Pneumatic Robot Arm Force Control
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Solution Overview
Problem
Existing robot arms for industrial, medical, and therapeutic applications face challenges with cost, robustness, weight, and safety, particularly when using pneumatic muscles as drive elements, as they can exert high forces or shocks, leading to potential injuries and are complex to operate.
Innovation Solution
A robot arm design featuring interlinked pivoted levers with pneumatic muscles, where the force exerted is detected and limited by a controller, and speed is controlled using pressure relief valves and passive damping elements, allowing for safe and flexible operation across various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pneumatic muscles are used as drive elements, then the robot arm structure becomes simpler and more cost-effective, but the robot arm can exert high forces or shocks that may cause injuries
Solution Approach 1:
The patent implements a controller that continuously monitors the forces exerted by the robot arm and provides feedback control. Sensors detect the actual forces and positions, and the controller adjusts the pneumatic muscle activation to maintain forces within safe limits, resolving the contradiction between simple pneumatic drive and force control safety.
Solution Approach 2:
The patent changes the operational parameters of the pneumatic muscles by controlling air pressure and flow rates. Pressure relief valves and controlled activation sequences modify the pressure parameters to limit maximum forces while maintaining the simplicity of pneumatic actuation, allowing safe operation with simplified structure.
2Weight of moving object
If pneumatic muscles are used for drive, then cost and weight are reduced, but the system becomes difficult to operate and activate
Solution Approach 1:
The robot arm system activates pneumatic muscles automatically based on control signals from the controller. The system self-regulates muscle activation sequences, air pressure distribution, and force limits without requiring manual intervention for each activation, making operation intuitive despite the complexity of pneumatic control.
Solution Approach 2:
The controller serves multiple functions: it manages pneumatic muscle activation sequences, monitors sensor data, enforces force limits, and adapts to different application scenarios. This multi-functionality consolidates complex control tasks into a single intelligent unit, simplifying the overall operation of the pneumatic system.
3Reliability
If force limits are implemented for safety, then safety is improved, but the robot arm loses flexibility in applying necessary forces for various tasks
Solution Approach 1:
The patent implements dynamic force limits that can be adjusted based on the current task, environment, and application mode. The controller modifies force parameters in real-time, allowing higher forces for industrial tasks while maintaining lower limits for therapeutic applications, thus preserving both safety and versatility through dynamic adaptation.
Data Source
AI summary
A robot arm formed from one or more optionally interlinked active pivoted levers, wherein a base is fixed to the one end of a support and a pivoting piece is pivotably mounted on the second end of the support with pneumatic muscles running form the base to the pivoting piece. Individual pneumatic muscles engage on opposing sides of the pivot axis of the pivoting piece and the base of a pivoting lever is fixed to the pivoting piece of the adjacent pivoting lever interconnected thereto. The controller measures the position of the individual pivoting levers and the pressure in the individual pneumatic muscles, calculates the externally acting forces from the pressure-distance diagrams for the individual pneumatic muscles and the geometric lever mechanical ratios for all pivoting levers and limits said forces.