Abstract
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.