Overhead Work Assist with Passive Gravity Compensation Mechanism and Horizontal Link Mechanism for Agriculture*

Busy agricultural seasons involve long-term continuous work and heavy labor. Particularly during overhead work, such as harvesting, gibberellin treatment, and bagging, workers need to consistently raise upper limb weights of approximately 2 to 4 kg with their own muscular strength, resulting in a high work burden. For long-duration work in the field, a passive and robust assist system is advantageous. Therefore, we propose an assistance device named TasKi that uses self-weight compensation mechanisms and horizontal link mechanisms to reduce the burden on a worker’s upper limbs during overhead work. TasKi can compensate for upper limb weight by using the force of a spring in various postures of the upper limbs without battery support. In this report, we describe the design of the TasKi mechanisms that achieve the upward work assist in actual agriculture with a simple structure. The mechanism of self-weight compensation and the degree of freedom and parameters of the link mechanism are studied.