A state machine-based mine dump truck drive-by-wire steering control system

Abstract

A state machine-based mine dump truck drive-by-wire steering control system, comprising the following steps: (1) the steering controller SCU receives the data of sensors and the vehicle controller VCU through the sensor data processing layer and the CAN message analysis layer; (2) the steering controller SCU integrates the input data of the first step and submits it to the fault processing layer for screening; (3) the input data and fault data are integrated and submitted to the state machine module for working mode switching; (4) the steering controller SCU executes the control strategy of the current steering mode and calculates the output; (5) the output control layer sends the output data to the actuator to drive the steering wheel; (6) the steering controller SCU feeds back the state information of the current system to the CAN message coding layer through the state feedback layer for message coding and finally sends it to the vehicle controller VCU.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dump trucks, in particular to a state machine-based mine dump truck steer-by-wire control system. BACKGROUND

[0002] Traditional mine dump truck steering systems are mostly mechanical steering and hydraulic power steering, which have single mode and do not need mode switching.

[0003] With the improvement of the automation and intelligence of mine dump trucks, manned steer-by-wire and even unmanned steer-by-wire have been developed. The steer-by-wire system needs to be flexibly switched between different modes to adapt to complex working environments.

[0004] At present, the steering system of mine dump trucks is mostly non-steer-by-wire. The control logic of non-steer-by-wire is that the driver provides the expected steering angle, speed and torque through the steering wheel, and the corresponding steering force is obtained through mechanical / hydraulic / electrical control system to drive the steering gear to complete steering.

[0005] The existing technology has the following disadvantages:

[0006] a. There is a mechanical connection between the steering wheel and the steering gear, which occupies a large space and has high maintenance cost;

[0007] b. The communication interface between the steering system and the VCU is simple, and the information interaction ability and safety are insufficient, making it difficult to realize software algorithm optimization;

[0008] c. Steering action is initiated by the driver, and the steering gear assists to complete the steering, which can only adapt to manned driving, the steering mode is single, and it is difficult to adapt to complex mine conditions. SUMMARY

[0009] The technical problem to be solved by the present application is to provide a state machine-based mine dump truck steer-by-wire control system to improve the response speed and stability of the steering system.

[0010] To solve the above technical problems, the technical solution of the present application is: a state machine-based mine dump truck steer-by-wire control system, comprising:

[0011] Sensor module: high-pressure filter signaling switch: used for detecting whether the steering filter is blocked, connected with the steering controller SCU through DI signal; steering pressure sensor: used for detecting steering oil pressure, connected with the controller through AI signal;

[0012] Steering controller SCU: the execution center of the steering system, which receives sensor signals and vehicle controller VCU instructions, and outputs control instructions after setting control logic and calculation to drive the actuator to act, achieving the purpose of controlling wheel steering;

[0013] VCU: sends control instructions and vehicle status information to the steering controller SCU through the CAN bus, and receives the status information of the steering controller SCU;

[0014] Actuator: including steering proportional valve, oil cylinder and wheel, the proportional valve receives the PWM signal of the steering controller SCU to control the opening of the valve to change the flow rate of the steering hydraulic oil, and finally drives the wheel steering through the steering cylinder;

[0015] Power source: including steering pump and emergency steering pump, when the steering pump fails, the emergency steering pump is used as a safety redundancy, the power source is controlled by the vehicle controller VCU, and the steering controller SCU sends power source control instructions to the vehicle controller VCU through the CAN bus;

[0016] The control method of the steering system, comprising the following steps:

[0017] (1) The steering controller SCU receives sensor and vehicle controller VCU data through the sensor data processing layer and CAN message analysis layer;

[0018] (2) The steering controller SCU integrates the input data of the first step and submits it to the fault processing layer for screening;

[0019] (3) The input data and fault data are integrated and submitted to the state machine module for working mode switching;

[0020] (4) The steering controller SCU executes the control strategy of the current steering mode and calculates the output;

[0021] (5) The output control layer sends the output data to the actuator to drive the steering wheel;

[0022] (6) The steering controller SCU feeds back the current system status information to the CAN message encoding layer through the state feedback layer for message encoding, and finally sends it to the vehicle controller VCU.

