This paper presents a soft Cable-Driven Parallel Robot for gastrointestinal surgery. The robot consists of an inflatable scaffold and a hydraulic variable stiffness end-effector and features six degrees of freedom. Experiments involving passage through a colon model, knot tying, and retraction have demonstrated its flexibility and the concept of navigating through the colon in a soft configuration, then increasing rigidity at the lesion site to collaborate with the endoscope in performing surgery. Meanwhile, the robot can sense the contact force through hydraulic pressure variations within the end-effector shaft, providing haptic feedback, which reduces the effects of Coulomb friction. When using the robot to calculate pressing forces, it achieved accuracy with a mean error of 0.051 N and a standard deviation (STD) of 0.066 N. For lifting forces, it achieved a mean error of 0.066 N and a STD of 0.083 N. These results demonstrate the potential of the robot for tissue palpation applications.

Benefiting from its hyper-redundant structure, the biomimetic snake-like manipulator retains its remarkable flexibility even within confined spaces. However, its motion planning and control pose significant challenges. This paper imitates the winding uncoiling behavior of snakes to achieve controllable constrained path following. Firstly, based on control points, a recursive computational model and an equivalent planning angle model are established, enabling efficient and analytical determination of joint positions, collision regions, and motion parameters during the path following. Subsequently, the sliding control point algorithm and motion smoothing restriction algorithm are designed. The former ensures that the remaining segments during following strictly remain within the collision-free regions defined by the base and path controls, while the latter smooths the control parameters based on velocity and acceleration limitations. Finally, simulation and practical experiments demonstrate the feasibility of the proposed methods. The prototype that applied our method can reach targets and accomplish tasks, further validating the applicability of the snake-like manipulator.

Cable-driven hyper-redundant manipulators (CDHRMs) enable unique tasks in confined spaces while presenting challenges for collision-free path planning. This article introduces a novel planning method called the stepwise follow-the-leader (SFTL) algorithm. SFTL consists of a local planner and a global planner. The local planner utilizes reinforcement learning to obtain a collision-free policy, optimizing target error, path length, angle fluctuation, and TE. The global planner incorporates an observation tree and reachability estimator to dynamically optimize extended path nodes for the local planner. The proposed sliding control points algorithm enables sequential movement along the planned path. The SFTL algorithm is applied to a coiled CDHRM and validated through simulations and practical experiments. Results show an average success rate of over 96% in various scenes, maintaining appropriate joint angles and cable tension. SFTL generates sensor-informed feasible paths, providing a robust planning framework for industrial CDHRM applications.

Operating in narrow spaces is an important challenge in the development of robots. Redundant manipulators are one way to solve this problem, but their mechanism design and control method still have much room for improvement. In this paper, we propose a coiled cable-conduit-driven hyper-redundant manipulator (C-CDHRM) with great slenderness and flexibility. In terms of mechanism design, it considers both compactness and operability. By imitating the structure and behavior of a constricting snake, it can be uncoiled sequentially from a coiled storage state, led by the head. In terms of control methods, we propose a multi-layer control system that can make remote operations more accurate and reliable. On the one hand, guiding, segmenting, and following the path overcome the planning ambiguity caused by redundancy. On the other hand, conduit transmission modeling and cable length correction overcome the nonlinear mapping of cable-driven joints and were verified in experiments. Through tests, the mobile integrated system composed of C-CDHRM has an excellent performance in operation precision and accuracy, ensuring safety and accessibility in narrow spaces. Finally, in field experiments, the inspection and cleaning of various types of electrical equipment have been successfully completed, showing excellent application prospects.