A Novel 3-DOF Parallel Robot and its Kinematic Analysis

Screw theory was introduced and inducted to the statics analysis and calculation of 6-DOF (Degree of Freedom) parallel robot. Based on the scheme, a 6-DOF parallel robot--hydraulic Stewart test platform was checked specially. The results reveal that, the platform design is appropriate, the analysis procedure is concise and the calculation operation is simple and convenient.

A novel 6-degree-of-freedom (6-DOF) parallel robot driven by six novel linear motors is designed and controlled in this paper. Detailed structures of linear motors are illustrated. A control strategy based on kinematics of the 6-DOF parallel robot is used, and six linear motors are controlled to track their own desired trajectories under a designed fractional-order active disturbance rejection controller (FOADRC). Compared with the normal ADRC, two desired trajectories and three different working situations of a linear motor are simulated to show good performances of the FOADRC. Experimental results show that six linear motors can track their own desired trajectories accurately under payloads and disturbances, and the novel 6-DOF parallel robot can be controlled well.

A computer-aided geometry approach for solving type design and performance analysis of 4-DOF parallel mechanism is put forward. By using the geometric constraint, the dimension constraint, the dimension equation and the dimension driving techniques of CAD, some simulation mechanisms of the novel 4-DOF parallel robot are created. When the driving dimensions of driving limbs are modified, the configuration of the simulation mechanisms are varied correspondingly, and the kinematic parameters of the moving platform are solved. The equation of forward and inverse displacement is established by the analytical result. The results of computer simulation prove that the computer aided geometric approach is not only fairly quick and straightforward, but also has the advantages of accuracy and repeatability. It also can conducted kinematic analysis of spatial parallel mechanisms without complicated analytics and program.

In the last years, due to the advantages presented by Delta 3 DOF parallel structure robots, they have been used in the field of high accuracy mechanical processing. In this field, it is demanded that the manufacture of components present high quality. The positioning accuracy for the parallel structure Delta 3 DOF robots can be affected by errors entered from the mechanical structure or by the control and command system. The accuracy class in which the mechanical elements are manufactured can affect the positioning accuracy within the robots with Delta 3 DOF parallel structure. In this paper, the authors study the ways in which the dimensional deviations of the kinematic elements influence the positioning accuracy. The method which is used correlates the dimensional deviations with the positioning accuracy. Therefore, the positioning accuracy of the Delta 3 DOF robots can be established within the design process.

This paper presents a novel 6-dof cable-driven parallel robot driven by eight cables and raises the method of designing the 6-dof configuration of the robot. As the basis, the static equilibrium model of the robot is obtained. Based on the achievements of predecessors, the wrench closure workspace (WCW) of the robot is analyzed, and the steps of analyze the translational and rotational WCW are presented. Through the translational WCW analysis of the robot, it reveals the relationship between the dimensions of the cable-driven robot and the translational WCW, which provides a guide to design the cable-driven robot oriented to workspace requirements.

A sliding mode controller with an integral-operation switching surface for 2- DOF parallel robot, which is derived by AC servo motors, is designed in this paper. Firstly, the variable structure controller with an integral operation switching surface is proposed to make the system of the parallel robot possess the properties of the insensitivity to the uncertainties and external disturbance. Next, the adaptive law is designed to achieve the online identify estimation of the system uncertainties of the parallel robot. Simulation results show that, by adopting the proposed control method in the parallel robot control system, the chattering of the conventional sliding mode control is alleviated, the practicability of the control system is improved through adjusting the controller's parameters timely in terms of the identified results and the control system has a perfect robust performance.

The paper presents design and control simulations of ISOGLIDE3 parallel robot. An innovative user interface for high-level control of a 3 DOF parallel robot is also pre-sented. The robot interface using virtual reality was veri-fied and tested, and results in MATLAB, Simulink, and SimMechanics were presented. The ISOGLIDE3 robot offers the superior characteristics with regards to the other parallel manipulators, such as the light weight construc-tion. The presented 3 DOF parallel robot can be used for surgery due to its overall precision, good dynamic behav-ior.

The concept of a medical parallel manipulator device applicable to chest compressions in the process of cardiopulmonary resuscitation (CPR) is proposed in this paper. According to the requirements of CPR action, a new translational parallel manipulator (TPM) is designed for such applications. And a thorough kinematic analysis and optimization are performed for the designed TPM. The mobility of the manipulator is analyzed using screw theory. The inverse kinematics and forward kinematics problems' are solved in details and the singularities are investigated afterwards. Utilizing a numerical search method, the manipulator workspace has been generated with the consideration of factors from medical aspects. The architectural optimization has been carried out based on a mixed performance being a weighted sum of global dexterity index and space utility ratio index, and the simulation results are presented. The research work provides a sound base for the development of a medical manipulator to assist in CPR operation.

