Comparison between 3 and 8 Leg 6-DOF shake table

The earthquakes are a constant risk on human lives and costly structures. To reduce loss, structures are tested for their resistance to earthquake. However, a 6-DOF seismic simulator (UPS-leg) having the existing design of eight actuators (four vertical actuators, two actuators each along X and Y axes) is very costly to afford. In this paper, an alternate design of shake table (3-legged RPRS 6-DOF, by 6 active actuators) is proposed for investigation having better motion capability, higher payload carrying capacity, ease in control, redundant, decoupled motion and at lower cost. To make a meaningful comparison between the two manipulators we choose stiffness parameters.