a bi - directional slide mechanism . a pair of master and slave disks engages opposite sides of the platform . rotational drivers are connected to master disks so the disks rotate eccentrically about their respective axes of rotation . opposing slave disks are connected to master disks on opposite sides of the platform by a circuitous mechanical linkage , or are electronically synchronized together using stepper motors , to effect coordinated motion . the synchronized eccentric motion of the pairs of master / slave disks compels smooth linear motion of the platform forwards and backwards without backlash . the apparatus can be incorporated in a mems device .