# Electromagnetic Switching Multiple Grasping Modes Robot Hand
The Robotiq underactuated hand has a compact design, low weight, easy control methods, but good general grasping ability. Its design concept is very efficient, and simple mechanical transmission can meet most operating requirements; however, its functions and diversity must be further developed for more complex operations. In addition, some underactuated hands have developed the coupled grasping mode, forming the coupled and self-adaptive robot hands, such as the Southampton hand [20], Manus hand [21], and ASIMO hand [22; 23]. They have endowed the robot hand with more anthropomorphic action characteristics and more detailed handling methods; however, the power and stability of the coupled grasping are limited. The TH-hand series [24; 25; 26] of Tsinghua University have realized the adaptive grasping of objects with different driving methods; they not only enrich the theoretical basis of underactuated robot hands but also give robot hands better performance. Polytechnique Montreal proposed a parallel-drive 3-DOF underactuated finger [27], which enhanced the performance and the versatility of underactuated hands. Cornell University used flexible materials to make a flexible gripper [28], which greatly improves the adaptability of underactuated hands. Driven by the above achievements, underactuated robot hands have made great progress, but disruptive changes are still needed to change their shortcomings of insufficient functions. After years of development, coupled grasping mode, parallel grasping mode, and self-adaptive grasping mode are three common and typical grasping modes [29]. With the continuous innovation of technology and science, most underactuated robot hands with a single drive source can include two grasping modes [30]. The Barrett hand [31], Yale Multi-grasp Hand [32], GR2 gripper [33], PASA hand [34; 35], LISA hand [36], DISA hand [37], and CISA-LS hand [38] of Tsinghua University are some of the best examples. Based on the concept of grasping modes integration, these achievements greatly expand the functions and applications of underactuated robot hands; they achieve multi-functional composite while ensuring good performance. Tsinghua University is constantly exploring ways to integrate various grasping modes, and their latest achievement, the COPASA hand [39], integrates three grasping modes into a three-joint finger, though its size is too large, and its grasping performance is limited. In the current development trend, people hope that robot hands have versatility and multifunction. To make the function of robot hands more powerful, robotics researchers are also committed to developing multi-grasping mode robot hands. Among the current achievements, the underactuated robot hands, which integrate two kinds of grasping modes, are common to see. However, integrating three common grasping modes (parallel grasping mode, coupled grasping mode, and self-adaptive grasping mode) is still hard work. This is not only because the integration requires abundant work but also because the three grasping modes are somehow mutually exclusive. Given this phenomenon, this paper conceives a switchable fusion method and then develops an ESMGM hand that combines the three typical grasping modes mentioned above. In the following sections of this paper, the ESMGM hand will be introduced in detail. Section 2 will give the design concept, Section 3 will describe the concrete structure of the ESMGM finger and ESMGM hand, Section 4 will analyze the properties of the grasping performance, Section 5 will present the prototype and the experimental results of the ESMGM hand, and finally, Section 6 will give the conclusion and prospects.