Tactile Robot Gripper Fingers for Recess Fitting Control

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Solution Overview

Problem

Existing robot hands face complexity in fitting objects into recesses due to the need for rotating and pressing with force sensors, complicating the structure and control.

Innovation Solution

An end effector device with a tactile sensor unit, comprising fingers, a palm, and a force-receiving portion with grasping and pressing surfaces, allowing for simple fitting by detecting forces and adjusting grip direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a force sense measuring device is provided at a portion of the robot hand that contacts with an object being grasped, then force sensing capability is improved, but the structure and control of the robot hand becomes complicated when fitting objects into recesses

Engineering Contradiction:
Improveforce sensing capabilityVSAvoidstructure and control complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The end effector is divided into multiple independent fingers, each equipped with its own tactile sensor unit. This segmentation allows each finger to independently sense and adjust to forces during the fitting operation, eliminating the need for complex centralized control while maintaining precise force sensing capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each finger is designed to perform multiple functions: grasping the object, sensing forces through the tactile sensor unit, and automatically adjusting orientation through compliant motion. The tactile sensor unit serves both as a force sensor and as part of the compliant mechanism that enables automatic orientation adjustment, reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the robot hand rotates about 90 degrees and presses the object with the force sense measuring device to fit it into a recess, then fitting capability is improved, but the control system becomes more complicated

Engineering Contradiction:
Improvefitting capabilityVSAvoidcontrol complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The finger structure incorporates compliant elements that allow dynamic adaptation to the recess geometry. The tactile sensor unit detects contact forces and the finger automatically adjusts its orientation and pressing motion through compliant motion, eliminating the need for complex rotational control sequences while maintaining high fitting capability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The tactile sensor unit provides real-time feedback on contact forces during the fitting operation. This feedback enables automatic control of the fitting process, where the system adjusts pressing force and orientation based on sensor readings, simplifying the control system compared to pre-programmed rotational sequences.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If the robot hand grasps the object and presses it against the recess opening edge, then fitting into the recess is enabled, but excessive load is applied to the fingers

Engineering Contradiction:
Improvefitting functionVSAvoidload on fingers
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The pressing function is localized to the tip portion of each finger, which is specifically designed to contact the recess opening edge. The tactile sensor unit is also positioned at the tip to locally sense pressing forces. This localized design concentrates the fitting function at the most effective point while distributing the load through the finger structure, reducing stress on other parts.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The tactile sensor unit detects contact with the recess opening edge before excessive force is applied. This preliminary detection allows the control system to adjust pressing force to the minimum required level, preventing excessive load on the fingers while still achieving the fitting function.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables efficient and durable fitting of objects into recesses with reduced load on the fingers, using tactile feedback for precise control and completion determination.

Implementation Method 1

a tactile sensor unit capable of detecting an external force from the object being grasped

Methodology Applied
Scientific EffectForce sensing: Force

Data Source

PatentEP3831552B1End effector device
Publication Date: 2026.03.04 OMRON CORP
  • EP3831552B1 patent drawingFigure 1
  • EP3831552B1 patent drawingFigure 2~3
  • EP3831552B1 patent drawingFigure 4~5

AI summary

The end effector includes a palm, a plurality of fingers capable of grasping operation of in which each of the plurality of fingers grasps an object being grasped, a tactile sensor unit capable of detecting an external force from the object being grasped, the tactile sensor being provided with each of the plurality of fingers, and a force receiving portion that receives a force from the object being grasped when the object being grasped is grasped by the plurality of fingers, the force receiving portion being connected to each of the plurality of fingers via the tactile sensor unit. The force receiving portion includes a grasping surface that receives a force from the object being grasped, the grasping surface being placed facing the object being grasped to be able to grasp the object being grasped, and a pressing surface that is placed further away from the palm than the second end portion of each of the plurality of fingers and extends in a direction intersecting the grasping surface.