KR19990057537A - Control Method of Adaptive Control Suspension System for Off-Road Vehicle Detection - Google Patents

Abstract

The present invention improves the ride comfort and the road grounding power of the wheels by the control logic that the road input variable varies the vehicle-mounted damper according to the frequency in the road detection method adaptive control suspension of off-road vehicles that frequently drive on the unpaved road. It is intended to serve.

The off-road vehicle is driven using the roughness of the road surface calculated using the vertical acceleration sensor and the vertical axle filter and the vertical axle displacement of the vehicle. It is characterized in that the damping force is kept soft when driving on rough roads such as non-paved roads, and when the anti-bounce logic is established n times in a row, it is converted to hard to prevent the phenomenon that the damping force is changed to hard on broken roads, thereby impairing the ride comfort. It is.

Description

Control Method of Adaptive Control Suspension System for Off Road Vehicles

The present invention relates to a road detection type electronically controlled suspension device applied to an off road vehicle that frequently runs on a non-paved road. More particularly, the present invention can improve the riding comfort and steering safety by recognizing the road surface from a vehicle sensor. It will be improved to be.

Conventionally, as shown in FIG. 1, a sensor unit for measuring the behavior of the vehicle, a central calculation unit 5 for calculating with the measured signal, a damper 6 for generating a damping force for controlling the vehicle behavior, and a control rod of the damper It is comprised by the electronic actuator 4 which rotates.

The sensor unit includes a vehicle speed sensor 2 for calculating a vehicle speed, a vertical acceleration sensor 1 for detecting acceleration in the up and down direction of the vehicle, and a wheel acceleration sensor 7 for detecting acceleration in the up and down direction of the axle. ) Determines the damping force of the appropriate damper using the signal of the sensor, and based on this, the position of the electronic actuator 4 on the top of the damper of the four-wheel is sequentially changed, and the damper 6 is variable in stages. It consists of a damper and an electronic actuator.

The damping force of the multi-stage variable damper in the damper 6 uses the electronic actuator 4 located above the damper to rotate the control rod 6 of the damper, thereby changing the size of the flow path while reducing the damping force of the 4-wheel damper. Switch to Soft, Medium or Hard.

The conventional electronically controlled suspension device configured as described above is composed of six separate logics according to each control situation. Dual anti-bounce control detects conditions such as bumper and driving, so if the vehicle speed is V ₁ kph or more and the vertical acceleration of the vehicle located in the center of gravity of the body and the vehicle (console box) is more than G ₁ g, It is switched and returns to its original state after ₁ second of release of the condition.

This eliminates the effects of low frequencies by using a high frequency filter such as

The damping force is selected according to the control map of FIG. 2 for the acceleration passing through the high frequency pass filter. Equation (2) selects the damping force according to the control map.

Selection of this damping force causes the front wheel to immediately change the damping force of the damper according to the judgment in Eq. (2) and the damping force of the damper with the time delay of Eq. (3) in the rear wheel. This time delay is obtained from equation (3).

This time delay prevents the impact shock caused by the damping force being increased before the rear wheels pass through the bumper by changing the damping force of the damper without the time delay.

The anti-bounce logic of the conventional electronically controlled suspension system is suitable for passenger cars, but in vehicles such as off-road cars, when driving on unpaved roads or irregular roads such as broken roads. There is a problem that the damping force is converted to hard to impair the riding comfort.

Therefore, in the present invention, in the road detection method adaptive control suspension device for off-road vehicles that frequently drive on unpaved roads, the comfort of the road and the road grounding force of the wheels are controlled by the control logic that the size of the road input varies the vehicle mounted damper according to the frequency. It is intended to improve the bar, which will be described in more detail with reference to the accompanying example drawings as follows.

1 is an exemplary diagram of an electronically controlled suspension system of an off-road vehicle;

2 is a control map of anti-bounce logic,

3 is a configuration diagram of a roughness calculation unit;

4 is a block diagram of anti-bounce control logic of an off-road vehicle;

* Explanation of symbols for main parts of the drawings

1: vehicle body up and down acceleration sensor 2: vehicle speed sensor

3: brake sensor 4: actuator

5: ECU6: Damping force variable damper

7: Axle up and down acceleration sensor 8: Body left and right acceleration sensor

The present invention comprises a sensor unit for measuring the behavior of the vehicle, a central computing device for calculating with the measured signal, a damper and an actuator for generating a damping force for controlling the vehicle behavior.

In the above configuration, the sensor unit is composed of an acceleration sensor 1 for detecting the acceleration in the vertical direction of the vehicle, and a wheel acceleration sensor 7 for detecting the acceleration in the vertical direction of the axle.

The central computing device 5 switches the position of the electronic actuator 4 on the top of the damper of the wheel according to the position of the damper determined by the control logic proposed in the present invention based on the signal of the sensor.

The damper 6 and the actuator are composed of a damping force variable damper and a multistage control electronic actuator.

Referring to the operation of the present invention configured as follows.