[0023] As an improvement, CAN 2.0B bus is used to realize the bidirectional communication between the steering controller SCU and the vehicle controller VCU, including the following communication frames: EPS mode control frame for realizing the switching control of steering mode, EPS reset control frame for realizing the system reset control, EPS calibration control frame for realizing the system calibration control, EPS steering angle control frame for realizing the precise control of steering angle, and EPS state feedback frame for realizing the state monitoring of the steering system.

[0024] As an improvement, there is a manual non-steer-by-wire mode: when the steering controller SCU is started, the steering system is automatically switched to the manual non-steer-by-wire mode, at this time, the steering system is in the non-steer-by-wire mode, and the steering controller SCU does not participate in the vehicle steering process, and the steering action is completely completed by the steering wheel and the steering gear.

[0025] As an improvement, there is a manual steer-by-wire mode: when the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "manual steer-by-wire", the steering controller SCU will switch the working mode of the steering system to the manual steer-by-wire mode when the switching conditions of the state machine are met, at this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes and calculates the steering wheel speed, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered; in this mode, the vehicle variable steering ratio is realized by changing the relationship between the steering wheel speed and the proportional valve opening.

[0026] As an improvement, there is an automatic steer-by-wire mode: when the steering system is in the manual non-steer-by-wire mode or the manual steer-by-wire mode, if the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "automatic steer-by-wire", the steering controller SCU will switch the working mode of the steering system to the automatic steer-by-wire mode when the switching conditions of the state machine are met, at this time, the steering controller SCU enters the preparation mode before automatic steering, the steering proportional valve opens to a certain opening to enter the ready state, and the vehicle maintains the current steering angle, and the steering wheel does not act.

[0027] As an improvement, there is an automatic steer-by-wire mode: when the steering system is in the manual non-steer-by-wire mode or the manual steer-by-wire mode, if the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "automatic steer-by-wire", the steering controller SCU will switch the working mode of the steering system to the automatic steer-by-wire mode when the switching conditions of the state machine are met, at this time, the steering controller SCU enters the preparation mode before automatic steering, the steering proportional valve opens to a certain opening to enter the ready state, and the vehicle maintains the current steering angle, and the steering wheel does not act.

[0028] As an improvement, there is an automatic steer-by-wire mode: when the steering system is in the manual non-steer-by-wire mode or the manual steer-by-wire mode, if the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "automatic steer-by-wire", the steering controller SCU will switch the working mode of the steering system to the automatic steer-by-wire mode when the switching conditions of the state machine are met, at this time, the steering controller SCU enters the preparation mode before automatic steering, the steering proportional valve opens to a certain opening to enter the ready state, and the vehicle maintains the current steering angle, and the steering wheel does not act.

[0029] As an improvement, there is a safety mode: when the steering controller SCU detects a secondary fault or a tertiary fault, the steering system will automatically switch to the safety mode, and the steering controller SCU will alarm, at this time, the steering system will execute the action process according to the manual non-steer-by-wire mode.

[0030] As an improvement, in the reset mode: the steering system is in the safe mode and the steering controller SCU secondary fault and tertiary fault disappear, if the reset flag signal of the VCU EPS_RESET_CTRL communication frame is set to "enable", the steering system will automatically switch to the reset mode, the steering controller SCU will start to execute the reset process, and after the reset process is completed, it will automatically switch to the manned non-linear control mode.

[0031] As an improvement, calibration mode: the steering system is in the manned non-linear control mode, if the calibration request signal of the VCU EPS_CALIBRATE_CTRL communication frame is set to "request", the steering controller SCU will switch the working mode of the steering system to the calibration mode when the state machine switching conditions are met, at this time the vehicle controller VCU can modify the steering parameters of the steering controller SCU through the related communication interface.

[0032] The beneficial effects brought by the present application compared with the prior art are:

[0033] A standard communication interface with real-time protection and safety design is proposed, through clear control module layering and state machine design, the steering system can be quickly, stably and reliably switched between different steering modes, and the working efficiency and safety of the mine dump truck are improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The figure is a control topology diagram of the steering system.

