Motor Controller Force Feedback for Low-Collision Robot Motion
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Solution Overview
Problem
Service robots face limitations in speed due to the potential for damaging collisions with unknown objects, as existing strategies like lightweight design, low inertia motors, and high overload capacity structures are often in conflict, leading to inefficiencies and instability.
Innovation Solution
A force-based motor control system that uses a correction force determined by a linear combination of externally controlled, set, and effective correction forces, along with a windup force signal, to efficiently manage collisions by stabilizing motor control and reducing collision energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of the robot is increased, then productivity is improved, but the collision energy increases causing damage to objects or the robot itself
Solution Approach 1:
The patent applies beforehand cushioning by introducing a damping force that is activated before collision occurs. The damping force is calculated based on the robot's current velocity and a damping coefficient, creating a preemptive resistance that reduces the impact energy during collision without requiring structural modifications or series elastic elements.
2Reliability
If structures with high overload capacity are used, then reliability is improved, but the weight of the robot increases
Solution Approach 1:
The patent replaces mechanical solutions (heavy structures, series elastic elements) with a control-theoretic approach. The damping force is generated through motor control algorithms rather than mechanical compliance, eliminating the need for heavy protective structures while maintaining collision resistance.
3Object-affected harmful factors
If the inertia of the motor is reduced, then the collision energy is decreased, but the stability of motor control deteriorates
Solution Approach 1:
The patent employs feedback by continuously monitoring the robot's velocity and using it to calculate the damping force. The damping coefficient is adjusted based on feedback from the system's dynamic state, ensuring stable motor control while maintaining low collision energy. The feedback loop allows the system to adapt to changing conditions without requiring high motor inertia.
Data Source
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AI summary
A force-based motor control is used in order to reduce the collision energy to deal with in case of collisions or shocks. That is, a basis, a force-based control is used: A set force obtained by correcting an externally controlled force by use of a correction force is subject to a limitation so as to obtain an effectively set force which is then subject to force-to-current conversion to determine a current to be applied onto the motor. The correction force is determined when using, in addition to a motor encoder signal of a motor encoder of the motor, a windup force signal formed and an effective correction force signal..