Navigating large-scale outdoor environments requires complex reasoning in terms of geometric structures, environmental semantics, and terrain characteristics, which are typically captured by onboard sensors such as LiDAR and cameras. While current mobile robots can navigate such environments using pre-defined, high-precision maps based on hand-crafted rules catered for the specific environment, they lack commonsense reasoning capabilities, especially the traversability analysis, that most humans possess when navigating unknown outdoor spaces. To address this gap, we introduce the Global Navigation Dataset (GND), a large-scale dataset that integrates multi-modal sensory data, including 3D LiDAR point clouds and RGB and 360° images, as well as multi-category traversability maps (pedestrian walkways, vehicle roadways, stairs, off-road terrain, and obstacles) from ten university campuses. These environments encompass a variety of parks, urban settings, elevation changes, and campus layouts of different scales. The dataset covers approximately$2.7 ~\text{km}^{2}$and includes at least 350 buildings in total. We also present a set of novel applications of GND to showcase its utility to enable global robot navigation, such as map-based global navigation, mapless navigation, and global place recognition. GND's website can be found at https://cs.gmu.edu/xiao/Research/GND/.

This work demonstrates an all-elastomer MEMS capacitive strain sensor with high dynamic range (5000:1), and features an inexpensive molding microfabrication process. The sensor is comprised of conductive elastometric comb capacitors embedded in a dielectric. Two different sensor designs, lateral combs (LC) and transverse combs (TC), were developed to evaluate sensor sensitivity as a function of load orientation. Both sensors have combs with a gap of 30 μm, length of 4 mm, and depth of 65 μm. A linear elastic analytical model was developed to predict change in capacitance as a function of strain, and experimental results show a reasonable agreement with the theoretical predictions. The observed strain responses have high linearity and dynamic range, and negligible hysteresis. The strain resolution of the LC and TC sensors is 100 μstrain and 500 μstrain, respectively, tested up to 50% strain.

Kapton strain-based hair sensors were designed and fabricated to measure flow on a micro air vehicle. The fabrication process is carried out using a single mask and a combination of cleanroom and regular lab room processing. The processing resulted in successful realization of 6.4 mm long sensors with high yield. Associated signal conditioning circuitry was developed to extract small variations in resistance due to flow while suppressing noise. Three sensors were deployed on a fuselage shaped structure and characterized in a wind tunnel. Static linear and nonlinear estimation schemes were obtained based on the characterization data to determine the angle of attack, sideslip angle and airspeed values. For small angles of perturbation, the estimation scheme demonstrated good accuracy in determining the variables of interest. The sensors along with the signal conditioning circuitry are sufficiently lightweight that they can be used for estimating velocity states on micro air vehicles.

Miniature legged robots have demonstrated fast locomotion at small sizes, but underactuation generally limits their performance in rapid turns and other dynamic maneuvers. In this work, the inertial effect of swinging a dynamic tail was studied as a method to achieve these rapid turns. An analytic model of a robot with a reaction wheel tail was developed to determine the effect of varying system parameters such as tail motor voltage, coefficient of friction, and tail inertia on inertial turning performance. This model was also validated experimentally using a modified off-the-shelf miniature legged robot. The same trends seen in the analytic study were also found in the experiments varying motor voltage, coefficient of friction, and tail inertia.

The goal of this research is to develop a lightweight, high bandwidth control actuator that can be integrated on a flapping wing nano air vehicle (NAV). Traditional control actuators for air vehicles including DC servomotors and shape memory alloy are either too heavy or too slow to control a fast moving NAV. This paper develops a new bio-inspired active tail mechanism to stabilize an inverted pendulum with the same mass and inertia as the NAV. An analysis of the dynamic model shows a critical angle at which the control actuator can no longer stabilize the pendulum varies significantly with link lengths and mass ratios. Based on this dynamic model, an LQR controller is developed and implemented as a state space controller on a microcontroller based test setup. Using a gyroscope to measure the pendulum's angular velocity and estimate the angle, the active tail mechanism was able to stabilize the pendulum for over five minutes before falling due to drift in the gyroscope sensor.

This paper describes the performance of a fluidic microrobot using Electrowetting on Dielectric (EWOD). A system to control the fluidic microrobot was designed, constructed and deployed in the NIST Mobile Microrobotics Challenge at ICRA 2011. The microrobots (0.1 M KCl and 550 μm diameter) demonstrated the ability to perform controlled maneuvers in 2-D while transporting hydrophilic objects. The EWOD system is composed of a DIP-mounted die produced via standard microfabrication techniques and containing the control electrodes / competition arena, and a transparent ITO cover slip for grounding. Key advantages of this platform include a scalable design for batch EWOD system fabrication, potential simultaneous control of multiple microrobots, and an easily portable, compact system design.

The first MEMS process integrating soft elastomers in a standard silicon-on-insulator (SOI) wafer without assembly has been demonstrated for use in microrobotic mechanisms. This process allows silicon and poly(dimethylsiloxane) (PDMS) features to be defined in-plane with feature sizes down to 2 μm. Test structures have been used to characterize the Young's modulus of the resulting PDMS at 1.4 MPa along with adhesion to silicon structures. In addition, compliant flexures have been designed, fabricated and characterized for eventual use in microrobot legs. Test structures have been mechanically folded 180° out of plane over 60 times without failure.