[0035] Figure 2 The figure is a communication interface diagram of the steering controller and the vehicle controller.

[0036] Figure 3 The figure is a steering system control software module diagram.

[0037] Figure 4 The figure is a steering system control state machine diagram. DETAILED DESCRIPTION

[0038] The present application will be further described below in conjunction with the drawings of the specification.

[0039] As Figure 1 shown, a mine dump truck linear steering control system based on a state machine includes:

[0040] Sensor module: high-pressure filter signaling switch: used for detecting whether the steering filter is blocked, connected with the steering controller SCU through a DI signal; steering pressure sensor: used for detecting the steering oil pressure, connected with the controller through an AI signal.

[0041] Steering controller SCU: is the execution center of the steering system, which receives sensor signals and vehicle controller VCU instructions, after the set control logic and calculation, output control instructions, drive the actuator to act, to control the purpose of the steering wheel.

[0042] Vehicle controller VCU: sends control instructions and vehicle state information to the steering controller SCU through the CAN bus, and receives the status information of the steering controller SCU.

[0043] Actuator: including steering proportional valve, oil cylinder and wheel, proportional valve receives the PWM signal of steering controller SCU to control the opening of the valve to change the flow rate of steering hydraulic oil, and finally drive the steering wheel through the steering cylinder.

[0044] Power source: including steering pump and emergency steering pump, when the steering pump fails, the emergency steering pump is used as a safety redundancy, the power source is controlled by the vehicle controller VCU, and the steering controller SCU sends power source control instructions to the vehicle controller VCU through the CAN bus.

[0045] As Figure 2 shown, the communication interface scheme of the present application realizes the bidirectional communication between the steering controller SCU and the vehicle controller VCU by CAN 2.0B bus, including the following communication frames:

[0046] a. EPS mode control frame (EPS_MODE_CTRL)

[0047] Function: realize the switching control of steering mode

[0048] Information contained:

[0049] Steering mode request (used to switch different steering modes)

[0050] Message serial number (to ensure communication reliability)

[0051] Check value (to ensure data integrity).

[0052] b. EPS reset control frame (EPS_RESET_CTRL)

[0053] Function: realize system reset control

[0054] Information contained:

[0055] Reset flag (trigger system reset)

[0056] Check value (to ensure data integrity).

[0057] c. EPS calibration control frame (EPS_CALIBRATE_CTRL)

[0058] Function: Realize system calibration control

[0059] Information contained:

[0060] Calibration request (trigger system enter / exit calibration mode)

[0061] Check value (ensure data integrity).

[0062] d.EPS rotation angle control frame (EPS_ANGLE_CTRL)

[0063] Function: Realize accurate control of steering angle

[0064] Information contained:

[0065] Steering angle (target steering angle value)

[0066] Steering angle enable (control instruction validity flag)

[0067] Message serial number (ensure communication reliability)

[0068] Check value (ensure data integrity).

[0069] e.EPS state feedback frame (EPS_INFO)

[0070] Function: Realize steering system state monitoring

[0071] Information contained:

[0072] SCU current mode (feedback current working state)

[0073] Error code (fault diagnosis information)

[0074] Message serial number (ensure communication reliability)

[0075] Check value (ensure data integrity).

[0076] The communication interface of the present application has the following advantages:

[0077] 1. Real-time guarantee: using CAN 2.0B bus to ensure real-time and reliability of communication; for important key communication frames, using message serial number cycle technology mechanism to detect communication interruption and ensure the timing of control instructions;

[0078] 2. Safety: each communication frame uses CRC check value to ensure data transmission accuracy; using error code feedback mechanism to realize timely detection and processing of faults;

[0079] 3. Mode switching protection: through the cooperation of mode control frame and state feedback frame, the reliability of mode switching is ensured; using reset control mechanism to provide emergency handling capability in system abnormality.

