# Multi-Mode Compound Grasping Robot Finger Driven by Linkage
###### Abstract
[21] present a study on real-time myoelectric control of multi-fingered hand prostheses using principal component analysis, hybrid flexible robotic gripper mechanism presented by [22] allows for improved grasping capabilities, including the implementation of a power grip through the sequential movement of the rigid link and the flexible mechanism. This mode allows the robotic hand to initially adopt a coupling motion, where both joints rotate in the same direction, and the distal phalanx rotates faster than the proximal phalanx. Upon contact with the object, the hand automatically switches to the self-adaptive grasping mode, enabling the distal phalanx to rotate until it touches the object. This results in a more anthropomorphic and stable grasp, increased grasping efficiency, and more reasonable force distribution [23; 24]. This mechanism has been extensively studied and developed by researchers, leading to several publications such as the COSA-FBA hand with five-gear mechanisms and built-in actuators [25], and the COSA-LET finger with a linear empty-trip transmission [26]. Applications of the COSA finger in humanoid robotic hands have demonstrated its potential to improve grasping performance [27; 28]. Similarly, the parallel self-adaptive grasping mode (PASA mode) combines the strengths of parallel and self-adaptive grasping mechanisms. A single-actuator gripper utilizing a crawler on the fingertip is proposed, enabling the lifting of thin objects and transitioning between grasp modes passively [29]. Ref. [30] introduces a parallel and self-adaptive underactuated finger with novel belt and cam-link mechanisms. The Velo gripper [31] demonstrates the ability to perform parallel, enveloping, and fingertip grasps using single active tendon actuation and passive adaptation for increased versatility. In this mode, the robotic hand initially adopts a parallel grasping motion, maintaining the posture of the distal phalanx relative to the base. Upon contact with the object, the hand automatically switches to the self-adaptive grasping mode, enhancing the practicability and versatility of the finger [32]. Changing the initial position of each finger joint during grasping is called gesture-changeable [33; 34]. The gesture changeable grasping mode includes self-adaptive grasping and pre-bending action functions. Before grasping the object, the mechanism can flexibly adjust the ready posture (initial configuration) of the finger to hold the object according to the size and shape of the object. The second motor is added to the self-adaptive underactuated finger to obtain more dexterity. This kind of finger adds the function of flexible changing position to the original self-adaptive underactuated finger, forming a more dexterous underactuated finger. Traditional robotic hands face challenges due to their complexity, sensing, control, and high costs. Underactuated fingers, such as parallel, coupling, and self-adaptive fingers, have been developed to address these limitations but still exhibit constraints in grasping capabilities. To overcome these issues, this paper introduces a novel multi-mode compound grasping robot finger driven by linkage (MCG finger), capable of performing six distinct grasping modes, including parallel (PA), coupling (CO), middle phalanx self-adaptive (M-SA), distal phalanx self-adaptive (D-SA), proximal gesture-changeable (P-GC), and distal gesture-changeable (D-GC), as well as their combinations. The MCG finger addresses the challenges faced by traditional dexterous hands by offering a versatile and adaptable solution with reduced complexity and cost. With its versatile range of motion, the MCG finger has a wide range of potential applications in industrial manufacturing [35], hand rehabilitation [36], medical treatment [37; 38], military robots [39], and other scientific fields.