Underactuated Robot Control for Stable Cooperative and Autonomous Modes
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Solution Overview
Problem
Existing robotic systems lack efficient control frameworks to seamlessly transition between collaborative and autonomous modes, particularly in underactuated jointed mechanisms with redundant degrees of freedom, which hinders their ability to interact effectively with human operators and adapt to varying task requirements.
Innovation Solution
A control framework that utilizes impedance control to manage the robotic system as a classic mass-spring-damper system, allowing for real-time switching between Cooperative and Autonomous Modes, with position and force sensors to detect contact and adjust the robotic system's behavior accordingly, ensuring safe and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robotic system operates in Collaborative Mode with physical interaction, then ease of operation is improved, but stability deteriorates due to oscillations
Solution Approach 1:
The system dynamically switches between Collaborative Mode and Autonomous Mode based on task requirements and interaction levels. The controller adjusts the level of physical interaction and control authority in real-time, allowing the system to be collaborative when needed while maintaining stability through autonomous operation when physical interaction would cause oscillations
Solution Approach 2:
The impedance parameters (stiffness, damping, inertia) are adjusted based on the operational mode and task requirements. By changing these parameters dynamically, the system can provide compliant collaborative interaction when safe, while maintaining stable autonomous control when physical interaction would be problematic
2Stability of the object's composition
If the robotic system operates in Autonomous Mode without physical interaction, then stability is improved, but ease of operation deteriorates
Solution Approach 1:
The system dynamically transitions between Autonomous Mode and Collaborative Mode based on the task phase and interaction requirements. During phases requiring fine manipulation or high compliance, the system switches to Collaborative Mode to improve ease of operation, while maintaining Autonomous Mode during phases where stability is paramount
3Adaptability or versatility
If the robotic system has redundant degrees of freedom, then adaptability is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into distinct modes (Autonomous and Collaborative) with specialized controllers for each. The redundant degrees of freedom are managed by assigning specific joints to specific modes, allowing independent optimization of each segment without requiring complex integrated control of all joints simultaneously
Solution Approach 2:
The redundant joints serve multiple functions: they provide additional workspace and dexterity for complex tasks, while also enabling the system to operate in simplified modes when full redundancy is not needed. The same physical hardware supports both autonomous and collaborative operations across different task requirements
4Ease of operation
If the robotic system allows physical interaction with operator, then ease of operation is improved, but reliability deteriorates due to contact detection challenges
Solution Approach 1:
The system employs multiple sensors (force sensors, position sensors, contact sensors) that provide continuous feedback about the interaction state. This multi-layered feedback mechanism reliably detects contact conditions, operator intent, and system state, enabling safe and reliable collaborative operation even with physical interaction
Solution Approach 2:
The system proactively detects potential contact conditions and transitions between modes before actual problematic contact occurs. By monitoring sensor inputs and predicting interaction outcomes, the system prepares appropriate control responses in advance, preventing reliability issues rather than reacting to them
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
Enables intuitive and efficient human-robot collaboration by maintaining stability and reducing oscillations, allowing the robotic system to respond optimally to operator input while minimizing physical interaction, thus enhancing task performance and safety.
Implementation Method 1
A control framework that utilizes impedance control to manage the robotic system as a classic mass-spring-damper system
Implementation Method 2
manage the robotic system as a classic mass-spring-damper system
Implementation Method 3
position and force sensors to detect contact and adjust the robotic system's behavior accordingly
Data Source
AI summary
A jointed mechanism includes a passive pendulum system attached to and suspended from the multi-axis robot. The system includes one or more position sensors configured to measure a joint angle on the pendulum system, at least one arm, and an end-effector attached to a distal end of the pendulum system. A controller implements a method to selectively control motion of the robot in a plurality of control modes. The control modes include a Cooperative Mode and an Autonomous Mode. The controller is configured to detect contact with the end-effector when operating in the Autonomous Mode, and to automatically initiate a control action in response to the contact. The pendulum system may be a parallelogram arrangement.