Rubber Piezoelectric Sensor for Fast Gripping Force Detection
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Solution Overview
Problem
Piezoelectric pressure-sensitive sensors, like those using PVDF, suffer from reduced sensitivity due to their stiffness, requiring time to deform and generate a voltage signal upon contact, especially when gripping soft objects, leading to delayed pressure detection and potential object damage.
Innovation Solution
A pressure-sensitive sensor with a pair of electrodes and an intermediate layer formed of rubber or rubber composition that deforms to generate electricity upon contact, offering higher sensitivity and faster signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF is used as a piezoelectric material for pressure detection, then the sensor does not require a power supply and has flexibility, but the Young's modulus is about 2 GPa which is considered stiff, causing delayed deformation and reduced pressure detection sensitivity at contact
Solution Approach 1:
The patent changes the material parameter from PVDF (Young's modulus 2 GPa) to rubber materials (Young's modulus 0.01-1 MPa), achieving a reduction of approximately 3 orders of magnitude in stiffness. This parameter change enables the sensor to deform rapidly upon contact, outputting voltage signals within 1 millisecond, thereby resolving the contradiction between reliability and speed in pressure detection
2Productivity
If PVDF is used for pressure-sensitive sensing, then the sensor is self-powered, but the stiffness of the material requires time to deform under load, leading to detection delays especially when gripping soft objects
Solution Approach 1:
The patent changes the material parameter from PVDF (Young's modulus 2 GPa) to rubber materials (Young's modulus 0.01-1 MPa), achieving a reduction of approximately 3 orders of magnitude in stiffness. This parameter change enables the sensor to deform rapidly upon contact, outputting voltage signals within 1 millisecond, thereby resolving the contradiction between reliability and speed in pressure detection
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 sensor achieves high pressure detection sensitivity upon contact, reducing the risk of object damage and enabling gripping speeds comparable to human sensation, while being power-free and resistant to detection delays.
Implementation Method 1
an intermediate layer between the pair of electrodes, the intermediate layer being formed of rubber or a rubber composition and configured to generate electricity when deformed by contact with a target object
Data Source
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AI summary
A gripping device 18 is provided at the front end of an arm of an assembly robot 2. The gripping device 18 includes a pair of grippers 20 and 22 capable of opening and closing. The side configured to come into contact with a part 4, of each gripper 20, 22 includes a pressure-sensitive sensor 24. The pressure-sensitive sensor 24 includes a first electrode and a second electrode serving as a pair of electrodes and an intermediate layer formed of rubber or a rubber composition between the pair of electrodes. The intermediate layer is configured to generate electricity when deformed by contact with an object (part 4). The side configured to come into contact with the object, of the intermediate layer is subjected to a surface modification treatment and has a higher hardness than the opposite side.