Animal-inspired design and aerodynamic stabilization of a hexapedal millirobot

Abstract

Abstract-The VelociRoACH is a 10 cm long, 30 gram hexapedal millirobot capable of running at 2.7 m/s, making it the fastest legged robot built to date, relative to scale. We present the design by dynamic similarity technique and the locomotion adaptations which have allowed for this highly dynamic performance. In addition, we demonstrate that rotational dynamics become critical for stability as the scale of a robotic system is reduced. We present a new method of experimental dynamic tuning for legged millirobots, aimed at finding stable limit cycles with minimal rotational energy. By implementing an aerodynamic rotational damper, we further reduced the rotational energy in the system, and demonstrated that stable limit cycles with lower rotational energy are more robust to disturbances. This method increased the stability of the system without detracting from forward speed.

Automatic identification of dynamic piecewise affine models for a running robot

“…For this analysis, we observed the dynamics of the VelociRoACH [1] running on a treadmill. The VelociRoACH is a hexapedal robot capable of stable running at 27 bodylengths per second with an alternating tripod gait.…”

“…These linkages are made with the Smart Composite Microstructures process [14], and convert rotary motion to leg abduction and adduction. See Haldane et al [1] for details on mechanical design and dynamic performance. A key feature of this robot is that the leg kinematics for each side are predetermined by the geometry of the kinematic linkages, i.e.…”

“…Biologically inspired millirobots are inexpensive to produce, highly robust, and can exhibit remarkable dynamic performance [1]. Due to their small size, it is important to minimize the number of actuators and the required actuator bandwidth.…”

“…Due to their small size, it is important to minimize the number of actuators and the required actuator bandwidth. Therefore, these robots [2][3] [1] have been designed to be open-loop stable, allowing them to convert feed-forward motor power into stable and robust locomotion. The ability of these robots to run dynamically has allowed us to observe a number of emergent dynamic maneuvers such as rapid turns, reversals, jumps exceeding body height, flips, and cartwheels.…”

Energy-efficacy comparisons and multibody dynamics analyses of legged robots with different closed-loop mechanisms

“…Jin's hexapod walking robot [33] weighted 5.26 kg, which was controlled autonomously by the torque distribution algorithm to minimize the system's energy cost. VelociRoACH [25] was a 30 × 10 −3 kg hexapedal millirobot capable of running at 2.7 m/s. Its creators developed a new gait tuning method for millirobots, which was designed for finding stable limit cycles which minimized the amount of rotational energy in their systems.…”