Discreteness Issues in Actuator Arrays

An actuator array is a form of distributed manipulation where an object being transported and manipulated rests on a large number of stationary supporting actuators. The authors have developed a macroscopic actuator array consisting of many motorized wheels. The analysis of such an array as opposed to a MEMS array requires the explicit modeling of the discreteness in the system, including the set of supports, distribution of weight, and generation of traction forces. Using an open-loop wheel velocity eld, discreteness causes undesirable behavior such as unstable rotational equilibria, suggesting the use of object feedback. Discrete distributed control algorithms are derived by inverting the dynamics of manipulation.