A 3 AXIS PARALLEL DRIVE MICROROBOT

In this article we present a three axis parallel drive microrobot. The robot consists of three linear actuators rigidly positioned in a plan e with their translational axes arranged in parallel. Each actuator is connected to one apex of a low mass rigid tetrahedral frame by a four axis elastic hinge. Movement of each of the three linear actuators re sults in displacements of the corresponding hinged apices and, hence, the rigid tetrahedral frame. The fourth apex acts as the working tip w hich may be positioned anywhere within a workspace determined by the g eometry of the robot and the displacement range of the actuators. When the actuator displacement is small compared to the dimensions of the frame the relationship between the displacement of the three actuators and the position of the working tip is well defined, being one to one and only mildly nonlinear (1% nonlinearity for 1.5 mm actuator displa cement on an 80 mm frame). A microrobot has been constructed with a wo rkspace measuring 3 mm axially and 5.65 mm transverse to the robot axi s. Below 100 Hz the working tip displacement is limited to 3 mm peak-t o-peak in the axial direction and 5.65 mm peak-to-peak transverse to t he axis. Above 100 Hz the working tip performance is acceleration limi ted with maximum displacement being inversely proportional to the squa re of the driving frequency, falling to 120 mu m peak-to-peak in the a xial direction at 500 Hz. (C) 1997 American Institute of Physics. [S00 34-6748(97)02711-1].