Simultaneous Planar Transport of Multiple Objects on Individual Trajectories Using Friction Forces

Friction forces can be used to move objects along a planar horizontal surface by vibrating the surface with two degrees of freedom. The method presented here uses a combination of horizontal and vertical oscillations to produce a non-zero resulting friction force. Using this principle, objects can be moved along any horizontal direction with variable speed. If many small surface elements are placed next to each other to form an array, moving multiple objects independently on individual trajectories at the same time is possible. The two-dimensional oscillations of the surface elements can be separated into a common horizontal motion of all surfaces and an individual vertical vibration. Therefore, one common actuator is used to create the horizontal motion of the surfaces and for the vertical motion only one actuator with one degree of freedom is needed for each array element. Both open loop and closed loop control strategies are possible. The use of appropriate force elds allow the positioning of objects without position feedback. The trajectories achievable are however limited by the dimensions and the geometry of the array cells. Using position feedback, multiple objects can travel on arbitrary trajectories as long as they are not too close to each other.