Robot Arm Free-Drive Activation Using Joint Sensor Thresholds
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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 leads 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 stationary under gravity and allows posture change only if sensor parameters meet predefined thresholds, preventing unintended movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If free-drive mode is activated without verification, then ease of operation is improved, but safety and reliability deteriorate due to incorrect payload weight calculations
Solution Approach 1:
The system performs preliminary verification of joint sensor parameters and payload weight specifications before allowing free-drive mode activation. The controller checks if the robot arm remains stationary under gravity and validates sensor readings within defined thresholds during an activation sequence, preventing activation with incorrect payload data.
Solution Approach 2:
The system continuously monitors joint sensor parameters and provides feedback during the free-drive activation process. The controller compares sensor parameter values against predefined thresholds and uses this feedback to determine whether to permit mode switching, ensuring payload weight correctness before activation.
2Reliability
If manual manipulation of individual joints is required, then reliability is improved by preventing unintended movements, but ease of operation deteriorates in confined spaces
Solution Approach 1:
The system changes the operational parameters of the robot arm by validating joint sensor parameters (position, velocity, acceleration) against predefined thresholds before permitting free-drive mode. This parameter-based control allows intuitive manual manipulation while maintaining safety through automated verification of motion boundaries.
3Device complexity
If payload weight is not correctly specified, then device complexity is reduced by manual entry, but harmful factors increase due to incorrect torque calculations
Solution Approach 1:
The system performs self-verification of payload weight specifications by automatically monitoring joint sensor parameters during free-drive activation. The controller checks whether the robot arm remains stationary under gravity and validates sensor readings, allowing the system to self-correct or prevent activation with incorrect payload data without requiring additional manual verification steps.
Data Source
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 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 then is configured to initiate a free-drive mode activation sequence including the steps of: in a predetermined activation sequence period of time monitor a value of at least one joint sensor parameter, and compare this value to a free-drive activation joint sensor parameter threshold value. The robot controller is configured to switch to the free-drive mode of operation if the at least one value does not exceed the free-drive activation joint sensor parameter threshold value within the predetermined activation sequence period of time.