Robot Arm Free-Drive Activation With 3D Motion Boundaries
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Solution Overview
Problem
Existing robot arms in free-drive mode require manual manipulation of individual joints, which can be difficult in confined spaces, and incorrect payload weight specification can lead to hazardous situations due to incorrect torque calculations.
Innovation Solution
A robot controller that switches to free-drive mode by monitoring joint sensor parameters within a defined activation sequence, ensuring the robot arm remains static under gravity and allows posture change only if the sensor parameters meet predefined thresholds, preventing unintended movements and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robot controller allows free-drive mode activation with simple button press, then ease of operation is improved, but risk of unintended activation and hazardous situations increases
Solution Approach 1:
The system performs preliminary verification by monitoring joint sensor parameters (torque, position, velocity) during a predetermined activation sequence period before allowing mode switching. This preliminary action ensures the robot arm is in a safe state and the user intends genuine activation, preventing accidental mode changes while maintaining simple activation through the button interface.
Solution Approach 2:
The robot controller continuously monitors joint sensor parameters and provides feedback during the activation sequence. The system checks whether monitored parameters remain within threshold values throughout the activation period, creating a feedback loop that verifies safe conditions before allowing free-drive mode activation, thus preventing unintended activation while keeping the interface simple.
2Reliability
If the robot controller monitors joint sensor parameters throughout free-drive operation, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The system applies partial monitoring by focusing only on critical joint sensor parameters (torque, position, velocity) rather than comprehensively monitoring all robot system parameters. The monitoring is excessive in the sense that it continues throughout the entire free-drive operation, but this targeted partial monitoring achieves adequate safety without requiring complex comprehensive monitoring of the entire robot system.
Solution Approach 2:
The robot controller uses its existing joint sensors and control infrastructure to perform safety monitoring during free-drive operation, rather than requiring separate dedicated safety sensors or systems. The control system serves dual purposes by both controlling robot motion and monitoring safety parameters, reducing overall system complexity while maintaining reliability.
3Reliability
If the robot controller requires prolonged activation sequence with parameter monitoring, then safety against unintended activation is improved, but activation time and productivity deteriorate
Solution Approach 1:
The activation process is structured as periodic sampling of joint sensor parameters at defined intervals during the activation sequence period, rather than continuous monitoring. The controller checks parameters at discrete points throughout the predetermined time period, providing adequate verification while minimizing the total activation time required for mode switching.
4Ease of operation
If the robot arm allows manual manipulation in confined spaces, then ease of operation is improved, but risk of collisions and unintended movements increases
Solution Approach 1:
Before allowing free-drive mode activation that enables manual manipulation, the system performs preliminary checks of joint sensor parameters to ensure the robot arm is in a safe state. This preliminary verification prevents activation under conditions that could lead to collisions in confined spaces, while still allowing manual manipulation when safe.
Solution Approach 2:
During free-drive operation in confined spaces, the robot controller continuously monitors joint sensor parameters and provides feedback to detect unintended movements or potential collisions. This real-time feedback enables the system to respond to hazardous conditions while allowing manual manipulation, balancing ease of operation with collision prevention in confined spaces.
Data Source
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AI summary
The invention relates to a robot controller controlling a robot arm, the robot controller is configured to maintain the robot arm in a static posture when only gravity is acting on the robot arm and allow change in posture of the robot arm 5 when an external force different from gravity is applied to the robot arm. The free-drive mode of operation is activatable by a user establishing a free-drive activation signal to the robot controller, which in free-drive mode of operation is configured within at a free-drive safety period to allow a part of said robot arm to be moved within a virtual three-dimensional geometric shape 10 surrounding the part of the robot arm.