[0080] As Figure 3 shown, the control method of the turning system of the application comprises the following steps:

[0081] (1) The steering controller SCU receives the data of sensors and the vehicle controller VCU through the sensor data processing layer and the CAN message analysis layer;

[0082] (2) The steering controller SCU integrates the input data of the first step and submits it to the fault processing layer for screening;

[0083] (3) The input data and fault data are integrated and submitted to the state machine module for working mode switching;

[0084] (4) The steering controller SCU executes the control strategy of the current steering mode and calculates the output;

[0085] (5) The output control layer sends the output data to the actuator to drive the steering wheel;

[0086] (6) The steering controller SCU feeds back the state information of the current system to the CAN message encoding layer through the state feedback layer for message encoding, and finally sends it to the vehicle controller VCU.

[0087] As Figure 4 shown, the state machine of the steering system comprises the following modes:

[0088] Manual non-linear control mode: when the steering controller SCU is started, the steering system automatically switches to the manual non-linear control mode, at this time the steering system is in the non-linear control mode, the steering controller SCU does not participate in the vehicle steering process, and the steering action is completely completed by the steering wheel and the steering gear.

[0089] Manual linear control mode: when the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "manual linear control", the steering controller SCU will switch the working mode of the steering system to manual linear control mode when the switching conditions of the state machine are met, at this time the specific process of vehicle steering is: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives the steering wheel speed and processes and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the direction, the steering cylinder acts, and the wheels turn; in this mode, by changing the relationship between the steering wheel speed and the proportional valve opening, the variable steering ratio of the vehicle is realized.

[0090] Manual mode: When the steering system is in the manual mode, if the steering mode request signal of the VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to the manual mode when the state machine switching condition is met, at this time the steering controller SCU enters the preparation mode before manual steering, the steering proportional valve opens a certain opening degree to enter the ready-to-work state, and the vehicle keeps the current steering angle and the steering wheel does not move.

[0091] Automatic steering mode: When the steering system is in the manual mode, if the steering angle enable signal of the VCU EPS_ANGLE_CTRL communication frame is set to "enable", the steering controller SCU will switch the working mode of the steering system to the automatic steering mode when the state machine switching condition is met, and the difference between the automatic steering mode and the manual mode is that the steering system will automatically complete the steering action according to the "steering angle" signal of the EPS_ANGLE_CTRL communication frame, and the steering process does not need the participation of the driver.

[0092] Manual takeover mode: When the working mode of the steering system is in the manual mode or the automatic steering mode, if the steering controller SCU detects that the steering wheel speed exceeds the set threshold value, the manual takeover mode will be automatically switched in, at this time the action flow of the steering system is executed according to the manual mode.

[0093] Safety mode: When the steering controller SCU secondary fault or tertiary fault is triggered, the steering system will automatically switch into the safety mode, and the steering controller SCU alarms, at this time the action flow of the steering system is executed according to the manual mode.

[0094] Resetting: When the steering system is in the safety mode and the steering controller SCU secondary fault and tertiary fault disappear, if the reset flag signal of the VCU EPS_RESET_CTRL communication frame is set to "enable", the steering system will automatically switch into the resetting mode, the steering controller SCU will start to execute the resetting process, and after the resetting process is completed, the steering system will automatically switch into the manual mode.

[0095] Calibration mode: When the steering system is in the manual mode, if the calibration request signal of the VCU EPS_CALIBRATE_CTRL communication frame is set to "request", the steering controller SCU will switch the working mode of the steering system to the calibration mode when the state machine switching condition is met, at this time the vehicle controller VCU can modify the steering parameters of the steering controller SCU through the related communication interface.

[0096] The state machine of the present application has the following characteristics:

[0097] 1. Clear mode switching conditions: use EPS_MODE_CTRL, EPS_ANGLE_CTRL, EPS_RESET_CTRL, EPS_CALIBRATE_CTRL, steering sensor, etc. control signals to realize mode switching and steering angle adjustment;

[0098] 2. Fault classification: SCU adopts a three-level fault classification strategy. When the fault is level two or level three, the safety mechanism is triggered;

[0099] 3. Safety mechanism: when detecting level two or level three faults in the system, automatically switch to safety mode to ensure vehicle safety.

