The performance of a robot is closely related to its structure. From the initial design of link lengths to structural optimization, it is still the research hotspot in recent years. To make the manipulator lightweight and ensure its working range and flexibility, researchers have proposed many optimization methods, most of which are for specific working scenarios, requirements, and robot structures, therefore their generality is limited. The optimization of the manipulator should be a comprehensive method. That is, we should pay attention to the joint configuration and each link length at the beginning of the design. Particularly, the geometric parameters of each link, which not only affect the range of the workspace but also have a direct impact on the working space, working efficiency, and flexibility of the manipulator. In this paper, a generalized optimization framework is proposed for multi-link manipulators. Starting from the optimization of manipulator link lengths, firstly, the geometry of the manipulator and workspace is parameterized; then the performance indicators are established; lastly, the geometric size of the manipulator is optimized according to the workspace limits and task requirements. Besides, we verified its feasibility and generality by applying this method to different TBM scenarios.

Compliance is good. However, it is challenging for one compliant continuum robot to finish both high precision manipulation and environmental-adapted motions. In this paper, a modular continuum robot with the alterable compliance characteristic is proposed. Besides, an actuation module is also proposed using a tubular-screw mechanism for non-slippage transmission. Kinematic analyses and dynamic co-simulation are performed to study the continuum robot. Furthermore, two potential application scenarios of pick-and-place manipulation and confined space navigating are carried out to demonstrate the advantages of the alterable compliance design. This study presents a capable continuum robotic solution for non-structural inspection tasks, with potential for in-situ applications in restricted and hazardous environments.

Regular maintenance of pipelines is an important task to ensure oil transportation and other operation (sewers, nature gas). Precise localization of pipeline damage can greatly improve the efficiency of maintenance work. Since the texture similarity and illumination change of pipe, traditional local descriptors for image matching like SIFT, SURF and ORB are easy to suffer from false correspondences. As to remove the false matches, the local neighborhood constraints (LNC) that contain spatial constructs around feature points are proposed. Good correspondences are essential for the high-accuracy localization and mapping solution given the limited textures and illumination in the pipes. The LNC method is also integrated into the state-of-the-art visual SLAM system. The proposed LNC image matching method and the SLAM system are evaluated on datasets gathered from the pipe environment. Compared with other state-of-the-art methods, our LNC image matching method achieves similar or better performance in precision, recall and runtime. The SLAM system provides state estimation and map reconstruction of the pipe in real-time, and the localization error is within 1%.

This study proposes a hybrid vision/force control scheme for interaction with the inner surface of the bottle-like object. Based on the geometry of the object, a new generalized constraint called the bottleneck (BN) constraint is proposed, which ensures the tool passes through a fixed 3-D region and avoid collisions with the boundary of the region. To realize the hybrid vision/force control under the BN constraint, a novel dynamic controller is designed inspired by the hierarchical operational space, which can complete the different tasks defined in the decoupled subspace. To enhance the robustness of the algorithm, we develop a data-driven method and an adaptive method to estimate the Jacobian matrix online in force space and image space, respectively. The asymptotic stability of the closed-loop system is rigorously proved by the Lyapunov theory. Experiments are conducted to validate the performance of the proposed method.

To cope with the requirements on efficiency and labour-saving of the out-pipe surface grinding tasks in the wild, several proposals are revealed and discussed. The one benefiting from the characteristics of planetary gear transmission and friction actuating mechanism are expatiated. To realize full coverage of out-pipe surface, the self-rotation and revolution motions of every polishing tool (cutter) are actuated by the same motor, and the friction force produced in grinding process acts as suitable tractive force for the forward travel of the grinding system. The friction statics analysis is established to illustrate the force transmission. Compression spring system are utilized to realize force equilibrium and support passive diameter adaptability. The proposed robotic grinding system is characterized by less actuator, online grinding capability and high working efficiency. It has clear advantages regarding manufacturing costs and control complexity. As the result of prototype experiments, performance of smooth grinding the out-pipe surface is confirmed.

Creative design of grippers on their configurations, mechatronics control system, and multi-component collaborative algorithms is often utilized to realize complex operations in industrial applications, due to the environmental constraints or specific task requirements. Firstly, this paper introduces the background problems. As the main automatic equipment -- the shield machine -- in the field of tunnel boring construction, needs frequent tool (cutter) replacement during underground process, but has no practical automatic method yet, due to heavy payload, complex environment and work procedure. Thus, an integrated solution was proposed by developing a specific gripper and a snake-like manipulator to accomplish tool replacement in a cooperative way. Through simple and unique design of relative components, the solution realizes a fully automatic and precise approach including heavy load tool grasping and regrasping, posture adjustment, unlocking and disassembly, and installation and locking. Finally, this paper also describes the experimental process of tool replacement by the prototype under a real working condition, and discusses the feasibility of putting the scheme into practical application through comparison.

In this paper, we updated an inspection robot with passive adaptation ability, which is used to detect small size water supply pipeline. By geometric calculation and kinematic verification, static model of the robot is checked for flexible movement in the pipeline. Besides, inertial measurement unit is leveraged to simultaneously detect the attitude of robot, and different algorithm is tested to compensate the camera image rotation, stabilizing the image output.

We present a novel method for caging grasps in this paper by stretching ropes on the surface of a 3D object. Both topology and shape of a model to be grasped has been considered in our approach. Our algorithm can guarantee generating local minimal rings on every topological branches of a given model with the help of a Reeb graph. Cages and grasps can then be computed from these rings, and physical experimental tests have been conducted to verify the robustness of our approach.