Robot Joint Safety Clutch Torque Limiting
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Solution Overview
Problem
Existing robot joints lack structural simplicity and safety features necessary for effective human-robot collaboration, particularly in handling forces and torques efficiently while ensuring safety during torque limitations and potential collisions.
Innovation Solution
A robot joint design featuring a drive wheel, driven wheel, gear device, motor, and safety clutch that disconnects when a predefined torque is exceeded, along with a sensor device to detect angular positions, allowing for safe and efficient transmission of forces and moments, and enabling passive movement during collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a robot joint is designed with simple structure for cost-effectiveness, then manufacturing cost is reduced, but safety features and torque limitation capabilities are compromised
Solution Approach 1:
The drive connection is segmented into modular components: motor shaft, safety clutch, gear device, and driven wheel. This segmentation allows the safety clutch to be integrated as a discrete element that can limit torque while maintaining overall structural simplicity and cost-effectiveness.
Solution Approach 2:
The safety clutch provides dynamic torque limitation by automatically disconnecting when a predetermined torque threshold is exceeded and re-engaging when torque decreases. This dynamic behavior ensures safety during collisions or overload conditions without requiring complex control systems.
2Reliability
If a safety clutch is integrated into the drive connection to limit torque, then safety during collisions is improved, but the complexity of the drive system increases
Solution Approach 1:
The safety clutch is merged with the existing drive connection components (motor shaft, gear device, driven wheel) to form an integrated torque-limiting mechanism. This combination allows torque limitation functionality to be added without significantly increasing overall system complexity.
Solution Approach 2:
The safety clutch operates autonomously based on torque conditions, automatically disconnecting and re-engaging without external control signals. This self-service capability simplifies the control system while maintaining safety functionality.
3Manufacturing precision
If the drive connection is made rigid for precise torque transmission, then transmission accuracy is improved, but the ability to allow passive movement during collisions is reduced
Solution Approach 1:
The drive connection transitions between rigid and compliant states dynamically: rigid during normal operation for precise torque transmission, and compliant during collisions when the safety clutch disconnects to allow passive movement. This dynamic adaptability resolves the contradiction between precision and safety.
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
The design provides a cost-effective, safe, and flexible robot joint capable of human-robot collaboration, allowing for intuitive operation and collision handling without disrupting movement, maintaining an acceptable payload and enabling modular expansion for various applications.
Implementation Method 1
a gear device coupling the drive wheel to the driven wheel for transmitting a drive torque
Implementation Method 2
a safety clutch designed to disconnect the drive connection between the motor shaft and the drive wheel when a predetermined limit torque is exceeded
Data Source
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AI summary
The invention relates to a robot joint (4.1, 4.2) having a robot element (6), a drive wheel (7) rotatably mounted on the robot element (6) and a driven wheel (8) rotatably mounted on the robot element (6), a gear device (9) coupling the drive wheel (7) to the driven wheel (8) for transmitting a drive torque, and a motor (M1) driving the drive wheel (7), the motor shaft (14) of said motor being connected, via a drive connection (13), to the drive wheel (7) for introducing the drive torque. The robot joint also comprises a safety coupling (15) which is designed to disconnect the drive connection (13) between the motor shaft (14) and the driven wheel (8) when a predefined threshold torque is exceeded and to reestablish the drive connection (13) between the motor shaft (14) and the driven wheel (8) when the torque falls below the predefined threshold torque, and a sensor device (21) which is designed to measure the angular position of the driven wheel (8). In addition, the invention relates to a corresponding robot (1) having at least one such robot joint (4.1, 4.2).