Robot Hand Sensor for Stable Viscoelastic Object Grip
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Solution Overview
Problem
Robot hands struggle to stably hold indefinite-shaped, soft, small, or slippy objects due to difficulties in maintaining a consistent holding force, especially with stretchy and flexible materials that exhibit viscoelastic behavior, leading to stress relaxation and potential object dropping.
Innovation Solution
A robot apparatus with an elastically deformable sensor portion and control device that includes a hand portion with two finger portions, each equipped with pressure detection elements, a signal generation section to adjust holding force based on sensor output and operation duration, and a viscoelastic body layer to improve detection accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stretchy and flexible materials are used in the sensor to detect holding force, then the sensor can detect pressure effectively, but the viscoelastic behavior causes the holding force to decrease over time (stress relaxation)
Solution Approach 1:
The control device continuously monitors the sensor output and adjusts the holding force in real-time based on feedback from the viscoelastic sensor portion, compensating for stress relaxation effects and maintaining stable holding force throughout the operation
Solution Approach 2:
The system dynamically changes the holding force parameter over time by introducing a correction value that increases with operation duration, counteracting the natural stress relaxation of the viscoelastic material and maintaining constant grip force
2Reliability
If the robot hand applies sufficient holding force to prevent dropping, then object security is improved, but the dead-zone region increases and measurement precision decreases
Solution Approach 1:
The control device uses real-time feedback from the sensor portion to continuously adjust and optimize the holding force, ensuring the object is securely held while maintaining precise pressure detection by operating within the optimal sensing range
Solution Approach 2:
The holding force is dynamically adjusted during operation rather than maintained at a fixed high value, allowing the system to optimize between security and measurement precision by increasing force only when necessary based on real-time sensor feedback
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
The solution enables the robot hand to maintain a stable holding force, reducing the dead-zone region and effectively preventing object dropping by accurately detecting pressure and shear forces, even with viscoelastic materials, thus ensuring reliable grip and handling of diverse objects.
Implementation Method 1
a separation layer that is disposed between the first pressure sensor and the second pressure sensor and is made of a viscoelastic material that is deformed by a load applied to the first pressure sensor
Implementation Method 2
Each of the first pressure sensor and the second pressure sensor may include a sensor electrode layer including a plurality of capacitive elements two-dimensionally disposed in a plane parallel to the holding surface, a reference electrode layer, and a deformation layer disposed between the sensor electrode layer and the reference electrode layer
Data Source
AI summary
A robot apparatus according to an embodiment of the present technology includes a hand portion, an elastically deformable sensor portion, and a control device. The hand portion includes at least two finger portions each having a holding surface capable of holding a workpiece. The sensor portion is disposed on the holding surface of at least one finger portion of the two finger portions and includes a plurality of detection elements that detects a pressure acting on the holding surface. The control device includes a signal generation section capable of generating a hold command to cause the hand portion to hold the workpiece with a predetermined holding force and capable of correcting the holding force on the basis of an output of the sensor portion and a duration of an operation of holding the workpiece.