Tactile Feedback Control for Soft Robotic Manipulator Contact
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Solution Overview
Problem
Robotic manipulators face challenges in minimizing energy or momentum transfer during collisions without compromising performance metrics like accuracy and productivity, as existing strategies such as reducing approach velocity, introducing compliance, or modifying mechanical impedance often result in impractical solutions or accuracy issues.
Innovation Solution
The implementation of a tactile sensor feedback loop that directly measures forces between the robotic manipulator end effector and objects using tactile sensors, aligns these measurements with the end effector's motion, and feeds them back into the controller to modify the mechanical impedance, reducing energy or momentum transfer during collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the magnitude of approach velocity of a robotic manipulator is reduced, then the transfer of energy or momentum during collision is reduced, but productivity decreases because the manipulator moves more slowly
Solution Approach 1:
The patent changes the mechanical impedance parameter of the robotic manipulator system by modifying feedback control gains. This allows the system to reduce energy transfer during collision without reducing approach velocity, thereby maintaining productivity while achieving softer interaction during contact events
Solution Approach 2:
The patent introduces dynamic modification of control parameters based on collision detection. The feedback control gains are adjusted in real-time during collision events, allowing the manipulator to maintain high velocity during normal operation and automatically reduce energy transfer when contact occurs
2Object-affected harmful factors
If mechanical compliance is introduced to the robotic manipulator, then the transfer of energy or momentum during collision is reduced, but trajectory tracking error increases, reducing accuracy
Solution Approach 1:
The patent implements dynamic switching between high-accuracy trajectory tracking mode and collision-compliant mode. During normal operation, the system maintains high feedback control gains for accurate trajectory tracking. Upon detecting a collision event, the system dynamically adjusts gains to reduce energy transfer, then returns to high-accuracy mode after the collision
Solution Approach 2:
The patent uses feedback control with dynamically adjustable gains that respond to collision events. The feedback mechanism detects contact through changes in motion dynamics and automatically modifies control parameters to reduce energy transfer while maintaining trajectory accuracy during non-collision periods
3Object-affected harmful factors
If feedback control gains are reduced to decrease mechanical impedance, then the transfer of energy or momentum during collision is reduced, but trajectory tracking error increases, reducing accuracy
Solution Approach 1:
The patent employs dynamic adjustment of feedback control gains rather than static reduction. The gains are maintained at high levels during normal operation for accurate trajectory tracking and are temporarily reduced only during detected collision events to minimize energy transfer
Solution Approach 2:
The patent implements periodic monitoring of collision events with dynamic gain adjustment. The system continuously monitors for collision conditions and periodically adjusts feedback control gains accordingly, maintaining high accuracy during normal operation while providing protective impedance reduction during collision events
Data Source
AI summary
Feedback control for controlling a robotic manipulator includes receiving measurement signals from one or more tactile sensors and filtering the measurement signals to align them with the directions of motion of the end effector to produce an impedance-shaping signal. The feedback control determines one or more control signals to the actuators to track a reference state of the end effector based on measurements of the state of the end effector and combines the control signal with the impedance shaping signal to produce control commands. Also, the feedback control may include submitting the determined control commands to the actuators causing a change in the state of the end effector, where the state of the end effector includes one or a combination of an end effector position, an end effector velocity, and an end effector force.