Robot Gripper Control Sequence for Low-Accuracy Workpiece Holding
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Solution Overview
Problem
Existing robot systems face challenges in accurately holding workpieces due to low position accuracy, leading to finger interference or other issues when moving the hand to the appropriate holding position.
Innovation Solution
A robot controller that includes a movement controller and an opening/closing controller, which enables the arm to perform contact, opening, and approaching actions to facilitate precise holding of workpieces by adjusting finger positions and forces, allowing for contact cancellation and following the workpiece surface shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hand is moved directly to the holding position, then the operation is simple and fast, but finger interference with the workpiece occurs due to low position accuracy
Solution Approach 1:
The method performs preliminary actions (contact action and opening action) before the final holding action. The contact action brings fingers into contact with the workpiece surface, the opening action separates fingers from the workpiece, and only then does the approaching action move the hand to the precise holding position. This preliminary sequence eliminates interference issues while maintaining operational simplicity.
Solution Approach 2:
The contact action and opening action serve as intermediary steps between the initial hand movement and the final holding position. These intermediary actions allow the system to adapt to the actual workpiece position and shape, mediating between the robot's low position accuracy and the requirement for precise holding.
2Productivity
If the hand is moved to the holding position without contact action, then the operation is fast, but the fingers cannot adapt to the workpiece shape, leading to holding failures
Solution Approach 1:
The contact action serves as a preliminary measurement step where fingers touch the workpiece surface to detect its actual position and shape. This preliminary action provides the information needed for the subsequent approaching action to achieve precise holding, maintaining both speed and precision.
Solution Approach 2:
The contact action provides feedback about the workpiece's actual position and shape, which is then used to adjust the hand's movement in the approaching action. This feedback mechanism allows the system to compensate for low initial position accuracy and achieve precise holding.
3Measurement precision
If multiple actions (contact, opening, approaching) are performed, then position accuracy is improved, but the operation time increases
Solution Approach 1:
The method uses periodic actions where the contact action and opening action are performed in a cycle before the final holding. This periodic structure allows the system to efficiently gather necessary position information without continuous adjustment, reducing overall operation time while maintaining precision.
Data Source
AI summary
A robot controller includes: a movement controller moving a robot arm including a hand; and an opening/closing controller opening and closing at least one of fingers included in hand in a predetermined direction. The movement controller causes the robot arm to bring at least one of the fingers into contact with a workpiece in a pressing direction. The opening/closing controller causes the at least one of the fingers to perform an opening action after the contact action. After the at least one of the fingers separates from the workpiece through the opening action, the movement controller causes the robot arm to perform an approaching action of moving the hand in the pressing direction to a holding position. The opening/closing controller causes the fingers to hold the workpiece by causing at least one of the fingers to close in a state where the hand is located at the holding position.