“…Although the counterweight approach is able to achieve static balancing in any direction of the Cartesian space of the mechanism, it introduces additional mass into the system, which results in larger inertia force (or inertial resistance) to the dynamical system. Alternatively, when springs are used for static balancing, the total potential energy (the gravitational energy plus elastic energy) of the mechanism can be kept constant and the weight of the whole mechanism can be balanced using a much smaller added mass than that using the counterweight approach, as pointed out by [14,15]. The static balancing method has also been introduced to reduce joint torques and improve performance of robots [16,17].…”