KR20040073006A - Intelligent four-wheel steering system - Google Patents

Abstract

PURPOSE: An intelligent 4-wheel steering system is provided to offer power steering of front and rear wheels by an electric motor separate from an engine. CONSTITUTION: An intelligent 4-wheel steering system comprises a signal input part(10); a main processor(20) processing a signal of the signal input part by a logic and a program built in and producing a control signal; and front and rear wheel drive devices(30,40) controlled according to the signal of the main processor. The signal input part comprises a vehicle speed sensor(11) sensing the vehicle speed of front wheels; a steering sensor(12) sensing steering angles of wheels; a torque sensor(13) producing torque of a steering wheel; and a yawing sensor(14) producing a yaw value of a vehicle body. The front drive device comprises a motion controller(31) outputting a control value of an object to be controlled according to an output signal of the main processor; a power amplifier(32) amplifying the signal of the motion controller; a steering motor(33) operating by the rotation determined according to the signal transmitted through the power amplifier; and a front steering part rotating a steering shaft by the steering motor. The rear drive device comprises a motion controller(41) outputting a control value of an object to be controlled according to the output signal of the main processor; a power amplifier(42) amplifying the signal of the motion controller; a steering motor(43) operating by the rotation determined according to the signal transmitted through the power amplifier; and a rear steering part moving a steering rack right and left by the steering motor.

Description

Intelligent four-wheel steering system

The present invention relates to a steering apparatus of a vehicle having a four-wheel steering function, and in particular, by steering a rear wheel together with the front wheel by a steering force generated independently of the vehicle engine by an electric motor to stabilize the behavior while maintaining a relatively short turning radius An intelligent four-wheel steering system is provided.

In general, the steering system of most vehicles controls the attitude or direction of the vehicle desired by the driver. A hydraulic power steering device is generally used to reduce hydraulic power of the driver's steering wheel by obtaining hydraulic assistance by a pump connected to the engine's crankshaft. Is used a lot.

However, such a hydraulic power steering device has a disadvantage in that the output of the engine is reduced because the hydraulic auxiliary power is obtained by a pump connected to the crankshaft of the engine, depending on the rotational speed of the engine and using the output of the engine.

When the vehicle is stopped or at low speed, despite the increase in the vehicle load applied to the tire of the vehicle, the engine rotation speed is low and the hydraulic assist power of the pump is low, while at the high speed of the vehicle, the load of the vehicle added to the tire of the vehicle is increased. In spite of the relatively small rotation speed of the engine, the hydraulic assistance power of the pump is increased, which is in contrast to the condition of the vehicle, that is, a large steering force is required at the time of stopping or at a low speed and a relatively small steering force is required at the high speed. Of course there is a problem.

Also, it is difficult to obtain the desired steering because the variables that determine steering are changed by road conditions or other external factors.

The present invention has been made to solve the above problems, and an object thereof is to provide power steering by an electric motor in which both the front wheel and the rear wheel are independent of the engine.

In addition, the present invention is to stabilize the behavior of the vehicle by steering the rear wheel of the vehicle in the same phase when the lane changes while driving the vehicle at high speed, and to steer the rear wheel in reverse phase at the time of low speed, parking or U-turn of the vehicle The purpose is to relatively reduce the turning radius of the vehicle.

1 is a block diagram of a steering motor controller system of an intelligent four-wheel steering system according to the present invention;

2 is a front wheel steering configuration of the intelligent four-wheel steering system according to the present invention,

3 is a cross-sectional view taken along line A-A of FIG.

4 is a rear wheel steering configuration of the intelligent four-wheel steering system according to the present invention,

5 is a software schematic diagram of an intelligent four-wheel steering system according to the present invention;

6 (A) and 6 (B) are high speed lane change state diagrams of a vehicle having an intelligent four-wheel steering system and a vehicle having a general steering function according to the present invention;

7 is a low-speed turning state diagram of a vehicle having an intelligent four-wheel steering system and a vehicle having a general steering function according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: signal input, 11: vehicle speed sensor,

