Dual-Wheel Travel Control for Stable Turning at Low Speed
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Solution Overview
Problem
Existing vehicle control systems face challenges in accurately controlling the turning and speed of vehicles with independent left and right wheel driving, leading to over-sensitive turning and potential wheel lock at low speeds, which can result in unwanted marks on the ground surface.
Innovation Solution
A traveling control device that includes a speed instruction value correction mechanism to adjust speed instructions based on operation instructions, using PI control to manage motor currents, and torque control for slippery conditions, thereby reducing over-sensitive turning and maintaining speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the integral term correction gain is set based on a derivation value obtained by determining a time derivative of the result of comparing the steering angle calculated from a yaw rate with the steered steering angle, then the vehicle behavior can be stabilized during unsteady steering, but the driving wheels may be locked at zero speed including extremely low speed, thus forming unwanted marks in the ground surface
Solution Approach 1:
The patent changes the control parameter from integral term correction gain based on steering angle derivative to integral term correction gain based on vehicle speed derivative. This parameter substitution resolves the contradiction by preventing wheel lock at low speeds while maintaining stabilization capability during unsteady steering operations.
Solution Approach 2:
The patent implements feedback control by continuously monitoring vehicle speed and adjusting the integral term correction gain accordingly. The feedback mechanism ensures that when vehicle speed is extremely low, the correction gain is limited to prevent driving wheel lock, thereby avoiding unwanted ground marks while still providing stabilization during steering operations.
2Productivity
If the operating handles are operated to turn the vehicle on the spot by rotating the pair of left and right driving wheels in opposite directions, then the vehicle can achieve tight turning radius, but the turning operation will be input over-sensitively without reaction force from transmission mechanisms
Solution Approach 1:
The patent introduces feedback control where the integral term correction gain is adjusted based on detected vehicle speed. During on-the-spot turning operations, this feedback mechanism provides stabilizing correction to counteract over-sensitive input responses, giving the operator better control feel while maintaining high turning speed capability.
Solution Approach 2:
The patent dynamically adjusts the integral term correction gain based on real-time vehicle speed conditions. During rapid turning operations, the gain adjustment provides appropriate stabilization without compromising the responsiveness needed for tight turning radius, thus balancing turning speed with operational control.
Data Source
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AI summary
Provided is a traveling control device capable of appropriately controlling the turning and the speed of a traveling vehicle. A traveling control device 1 of a traveling vehicle including a traveling control unit 3 having a pair of left and right configurations capable of respectively driving a pair of left and right driving wheels 2 includes: an instruction receiving portion 31 that receives an operation instruction directed to each of the pair of left and right driving wheels 2; a speed instruction value calculation portion 32 that calculates a speed instruction value that is to be instructed to the traveling control unit 3, based on each of the operation instructions; an operation instruction determination portion 33 that determines, based on each of the operation instructions, whether the operation instruction is an operation instruction to rotate the pair of left and right driving wheels 2 in the same direction as each other, or an operation instruction to rotate the pair of left and right driving wheels 2 in different directions from each other; and a speed instruction value correction portion 34 that corrects, if the operation instruction is an operation instruction to rotate the pair of left and right driving wheels 2 in the same direction as each other, one of the speed instruction values calculated for the traveling control unit 3 by the speed instruction value calculation portion 32, based on the other speed instruction value.