Gravity Balancing of a Seven-DOFs Hybrid Manipulator

The main focus of this work is to perform the gravity balancing of a seven degrees-of-freedom (DOFs) hybrid manipulator. A hybrid manipulator is a combination of openand closed-loop chains and contains planar and spatial links. Gravity balancing is an important aspect for robotic manipulators, especially for serial manipulators, where with increase in number of links, the gravitational effect of succeeding links increases on preceding joints. This leads to reduced positional accuracy, low payload carrying capacity, and high power requirement of the serial manipulator. In such situations, gravity compensation needs to be provided in order to improve the performance. In this paper, the concept of gravity balancing is used and extended for a hybrid manipulator. The gravity balancing for hybrid manipulators has been demonstrated on the case study of a hybrid manipulator, which is to be used for medical surgery.