The periodic inspection for oil pipelines is required due to the deterioration over time. A multitude of factors brings such a deterioration, from corrosion, leaks, to cracks, which may lead to blowbacks and cause the damages for operators and the environments. With the progress of robotics technology, various types of mobile robots and mechanisms are designed to cope with this issue. Rather than the assignment of human workers in hazardous environments, the deployment of such kinds of inspection robots can take on this duty more time-efficiently and safely, preventing the human workers from the high-risk of the inspection task in the oil pipelines. This paper presents a novel design of a mobile robot for oil pipeline inspection, which is cooperated with the China National Petroleum Corporation (CNPC). With the improvement of the previous inspection robot used in CNPC’s standard oil pipelines, the newly designed robot is composed of six groups of symmetrical supporting wheels, and a more powerful motors as well as a more advanced control system. This new design endows the oil pipeline inspection robot with better performance on six aspects: traction, obstacle-adaptivity, operation endurance, gradeability, visual perception, and stability. The field testing results at multiple oil transfer stations across several months demonstrate the reliability of this mobile robot under various severe situations in China and validate its performance in the studied aspects.

This article presents the design modeling of a novel 3-RRS spherical parallel mechanism for ankle rehabilitation applications. The kinematics of the 3-RRS spherical parallel mechanism is established. The degree of freedom of 3-RRS spherical parallel mechanism is calculated using screw theory. The inverse kinematics of 3-RRS spherical parallel mechanism is solved. Eight groups of inverse solutions of 3-RRS spherical parallel mechanism are obtained. A method for forward position analysis is developed with variation and iteration approaches, which is suitable for motor position control. The ankle rehabilitation robot can be widely used in clinical treatment and can also be used at home, hotels, and fitness centers for ankle muscle relaxation.

Decoupled parallel mechanisms (DPMs) have the characteristics of compact structure and simple control with wide applications. This paper presents a new method of type synthesis for DPMs by virtue of Lie groups and screw theory. The method consists of synthesis at limb level and configuration level. At limb level, Lie group is used to synthesize the limbs with required DOFs. At configuration level, screw theory is adopted to determine configuration with synthesized limbs that satisfy the type synthesis criteria of DPMs. The type synthesis criteria including limb decoupling and selection of the driving pairs are presented. Upon the formulation, the procedure of type synthesis of DPMs is developed. Type synthesis is conducted with the proposed method, which leads to new spatial and planar fully decoupled 2T1R mechanisms.

The paper presents an innovative hexapod walking robot built with 3-UPU parallel mechanism. In the robot, the parallel mechanism is used as both an actuator to generate walking and also a connecting body to connect two groups of three legs, thus enabling the robot to walk with simple gait by very few motors. In this paper, forward and inverse kinematics solutions are obtained. The workspace of the parallel mechanism is analyzed using limit boundary search method. The walking stability of the robot is analyzed, which yields the robot’s maximum step length. The gait planning of the hexapod walking robot is studied for walking on both flat and uneven terrains. The new robot, combining the advantages of parallel robot and walking robot, has a large carrying capacity, strong passing ability, flexible turning ability, and simple gait control for its deployment for uneven terrains.