In this paper, we present a spherical mobile robot BYQ_III, for planetary surface exploration and security tasks.The driving torque for the rolling robot is generated by a new type of mechanism equipped with a counter-pendulum. This robot is nonholonomic in nature, and underactuated. In this paper, the three-dimensional (3-D) nonlinear dynamic model is developed, then decoupled to the longitudinal and lateral motions by linearization. Two sliding-mode controllers are proposed to asymptotically stabilize the tracking errors in lean angle and spinning angular velocity, respectively, and indirectly to stabilize the desired path curvature, because the robot steers only by leaning itself to a predefined angle. For the task of path following, a path curvature controller, based on a geometrical notion, is employed. The stability and performance analyses are performed, and also the effectiveness of the controllers is shown by numerical simulations. To the best of author's knowledge, similar results could not be obtained in the previous spherical robot control system based on the dynamics. The work is of significance in understanding and developing this type of planning and controlling motions of nonholonomic systems.

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Abstract. In this paper, an improved algorithm for particle swarm optimization is proposed for the application of underwater robot in the complex marine environment. Not only did consider to avoid obstacles when path planning, but also considered the current direction and the size effect on the performance of the robot dynamics. The algorithm uses the trunk binary tree structure to construct the path search space and A * heuristic search method is used in the search space to find a evaluation standard path. Then the particle swarm algorithm to optimize the path by adjusting evaluation function, which makes the underwater robot in the current navigation easier to control, and consume less energy. IntroductionPath planning is one of the most important tasks in underwater robot navigation, and it represents a degree of intelligence on underwater robots. The overall path planning consists of three parts: 1. Model the environmental information of the robot in relation to the environment.2.Get a search space that contains environmental information.3.Search in the search space using the corresponding search algorithm [1]. Before the underwater robot path planning, it must first model environment, described the underwater robot activity space by the external environment of the original form through a series of processing into a suitable planning model of the algorithm. A reasonable environment is conducive to reducing the amount of search in the plan and the overhead of space and time [2]. Path search algorithm search the feasible space of the path from the environment model, while the path generated from search to the path of the feasible to generate a feasible path in the space. Path optimization is considering basis dynamic characteristics of the intelligent underwater robot, in order to let more conducive to the implementation of underwater robot path for a smooth path [3].

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The printing machine’s sleeves installation operation is a typical peg-in-hole assembly problem. The printing machine’s sleeves are usually heavy, and the precision requirement of fit is high. Therefore it is hard to fit them together, and the assembly efficiency is low. What’s more the assembly tasks may make great damage to the worker who assembles it. To solve these problems, a Gough-Stewart parallel peg-in-hole assembly robot with high precision is designed. The robot has a stereoscopic laser measurement system to obtain position and speed information to realize closed-loop workspace control of the robot. The stereoscopic laser measurement system can also ease the impact in the assembly process. The robot has a passive flexibility wrist to solve the jamming question. The assembly parallel robot is designed. The kinematics model of the stereoscopic laser measurement system and the dynamic model of the Gough-Stewart parallel robot are built. A sliding mode controller is designed for the control of this robot and the parameters of the controller are optimized. The validity of the system dynamic model and stability of the sliding mode controller is proved by Matlab simulation results. Gough-Stewart Parallel Robot’s application range could be widen by the presented work.