2019 年 85 巻 879 号 p. 19-00219
This study aims at realization of Mechanical Gravity Canceller with tension transmission function via two rotational axes, which achieves a good balance between suitability for M-DOF and high load capacity. Providing high power of conventional manipulators causes a problem of increase in their size and weight. To solve this problem, it has been expected to use Mechanical Gravity Canceller (MGC), a device which can compensate torques by the manipulator’s weight and load with tension spring. While MGC succeeded in compensating the weight of M-DOF manipulator completely, there remains a risk of fatigue fracture of wire ropes in its actual use. This is caused by their large curvature bending. CT-MGC (Compression Type-MGC), a type of MGC consisting of compression spring and block slider crank mechanism, was developed to ensure the rigidity and safety of MGC. However, CT-MGC occupies a large space and so is not appropriate for an installment in M-DOF manipulator. To solve these problems of conventional MGC series, HLCC-MGC (High Load Capacity and Compact MGC) is developed. HLCC-MGC can avoid bending of wire rope in large curvature by transmitting tension via two rotational axes. This feature consists of two elements: arrangement of pulleys considering both a range of movement and a configuration of DOF, and use of parallel link rotator, newly developed rotational mechanism. The testing machine with two HLCC-MGCs can compensate gravity force of tip load imitating an end effector whose weight is 5.06 kg, while the weight itself is 5.88 kg.
