Spatial Position Estimation of Lightweight and Delicate Objects using a Soft haptic Probe

This paper reports on the use of a soft probe as a haptic exploratory device with Force/Moment (F/M) Readings at its base to determine the position of extremely lightweight and delicate objects. The proposed method uses the mathematical relationships between the deformations of the soft probe and the F/M sensor outputs, to reconstruct the shape of the probe and the position of the touched object. The Cosserat rod theory was utilized in this way under the assumption that only one contact point occurs during the exploration and friction effects are negligible. Soft probes in different sizes were designed and fabricated using a Form3 3D printer and Elastic50A resin, for which the effect of gravity is not negligible. Experimental results verified the performance of the proposed method that achieved a position error between of -0.7-13mm, while different external forces (between 0.01N to 1.5N) were applied along the soft probes to resemble the condition of touching lightweight objects. Eventually, the method is used to estimate position of some points in a delicate card house structure.