Geometric Design-based Dimensional Synthesis of a Novel Metamorphic Multi-fingered Hand with Maximal Workspace

Current research on robotic dexterous hands mainly focuses on designing new finger and palm structures,as well as developing smarter control algorithms.Although the dimensional synthesis of dexterous hands with traditional rigid palms has been carried out,research on the dimensional synthesis of dexterous hands with metamorphic palms remains insufficient.This study investigated the dimensional synthesis of a palm of a novel metamorphic multi-fingered hand,and explored the geometric design for maximizing the precision manipulation workspace.Different indexes were used to value the workspace of the metamorphic hand,and the best proportions between the five links of the palm to obtain the optimal workspace of the metamorphic hand were explored.Based on the fixed total length of the palm member,four nondimensional design parameters that determine the size of the palm were introduced;through the discretization method,the influence of the four design parameters on the workspace of the metamorphic hand with full-actuated fingers and under-actuated fingers was analyzed.Based on the analysis of the metamorphic multi-fingered hand,the symmetrical structure of the palm was designed,resulting in the largest workspace of the multi-fingered hand,and proved that the metamorphic palm has a massive upgrade for the workspace of underactuated fingers.This research contributed to the dimensional synthesis of metamorphic dexterous hands,with practical significance for the design and optimization of novel metamorphic hands.

A novel line-symmetric Goldberg 6R linkage with bifurcation property

This paper proposes a novel reconfigurable Goldberg 6R linkage,conformed to the construction of variant serial Goldberg 6R linkage,while simultaneously satisfying the line-symmetric Bricard qualifications.The isomeric mechanism of this novel reconfigurable mechanism is obtained in combination with the isomerization method.The geometrically constrained conditions result in variable motion branches of the mechanism.Based on the singular value decomposition of the Jacobian matrix,the motion branches and branch bifurcation characteristics are analyzed,and the schematics of bifurcations in joint space is derived.This novel 6R linkage features one Goldberg 6R motion branch,two line-symmetric Bricard 6R motion branches,and one Bennett motion branch.With regards to the line-symmetric Bricard 6R motion branches,a similar function for the disassembly and recombination process can be achieved by reconstructing an intermediate configuration through bifurcation.Then,the isomerized generalized variant Goldberg 6R linkage is explicated in a similar way.Acting as a bridge,reconfigurability connects two families of overconstrained mechanisms.

Trot Gait with Twisting Trunk of a Metamorphic Quadruped Robot

This paper proposes a metamorphic quadruped robot with a moveable trunk, called Origaker I. From the angle view of bionics, the robot can imitate the natural quadrupeds to twist its trunk. As we all know, most natural quadrupeds twist their trunk when running. The twisting trunk must bring significant benefits to their locomotion. Nevertheless there are few researches focusing on running gaits with twisting trunk of quadruped robots. Therefore, this paper investigates the trot gait with twisting trunk. One gait cycle of a lizard with twisting trunk is observed. Apart from the observation, the gait is designed based on the Zero Moment Point （ZMP） method and by con- sidering three points related to the twisting trunk. A simulation and an experiment are carried out to verify the efficiency of the trot gait with twisting trunk. It is found that the twisting trunk helps the quadruped robot get larger stride length and further perform higher lo- comotion speed than that with rigid trunk.