12: steering angle sensor, 13: handle torque sensor,

14: yawing sensor, 20: main processor,

30: front wheel drive, 31,41: motion controller,

32,42: power amp, 33,43: steering motor,

34,44: linear potentiometer, 35,45: current sensor,

36,46: encoder, 37: steering shaft,

38: worm gear, 39: worm,

40: rear wheel drive device, 50: ball screw reader,

51: ball screw, 52: steering rack,

53: electronic clutch, 54: connecting plate,

60: pressure device, 61: support plate,

62: housing, 63: pressure spring

In order to achieve the above object, the intelligent four-wheel steering system of the present invention comprises a signal input unit for detecting various types of data by a sensor, and processing signals according to built-in logic and programs to control signals. It consists of a main processor and a front and rear wheel drive device controlled according to the control signal of the main processor, wherein the front wheel drive device controlled by the main processor is a power amplifier for amplifying the signals of the motion controller and the motion controller, the The steering motor is operated by the amount of rotation transmitted according to the signal transmitted through the power amplifier and the front wheel steering unit for rotating the steering shaft in accordance with the rotational force of the steering motor, the rear wheel drive device amplifies the signal of the motion controller and the motion controller The power amplifier is operated by the amount of rotation transmitted according to the signal transmitted through the power amplifier Depending on the direction motor and the rotational force of the steering motor is constituted by the rear wheel steering to the left and right movement of the steering rack.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram of a steering motor controller system of an intelligent four-wheel steering system according to the present invention, FIG. 2 is a block diagram of a front wheel steering unit of the intelligent four-wheel steering system according to the present invention, and FIG. 4 is a sectional view taken along line AA, Figure 4 is a block diagram of the rear wheel steering of the intelligent four-wheel steering system according to the present invention.

As shown in FIG. 1, the present invention processes and controls a signal input unit 10 that detects data by a sensor, and a signal of the signal input unit 10 according to built-in logic and program. It consists of a main processor 20 for generating a signal and front and rear wheel drive devices 30 and 40 controlled according to a control signal of the main processor 20.

The main processor 20 uses 80C196KC of Intel Corporation, and the motion controllers 31 and 41 use LM628 / 9 of National Corporation.

Here, the front wheel drive device 30 controlled by the main processor 20 is a motion controller 31 for outputting a control value of the control target according to the output signal of the main processor 20, and the motion controller 31 The steering shaft 37 is operated by the power amplifier 32 for amplifying the signal, the steering motor 33 and the steering motor 33 operated at a predetermined rotation amount according to the signal transmitted through the power amplifier 32. It is composed of a front wheel steering to rotate.

The rear wheel drive device 40 may include a motion controller 41 for outputting a control value of a control object according to an output signal of the main processor 20, and a power amplifier 42 for amplifying a signal of the motion controller 41. The steering wheel 43 is operated according to the signal transmitted through the power amplifier 42, and the rear wheel steering unit for moving the steering rack 52 to the left and right by the steering motor 43. .

The front and rear wheel drive devices 30 and 40 form a main processor 20 and a feedback circuit, respectively, for the stability of the control. That is, the main processor 20 includes the steering motors 33 and 43. Sensing the power supply to the linear potentiometer (34, 44) and the steering motor (33, 43) for detecting the rotational degree of the encoder (36, 46) and the steering motor (33, 43) for detecting the operating current The current sensor (35, 45) to detect the state, respectively, while also detecting the state of the motion controller (31, 41) to close the respective closed loops to control the front wheel drive device (30, 40) optimally Loop is formed.

Here, the motion controllers 31 and 41 of the front and rear wheel drive devices 30 and 40 are configured to supply the operating current and the operating power of the steering motors 33 and 43 to the encoders 36 and 46 and the current sensors 35 and 36, respectively. ) Form a closed loop to detect through

The signal input unit 10 includes a vehicle speed sensor 11 for detecting a speed of a vehicle, a steering sensor 12 for detecting a steering angle of a steering wheel, a torque sensor 13 for calculating torque of a steering wheel, and yawing of a vehicle body. Yaw sensor 14 for measuring the value, the front wheel drive device 30, the vehicle speed, steering angle and steering torque is input to the main processor 20, the rear wheel drive device 40, the vehicle speed, steering angle and yawing A value is input to the main processor 20.

