Industrial Robot Lead-Through Control With Virtual Snap Points
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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 during lead-through programming.
Innovation Solution
A method that generates virtual positions and orientations in space, allowing the robot controller to actively control the robot's motions when it approaches these defined points, enabling the robot to snap to or be attracted/repelled from them, thereby facilitating both precise and large sweeping motions during programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robot is controlled in passive compliance mode during lead-through programming, then the robot becomes easy to move by hand and fully compliant in all directions, but it becomes difficult to program precise movements such as linear movements
Solution Approach 1:
The control mode of the robot is made dynamic by automatically switching between passive compliance mode and active control mode based on the operator's manipulation speed. When the speed exceeds a threshold, the system transitions from passive to active control, providing precise positioning. When speed is below the threshold, it returns to passive mode for easy manual movement. This dynamic adaptation resolves the contradiction between ease of operation and movement precision.
Solution Approach 2:
The stiffness parameter of the robot manipulator is dynamically changed based on operating conditions. In passive mode, the stiffness is reduced to enable easy manual movement. When precise positioning is detected (through speed threshold), the stiffness is increased to enable precise movements. This parameter change allows the system to adapt to different operational requirements.
2Adaptability or versatility
If traditional scripting programming is used, then maximum flexibility is achieved, but it requires previous expertise and experience
Solution Approach 1:
The system introduces an automatic control mode as an intermediary between manual lead-through programming and traditional scripting. This intermediary mode provides the flexibility and precision of scripted programming while maintaining the ease of manual operation. The automatic control acts as a mediator that translates simple manual movements into precise robotic actions without requiring programming expertise.
Solution Approach 2:
The robot system performs self-positioning and self-correction during automatic control mode, eliminating the need for operator expertise in programming precise movements. The system automatically calculates and executes the necessary adjustments to achieve precise positioning, making the programming process self-sufficient and easy to operate.
3Ease of operation
If the robot stiffness is reduced to make it compliant, then the manipulator becomes easy to move by hand, but it loses the capability to maintain precise positions
Solution Approach 1:
The stiffness of the manipulator is dynamically adjusted based on the operational phase. During manual lead-through movements, the stiffness is reduced for compliance and ease of movement. When precise positioning is required (detected through speed threshold), the stiffness is automatically increased to maintain position accuracy. This dynamic stiffness adjustment resolves the contradiction between compliance and precision.
Data Source
AI summary
An industrial robot having a manipulator and a robot controller 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 or virtual orientation defined in space, and to actively control the motions of the robot in relation to the at least one virtual position 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.