Motion Control Using Tangent-Vector Targets for Smooth Trajectory Tracking
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Solution Overview
Problem
Existing motion control methods for work machines, such as construction equipment and AGVs, face challenges in smoothly following target trajectories due to varying acceleration, which can lead to inaccurate and inefficient movement.
Innovation Solution
A motion control apparatus that includes a position acquisition unit, a target trajectory generation unit, a moving velocity determination unit, a control target position calculation unit, and a control input calculation unit, which together enable feedback control to smoothly follow a target trajectory by setting a control target position on the tangent vector of the trajectory, ensuring high accuracy and velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If intermediate target points are sequentially switched to follow a continuous target trajectory, then the work machine can approximately achieve trajectory following, but the acceleration varies greatly causing non-smooth movement
Solution Approach 1:
The control target position is dynamically adjusted based on the present velocity and tangent vector of the target trajectory. Instead of using fixed intermediate target points, the system continuously updates the control target position along the tangent direction, allowing smooth adaptation to velocity changes and eliminating abrupt acceleration variations.
Solution Approach 2:
The invention changes the parameter used for feedback control from fixed intermediate target points to a dynamically calculated control target position based on present velocity and tangent vector. This parameter change enables continuous adjustment of the control target, resulting in smooth acceleration transitions while maintaining trajectory following accuracy.
2Speed
If feedback control is used with proportional control input to error, then the work machine moves at higher velocity when error is large, but this causes acceleration variations and non-smooth movement
Solution Approach 1:
The system uses feedback control where the control target position is calculated based on present velocity and the tangent vector of the target trajectory. The feedback mechanism continuously adjusts the control target position to maintain both high velocity and smooth acceleration, resolving the contradiction between speed and acceleration stability.
3Productivity
If the control target position is set on the tangent vector of the target trajectory, then the work machine can follow the trajectory smoothly at high velocity, but requires complex calculation of tangent vectors and control target positions
Solution Approach 1:
The system performs preliminary calculation of the tangent vector and control target position based on present velocity before executing the movement. This preliminary action allows the complex calculations to be done in advance, enabling smooth high-velocity trajectory following without real-time computational delays or excessive complexity during execution.
Data Source
AI summary
A motion control apparatus for controlling a control object to follow a target trajectory includes a position acquisition unit that acquires a present position of the control object, and a target trajectory generation unit that generates the target trajectory from the present position to a final position where the control object reaches. The apparatus includes a moving velocity determination unit that determines a moving velocity at which the control object moves in each position on the target trajectory, and a control target position calculation unit that sets a control target position in a traveling direction on a tangent vector of the target trajectory at the present position in order to perform feedback control so that the control object follows the target trajectory at the moving velocity. A control input calculation unit calculates a control input to the control object by the feedback control using the control target position as a target value.