Design of a Novel Long-Reach Cable-Driven Hyper-Redundant Snake-like Manipulator for Inspection and Maintenance  
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1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [EMAIL_ADDRESS] (D.L. ); [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (R.G. ); [EMAIL_ADDRESS] (L.D.M.C.V. ); [EMAIL_ADDRESS] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [EMAIL_ADDRESS] (D.L. ); [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (R.G. ); [PERSON].C.V. ); [EMAIL_ADDRESS] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [PERSON](D.L. ); [EMAIL_ADDRESS] (P.G. ); [PERSON]R.G. ); [PERSON].C.V. ); [PERSON]S] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [PERSON](D.L. ); [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (R.G. ); [PERSON].C.V. ); [EMAIL_ADDRESS] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [PERSON](D.L. ); [PERSON]] (P.G. ); [EMAIL_ADDRESS] (R.G. ); [PERSON].C.V. ); [PERSON]S] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [PERSON](D.L. ); [PERSON]] (P.G. ); [PERSON]R.G. ); [EMAIL_ADDRESS] (L.D.M.C.V. ); [EMAIL_ADDRESS] (G.S. ); [EMAIL_ADDRESS] (D.G.C.) [PERSON]  
1 Istituto Italiano di Tecnologia, ADVR Advanced Robotics, 16163 Genoa, Italy; [EMAIL_ADDRESS] (A.P. ); [EMAIL_ADDRESS] (A.P. ); daniele.loudvico@it. to inspecting confined (air deprived) and harsh environments. The robot, called SLIM (Snake-Like manipulator for Inspection and Maintenance), is designed to access large volumes through small openings such as storage tanks, containment vessels and power generators. The ability to withstand high temperatures, operate in hazardous environments and gain access through small apertures is the key feature driving the design. By definition, hyper-redundant robots have a number of degrees of freedom (DOFs) much greater than the number of variables necessary to complete a specific task. These robots are widely employed since they can perform grasping, manipulation, and articulated movements within narrow spaces crowded with obstacles [7]. Their design is often bio-inspired: some examples are elephant trunk [8, 9], octopus [10], and snake [11] robots. Unlike traditional 6-DOFs anthropomorphic industrial robots, inspection and, in particular, hyper-redundant robots are still an emerging market with demand from industrial [12, 13], surgical, and medical applications [14]. Implementing cable actuation in robotics can improve actuators safety, payload capability and structural compliance. For example, in the medical field, where accurate motion, dexterity and safe interactions are crucial, the cable-driven mechanism is adopted for minimally invasive surgery [15]. In industrial fields, cable-driven mechanisms appear in various applications ranging from a parallel robot for logistics [16, 17] to hyper-redundant robots for the inspection of complex and constrained devices [4, 18, 19] or maintenance in harsh environments [20, 21] that cannot be reached by humans. In bio-inspired robots, cable-driven mechanisms are often used to mimic limb tendons [22, 23]. A drawback of cable-driven mechanisms is the need to route the cables all along the structure complicating the design [24] and introducing friction effects due to their interaction with bushing and pulleys. Delivering motion accuracy requires precise modelling of the cable-drive mechanism to fully consider friction phenomena [25, 26, 27]. Another critical aspect is the intrinsic compliance of the cable transmission. The elasticity decreases performances concerning trajectory tracking, stability margin and residual vibrations.