In this paper, kinematic analysis and motion planning of a quadruped robot are presented by regarding the robot as an equivalent parallel platform-type mechanism with RRRS limb structure. Based on screw theory, the mobility of the quadruped robot with different touchdown legs is analyzed, and proves that the design for degree of freedom (DOF) is available. Base on the established kinematic model of a single leg in terms of POE formula of screw theory, several typical patterns of walking motion planning are implemented and verified by the ADAMS-based simulation. In order to show a good maneuverability and potential manipulation capability of the quadruped robot as a parallel manipulator, the gait planning reflecting two rotating motion patterns (including the rotating motion and walking motion) is modeled and simulated by kinematics of the equivalent parallel manipulators. Finally, a prototype of the quadruped robot has been built. Experimental test shows the practical walking and rotating ability as desired.

This paper focuses on the systematic type synthesis of parallel robot manipulators by using new structural formulas based on the screw theory. New structural formulas as a total number of screw in kinematic pairs , number of screws with variable pitch , total number of screws that represent the contact geometry of lower and higher joint elements (t), mobility equation for robot manipulators (M), dimension of the closed loop , motion of end effector of parallel manipulator , number degree of freedom of kinematic pairs , refers to find the kinematic structure of robot manipulators realizing a specified motion requirement. Twenty kinematic pairs with structural parameters are introduced. History of six structural formulas using for structural synthesis of parallel robot manipulators from space and different subspaces are presented as a table with equations, authors, years and some commentaries. The structural synthesis approach is based on the elementary notions of screw theory. Using the proposed of structural formulas approach, families of platform manipulators are constructed from a set of structural units. This paper is appropriate for engineers with interest in robotics, rovers, space docking parallel manipulators and screw theory.

Analysis of a novel cylindrical 3-DoF parallel robot

Kinematic analysis and error modeling of TAU parallel robot

This paper introduced an original setup for the validation of vision-based position control methodologies dedicated to 6-DoF Cable-Driven Parallel Robots. The cable robot is an INCA 6D with eight cables initially developed by Haption as a haptic interface, equipped with a motion-capture system Bonita developed by Vicon to measure the end-effector pose. In addition to the description of this setup, this paper reports simulation and experiment results obtained with an original control scheme based on a cascaded control architecture in two parts. First is the position control to ensure an accurate end-effector positioning, which includes two nested closed-loops: an external vision-loop based on the pose measurement that drives the motors, equipped of inner speed-loop previously designed in order to control each speed in a decoupled fashion when rejecting the inherent non-linear behaviour of the cables. Second is the tension distribution to maintain the cables under feasible tensions, the paper makes an extensive review of the available methods and presents an algorithm inspired from one of them extended to the dynamic control.

In this paper we present the kinematic and dynamic analysis of a parallel architecture manipulator with linear actuators, consisting of two 3-RRPS mechanisms through the screw theory and the principle of virtual work, respectively. The equations of input / output speed and acceleration are obtained by applying the Klein form of the Lie algebra. In addition, the generalized forces of the mechanism are determined by combining the above theory with the principle of virtual work. Finally, we present a case of study; the numerical results are compared with simulations using ADAMS software.

Parallel robots are preferred over serial robots owing to their enhanced accuracy and rigidity which comes from their higher stiffness. However, there are applications both in industry and in healthcare where higher accuracy is required alongside high compliance (reduced stiffness). Accuracy and compliance being conflicting to each other are difficult to achieve simultaneously. To address this issue, an intrinsically compliant 6-dof parallel robot is proposed in this work. Kinematic and analytical modeling is performed for its conceptual design to obtain the Jacobian matrix and thereby map the joint and Cartesian spaces. Robot’s structure design is analyzed, and the wrench analysis is also carried out to estimate the link forces and stiffness. It is shown that by small changes in the proposed robot design; its compliance can be altered making it suitable for a range of applications. It is also shown mathematically that the robot design can be optimized to maintain higher accuracy together with higher compliance. To carry out design optimization, three important performance criteria, namely; global condition number (for higher accuracies), norm of link forces (to reduce actuator power requirement) and robot compliance (for response to an external wrench) are mathematically formulated. Later, a multi-criteria optimization is performed using an evolutionary algorithm to simultaneously optimize these performance criteria. From the final robot design selected, it is evident that a higher robot compliance with optimal condition number and link forces can be achieved.