Omnidirectional Trolley Control for Turning Stability
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Solution Overview
Problem
Existing trolleys with omnidirectional wheels face difficulties in performing accurate turning operations due to the challenge of applying a moment about the vertical axis without unintended lateral load, leading to unwanted movement in the left-right direction.
Innovation Solution
A trolley equipped with left and right omnidirectional wheels, a handle, sensors for detecting longitudinal, lateral loads, and moments, and a control device that sets and corrects target velocities based on these inputs to prevent unintended lateral movement during turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control device sets target lateral velocity based on lateral load and drives omnidirectional wheels during turning, then the trolley responds to user input, but unintended lateral movement occurs because lateral load cannot be applied without moment during turning operations
Solution Approach 1:
The control device uses feedback from the moment sensor about the vertical axis to dynamically adjust the target lateral velocity. When a turning moment is detected, the system feeds back this information to modify the lateral velocity command, reducing it proportionally to the detected moment. This feedback mechanism allows the system to distinguish between intentional lateral movement and moment-induced lateral movement, resolving the contradiction between operational ease and positioning accuracy.
Solution Approach 2:
The system changes the parameter of target lateral velocity based on the detected moment about the vertical axis. By dynamically adjusting this parameter according to the turning operation intensity, the system adapts the lateral velocity to prevent unintended movement while maintaining responsive control. This parameter change approach allows the same control structure to handle both straight-line and turning operations accurately.
2Device complexity
If the control device uses only moment about vertical axis to control turning, then rotational control is simplified, but lateral load cannot be avoided during turning leading to unintended lateral movement
Solution Approach 1:
The target lateral velocity acts as an intermediary parameter that mediates between the moment input and the actual lateral movement output. By introducing this intermediate variable that can be adjusted based on moment detection, the system maintains a simple control structure while achieving reliable turning accuracy. The intermediary allows decoupling of the moment control from direct lateral velocity execution.
Data Source
AI summary
A trolley includes: a vehicle body; omnidirectional wheels; drive units; a handle; a sensor; and a control device for controlling the drive units based on the longitudinal load, lateral load, and moment about the vertical axis applied to the handle detected by the sensor. The control device: sets a target longitudinal velocity of the vehicle body based on the longitudinal load, a target lateral velocity of the vehicle body based on the lateral load, and a target angular velocity about the vertical axis of the vehicle body based on the moment about the vertical axis; corrects the target lateral velocity based on the target angular velocity so that an absolute value of the target lateral velocity decreases as an absolute value of the target angular velocity increases; and controls the drive units based on the target longitudinal velocity, the corrected target lateral velocity, and the target angular velocity.