An Investigation on a Planar 3 Degree-of-Freedom Underactuated Mechanism

Abstract

The fully-actuated mechanisms ensure control and feedback linearization within the defined workspace but they are required additional design considerations such as control complexity, design or cost. On the other hand, the underactuated mechanisms have advantages in terms of control complexity, design and cost. In this study, a planar three degree-of-freedom parallel underactuated mechanism is introduced. In this design, only one actuator is used and the particularity of this study resides in the configuration of mechanism, which uses non-zero length compression springs instead of prismatic joints at each of its three links. This particular design allows for three equilibrium positions are determined by solving static Newton’s equation of resulting forces. The objective of designed control is determining accuracy of under actuation in reaching a desired equilibrium goal position from given equilibrium starting position. Results show that more than one actuator is needed to control the mechanism and reach the desired position.