Parametric study of natural frequencies and mode shapes of planar flexible-link robots with elastic rotational restraints at the joint-link couplings

Most studies on the dynamics of planar multilink flexible robots idealise the actuator gearhead shaft- link couplings as clamped connections. Traditional clamped actuator gearhead shaft- link coupling is a good approximation when there is no relative motion at the connection. However, in those situations where there is relative motion at the actuator gearhead shaft- link coupling, elastic rotational restraint connection is more accurate to capture the true behaviour of the system. In this paper, parametric study of natural frequencies and mode shapes is conducted for planar multilink lightweight manipulators with flexible actuator gearhead shaft- link couplings. Each link is considered to be connected to the actuator gearhead shaft through a rotational spring. The natural frequencies and mode shapes of the links are investigated for different values of rotational spring stiffness. The results demonstrated that the relative motions at the actuator gearhead shaft- link couplings have significant influence on the natural frequencies and mode shapes of the flexible links.