Differential Wheel Speed Control for Slip-Compensated Vehicle Yaw
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Solution Overview
Problem
Existing vehicle control systems, such as those in riding electric lawn mowers, suffer from reduced robustness due to differences in slip ratios and ground contact between left and right driving wheels, leading to compromised straight-line travel and turning performance.
Innovation Solution
A vehicle control device that adjusts the rotational speeds of left and right driving motors based on target vehicle speeds and yaw rates, incorporating correction values for wheel slip and ground surface shape differences to enhance stability and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the vehicle offsets the driving force of the left and right driving wheels based on the bank angle of the inclined surface, then the traveling in a straightforward manner is improved, but the robustness deteriorates due to disturbances such as differences in slip ratio and ground contact surface shape
Solution Approach 1:
The control device calculates actual yaw rates from wheel speed differences and compares them with target yaw rates, using the deviation as feedback to generate correction values. This closed-loop feedback mechanism continuously adjusts driving forces to compensate for disturbances like slip ratio differences and ground contact variations, maintaining robust straight-line traveling performance.
Solution Approach 2:
The system dynamically changes control parameters (driving force correction values) based on real-time conditions. By calculating correction values from actual yaw rate deviations and applying them to adjust the driving forces of left and right wheels, the system adapts to varying slip ratios and ground contact conditions, resolving the contradiction between straightforward traveling performance and robustness.
2Adaptability or versatility
If the vehicle uses wheel speed difference for turning control, then turning capability is achieved, but straight-line traveling accuracy deteriorates due to yaw rate components generated by slip and ground surface differences
Solution Approach 1:
The control device continuously monitors wheel speed differences, calculates actual yaw rates, and compares them with target yaw rates. This feedback loop enables the system to distinguish between intentional turning commands and unintentional yaw rate deviations caused by slip or ground surface variations, allowing accurate straight-line traveling while preserving turning capability.
Solution Approach 2:
The system segments the yaw rate control into two independent components: target yaw rate (for intentional turning) and correction yaw rate (for compensating slip and ground surface effects). By calculating and applying correction values separately, the system maintains turning capability while eliminating unwanted yaw rate deviations that would compromise straight-line traveling accuracy.
Data Source
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AI summary
A vehicle control device (26) for controlling a vehicle (10) that can turn according to a difference between the wheel speed of a left drive wheel (14L) and the wheel speed of a right drive wheel (14R), wherein: the vehicle control device calculates a target wheel speed for the left drive wheel and a target wheel speed for the right drive wheel by using a target vehicle speed, a target yaw rate, a first correction value that corresponds to a yaw rate component generated due to slip of the left drive wheel and slip of the right drive wheel, and a second correction value that corresponds to a yaw rate component generated due to the grounding surface shape of the left drive wheel and the grounding surface shape of the right drive wheel; and the vehicle control device controls the rotation speed of left and right driving motors on the basis of the target wheel speeds for the left and right drive wheels.