Robotic Soft-Object Manipulation With Adaptive Force-Position Control
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Solution Overview
Problem
Current robotic systems are not equipped to handle soft body objects with nonuniform characteristics, such as soft tissue, due to their inability to adapt to the unique texture, consistency, and pressure points, which leads to instability and inefficiency in manipulation tasks.
Innovation Solution
A robotic control system that dynamically adjusts its contact point and torque motor commands based on sensed force and orientation, using a composite controller that integrates force and position goals, and employs multiple reference frames to maintain stability and achieve manipulation goals, including applying specific forces and torques to soft objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time control is used to monitor robot actions, then control precision is improved, but the system cannot adapt to nonuniform soft body objects with varying texture and consistency
Solution Approach 1:
The control system dynamically adjusts controller gain based on sensed orientation of the surface and modifies torque motor commands in real-time. The system transitions from static control parameters to dynamic adaptation, allowing the robot to respond to varying mechanical properties of soft body objects while maintaining control precision.
Solution Approach 2:
The system employs force sensing feedback to detect contact characteristics and uses this information to selectively adjust controller gain. The feedback loop enables the robot to adapt to nonuniform characteristics of soft objects by continuously monitoring contact forces and modifying control parameters accordingly.
2Productivity
If the robot applies force to manipulate soft objects, then manipulation effectiveness is improved, but instability occurs due to nonuniform pressure points and tissue characteristics
Solution Approach 1:
The control system changes physical parameters including controller gain and torque motor commands based on sensed force and orientation. By dynamically adjusting these parameters, the system maintains stable manipulation despite variations in soft object characteristics such as tissue consistency and pressure points.
Solution Approach 2:
The system defines a control frame of reference at a position inside the object being manipulated and selectively adjusts control parameters relative to the sensed orientation of the contact surface. This localized adaptation allows different parts of the object to be manipulated with appropriate force levels, maintaining stability across nonuniform structures.
3Speed
If the robot progresses to next positional goals, then task completion speed is improved, but position control is lost due to excessive force components
Solution Approach 1:
The system uses pose and force goals to selectively modify controller gain, applying partial force components when necessary to maintain position control while still progressing toward the next positional goal. This partial action approach prevents excessive force that would disrupt position control while maintaining adequate progress speed.
Data Source
AI summary
A system, method, and apparatus for a robot system that manipulates the surface of an object effect programmed manipulation goals such as reaching specific locations on the surface of the object, displacing the surface of the object, applying a predetermined force and torque to the surface of the object, dynamically changing the contact point between the robot and the object, and applying force to structures below the surface of the object. The system and method determine the state of the object through a sensing method that includes, without limitation: torque and force measurement, visible light sensors, range and depth sensors, ultrasound sensors, thermographic sensors, and worktable force measurement.