Zhenlin Jin

New kinematic structures for 2-, 3-, 4-, and 5-DOF parallel manipulator designs

In this paper, several types of composite pairs and new kinds of sub-chains (limbs or legs) with specific degrees of freedom are proposed. Based on the special Plucker coordinates for describing the displacement of the output link of a limb, the principle for design of structures of parallel robotic mechanisms is presented. And several new types of 2-, 3-, 4- and 5-DOF parallel robotic mechanisms are obtained.

Optimum design of 3-DOF spherical parallel manipulators with respect to the conditioning and stiffness indices

This paper concerns the use of evaluation criteria, such as, the conditioning index, the stiffness to select the link lengths of 3-DOF spherical parallel manipulators (3-DOF SPMs) and analyze their operational performance. The atlases of the global conditioning index and the global stiffness index are obtained in the solution space to optimize the link lengths of 3-DOF SPMs; the dexterity and stiffness maps of the manipulators are presented to analyze the operational performance, from which we can see that the global or local conditioning index is identical with global or local stiffness index. A method for obtaining these maps for 3-DOF SPMs is presented. The maps will reveal the existence of zones where the stiffness is not acceptable and will also help the designer by proving a more accurate representation of the properties of the manipulator. The technique has wide application in the design of the serial and parallel robots.

Type synthesis of parallel mechanisms having the first class gf sets and one-dimensional rotation

A method is presented for the type synthesis of a class of parallel mechanisms having one-dimensional (1D) rotation based on the theory of Generalized Function sets (GF sets for short), which contain two classes. The type synthesis of parallel mechanisms having the first class GF sets and 1D rotation is investigated. The Law of one-dimensional rotation is given, which lays the theoretical foundation for the intersection operations of GF sets. Then the kinematic limbs with specific characteristics are designed according to the 2D and 3D axis movement theorems. Finally, several synthesized parallel mechanisms have been sketched to show the effectiveness of the proposed methodology.

State Classification for Human Hands

The human hand, which is a perfect model for dextrous hands, is a masterpiece of mechanical complexity. A full understanding of the human hand will provide more inspiration for the successful implementation and application of dextrous hands. The purpose of this paper is two-fold. First, the characteristic tree of the human hand is established for kinematic characteristics analysis. Second, a systematic classification for the human hand states is issued from the view point of topology. Moreover, the kinematic characteristics of the palm or finger tips are achieved via the Generalized Function (GF) set theory with the aim of achieving deeper insight into the capabilities of the human hand. Finally one application example is given to show the effectiveness of the exploitation of the GF set theory and the usefulness of this methodology for dextrous hands.

Modeling and experiment of a planar 3-dof parallel micromanipulator

In this paper, a planar 3-DOF XYγ parallel micromanipulator with monolithic structure is presented. The micromanipulator is driven by three piezoelectric (PZT) actuators. To achieve highly accurate control, a new approach investigating the relationship among input-force, payload, stiffness, and displacement (IPSD model) of the XYγ micromanipulator is proposed in analytical style, and the analytical expression of the relationship between driving voltages of PZT actuators and outputs of end-effector is deduced based on the IPSD model. Finally, in order to verify the IPSD model, the simulations by finite element method and experiment are performed. The micromanipulator can be used to do microtasks that need the manipulator perform only planar motion, such as microoperation and microassembly, and the proposed IPSD model is useful for both digital control and design of the XYγ micromanipulator.

State classification for humanoid robots

In this paper, we decouple the motion-planning problem of humanoid robots into two sub-problems, namely topological state planning and detailed motion planning. The state classification plays a key role for the first sub-problem. We propose several basic states, including lying, sitting, standing and handstanding, abstracted from the daily exercises of human beings. Each basic state is classified further from the topological point of view. Furthermore, generalised function GF set theory is applied with the aim of analysing the kinematic characteristics of the end effectors for each state, and meaningful names are assigned for each state. Finally a topological state-planning example is given to show the effectiveness of this methodology. The results show that the large amounts of states can be described using assigned names, which leads to systematic and universal description of the states for humanoid robots.

Classification of Standing States for the Humanoid Robot SJTU-HR1

The humanoid robot platform, SJTU-HR1, is developed to function within the human-centered environment, which means that it is necessary to study the human-robot interaction, robot-robot interaction, robot-environment interaction, and robot self-interaction. To solve the issue of robot-environment interaction and robot self-interaction, this study presents the state classification from the topological point of view for the SJTU-HR1, particularly the standing states. The generalized function set (GF set for short) theory is exploited to achieve the characteristics of the end-effectors of interest of the SJTU-HR1 for each specific standing state, which can provide deeper insight into the capabilities of the SJTU-HR1. One application example is given to show that the proposed methodology can simplify and clarity the complicated state planning issue for humanoid robots. Moreover, the standing states, including robot-environment interaction and robot self-interaction, can be described using the meaningful notations sufficiently. Although we have focused on the application of the GF set theory on the humanoid robot platform SJTU-HR1, this methodology can also be applied to other biped robots and quadruped robots.