Data for A three-row opposed gripping mechanism with bioinspired spiny toe pads

The two linear stages (X-LRM150A-E03-KX14A and X-LRM050A-E03-KX14A, Zaber Technologies Inc., Canada) generate linear motions in two orthogonal axis, which are parallel and perpendicular to the testing surface, namely the x- and y-axis respectively. Two sensors (LSM250, FUTEK Advanced Sensor Technology, Inc., USA) are connected to the y-axis linear stage, which measure the contact forces of a single spiny toe pad or a toe pad array in the x- and y- direction.

We chose sandpaper (P60 &P80, MATADOR Germany) as the testing surface to serve as a standard for experimental measurement. During the testing of the array, sandpaper was installed onto the acrylic board to fit the width of the array. The experimental procedure is as follows: The y-axis stage first moves a single toe pad or a toe pad array towards the sandpaper to a position where it just contacts the surface, namely the origin position.

Then, the y-axis stage presses a single toe pad or a toe pad array towards the sandpaper in the –y direction for a certain distance representing as yp, reaching the compression position. After that, the x-axis and y-axis stage drags and lifts a single toe pad or a toe pad array in +x and +y axis respectively. The speed of the tangential dragging expressed as vx=0.1mm/s and the normal lifting represented as vy={0.01, 0.02, 0.03, 0.04}[mm/s] to exert different path.

The test is repeated with different positions yp {0.2,0.4,0.6,0.8,1.0,1.2}[mm].