Discretely assembled walking machines

Abstract

We introduce a discrete approach to robotic construction that enables the integration of structure, mechanism, and actuation and offers a promising route to on-demand robot fabrication. We demonstrate this with the assembly of two centimeter-scale electromechanical systems: a Discretely Assembled Walking Motor (DAWM) capable of producing large scale linear or rotary motion from five millimeter-scale part types as well as a Modular Tiny Locomoting Element (MOTILE) that can locomote on a variety of ferrous surfaces. The five part types each embody a limited capability including rigid (strut and node), flexural, magnetic, or coil. Through their arrangement in a three-dimensional lattice, we demonstrate the assembly of actuated mechanical degrees-of-freedom in useful small-scale machines. This work extends prior research in discrete material systems with the inclusion of flexural and actuation components. Actuation is accomplished with the use of voice coil actuator components that produce up to 42 mN of force and strokes of 2 mm. This performance compares well with other millimeter scale actuators and provides sufficient force to lift 28 connected nodes in our assembled lattice, or 7 other actuator components. DAWM is capable of stepping at rates of up to 35 Hz, resulting in velocities of up to 25 mm/s. Multiple DAWM systems can be stacked to add force and can be driven in-phase or out-of-phase to produce intermittent or continuous force, respectively. MOTILE can climb vertical surfaces at speeds of 2.46 body-lengths per second, representing the fastest vertical climbing robot in recently reported research. This approach to robot fabrication discretizes robotic systems at a much finer granularity than prior work in modular robotics and demonstrates the possibility of assembling useful small-scale machines from a limited set of standard part types.

Self-replicating hierarchical modular robotic swarms

“…For actuation, we used commercially available digital servo motors, with an average net force output of roughly 57 N/kg and upper torque limits of around 10 N m 34 . This granularity limits the system scalability, which could be addressed through the serial and parallel addition of one-bit actuators 26 . Beyond selfreplication and hierarchy, this system also enables a large design space in robot morphology.…”

“…These relative carrier robots are designed to register to the lattice, enabling large-scale construction without typical penalties for metrology systems, and teams of robots can use the lattice to coordinate their motion. Smaller scale, discrete robotic systems have been demonstrated through the addition of degrees of freedom and modular actuation components 26 . These systems offer an alternative to the traditional division between monolithic robots (which are capable but not flexible) and modular robots (which are flexible but less capable), however, their numbers and sizes have been fixed.…”