Articulated Work Machine Steering Control Under Sensor Faults
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Solution Overview
Problem
Existing work machines with hydraulic steering systems can experience unintended speed limiting when sensors for detecting the rotation angle of the front frame relative to the rear frame malfunction, leading to potential impacts during steering.
Innovation Solution
A work machine with redundant sensors and a controller that determines the fault state of these sensors to execute speed limit controls, preventing unintentional steering speed limitations by adjusting the hydraulic flow rates based on sensor health.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor for detecting the rotation angle of the front frame is used to control steering speed, then the impact at the steering end can be mitigated, but unintentional steering speed limiting may occur when the sensor malfunctions
Solution Approach 1:
The system continuously monitors the sensor output signal and compares it against valid ranges to detect malfunctions. When a malfunction is detected, the control strategy automatically switches from active speed limiting to normal steering control, preventing unintentional limitations while maintaining safe operation
Solution Approach 2:
The steering speed limiting control is dynamically adjusted based on sensor health status. The system transitions between two operational modes: normal control mode when the sensor is functioning properly, and speed limiting mode when the sensor is detected to be malfunctioning, ensuring appropriate response to actual system conditions
2Length of moving object
If the front frame is mechanically limited at the maximum steering angle, then the steering range is defined, but a large impact occurs when the front frame contacts the rear frame
Solution Approach 1:
The control system proactively reduces steering speed before the front frame reaches the maximum steering angle where contact with the rear frame would occur. By anticipating the potential impact zone and reducing speed in advance, the system prevents large impact forces while maintaining the full mechanical steering range
Solution Approach 2:
The system dynamically changes the steering speed parameter based on the detected rotation angle. As the front frame approaches the maximum steering angle, the controller automatically reduces the steering speed parameter to mitigate impact forces, while the mechanical steering angle range remains unchanged
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents unintentional steering speed limitations and mitigates impacts by dynamically adjusting hydraulic flow rates based on sensor fault states, ensuring safe and controlled steering operations.
Implementation Method 1
Hydraulic oil for driving the hydraulic cylinder is supplied from a hydraulic pump through a main valve
Implementation Method 2
the controller is configured to execute a speed limit control to limit a rotation speed of the second frame... by dynamically adjusting hydraulic flow rates
Data Source
AI summary
A work machine includes a first frame, a second frame, an actuator, an operating member, a first sensor, and a controller. The second frame is connected to the first frame. The second frame is rotatable within a predetermined angle range relative to the first frame. The actuator rotates the second frame relative to the first frame. The operating member is used to input a rotational movement of the second frame relative to the first frame. The first sensor detects a rotation angle of the second frame relative to the first frame. The controller executes a speed limit control, based on a fault state of the first sensor, to limit a rotation speed of the second frame in response to an input from the operating member, when the controller determines, based on a detection value of the first sensor, that the second frame is located within an end range of the predetermined angle range.