2 and 3, the front wheel steering portion rotates according to the steering of the driver's steering wheel, and has a steering shaft 37 having a worm gear 38 at a predetermined position, and a worm gear of the steering shaft 37. 38) a steering motor 33 having a worm 39 engaged with the front wheel, and a front wheel steering rack (not shown) which is moved left and right by a steering gear (not shown) as the steering shaft 37 rotates. do.

And, as shown in Figure 4, the steering motor 43 of the rear wheel drive device 40 is provided with a rear wheel steering unit for manipulating a steering rack 52 for steering the rear wheels in accordance with the rotational force of the steering motor 43. The rear wheel steering unit is provided with an electronic clutch 58 connected with the operation of the steering motor 43, a connecting plate 59 operated by the electronic clutch 58, and a connecting rack 59. The ball screw reader 50 for moving the steering rack 52 as it is engaged in the ball screw 51 section of the ball screw 51 and the pressurizing device 60 for generating a repulsive force according to the movement of the steering rack 52. It consists of.

Here, the pressurizing device 60 has a housing 62 which forms an empty space so as to surround the support plate 61 formed integrally with the steering rack 52, and both the support plate 61 in the housing 62. Composed of a pressure spring 63 installed in.

The pressing spring 63 is installed in the housing 62 in a pressurized state by applying pressure to both sides so as to have a length smaller than the length of the spring in the free state to have a greater elastic force.

5 is a software schematic diagram of an intelligent four-wheel steering system according to the present invention.

As shown in Figure 5, the main processor 20 for controlling the front and rear wheel drive device (30, 40) is largely composed of a main program, a control program and a communication program for the control, the main program is controlled Since the system variables and other memory variables required for initialization are initialized and the offset value (Off-Set Value) of each sensor signal is determined, as shown in FIG. 4, a car speed interrupt routine and a watchdog timer interrupt routine ( Watch Dog Timer Interrupt Routine) signal is inputted.

In addition, the control program operated by the main program is a motion controller 31 via a software time interrupt interrupted by a current state detection signal among feedback signals of the front and rear wheel drive devices 30 and 40. And a control algorithm for generating a control command of (41).

In addition, a communication program for communication between the main program and the motion controllers 31 and 41 of the front and rear wheel drive devices 30 and 40 or other external devices may be interfaced (for example, the motion controllers 31 and 41). Interface) and communication protocols (Communication Protocol).

Hereinafter, the operation of the present invention will be described in detail.

As the vehicle travels, when the vehicle speed sensor 11, the steering angle sensor 12, the steering torque sensor 13, and the yawing sensor in the signal input unit 10 measure data, the front wheel drive apparatus uses the main processor 20. Acceleration vehicle speed, steering angle and steering torque are input, and in the rear wheel drive system, the main processor 20 receives the vehicle speed, steering angle and yaw value so that the main program of the main processor 20 receives the preset vehicle speed signal and watchdog timer. It is initialized with parameters to generate control values.

Subsequently, a control signal of the main program generates a control command through a control algorithm to manipulate the motion controllers 31 and 41, wherein the control algorithm controls the current state of the steering motors 33 and 43 to the encoders 34 and 44. The control algorithm is interrupted and re-run under the set condition according to the detected signal.

At this time, the control algorithm for controlling the motion controllers 31 and 41 is performed through a communication program having a communication protocol for communicating with the main program through the interface of the motion controllers 31 and 41.

Referring to the operation of the front wheel drive device 30 that is steered in accordance with the control process of the main processor 20 in more detail, the steering wheel is used to change the position of the driving vehicle (when changing lanes or turning). In operation, the steering angle of the steering wheel is input to the main processor 20 together with the vehicle speed and the steering torque via the steering angle sensor 12 via the signal input unit 10.

Subsequently, the main processor 20 transmits a control signal corresponding to the steering angle sensed by the front wheel motion controller 31 and the vehicle speed and the steering torque, and the signal of the front wheel motion controller 31 is the power amplifier 32. It is input to the steering motor 33 through, to rotate the steering motor 33 clockwise or counterclockwise.

