Tactile-Sensing End Effector for Grasp Shift Correction
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Solution Overview
Problem
The slide type chuck struggles to correct position shifts of a grasped object when the contact force between the fingers and the object is not uniform, leading to difficulties in accurately inserting the object into another part.
Innovation Solution
An end effector device with a palm and fingers equipped with tactile sensors that detect external forces in three axial directions, allowing for determination of position shifts and correction by moving the palm in the opposite direction of the shift to align the object with a fitting recess.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the contact force between all the fingers and the grasped part is not uniform, then the slide type chuck cannot correct the position shift of the grasped part, but increasing contact force uniformity would require additional control complexity
Solution Approach 1:
The patent employs feedback control by using tactile sensors to detect contact forces between fingers and the grasped object, then using this information to adjust finger positions and correct object position shifts. The control unit continuously monitors contact force states and modifies gripping actions based on detected deviations, creating a closed-loop system that improves positioning accuracy without requiring overly complex mechanical structures.
Solution Approach 2:
The patent replaces complex mechanical positioning mechanisms with a control-based system that uses tactile sensing and software algorithms to achieve precise positioning. Instead of relying on mechanically perfect uniform contact forces, the system uses sensors and control logic to detect and correct position shifts, substituting mechanical complexity with intelligent control.
2Manufacturing precision
If the slide type chuck controls contact force to be uniform to enable accurate insertion, then positioning accuracy improves, but the insertion time increases due to additional correction operations
Solution Approach 1:
The patent applies preliminary action by performing position correction operations before the final insertion step. The tactile sensors detect contact forces during the approach phase, and the control unit corrects position shifts while the object is still being approached, rather than after contact is made. This preliminary correction prevents the need for time-consuming post-contact adjustments, maintaining both accuracy and speed.
Solution Approach 2:
The patent ensures continuity of useful action by making the position correction process occur continuously during the approach and grasping phases, rather than as separate discrete steps. The tactile sensors continuously monitor contact forces, and corrections are made in real-time as part of the normal grasping motion, eliminating idle time between detection and correction operations.
3Measurement precision
If tactile sensors are added to detect external forces in three axial directions, then position shift detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by designing the tactile sensor system to serve multiple functions: detecting contact force magnitude, determining contact direction, identifying position shifts, and providing feedback for control adjustments. The same three-axis force sensors used for basic force measurement are also utilized for position shift detection and correction control, eliminating the need for separate sensor systems and reducing overall complexity.
Data Source
AI summary
The end effector device includes an end effector including a palm and a plurality of fingers, a drive device, a position shift direction determination unit and a position shift correction unit. Each finger includes a tactile sensor unit capable of detecting external forces in at least three axial directions. The position shift direction determination unit determines in which direction the object being grasped is position-shifted with respect to the fitting recess based on a detection result detected by the tactile sensor unit in a case where at least one of the external forces detected by the tactile sensor unit is a specified value or more. The position shift correction unit moves the palm in a direction opposite to a position shift direction of the object being grasped determined by the position shift direction determination unit.