Collective Actuation ( Extended

Modular robot designers confront an inherent tradeoff between size and power: Smaller, more numerous modules increase the adaptability of a given volume or mass of modules – allowing the aggregate robot to take on a wider variety of configurations – but do so at the expense of the power and complexity of each module. Fewer, larger modules can incorporate more powerful actuators, more powerful bonds, and stronger hinges but at a cost of overspecializing the resulting robot in favor of corresponding uses. We describe a technique for coordinating the efforts of many tiny modules to achieve forces and movements beyond those possible for individual modules. Our approach is predominantly applicable to spherical and cylindrical modules and their faceted counterparts, but may apply to some chain-style modular robot systems. Thus actuator capacity and range becomes a function of software and dynamic topology as well as of hardware. An important aspect of this technique is its ability to bend complex and large-scale structures and to realize the equivalent of large scale joints.