Issue link: https://htpgraphics.uberflip.com/i/1385717
REMOTE HANDLING UNIQUENESS // RAIN-Hex, with the reconfigurability in the leg layout platform, can perform manufacturing/repair operations. It employs an optimised configuration by the implementation of appropriate kinematic models and mechanisms to modify the morphology to suit different machining/walking conditions. Specifically, the moving platform is integrated with a novel repositioning mechanism which consists of six identical clutches and a closed-loop rope-pulley mechanism driven by a single motor (see Fig. 1b). In each spherical-prismatic-spherical (SPS) limb, the upper S-joint is fixed with the clutch, which allows repositioning of the limb layout on the moving platform. Furthermore, in contrast to conventional Parallel Kinematic Machines (PKMs), by removing the lower fixed base, together with the reconfiguring of the upper joints of the limbs, the proposed Reconfigurable Parallel Kinematic Walking Machine (RPKWM) provides not only the flexibility to adapt to the intervention site with free- positioning feet directly but also the advanced walking capability under challenging conditions, such as uneven surfaces, constrained spaces, and slopes. 63 RAIN PROGRESS // The main achievements are listed as follows: COMPREHENSIVE THEORETICAL ANALYSIS (1) A novel family of RPKWMs concept is proposed with its upper joints repositionable on the moving platform and the lower joints free from a fixed base, (2) A novel Fourier-based optimisation algorithm is proposed and proven to reduce the burden on the identification of unstable configurations and by combining with genetic algorithms, it can present an enhanced stiffness configuration free of singularities, (3) Gait analysis and optimisation is carried out for various configurations of the RAIN-Hex by considering different walking conditions (i.e. low friction surfaces, slopes, obstacle avoidance). DESIGN AND DEVELOPMENT (1) A novel SMA-based clutch mechanism is designed by applying shape memory alloy (SMA) and integrating into the moving platform for reconfiguring the layout of upper joints, which only requires a single motor to actuate several DoFs (e.g. 6 DoFs in RAIN-Hex) separately or simultaneously; (2) Elaborated design and prototype is completed and tested. DEMONSTRATION (1) Walking Demonstrations on flat (obstacle avoidance) and inclined surfaces (max. 10 deg) (see Fig 2) have been performed. (2) Machining Demonstration of slot milling (e.g. through-wall sampling) has been carried out on various materials (inc. PLA, Aluminium, Steel) (see Fig. 3). FUTURE ASPIRATIONS // To demonstrate the capabilities of the RAIN-Hex in a real-case scenario, a walking demonstration at RACE mock-up site and a machining (sampling) demonstration with Rolls-Royce plant section mockup have been under consideration. In future research developments, we aim to achieve a fully autonomous walking and machining Hexapod by integrating calibration cameras and SLAM system. By collaborating and interacting with internal partners in RAIN (e.g. OXF, Sellafield Ltd, Rolls-Royce), we can develop a higher TRL robotic system and demonstrate/ implement on a real-case site to perform the in-situ repair and maintenance tasks. Fig. 3. Demonstration of the RAIN-Hex slot milling on a steel plate.