Claims

1. A state machine based mine dump truck steer-by-wire control system, characterized in that, include: Sensor modules: High-pressure filter signal switch: used to detect whether the steering filter is clogged, connected to the steering controller SCU via DI signal; Steering pressure sensor: used to detect steering fluid pressure, connected to the controller via AI signal; Steering Controller (SCU): The execution center of the steering system. It receives sensor signals and vehicle controller (VCU) commands, and after setting control logic and calculation, outputs control commands to drive the actuators to perform actions, thereby achieving the purpose of controlling wheel steering. Vehicle Control Unit (VCU): Sends control commands and vehicle status information to Steering Control Unit (SCU) via CAN bus, and receives status information from Steering Control Unit (SCU). Actuators include a steering proportioning valve, a hydraulic cylinder, and wheels. The proportioning valve receives a PWM signal from the steering controller SCU to control the valve opening, thereby changing the flow rate of the steering hydraulic oil, which ultimately drives the wheels to steer through the steering cylinder. Power source: including steering pump and emergency steering pump. When steering pump fails, emergency steering pump is put into use as a safety redundancy. The power source is controlled by vehicle controller VCU. Steering controller SCU sends power source control commands to vehicle controller VCU through CAN bus. The control method for the steering system includes the following steps: (1) The steering controller SCU receives data from the sensors and the vehicle controller VCU through the sensor data processing layer and the CAN message parsing layer; (2) The steering controller SCU integrates the input data from the first step and submits it to the fault handling layer for screening; (3) Input data and fault data are integrated and submitted to the state machine module for working mode switching; (4) The steering controller (SCU) executes the control strategy of the current steering mode and calculates the output; (5) The output control layer sends the output data to the actuator to drive the steering wheel; (6) The steering controller SCU feeds back the current system status information to the CAN message encoding layer through the status feedback layer for message encoding, and finally sends it to the vehicle controller VCU.

2. A state machine based automated steering control system for a mine dump truck as claimed in claim 1, characterized in that: The CAN 2.0B bus is used to realize bidirectional communication between the steering controller SCU and the vehicle controller VCU, including the following communication frames: EPS mode control frame for switching steering modes, EPS reset control frame for system reset control, EPS calibration control frame for system calibration control, EPS steering angle control frame for precise control of steering angle, and EPS status feedback frame for monitoring the status of the steering system.

3. A state machine based automated steering control system for a mine dump truck as claimed in claim 1, characterized in that: Passenger-controlled non-drive-by-wire mode: When the steering controller SCU is activated, the steering system automatically switches to passenger-controlled non-drive-by-wire mode. At this time, the steering system is in non-drive-by-wire mode, and the steering controller SCU does not participate in the vehicle steering process. The steering action is completed entirely by the steering wheel and steering gear.

4. The state machine based mine dump truck steer-by-wire control system of claim 1, wherein: Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered. In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening.

5. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered.

6. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening.

7. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered.

8. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening.

9. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered. In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening. Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered. In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening. Manual mode: When the steering mode request signal of VCU EPS_MODE_CTRL communication frame is set to "manual", the steering controller SCU will switch the working mode of the steering system to manual mode when the state machine switching conditions are met. At this time, the specific process of vehicle steering is as follows: the driver turns the steering wheel, the steering sensor SASA collects the steering wheel speed, the steering controller SCU receives and processes the steering wheel speed and calculates it, the steering controller SCU controls the steering proportional valve according to the steering wheel speed and the steering cylinder action, and the wheels are steered. In this mode, the variable steering ratio of the vehicle is realized by changing the relationship between the steering wheel speed and the proportional valve opening.

10. A state machine based automated steering control system for a mining dump truck as claimed in claim 1, characterized in that: Calibration mode: the steering system is in the manned non- steer-by-wire mode, if the calibration request signal of the VCU EPS CALIBRATE CTRL communication frame is set to "request", the steering controller SCU will switch the working mode of the steering system to the calibration mode when the switching conditions of the state machine are met, at this time the vehicle controller VCU can modify the steering parameters of the steering controller SCU through the related communication interface.

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