# Electromagnetic Switching Multiple Grasping Modes Robot Hand
## 6 Experiments of the ESMGM Hand
### Grasping Forces Analysis Experiments  
To verify the grasping force of the ESMGM hand, several grasping experiment scenarios are settled for validation experiments. The membrane pressure sensors are attached to each phalange, and the grasping forces are exerted through the elastic element to ensure the stability and uniformity of forces. The three grasping experiment scenarios are shown in Figure 23. In scenario 1, the ESMGM hand grasps the rectangular object with parallel grasping mode. The size of the object is 80 mm \(\times\) 60 mm. In scenario 2, the ESMGM hand grasps the screwdriver with coupled grasping mode; the diameter of the contact part is 12 mm. In scenario 3, the ESMGM hand grasps the cylindrical object with PASA mode and COSA mode, respectively; the diameter of the cylindrical object is 80 mm.  
During the experiments, the variety of grasping forces of the distal and proximal phalanges have been recorded and shown in Figure 24. For statistical analysis of several key parameters when the ESMGM robot hand realizes stable grasping of the objects, six validation experiments with the same group of configurations are performed, and the mean values and standard deviations of the measured parameters are calculat  
Figure 23: Grasping experiments scenarios: (**a**) Grasping experiment with parallel mode; (**b**) Grasping experiment with coupled mode; (**c**) Grasping experiment with PASA mode and COSA mode.  
Figure 22: ESMGM hand grasping experiment.  
Figure 24: Grasping experiments results: (**a**) Grasping force of distal phalange in experiment scenario 1; (**b**) Grasping force of distal phalange in experiment scenario 2; (**c**) Grasping force of proximal phalange in experiment scenario 3; (**d**) Grasping force of distal phalange in experiment scenario 3; (**e**) Grasping force of proximal phalange in experiment scenario 4; (**f**) Grasping force of distal phalange in experiment scenario 4.  
The above results in Figure 24 and Table 3 indicate that the variety of grasping forces under different grasping modes in experiments is consistent with the theoretical analysis results despite some differences. Considering friction, assembly error, and other factors, this is acceptable. In addition, through many experiments, some key properties of the ESMGM hand have been measured and recorded in Table 4. The test results of key properties in the grasping process also reflect the excellent characteristics of the ESMGM robot hand, such as its fast response, large grasping space, and adequate grasping force.  
Table 5 shows the grasping performance of the ESMGM hand compared with some other gripers. The biggest advantage of the ESMGM robot hand is that it integrates three typical grasping modes by using a specifically designed switchable underactuated mechanism. Thus, it has a versatile grasping function and a strong adaptive ability for different shapes, sizes, and materials. At the same time, compared with the current mainstream gripers on the market, it has a relatively large grasping stroke, sufficient grasping force, good grasping stability, fast response, and smooth grasping motion. The ESMGM robot hand still has disadvantages; for example, the size is slightly larger than a human hand, the weight is slightly heavier, and the accuracy of grasping is slightly worse than the Barret hand, all of which need to be further improved.