Overall Structure - This is a strain-gauge-based three DOF force sensor which can provide 3 axis force vector for the controller by measuring the force real time. I accomplished the whole design of force sensor system including mechanical, circuit and software design.
This force sensor won the Gold Medal in the competition of Outstanding Undergraduate Thesis of Jiangsu Province in 2009.
The Mechanical structure of this sensor is composed of four parts: elastic body, pedestal, sealing cover and chassis.
Elastic Body - The structure design of the elastic body of the force sensor is the core technology which may affect the performance of the sensor. A spoke-type elastic body, which consists of the center support, cross elastic beam, compliant beam and the rigid rim, has been adopted. The elastic body can detect the force information in three DOF space. And the applied force is transferred to the elastic beam through the axle which is fixed in the center support.
Finite Element Analysis - In order to study the mechanical characteristic of the elastic body of the three DOF force sensor, software ANSYS is adopted for the Finite Element Analysis of the elastic body.
I analyzed the spoke-type elastic body which consists of the center support, cross elastic beam, compliant beam and rigid rim. Then I calculated the static couple under three force components with a reasonable finite element computation model, and appraised the rationality of the structure.
Measuring Principle - Take the single force in X or Y direction as an example. When a single force in X or Y direction is applied to the elastic body through the center, deformation of stain gauges happens on the lateral surface of the cross beams. Thus, the force in X or Y direction can be measured by Hilton Bridge Circuit which is composed of strain gauges on the lateral surface of cross beams. The aboved figure shows the deformation condition of elastic body when a single force in X direction is applied.
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