Robot Hand Grip Force Control via Finger Position Feedback
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Solution Overview
Problem
Existing methods for controlling robot hand grip force are inaccurate due to frictional changes and require external force sensors, making it difficult to achieve precise grip force adjustment, especially when handling various products with different physical properties.
Innovation Solution
A robot hand controlling method that calculates the driving quantity of the actuator based on the position of the fingers to adjust grip force, using a correlation between grip force and finger position to accurately control grip force without external sensors, allowing for precise grip force adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a disturbance estimation observer is used to control grip force, then grip force control is enabled, but frictional force changes cause inaccurate estimation and control difficulty
Solution Approach 1:
The patent uses feedback from position sensors to detect finger position changes and uses this information to calculate actuator driving quantities. This feedback mechanism enables accurate grip force control by continuously monitoring position and adjusting driving quantity accordingly, resolving the estimation accuracy problem caused by friction variations.
Solution Approach 2:
The system uses its own position sensor data to control grip force without requiring external force sensors. The robot hand's position detection capability is leveraged to infer grip force information, making the system self-sufficient and eliminating the need for additional measurement devices.
2Measurement precision
If an external force sensor is added to measure grip force, then grip force measurement is enabled, but device complexity and cost increase
Solution Approach 1:
The patent makes the robot hand self-sufficient by using its existing position sensors to infer grip force information. The system processes position data from its own sensors to calculate the driving quantities needed for grip force control, eliminating the need for external force sensors and reducing device complexity.
Solution Approach 2:
The position sensors serve dual purposes: they detect finger position for motion control and provide data for grip force calculation. This multi-functionality allows the same sensor to perform both positioning and force measurement tasks, reducing the need for additional specialized sensors.
3Measurement precision
If an external force sensor is added to measure grip force, then grip force measurement is enabled, but robot hand size and cost increase
Solution Approach 1:
The robot hand uses its own position sensing capability to infer grip force information, making the system self-sufficient without requiring external force sensors. This approach maintains compact robot hand dimensions while enabling accurate grip force measurement and control.
4Stability of the object's composition
If friction compensation is attempted with hysteresis in disturbance estimation observer, then friction transition is handled, but grip force control accuracy deteriorates
Solution Approach 1:
The patent uses real-time position feedback to calculate the required actuator driving quantity. By continuously monitoring position changes and using this feedback to adjust driving commands, the system achieves accurate grip force control without relying on friction compensation models that introduce hysteresis and accuracy degradation.
Data Source
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AI summary
A robot hand controlling method executes calculating a position and changing grip force when the grip force for gripping a work W is to be changed in a state that fingers are gripping the work W with first grip force. In the calculating the position, the hand controlling unit uses a correlation value indicating a relationship between the grip force of the fingers and position of fixing portions, the first grip force, and second grip force that is a target value of the grip force to calculate the position of the fixing portions in gripping the work W with the second grip force. In the changing the grip force, the hand controlling unit drives a motor by calculating a driving quantity of the motor necessary for moving the fingers to the calculated position of the fixing portions.