The anti-bounce control logic applied to the off-road vehicle electronically controlled suspension system includes a roughness calculator that calculates the roughness of the road, a bounce detector that detects bumps, and an improved road that distinguishes broken roads from actual bumps. Consists of the sword part.

roughness calculator

The roughness calculation unit calculates the roughness of the actual road surface from the vertical acceleration of the damper of the vehicle body and the vertical acceleration sensor of the low arm.

FIG. 3 shows the configuration of the roughness calculation unit, in which the acceleration measured by the vertical acceleration sensor of the vehicle body and the vertical acceleration sensor of the low arm is passed through a high frequency pass-pass filter to the vertical acceleration (a _s). ^h ), the road surface roughness is calculated by equation (4) from the vertical displacement of the axle (d _u ) calculated by integrating the filtered axle vertical acceleration (a _s ^h ) and the axle acceleration signal twice. Calculate the roughness indicated.

r (t) = c1 × a _s ^h + c2 × a _u ^h + c3 × d _u (4)

In the road surface calculation, the vertical body acceleration and the filtered vertical body acceleration are obtained by passing the body vertical acceleration and the axle vertical acceleration through the high frequency backpass filter, respectively.

Equation (5) shows how to calculate the filtered vertical body acceleration from the body vertical acceleration by the high frequency backpass filter equation.

In addition, the integrator for calculating the displacement of the axle of Equation (4) is a high frequency pass type integrator, which removes the signal below the set frequency from the acceleration and calculates the vertical velocity and vertical displacement in the frequency region desired by the designer.

Equation (6) is the filter expression of this integrator.

Using (4), (5) and (6), calculate the road surface on which the actual vehicle travels.

From this calculated road surface, the roughness which is the time inverse power value of the road surface of the high frequency component corresponding to the axle resonance frequency is calculated.

This roughness calculator consists of a high frequency passpass filter and a time reverse power calculator.

The calculated road surface signal passes through the high frequency signal plane through the filter of equation (7), and the signal passing through the equation (7) passes through the filter of equation (8) again to calculate the roughness, which is a time inverse power value.

The time inverse power calculator calculates a time inverse power value of the axle resonance region. Equation (8) is an expression of the time inverse power calculation unit.

The roughness representing the roughness of the road surface is calculated from the power value h (s), which is the high frequency component of the road surface corresponding to the axle resonance region.

Broken road detection and bounce logic

As you pass through broken roads and pass bumps, you can actually see vertical accelerations of similar magnitude.

In order to prevent the damping force from converting to hard when passing through the broken part of the road, the bounce logic is constructed as follows in combination with the roughness obtained in the previous section (Fig. 4).

Condition 1 is the conventional basic anti-bounce logic.

Establishment condition 2 is a method to prevent the damping force from converting to hard when the bounce logic is activated when the vehicle travels on a rough road such as a gravel road.

Establishment condition 3 is a method to prevent the damping force from converting to hard when the bounce logic is activated when passing the broken road surface while driving.

That is, the damping force is converted to hard only when the conditions 1, 2 and 3 are satisfied.

Establishment condition 1.

It follows the same filter structure and control map as conventional anti-bounce logic.

Establishment condition 2.

However, if the roughness value is detected above the set value, it passes through soft.

Establishment Condition 3.

The damping force is converted to hard only when the anti-bounce logic is established after a certain time t1 after the anti-bounce logic is established. The constant time t1 of is based on the loop time of the logic. It is also possible to detect the state after t1 time (count n times).

According to the present invention as described above, in the road surface detection method adaptive control suspension of off-road vehicles that frequently drive on the unpaved road, the vertical acceleration sensor mounted on the upper side of the bumper and the axle vertical acceleration sensor mounted on the axle It recognizes the road surface being driven and controls the damping force by distinguishing the actual bump, broken road and rough road surface, and the control logic that the vehicle input damper is variable according to the frequency of the road input to improve the riding comfort and road traction. Will be.

This control logic prevents the damping force from converting to hard on the broken roads and rough roads, and impairs the ride. In fact, the control logic converts the damping force into hard to minimize the body movement.

Claims (3)

The off-road vehicle is driven using the roughness of the road surface calculated using the vertical acceleration sensor and the vertical axle filter and the vertical axle displacement of the vehicle. A control method for a road surface sensing method adaptive control suspension of an off-road vehicle, characterized in that the damping force is softly maintained when driving on rough roads such as unpaved roads. The off-road car according to claim 1, wherein the anti-bounce logic is converted to hard only when n anti-bounce logic is established n times to prevent a phenomenon that the damping force is converted to hard in a broken road or the like to impair ride comfort. ) Control method of road surface sensing type adaptive control suspension system of vehicle. According to claim 1, wherein the roughness calculator is a vertical acceleration (a _s ^h ), filtered axle to the filtered difference by passing the acceleration measured by the vertical acceleration sensor of the vehicle body and the vertical acceleration sensor of the low arm through a high frequency pass-pass filter After calculating the road surface by equation (4) from the vertical displacement (d _u ) of the axle acceleration signal obtained by integrating the vertical acceleration (a _s ^h ) and the axle acceleration signal twice, calculating the roughness indicating the roughness of the road surface. A control method for a road detection method adaptive control suspension device of an off-road vehicle. r (t) = c1 × a _s ^h + c2 × a _u ^h + c3 × d _u (4)