Backdrivable Robot Joint Control With Speed-Dependent Resistance
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Solution Overview
Problem
Existing robotic systems lack effective methods to provide differentiated haptic feedback during joint backdriving, which can lead to undesirable operating conditions and hinder user control.
Innovation Solution
Implementing a computer-assisted system with a controller that switches between control modes, providing a speed-dependent resistance in response to joint backdriving, allowing users to differentiate modes through tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller provides speed-dependent resistance during joint backdriving, then user control and safety are improved, but device complexity increases
Solution Approach 1:
The controller dynamically adjusts the resistance torque based on the measured backdriving speed of the joint. The resistance is not static but varies with the speed at which the external articulation backdrives the joint, allowing the system to adapt its mechanical response in real-time to maintain safety while preserving backdrivability.
Solution Approach 2:
The controller implements a feedback mechanism by continuously monitoring the backdriving speed of the joint and using this information to modulate the resistance torque. This closed-loop control provides haptic feedback to the external articulation, enabling the user to感知 the control mode through tactile sensation while maintaining operational safety.
2Loss of information
If the controller provides haptic feedback through resistance, then control mode differentiation is improved, but ease of operation deteriorates
Solution Approach 1:
The controller differentiates between control modes by changing the parameters of resistance torque applied during backdriving. By modulating the magnitude and characteristics of the resistance based on the control mode and backdriving speed, the system provides distinct haptic signatures that allow users to identify control modes through tactile feedback without completely impeding backdriving capability.
3Adaptability or versatility
If the joint allows backdriving for reconfiguration, then adaptability is improved, but control precision deteriorates
Solution Approach 1:
The system dynamically switches between allowing backdriving for reconfiguration and providing controlled resistance for precision maintenance. The controller can transition between compliant modes that facilitate external repositioning and controlled modes that maintain positional accuracy, adapting the joint's mechanical characteristics based on operational requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances user control by enabling distinct haptic feedback for different control modes, preventing undesirable joint movements and improving operational safety and efficiency.
Implementation Method 1
the controller being configured to, in the first control mode, command the actuator mechanism to provide a first speed-dependent resistance in response to the joint being backdriven at a first backdriven speed above a first speed threshold
Data Source
AI summary
A computer-assisted system includes a manipulator arm including a joint, an actuator mechanism configured to drive the joint, and a controller including a computer processor. The controller is communicatively coupled to the manipulator arm and configured with a first control mode and a second control mode. In each of the first control mode and the second control mode, the controller commands the actuator mechanism to allow an external articulation to reconfigure the manipulator arm by backdriving the joint. The first control mode is distinguished from the second control mode at least by the controller being configured to, in the first control mode, command the actuator mechanism to provide a first speed-dependent resistance in response to the joint being backdriven at a first backdriven speed above a first speed threshold. The first speed-dependent resistance opposes the joint being backdriven.