Mechanical Structure Of Robot Research Articles

Kinematic solution of a quadruped walking robot - posture analysis of TITAN-VIII

The crawl motion of a quadruped walking robot is considered as the combination of two forms. One results from a parallel manipulator composed of the standing legs and robot's body, and the another is the swing leg's movement. The walk conditions satisfied with the constraint of robot's mechanical structure are derived and the closed-form direct kinematics solution of a quadruped robot is presented. It is shown that the direct kinematics of the robot involves solving a sixteenth-degree polynomial of a single variable. A numerical example is also presented and the results are verified by an inverse kinematics analysis. The approach can be used to derive the kinematics of the other gaits for quadruped robots.

Wrist Force Sensor Feedback for Improved Actuation Performance in Conventional Arms

Torque control is an effective technique for improving robot performance. However, most conventional robots are not equipped with torque sensors, and they are difficult to add without modifying the robot's mechanical structure. The paper presents a new method that allows torque feedback to be implemented in the absence of joint-torque sensors. This technique estimates the torque components acting in the force-control subspace, using a conventional wrist force sensor. This approach has been implemented and experimentally validated using a PUMA 560 manipulator. The results confirm the effectiveness of this method in dealing with the limitations of conventional actuation/transmission systems.

A New Design of a 6-DOF Parallel Robot

This paper presents a six-degree-of-freedom parallel robot which has been recently designed. The design is based on a three-degree-of-freedom parallel robot called DELTA which was designed in Switzerland by EPFL. First, we give equations corresponding to different models of the DELTA robot: forward and inverse kinematics as well as inverse dynamics. An important feature of our method in deriving these models is to use a “good” set of parameters in order to simplify the equations. Then, in an attempt to extend the principle of the DELTA robot mechanical structure to a six-degree-offreedom parallel robot, we propose a new design called HEXA. Equations for kinematics and dynamics of the HEXA robot are presented and show that it has the same dynamic capabilities as the DELTA robot because, like the DELTA robot, it can be built with light-weight materials and easily modeled. Finally, we discuss optimization of the HEXA robot mechanical structure.