, The position of the rear wheel is adjusted without feedback, and the front wheel is at a steady state different from zero. When at a certain steering angle, after reaching the maximum value, the value should be reduced to zero, the rear wheels The maximum value of the steering angle of the rear wheels when the position adjustment is in the same way and this maximum value is reached. The steering angle change of the rear wheels before and after the curve angular speed, yawing speed, and the floating angle should be selected so that it always has the characteristic of not having excessive deflection; A method characterized by: 2. The position adjustment of the rear wheels in the same direction is measured from the start of the steering movement of the front wheels to determine the vehicle speed. 2. The method according to claim 1, characterized in that it is carried out after a dead time that depends on the degree of . 3. Use PD2T2 transmission member to control the rear wheels depending on the control of the front wheels The method according to claim 1 or 2, characterized in that. 4. Claim 3, characterized in that the PD2T2 control is weighted with the PDT1 control. Method described. 5. When the running speed of the vehicle is low, PDT1 control is dominant, and the running speed of the vehicle is Claim characterized in that PD2T2 control is dominant when the speed is high. The method described in Section 4. ”