Design of planar variable-payload balanced articulated manipulators with actuated linear ground-adjacent adjustment

Supporting different payloads has been shown to be effective for developing a multitasking manipulator. This paper presents a method for designing a planar, statically balanced, articulated manipulator for supporting variable payloads. The balancing equations for the gravitational and spring elastic energies are developed using a stiffness block matrix, which represents interacting potential energies between the links. It is shown that the springs can be classified according to the roles they play in the balancing equations. Thus, the installation parameters can be divided into payload-dependent parameters (PDPs) and payload-independent parameters (PIPs). The admissible spring configurations for supporting variable payloads are determined using the required number of PDPs, and PDP adjustment devices are used to adjust PDPs as the payload changes. Based on the interrelation between PDPs and PIPs, the number of PDPs can be reduced through proper arrangement of PIPs. The displacement of different PDPs can be equalized to fit attachment points in the same adjustment device. Therefore, the number of PDP adjustment devices is minimized to one. Variable-payload balanced articulated manipulators with five springs and three degrees of freedom are shown as illustrative examples. The energy consumption is estimated accordingly.