Development of underactuated tendon driven manipulator incorporated with energy saving bistable electromagnetic coupling mechanism

Kaluarachchi, Malaka Miyuranga (2020) Development of underactuated tendon driven manipulator incorporated with energy saving bistable electromagnetic coupling mechanism. PhD thesis, University of Nottingham.

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Lightweight manipulator design is one of the diverse and rich research fields in the area of robotics. The lightweight manipulator development has become increasingly essential because of its distinctive benefits such as reduced inertia, low energy consumption and safer operation that are the key challenges in optimising a manipulator design. Various designs approaches have been proposed over the past decades in the development of lightweight manipulators. However, majority of lightweight manipulator designs from the literature are developed following the conventional design approach such as positioning the actuators at base or allocating a dedicated actuator for each degree of freedom. Reduction of number of actuators (underactuation) utilised has significant benefits such as cost reduction, compactness and reduced weight. Thus, incorporation of underactuation concept with the lightweight manipulator design will integrate the features of underactuation concept with lightweight manipulator that enhance the design. More interestingly, development of tendon driven manipulators incorporating underactuated concept has not been explored extensively in the field of lightweight manipulator design. In addition, electromagnetic clutches have been widely utilised in underactuated systems as a coupling device due to its advantages such as fast activation and electrical controllability. However, a continuously supply of electrical energy is essential to sustain the engaged state of an electromagnetic clutch during operation. Therefore, an electromagnetic clutch consumes substantial amount of electrical energy during the operation. Moreover, conventional electromagnetic clutch is not fail safe in unexpected power failure conditions. These factors have a significant impact on energy efficiency and safety of the manipulator design, that are vital design aspects of underactuated lightweight manipulators.

These elements are addressed in this research through the development of underactuated tendon driven manipulator incorporated with bistable electromagnetic coupling mechanism. The tendon driven manipulator developed in this work utilises reduced number of motors for the actuation, adopting the underactuation concept in the design. The developed manipulator is with the capability of reducing driving joint torques required for actuation. The effectiveness of the proposed design in reducing driving joint torques is examined via theoretical and experimental studies. The experimental and theoretical results have highlighted the significance of the developed tendon driven manipulator design in reducing the driving joint torques with comparison to the conventional manipulator. In addition, the proposed tendon driven manipulator is incorporated with energy saving bistable coupling mechanisms. The developed bistable electromagnetic coupling mechanism has the capability to maintain stable mechanism states either engaged or disengaged without a continuous electrical power supply. Thus, the design is with the potential of minimising electric energy usage and providing a failsafe coupling mechanism. Moreover, bistable electromagnetic coupling mechanism comprises the advantages of conventional electromagnetic clutch such as rapid activation and electrical controllability. The experimental results showed that the proposed bistable electromagnetic coupling mechanism has utilised only 1.104 J of energy throughout the entire operation of the coupling mechanism. The experimental results further illustrated that the proposed bistable coupling mechanism based actuation approach has reduced the energy consumption by 188 J and 144 J during the actuation of manipulator joints. Experimental studies have highlighted the potential of the proposed manipulator design in reducing both driving joint torques and the energy consumption. Furthermore, the tendon driven manipulator design introduced in this study comprises the advantages of the underactuation concept. Thus, the proposed tendon driven manipulator design incorporated with bistable electromagnetic coupling mechanisms makes a promising design approach in the field of lightweight manipulator development.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Hou, Ho Jee
Yahya, Samer
Teh, Sze Hong
Keywords: lightweight manipulator, underactuated robot, tendon driven manipulator, bistable coupling mechanism, underactuated systems, underactuated manipulators, energy efficient robot mechanism
Subjects: T Technology > TJ Mechanical engineering and machinery
Faculties/Schools: University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Item ID: 59813
Date Deposited: 22 Feb 2020 04:40
Last Modified: 21 Feb 2022 04:30

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