When the driver rotates the steering wheel, when a large amount of force is required, such as at a low speed, the driver rotates the steering motor 33 in the same direction as the rotation direction of the steering wheel by the driver so that the rotation is smoothly performed. In such a case, the steering motor 33 is rotated in a direction opposite to the direction of rotation of the steering wheel by the driver so that a large amount of force is required for rotation, thereby ensuring driving stability during high-speed driving.

That is, it is possible to actively control the steering wheel steering force according to the speed change of the vehicle and at the same time set the steering wheel steering force according to the driver's taste.

In addition, when the operation of the rear wheel drive device 40 is described in detail, when the driver operates the steering wheel, the steering angle of the steering wheel passes through the signal input unit 10 through the steering angle sensor 12, and the vehicle speed and yaw value are combined together. It is input to the processor 20.

Subsequently, the main processor 20 rotates the steering motor 43 clockwise or counterclockwise in the same manner as the front wheel drive apparatus.

At this time, since the electronic clutch 53 of the hardware is operated together with the operation of the steering motor 43 to connect the connection plate 54 and the steering motor 43, the ball screw reader 50 of the connection plate 54. Steering rack (52) formed with the ball screw (51) section engaged with the) is moved in one of the left and right directions in accordance with the rotation direction of the steering motor 43 to steer the rear wheel.

On the other hand, in the front and rear wheel drive device, the main processor 20 detects the rotation amount and the current state of the steering motors 33 and 43 operated by the linear potentiometers 34 and 44 and the encoders 36 and 46, respectively. In addition, the state of the power supply to the steering motor (33, 43) is sensed together, and at the same time to the state of the motion controller (31, 41) that the signal of the power and current state supplied to the steering motor (33, 43) is fed back. It detects the electric signal and generates the electric signal value corresponding to the desired steering angle continuously and controls the motion controllers 31 and 41 through the H-bridge circuit of the power amplifiers 32 and 42. (33,43) is controlled.

Here, the pressurizing device 60 installed to generate a repulsive force in accordance with the movement of the steering rack 52 in the rear wheel steering unit allows a quick return operation after the movement of the steering rack 52, and also provides an intelligent four-wheel drive in need. If a problem occurs in the steering system, it is to switch from the four-wheel steering system to the general steering system.

That is, when the steering rack 52 is moved to the left side of FIG. 4, the compression spring 63 located on the left side of the pressurizing device 60 is compressed, and then the compressed pressure spring 63 is restored upon returning to the original position. Since the support plate 62 of the steering rack 52 is pushed, the return of the steering rack 52 is quickly returned with a relatively small force.

In addition, in the event of a failure of the controller or steering motor 43 of the rear wheel drive system, the pressure spring 63 quickly returns the steering rack 52 to its original position, thereby turning the four wheel steering system into a general front wheel steering system. To switch.

The pressing spring 63 is installed in the housing 62 in a pressurized state by applying pressure to both sides so as to have a length smaller than the length of the spring in the free state to have a greater elastic force.

Figure 6 (A), (B) is a high speed lane change state diagram of a vehicle having an intelligent four-wheel steering system and a vehicle having a general steering function according to the present invention, Figure 7 is an intelligent four-wheel steering system according to the present invention This is a state diagram at low speed of a vehicle having a vehicle and a vehicle having a general steering function.

As shown in FIG. 6, FIG. 6 (A) of the present invention shows that the front and rear wheels of the vehicle are steered in phase so that the direction of the vehicle body is always constant, while FIG. 6 (B) shows two-wheel steering of the vehicle body. The direction changes to the changing lane, causing momentary instability.

In addition, as shown in Figure 7, the intelligent four-wheel steering and the conventional two-wheel steering vehicle of the present invention showing the low-speed turning of the present invention, the intelligent four-wheel steering vehicle of the present invention, the rear wheel is steered in reverse phase with the front wheel when turning the rotation While the radius decreases, the turnability increases, while the two-wheel steering vehicle has a large turn radius, thereby reducing the turnability.

The intelligent four-wheel steering system of the present invention is not limited to the above-described embodiments, and may be variously modified and implemented within the range allowed by the technical idea of the present invention.

According to the present invention the intelligent four-wheel steering system as described above has the following effects.

