University of Twente Student Theses


3D printed interaction force sensors for robotic fingers

Doshi, Ajinkya Ajaykumar (2021) 3D printed interaction force sensors for robotic fingers.

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Abstract:The field of 3D printing has seen recent advancements in fabricating sensors for a large number of applications- biosensors, strain, pH, tactile, temperature sensors, to name a few. 3D printed sensors give the advantage of on-demand manufacturing, high modularity, batch production, among others. Additionally, structures with sensors embedded in them can be manufactured with this method. In this assignment, flexible fully 3D printed interaction force sensors are designed and fabricated for the Pisa/IIT SoftHand 2. Implementing force sensors on the robotic hand gives important tactile information while performing basic in-hand manipulation tasks, such as object grasping. The sensors are iteratively designed, and the final design is fabricated with PLA, TPU and e-TPU. The sensor is designed such that it mounts over the SoftHand fingers and consists of two strain gauges on opposite sides. Next, the behavior of the material is experimentally studied in order to characterize the sensors. The material is strained cyclically and the change in resistance is recorded. It is shown that these materials are intrinsically nonlinear and a relation between strain-resistance change is obtained. The sensor is then characterized using a finite element model and a measurement setup that applied shear and normal force up to 10 N. The sensor can detect normal force and can distinguish between the direction of shear force. However, the normal force and shear force components could not be separated. Finally, a setup is developed for using the sensor on the SoftHand. Experiments are performed to demonstrate the applicability of the sensor. It is shown that the sensor can detect grasping and slip of objects from the SoftHand. We conclude with showcasing the possibility of using the sensors in an open-loop control of the SoftHand.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:52 mechanical engineering
Programme:Systems and Control MSc (60359)
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