In a microfluidic device, respective motion of a plurality of objects along corresponding trajectories is achieved by determining a force field, such as an underlying fluid flow which, when applied to the plurality of object, moves each object along its corresponding trajectory. The force field is a linear superposition of a subset of all force fields supported by the physical characteristics of the microfluidic device. Once the fields have been ascertained, a plurality of actuation signals corresponding to the fields is applied to actuators installed on the microfluidic device to cause the force on each object. By implementing a feedback structure, corrections for positional errors may be made by computing a corrective force for each object and adjusting the actuation signals appropriately thereto.