First, since both front and rear wheels of the vehicle are equipped with independent steering control functions by the motor and are controlled by the microprocessor as well as steering stability, there is an effect of preventing the reliability deterioration due to the driver's instability during a sudden situation.

Second, the present invention is to stabilize the behavior of the vehicle by steering the rear wheels of the vehicle in the same phase when the lane changes while driving the vehicle at high speed while steering the rear wheels in reverse phase when the vehicle is parked or U-turn (U-Turn) The turning radius of the vehicle is relatively reduced compared to the two-wheel steering vehicle.

Third, the present invention can be manufactured in a small size as well as steering the vehicle by the electric motor without a separate hydraulic device has a large expandability effect.

Fourth, the present invention is to install a pressure spring in the housing in a pressurized state by applying pressure to both sides to have a length less than the length of the spring in the free state, it is possible to obtain a larger elastic force, returning the steering rack to its original position It requires a quick and relatively low force, and if an abnormality occurs in the system of the present invention in the event of an emergency to switch from the intelligent four-wheel steering system to the general steering system has the effect of further improving the system safety.

Fifth, in the front wheel drive system, the vehicle speed, steering angle and steering torque are input to the main processor, and in the rear wheel drive system, the front and rear wheels can be more accurately controlled as the vehicle speed, steering angle and yaw value are input to the main processor, thereby improving stability. Can be.

Claims (5)

A signal input unit including a vehicle speed sensor for detecting a vehicle speed of a front wheel, a steering sensor for detecting a steering angle of a steering wheel, a torque sensor for calculating torque of a steering wheel, and a yawing sensor for calculating a yaw value of the vehicle body; A main processor configured to process a signal of the signal input unit according to embedded logic and a program to generate a control signal; Consists of the front and rear wheel drive device controlled according to the generated signal of the main processor, The main processor, The front wheel drive receives the vehicle speed, steering angle and steering torque, and the rear wheel drive receives the vehicle speed, steering angle and yaw value to continuously feed back and detect the operation results of the front and rear drive systems operated by the output control values. Construct a closed loop independent of the front and rear wheel drive, The front wheel drive device, A motion controller for outputting a control value of a control target according to an output signal of the main processor; A power amplifier for amplifying the signal of the motion controller; A steering motor operated at a predetermined rotation amount according to the signal transmitted through the power amplifier; It is composed of a front wheel steering unit for rotating the steering shaft by the steering motor, The rear wheel drive device, A motion controller for outputting a control value of a control target according to an output signal of the main processor; A power amplifier for amplifying the signal of the motion controller; A steering motor operated at a predetermined rotation amount according to the signal transmitted through the power amplifier; Intelligent four-wheel steering system comprising a rear wheel steering unit for moving the steering rack left and right by the steering motor. The method of claim 1, The steering motors of the front and rear wheel drive devices are connected to the main processor to detect the operating current, the rotation amount and the supplied power state through the encoder, the linear potentiometer and the current sensor, and through the interface to receive the control signals. Intelligent four-wheel steering system, characterized in that the state of the motion controller is detected by the main processor. The method of claim 2, The motion controller is an intelligent four-wheel steering system, characterized in that for forming a closed loop to sense the operating current and the operating power of the steering motor through the encoder and the current sensor, respectively. The method of claim 1, The front wheel steering unit A steering shaft which rotates according to the steering of the driver and has a worm gear at a predetermined position; A steering motor having a worm engaged with the worm gear of the steering shaft; Intelligent four-wheel steering system, characterized in that consisting of a steering rack which is moved left and right by a steering gear as the steering shaft rotates. The method of claim 1, The rear wheel steering portion Electronic clutch connected with the operation of the steering motor; A connection plate actuated by the electronic clutch; A ball screw reader provided on the connection plate to move the steering rack as it is engaged in the ball screw section of the steering rack and moved left and right; Composed of a pressurizing device for generating a reaction force in accordance with the movement of the steering rack, The pressurizing device is installed in the housing in a pressurized state to have a length less than the length of the housing which forms an empty space so as to surround the support plate integrally formed in the steering rack and the spring in the free state on both sides of the support plate in the housing. Intelligent four-wheel steering system, characterized in that consisting of a pressure spring having a greater elastic force.