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This paper aims to present a detailed mechanical design of a seven-degrees-of-freedom mobile parallel robot for the tungsten inert gas (TIG) welding and machining processes in fusion reactor. Detailed mechanical design of the robot is presented and both the kinematic and dynamic behaviors are studied.

First, the model of the mobile parallel robot was created in computer-aided design (CAD) software, then the simulation and optimization of the robot were completed to meet the design requirements. Then the robot was manufactured and assembled. Finally, the machining and tungsten inert gas (TIG) welding tests were performed for validation.

Currently, the implementation of the robot system has been successfully carried out in the laboratory. The excellent performance has indicated that the robot’s mechanical and software designs are suitable for the given tasks. The quality and accuracy of welding and machining has reached the requirements.

This mobile parallel industrial robot is particularly used in fusion reactor. Furthermore, the structure of the mobile parallel robot can be optimized for different applications.

This paper aims to present an iterative path-following method with joint limits to solve the problem of large computation cost, movement exceeding joint limits and poor path-following accuracy for the path planning of hyper-redundant snake-like manipulator.

When a desired path is given, new configuration of the snake-like manipulator is obtained through a geometrical approach, then the joints are repositioned through iterations until all the rotation angles satisfy the imposed joint limits. Finally, a new arrangement is obtained through the analytic solution of the inverse kinematics of hyper-redundant manipulator. Finally, simulations and experiments are carried out to analyze the performance of the proposed path-following method.

Simulation results show that the average computation time is 0.1 ms per step for a hyper-redundant manipulator with 12 degrees of freedom, and the deviation in tip position can be kept below 0.02 mm. Experiments show that all the rotation angles are within joint limits.

Currently , the manipulator is working in open-loop, the elasticity of the driving cable will cause positioning error. In future, close-loop control based on real-time attitude detection will be used in in combination with the path-following method to achieve high-precision trajectory tracking.

Through a series of iterative processes, the proposed method can make the manipulator approach the desired path as much as possible within the joint constraints with high precision and less computation time.

The purpose of this paper is to present an alternative solution for press-fit technology processes, which could improve the precision of the positioning movements and the stiffness of the structural elements.

A concept is presented and the related kinematics is described. Then, preliminary embodiment evaluations have been performed in terms of kinematics, force control and load distribution on the main structural elements.

Thanks to the additional leg, the proposed solution allows a preload that is capable of compensating the backlash of joints. The particular structure with four extendible legs and eight cardan joints ensures the parallelism between the ground and the plate holding the end effector, without any need of additional controls. However, it implies that the legs are not subjected to pure tension–compression stresses.

This work is focused on the conceptual phase of the design process, with only preliminary embodiment analysis that paves the way for subsequent and more detailed design steps. Especially concerning the actual stiffness of the system, comprehensive evaluations could be performed only after the identification of the particular parts/devices used to implement the main functional elements.

To the best of the authors’ knowledge, this is the first research work that comprehensively describes and analyzes the considered kinematics, within a real industrial application context.