Industrial Robot Lead-Through Control With Virtual Position Guidance
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Solution Overview
Problem
Lead-through programming of industrial robots faces challenges in achieving both precision and speed, as existing methods struggle to accurately control robot movements, particularly in programming linear and precise movements, due to the robot's compliance mode which makes it difficult to program precise movements while maintaining flexibility.
Innovation Solution
A method that generates virtual orientations and positions in space using 3D geometrical formulas, allowing the robot controller to actively control the robot's motions when it approaches these virtual points, providing haptic feedback and snapping or attracting the robot to precise positions, enabling both precise and sweeping motions during programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robot is passively controlled during lead-through programming, then the manipulator becomes fully compliant and easy to move by hand, but it becomes difficult to program precise movements such as linear movements
Solution Approach 1:
The system dynamically switches between passive control mode (for large sweeping motions) and active control mode (for precise movements). The controller transitions from compliant behavior that allows free hand movement to restrictive behavior that guides movements along predefined paths, enabling both ease of operation and programming precision at different stages of the programming process
Solution Approach 2:
The control system changes the stiffness parameter of the manipulator dynamically. In passive mode, the stiffness is reduced to enable compliant hand movement. When precise positioning is needed, the system switches to active mode where the stiffness is increased through restrictive control, allowing the manipulator to follow predefined trajectories accurately
2Manufacturing precision
If the robot is actively controlled to restrict movements to one direction, then precise linear movements can be programmed, but the user cannot freely lead the robot arm in any direction
Solution Approach 1:
The system implements dynamic control mode switching where the level of restriction is adjusted based on programming needs. During active control for precise linear movements, restrictions are applied only in specific directions while maintaining freedom in others. The system can transition between highly restrictive active mode and fully compliant passive mode, providing adaptability for different programming scenarios
3Ease of operation
If the stiffness of the manipulator is reduced to make it compliant, then the robot becomes easy to move by hand, but the manipulator cannot maintain precise positioning
Solution Approach 1:
The control system dynamically adjusts the stiffness characteristics based on the programming phase. During passive lead-through, low stiffness enables compliant hand movement. When approaching target positions or during active control phases, the system increases stiffness through restrictive control to maintain precise positioning, effectively decoupling the compliance needed for movement from the stiffness needed for positioning accuracy
Data Source
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AI summary
The present invention relates to an industrial robot (1) comprising a manipulator (3) and a robot controller (2) configured to control the motions of the manipulator. The robot controller is configured during lead-through programming of the robot to compare a robot position or a robot orientation (TCP) with at least one virtual position (12) or virtual orientation defined in space, and to actively control the motions of the robot in relation to the at least one virtual position (12) or virtual orientation when the difference between the robot position or robot orientation and the least one virtual position or virtual orientation is smaller than an offset value (L).