Moreover, the slope fitted by adopt

Moreover, the slope fitted by adopting the least-squares linear fits of the laser sensor hysteresis-loop data is depicted in figure 13(c). As shown in figure 13(c), the output displacement of the microgripper was approximately 213.9 μm, and the gripping range was 427.8 μm. Assuming that the PSA could deliver a maximum input displacement of 10 μm at the drive voltage of 75 V, the amplification ratio of the microgripper was derived as 21.4. Compared with the amplification ratio predicted by Eq. (6), the measured amplification ratio was smaller. The discrepancy arose from the fact that the assumed ideal flexure hinges deviate from the ideal position in the prototype.To verify the calibration result of the strain-gage force sensor, forces of 10 mN, 20 mN and 50 mN were separately exerted to the microgripper. The relationship between the force sensor voltages and the gripping forces are illustrated in figure 14. As shown in figure 14, the theoretical slope predicted by the force calibration result and the measured slope were 2.062 mN/mV and 2.213 mN/mV, respectively. Hence, the relative error was 7.3%. The force sensor could accurately measure the gripping force of the microgripper.