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The ideal microrobots are millimeter sized with integrated actuators, power sources, sensors, and controllers. Many researchers take the inspiration from insects for the mechanical or electrical designs to construct small sized robotic systems. Previously, the authors proposed and demonstrated microrobots which can replicate the tripod gait locomotion of an ant and the legs were actuated by shape memory alloy actuators. Shape memory alloy provided a large deformation and a large force, but the power consumption was as high as 94 mW to actuate a single leg. This paper discusses the silicon electrostatic inchworm motor chip with low energy consumption for the robot leg by using a small-size power source. The inchworm motor chip has actuated by electrostatic motors. The power consumption is low as 1.0 mW compering with shape memory alloy actuators. The reciprocal motion of the inchworm motor chip is power by the silicon photovoltaic cells. Results show the 7.5 mm square size photovoltaic cells could produce 60 V to actuate the inchworm motor chip. The generated force is enough to move the leg of the microrobot. We have shown actuation of the microrobot leg using an electrostatic inchworm motor chip. This result is the first instance of an electrostatic motor driving an off-chip structure.

The design of gaits for robot locomotion can be a daunting process which requires significant expert knowledge and engineering. This process is even more challenging for robots that do not have an accurate physical model, such as compliant or micro-scale robots. Data-driven gait optimization provides an automated alternative to analytical gait design. In this paper, we propose a novel approach to efficiently learn a wide range of locomotion tasks with walking robots. This approach formalizes locomotion as a contextual policy search task to collect data, and subsequently uses that data to learn multi-objective locomotion primitives that can be used for planning. As a proof-of-concept we consider a simulated hexapod modeled after a recently developed microrobot, and we thoroughly evaluate the performance of this microrobot on different tasks and gaits. Our results validate the proposed controller and learning scheme on single and multi-objective locomotion tasks. Moreover, the experimental simulations show that without any prior knowledge about the robot used (e.g., dynamics model), our approach is capable of learning locomotion primitives within 250 trials and subsequently using them to successfully navigate through a maze., 8 pages. Accepted at RAL+ICRA2018

We demonstrate high-force-density rapid actuation of electrostatic gap-closing actuator (GCA) arrays operating in an aqueous environment. These devices are designed to generate up to 4.6 mN at 6 V drive signal amplitudes and have measured pull-in times as fast as 121 μs with no electrolysis. We present a new model for the dynamics of aqueous GCA operation which includes the inertia of the squeezed fluid and proximity of the substrate to the device layer. The actuators operate in deionized water, and preliminary tests demonstrate actuation in ionic solutions (10 mM) and partial operation of submerged inchworm motors based on GCA arrays.

This work describes the design, fabrication, and assembly of a MEMS aerodynamic control surface for use in millimeter-scale rockets and other miniature aerial vehicles (MAVs). Aerial vehicles of this scale require very small and light control surfaces to operate effectively. We designed MEMS aero-dynamic control surfaces using electrostatic inchworm motors and planar silicon pin-joints. These were fabricated in a silicon-on-insulator (SOI) process. The fully assembled fin structure demonstrated maximum torque outputs of 1.6 μNm which is enough to maintain an aerodynamic lift force of 1.4 mN.

This work presents the locomotion of a ground-based single-legged silicon robot. The robot measures 5mm × 6mm × 0.5mm and weighs 18mg. Fabricated in a silicon-on-insulator (SOI) process, the robot is based on electrostatic inchworm motors that drive a 2 degree-of-freedom (DOF) planar silicon linkage that acts as the leg. The leg sweeps out an area of approximately 500μm × 500μm off the edge of the chip. The chip is connected to power and control by long flexible wires which also act to support the robot upright. The robot exerts over 1.5× its weight in the vertical axis, enough to lift its body and push itself forward.

The bulk of current research in the realm of pico air vehicles has focused on biologically inspired propulsion mechanisms. In this work we investigate the use of electrohydrodynamic thrust produced by a microfabricated corona discharge device as a mechanism to create flying microrobots with no moving parts. Electrodes of various geometries are fabricated from a silicon-on-insulator wafer with a two mask process. Electrical characterization is performed to analyze the effect of inter-electrode gap and emitter electrode width on corona discharge and compare findings to simulation. Outlet air velocity and thrust are directly measured to analyze the effects of collector electrode geometry on performance. A roughly 100 cubic millimeter, 2.5mg thruster is assembled with a thrust to weight ratio exceeding 20.

This work presents the initial characterization of planar silicon pin-joints for use in linkages for walking microrobot legs. A major goal in walking microrobotics is the creation of robust leg structures driven by low-power motors capable of lifting a 20mg mass and propelling it forward. Hinged joint structures, rather than stiff flexures, are ideal for this task. However, since joints are not fully rigid structures, the possibility of pull-out failure is important to take into account. The joints we use are fabricated in a silicon-on-insulator (SOI) process. They have demonstrated pull-out forces ranging from 1mN to 29mN, well over the strength of our motor designs and capable of handling the intended mass of the robot. Additionally, the frictional coefficient during pull-out was found to be dependent on the load from the joint holder.

We present the instrument design and first light observations of KAPAO, a natural guide star adaptive optics (AO) system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. The KAPAO system has dual science channels with visible and near-infrared cameras, a Shack-Hartmann wavefront sensor, and a commercially available 140-actuator MEMS deformable mirror. The pupil relays are two pairs of custom off-axis parabolas and the control system is based on a version of the Robo-AO control software. The AO system and telescope are remotely operable, and KAPAO is designed to share the Cassegrain focus with the existing TMO polarimeter. We discuss the extensive integration of undergraduate students in the program including the multiple senior theses/capstones and summer assistantships amongst our partner institutions. This material is based upon work supported by the National Science Foundation under Grant No. 0960343.

We describe KAPAO, our project to develop and deploy a low-cost, remote-access, natural guide star adaptive optics (AO) system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. We use a commercially available 140-actuator BMC MEMS deformable mirror and a version of the Robo-AO control software developed by Caltech and IUCAA. We have structured our development around the rapid building and testing of a prototype system, KAPAO-Alpha, while simultaneously designing our more capable final system, KAPAO-Prime. The main differences between these systems are the prototype's reliance on off-the-shelf optics and a single visible-light science camera versus the final design's improved throughput and capabilities due to the use of custom optics and dual-band, visible and near-infrared imaging. In this paper, we present the instrument design and on-sky closed-loop testing of KAPAO-Alpha as well as our plans for KAPAO-Prime. The primarily undergraduate-education nature of our partner institutions, both public (Sonoma State University) and private (Pomona and Harvey Mudd Colleges), has enabled us to engage physics, astronomy, and engineering undergraduates in all phases of this project. This material is based upon work supported by the National Science Foundation under Grant No. 0960343., 10 pages and 11 figures