William E. Green

Flying insect inspired vision for autonomous aerial robot maneuvers in near-earth environments

Near-earth environments are time consuming, labor intensive and possibly dangerous to safe guard. Accomplishing tasks like bomb detection, search-and-rescue and reconnaissance with aerial robots could save resources. This work describes the adoption of insect behavior and flight patterns to develop a MAV sensor suite. A prototype called CQAR: closed quarter aerial robot, which is capable of flying in and around buildings, through tunnels and in and out of caves is used to validate the efficiency of such a method when equipped with optic flow microsensors.

A MAV that flies like an airplane and hovers like a helicopter

Near-earth environments, such as forests, caves, tunnels, and urban structures make reconnaissance, surveillance and search-and-rescue missions difficult and dangerous to accomplish. Micro-air-vehicles (MAVs), equipped with wireless cameras, can assist in such missions by providing real-time situational awareness. This paper describes an additional flight modality enabling fixed-wing MAVs to supplement existing endurance superiority with hovering capabilities. This secondary flight mode can also be used to avoid imminent collisions by quickly transitioning from cruise to hover flight. A sensor suite which allows for autonomous hovering by regulating the aircrafts yaw. pitch and roll angles is also described

Optic-Flow-Based Collision Avoidance

Flying in and around caves, tunnels, and buildings demands more than one sensing modality. This article presented an optic-flow- based approach inspired by flying insects for avoiding lateral collisions. However, there were a few real-world scenarios in which optic flow sensing failed. This occurred when obstacles on approach were directly in front of the aircraft. Here, a simple sonar or infrared sensor can be used to trigger a quick transition into the hovering mode to avoid the otherwise fatal collision. Toward this end, we have demonstrated a fixed-wing prototype capable of manually transitioning from conventional cruise flight into the hovering mode. The prototype was then equipped with an IMU and a flight control system to automate the hovering process. The next step in this research is to automate the transition from cruise to hover flight.

Autonomous hovering of a fixed-wing micro air vehicle

Recently, there is a need to acquire intelligence in hostile or dangerous environments such as caves, forests, or urban areas. Rather than risking human life, backpackable, bird-sized aircraft, equipped with a wireless camera, can be rapidly deployed to gather reconnaissance in such environments. However, they first must be designed to fly in tight, cluttered terrain. This paper discusses an additional flight modality for a fixed-wing aircraft, enabling it to supplement existing endurance superiority with hovering capabilities. An inertial measurement sensor and an onboard processing and control unit, used to achieve autonomous hovering, are also described. This is, to the best of our knowledge, the first documented success of hovering a fixed-wing micro air vehicle autonomously

Autonomous Landing for Indoor Flying Robots Using Optic Flow

Urban environments are time consuming, labor intensive and possibly dangerous to safe guard. Accomplishing tasks like bomb detection, search-andrescue and reconnaissance with aerial robots could save resources. This paper describes a prototype called CQAR: Closed Quarter Aerial Robot, which is capable of flying in and around buildings. The prototype was analytically designed to fly safely and slowly. An optic flow microsensor for depth perception, which will allow autonomous takeoff and landing and collision avoidance, is also described.

Design, Development, and Testing of an Automated Laparoscopic Grasper with 3-D Force Measurement Capability

Advancements in robotics have led to significant improvements in robot-assisted minimally invasive surgery. The use of these robotic systems has improved surgeon dexterity, reduced surgeon fatigue, and made remote surgical procedures possible. However, commercially available robotic surgical systems do not provide any haptic feedback to the surgeon. Just as palpation in open procedures helps the surgeon diagnose the tissue as normal or abnormal, it is necessary to provide force feedback to the surgeon in robot-assisted minimally invasive procedures. Therefore, a need exists to incorporate force feedback in laparoscopic tools for robot-assisted surgery. This paper describes our design of a laparoscopic grasper with tri-directional force measurement capability at the grasping jaws. The laparoscopic tool can measure grasping forces and lateral and longitudinal forces, such as those forces encountered in the probing of tissue. Initial testing of the prototype has shown its ability to accurately characterize artificial tissue samples of varying stiffness.

An aerial robot prototype for situational awareness in closed quarters

More often homeland security, disaster mitigation and military operations are performed in urban environments. Time consuming, labor intensive and possibly dangerous tasks like bomb detection, search-and-rescue and reconnaissance done with robots could save resources. An aerial robot capable of flying in closed quarters like warehouses, stadiums, underground parking lots and tunnels is featured. The working prototype can fly slowly, safely and transmit wireless video for situational awareness. The design is analytic and employs a multi-disciplinary design optimization to formulate the integration of aerodynamics, sensor suite and task performance.

A fixed-wing aircraft for hovering in caves, tunnels, and buildings

Micro air vehicles (MAVs) are small bird-sized aircraft with applications in reconnaissance, search-and-rescue, airborne agent and pathogen detection, and target acquisition. Fixed-wing MAVs cannot hover and thus, are not able to fly in tight, enclosed spaces. Rotary-wing platforms can hover but are limited by endurance. This paper presents a fixed-wing MAV with a secondary flight mode (i.e. hovering) allowing it to fly in caves, tunnels, and buildings. The sensing and control system used to achieve autonomous hovering is also described. This is, to the best of our knowledge, the first documented success of autonomously hovering a fixed-wing MAV in the open literature

A competition to identify key challenges for unmanned aerial robots in near-earth environments

Tasks like bomb-detection, search-and-rescue, and reconnaissance in near-Earth environments are time, cost and labor intensive. Aerial robots could assist in such missions and offset the demand in resources and personnel. However, flying in environments rich with obstacles presents many more challenges which have yet to be identified. For example, telephone wire is one obstacle that is known to be hard to detect in mid-flight. This paper describes a safe and easy to fly platform in conjunction with an aerial robot competition to highlight key challenges when flying in near-Earth environments

A Hybrid MAV for Ingress and Egress of Urban Environments

Small bird-sized aerial robots are expendable and can fly over obstacles and through small openings to assist in the acquisition and distribution of intelligence during reconnaissance, surveillance, and search-and-rescue missions in urban environments. However, limited flying space and densely populated obstacle fields require a vehicle that is capable of hovering but is also maneuverable. A secondary flight mode was incorporated into a fixed-wing aircraft to preserve its maneuverability while adding the capability of hovering. An inertial measurement sensor and onboard flight control system were interfaced and used to transition the hybrid prototype from cruise to hover flight and sustain a hover autonomously. Furthermore, the hovering flight mode can be used to maneuver the aircraft through small openings such as doorways. An ultrasonic and infrared sensor suite was designed to follow exterior building walls until an ingress route was detected. Reactive control was then used to traverse the doorway and gather reconnaissance. This paper describes the holistic approach of platform development, sensor suite design, and control of the hybrid prototype.