Robotic inspection and maintenance are gaining importance due to the number of different scenarios in which robots can operate. The use of robotic systems to accomplish such tasks has deep implications in terms of safety for human workers and can significantly extend the life of infrastructures and industrial facilities. In this context, long-reach cable-driven hyper-redundant robots can be employed to inspect areas that are difficult to reach and hazardous environments such as tanks and vessels. This paper presents a novel long-reach cable-driven hyper-redundant robot called SLIM (Snake-Like manipulator for Inspection and Maintenance). SLIM consists of a robotic arm, a pan and tilt mechanism as end-effector, and an actuation box that can rotate and around which the arm can wrap. The robot has a total of 15 degrees of freedom and, therefore, for the task of positioning the tool centre point in a bi-dimensional Cartesian space with a specific attitude, it has 10 degrees of redundancy. The robot is designed to operate in harsh environments and high temperatures and can deploy itself up to about 4.8 m. This paper presents the requirements that drove the design of the robot, the main aspects of the mechanical and electronic systems, the control strategy, and the results of preliminary experimental tests performed with a physical prototype to evaluate the robot performances.

Cable-driven hyper-redundant robots have been adopted in many fields for accessing harsh and confined environments that may be inaccessible or dangerous for humans. The cable actuation strategy makes the robot hardware safer and increases the robot payload reducing its weight. In this paper, a novel design of a fully actuated cable-driven hyper-redundant robot has been proposed. This solution is a pulleyless design that decreases the mechanical complexity, allowing to have a compact arm diameter and avoid tension losses on the cables during the motion. Three different joint designs have been taken into account and experiments have been carried to study their performances.The kinematics for the n-joint robot has been formulated, and two cable routing optimization methods, based on a genetic algorithm, have been proposed and applied to a five-joint robot.

Due to their uniqueness, hyper-redundant manipulators are becoming increasingly relevant in robotics research. The abundance of degrees of freedom makes them adaptable to a variety of applications across various fields, including inspection, medical procedures, and space exploration. These manipulators are particularly effective where high maneuverability is needed, particularly in constrained environments, thanks to their surplus of degrees of freedom. While this hyper-redundancy offers significant benefits, it also introduces complexities in developing effective actuation strategies and innovative design solutions. This work is the first of two parts of a survey conducted on hyper-redundant manipulators, their design, and actuation strategies. This first part of the review provides an examination of the current state of tendon-driven hyper-redundant manipulator design and actuation, analyzing both continuum and rigid-link manipulators. The article synthesizes recent advancements, explores various designs, and identifies key challenges.

Nowadays, robotic research focuses more and more on attaining energy-efficient and safe solutions. They are key-aspects of industrial robots, such as inspection and maintenance robots. The introduction of a mechanism that passively compensates the joint torque caused by the weight of the robot may offer a valid solution. Avoiding the need for actuators to balance gravity torques helps decrease the power consumption and the size of the actuators. Furthermore, a passive gravity compensation mechanism allows the robot to hold a static position without the need for an external power source, hence avoiding the risk of collapsing in case of failure of the actuators. This work focuses on designing a torque generator composed of a non-circular pulley and a spring, which, by solving a convex optimisation problem, offers a new methodology for creating any generic torque and thereby also succeeds in solving gravity compensation problems. This methodology guarantees the outcome of feasible non-circular pulleys which minimise the torque required to perform any specific task.

Due to their distinctiveness and potential uses, hyper-redundant manipulators are becoming increasingly relevant in robotics research. The high number of degrees of freedom makes them suitable for various applications across various fields, including inspection, minimally invasive surgery, and space applications. These manipulators are especially useful where high manoeuvrability is needed, particularly in constrained environments, thanks to their abundance of degrees of freedom. While having significant benefits, this redundancy introduces complexities in developing robust actuation and innovative designs. This work is the second of two parts of a survey conducted on hyper-redundant manipulators, analyzing continuum, and rigid-link manipulators. The aim of this survey is to provide a comprehensive analysis of non-tendon-driven hyper-redundant manipulators, examining their unique design and actuation strategies and identifying their potential advantages and challenges compared to tendon-driven counterparts. By focusing on these alternatives, this survey seeks to expand the understanding of hyper-redundant manipulator technology and highlight innovative approaches in this evolving field. The article synthesizes recent advancements, explores various designs, and identifies critical challenges.