Onboard power remains a major challenge for miniature robotic platforms. Locomotion at small scales demands high power densities from all system components, while limited payload capacities place severe restrictions on the size of the energy source, resulting in integration challenges and short operating times when using conventional batteries. Wireless power delivery has the potential to allow microrobotic platforms to operate autonomously for extended periods when near a transmitter. This paper describes the first demonstration of RF wireless power transfer in an insect-scale ambulatory robot. A wireless power transmission system based on magnetically coupled resonance is designed for the latest iteration of the Harvard Ambulatory MicroRobot (HAMR), a piezoelectrically driven quadruped that had previously received power through a tether. Custom power and control electronics are designed and implemented on lightweight printed circuit boards that form a part of the mechanical structure of the robot. The integration of the onboard receiver, power and control electronics, and mechanical structure yields a 4cm, 2.1g robot that can operate autonomously in two wireless power transmission scenarios.

Transmission and actuator selection are crucial for robot locomotion at any scale. This is especially true at small scales where actuation choices are limited and locomotion is energetically expensive. These components control the payload capacity and determine the height of the obstacles the robot can navigate over. In this study, we analyze the drivetrain of the new Harvard Ambulatory MicroRobot (HAMR-V) to improve its walking performance. We modeled several transmission and actuator design concepts and investigated their force and displacement outputs. The results led to the selection of improved actuator and transmission designs. Using these new insights, we constructed a miniature quadruped with a payload capacity of 63% of its weight that can be used for on-board electronics for sensing, control, and power.

Here we present the design of a 1.27g quadrupedal microrobot manufactured using “Pop-up book MEMS” the first such device capable of locomotion. Implementing popup assembly techniques enables manufacturing of the robot's exoskeleton and drivetrain transmissions from a single 23-layer laminate. Its demonstrated capabilities include payload capacity greater than 1.35g (106% of body mass), maneuverability on flat terrain, and high-speed locomotion up to 37cm/s. Additionally, locomotion performance is compared to a hand-assembled quadruped with similar design parameters. The results demonstrate that the pop-up manufacturing methodology enables more complex mechanisms while simultaneously increasing performance over hand-assembled alternatives.

Insect-scale legged robots have the potential to locomote on rough terrain, crawl through confined spaces, and scale vertical and inverted surfaces. However, small scale implies that such robots are unable to carry large payloads. Limited payload capacity forces miniature robots to utilize simple control methods that can be implemented on a simple onboard microprocessor. In this study, the design of a new version of the biologically-inspired Harvard Ambulatory MicroRobot (HAMR) is presented. In order to find the most suitable control inputs for HAMR, maneuverability experiments are conducted for several drive parameters. Ideal input candidates for orientation and lateral velocity control are identified as a result of the maneuverability experiments. Using these control inputs, two simple feedback controllers are implemented to control the orientation and the lateral velocity of the robot. The controllers are used to force the robot to track trajectories with a minimum turning radius of 55 mm and a maximum lateral to normal velocity ratio of 0.8. Due to their simplicity, the controllers presented in this work are ideal for implementation with on-board computation for future HAMR prototypes.

Here we present an autonomous 1.7g hexapod robot as a platform for research on centimeter-scale walking robots. It features six spherical five-bar linkages driven by high energy density piezoelectric actuators and onboard power and control electronics. This robot has achieved autonomous ambulation using an alternating tripod gait at speeds up to 0.9 body lengths per second, making this the smallest and lightest hexapod robot capable of autonomous locomotion.

Here we present the design, modeling, and fabrication of a 2g mobile robot. By applying principles from biology and existing meso-scale fabrication techniques, a 5.7cm hexapod robot with sprawled posture has been created, and is capable of locomotion up to 4 body-lengths per second using the alternating tripod gait at 20Hz actuation frequency. Furthermore, this work proves the viability of a new mechanical linkage design, fabricated using the smart composite microstructure process, to provide desirable leg trajectories for successful ambulation at the insect-scale.