Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Design of a Cable-Driven Continuum Manipulator for Applications in Confined Spaces at Elevated Heights

Landong Martua and Mustafa Shabbir Kurbanhusena

Engineering Cluster, Singapore Institute of Technology, 10 Dover Drive, 138683, Singapore


Inspecting confined spaces at elevated locations such as pot bearing housings in railway viaducts are challenging. Elevated work platforms are typically used to hoist people and equipment to conduct the inspection manually, which are often time-consuming, laborious and at times, physically inaccessible. A unique combination of a tethered aerial drone, integrated with a lightweight manipulator is proposed to overcome this challenge, where the lightweight manipulator is based on a cable-driven concept with a continuous backbone design. The cable-driven concept allows the manipulator to be lightweight enough to be mounted onto the aerial drone as the driving cables on the manipulator are connected via a tethering line to the cable winching units that are housed on the ground. The continuous backbone design, on the other hand, offers selective flexibility and rigidity in different planes to maneuver in confined complex spaces. In this paper, a four degrees-of-freedom cable-driven manipulator is presented, along with a continuous backbone design, inspired by the flexible ruler, which offers high bending stiffness in the vertical direction to minimize downward deflection of the manipulator, with low bending stiffness in the horizontal direction to maximize the flexibility of maneuvering in confined and complex spaces. The kinematics model is derived using the modified D-H method, with a constant curvature compensation factor, followed by FEA studies, before developing the actual prototype. Experimental validations on the accuracy of the derived kinematic model and the FEA simulations were found to be approximately 95%. The resulting prototype is a metre long lightweight cable-driven manipulator with a 50mm cross-sectional diameter, weighing less than 650 grammes, and driven by eight actuating cables to achieve the four degrees-of -freedom motion required for the inspection task in confined spaces at elevated locations.

Keywords: Cable-driven robots, Continuum robots.

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