An experimental methodology of force transmission analysis

Our experimental methodology of force transmission analysis was planned in two different stages. The first is to analyze the force transmission characteristics of each of the low-cost surface coating materials produced when kept under the constant weight. For this, a 0.2″ diameter force-sensing resistor (FSR) (Interlink Electronics, 2010) was placed on a fixed platform and then covered with the produced materials. Constant weight was applied to the outlined test setup by an increasing load from 10 g to 190 g in 20 g increments. Thus, the force transmission characteristics of each produced material were observed and analyzed under the constant weight.

In Eq. (1), R_M is the measuring resistor (kΩ), R_FSR is the force-sensing resistor (kΩ), V_i is the input voltage (V), and V_out is the output voltage (V). The slope angle (α) between V_out (V) and force (g) is 0.001795 π/rad (Interlink Electronics, 2010). A V_i of +5 V and R_M of 3 kΩ was used. Equation (2) was used to transform V_out to F_measure. Equation (2) was calculated by using the catalog values of the sensor (Interlink Electronics, 2010).

The second stage was to analyze the force transmission characteristics during grasping for each of the low-cost surface coating materials produced. To analyze the grasping force, a two-fingered gripper, which is Model T42 (Ma & Dollar, 2017) was built with (Interlink Electronics, 2010). Subsequently, three different kinds of objects were used to measure the force feedback value of the FSR. These were a plastic sphere, an anti-static sponge rectangle prism, and a wood rectangle prism. The condition shown in Eq. (3) was applied to fix the position of the actuator of the gripper. Equations (1) and (2) were again used to transform V_out to F_measure. In Eq. (3), F_i refers to the measured value of the grasping force (F_measure) at i time.