A General Purpose Configurable Navigation Controller for Micro Aerial Multirotor Vehicles

In this paper, we consider the problem of autonomous navigation of multirotor platforms in GPS-denied environments. The focus of this work is on safe navigation based on unperfect odometry measurements, such as on-board optical flow measurements. The multirotor platform is modeled as a flying object with specific kinematic constraints that must be taken into account in order to obtain successful results. A navigation controller is proposed featuring a set of configurable parameters that allow, for instance, to have a configuration setup for fast trajectory following, and another to soften the control laws and make the vehicle navigation more precise and slow whenever necessary. The proposed controller has been successfully implemented in two different multirotor platforms with similar sensoring capabilities showing the openness and tolerance of the approach. This research is focused around the Computer Vision Group's objective of applying multirotor vehicles to civilian service applications. The presented work was implemented to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012, gaining two awards: the Special Award on "Best Automatic Performance - IMAV 2012" and the second overall prize in the participating category "Indoor Flight Dynamics - Rotary Wing MAV". Most of the code related to the present work is available as two open-source projects hosted in GitHub.

Controlling Minimally-Actuated Vehicles for Applications in Ocean Observation

Establishing a persistent presence in the ocean with an AUV to observe temporal variability of large-scale ocean processes requires a unique sensor platform. In this paper, we propose a strategy that utilizes ocean model predictions to increase the autonomy and control of Lagrangian or profiling floats for precisely this purpose. An A* planner is applied to a local controllability map generated from predictions of ocean currents to compute a path between prescribed waypoints that has the highest likelihood of successful execution. The control to follow the planned path is computed by use of a model predictive controller. This controller is designed to select the best depth for the vehicle to exploit ambient currents to reach the goal waypoint. Mission constraints are employed to simulate a practical data collection mission. Results are presented in simulation for a mission off the coast of Los Angeles, CA USA, and show surprising results in the ability of a Lagrangian float to reach a desired location.

A co-operative formation-based collision avoidance approach for a group of autonomous vehicles (Special Issue on Adaptive Control and Signal Processing in Marine System)

This paper employs a unique decentralised cooperative control method to realise a formation-based collision avoidance strategy for a group of autonomous vehicles. In this approach, the vehicles' role in the formation and their alert and danger areas are first defined, and the formation-based intra-group and external collision avoidance methods are then proposed to translate the collision avoidance problem into the formation stability problem. The extension–decomposition–aggregation formation control method is next employed to stabilise the original and modified formations, whilst manoeuvring, and subsequently solve their collision avoidance problem indirectly. Simulation study verifies the feasibility and effectiveness of the intra-group and external collision avoidance strategy. It is demonstrated that both formation control and collision avoidance problems can be simultaneously solved if the stability of the expanded formation including external obstacles can be satisfied.

A General Purpose Configurable Controller for Indoors and Outdoors GPS-Denied Navigation for Multirotor Unmanned Aerial Vehicles

This research on odometry based GPS-denied navigation on multirotor Unmanned Aerial Vehicles is focused among the interactions between the odometry sensors and the navigation controller. More precisely, we present a controller architecture that allows to specify a speed specified flight envelope where the quality of the odometry measurements is guaranteed. The controller utilizes a simple point mass kinematic model, described by a set of configurable parameters, to generate a complying speed plan. For experimental testing, we have used down-facing camera optical-flow as odometry measurement. This work is a continuation of prior research to outdoors environments using an AR Drone 2.0 vehicle, as it provides reliable optical flow on a wide range of flying conditions and floor textures. Our experiments show that the architecture is realiable for outdoors flight on altitudes lower than 9 m. A prior version of our code was utilized to compete in the International Micro Air Vehicle Conference and Flight Competition IMAV 2012. The code will be released as an open-source ROS stack hosted on GitHub.

Report on permanent grade and a system of sewerage for the city of Peoria : made by the special committee appointed for that purpose by the city council, transmitting a report on the subject made to them /by N.R. Gibson.

Mode of access: Internet.

By-laws ... adopted at a special town meeting called for that purpose March 16, 1909.

Cover-title.

Minutes of evidence and report of the special committee of the House of assembly of Lower Canada on the bill to make a new division of the province into counties for the purpose of a more equal representation in the House of assembly.

Mode of access: Internet.

Organizational, direct support maintenance repair parts and special tools list : tent, general purpose, small, FSN 8340-753-6471, medium, FSN 8340-543-7788, large, FSN 8340-285-5599.

Includes index.

Direct support, and general support, maintenance repair parts and special tools list : shop equipment, general purpose repair, semitrailer mounted (southwest truck body model SGPRSMD) (serial no. Range S-11-204 through S-11-265) (4940-01-006-3229).

"May 1982."

Organizational and direct support maintenance repair parts and special tools list : welding set, arc, inert gas shielded, water cooled, aluminum welding, general purpose (Airco model 23511209), FSN 3431-731-4163.

"December 1970."

Organizational maintenance repair parts and special tools lists : loader, scoop type, DED, 4-wheel drive, pneumatic tired hinged frame steer 2 1/2 cu yd, multi-purpose bucket, NSN 3805-00-169-4711, J.I. Case model MW24B.

Includes index.

Direct support and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools) : loader, scoop type, DED, 4-wheel drive, pneumatic tired hinged frame steer 1 1/2 cu yd, multi-purpose bucket, NSN 3805-00-169-4711, J.I. Case model MW24B.

Includes index.

Unit maintenance repair parts and special tools lists : loader, scoop type, DED, 4 x 4, articulated frame steer, 4 1/2 to 5 cu. yd., (CCE), Army model H100C RB, type I with 4 1/2 cu. yd. rock bucket, NSN 3805-01-052-9042, Army model H100C GPB, type II with 5 cu. yd. general purpose bucket, NSN 3805-01-052-9043.

Includes indexes.

Direct and general support maintenance repair parts and special tools list (including depot maintenance repair parts and special tools) : loader, scoop type, pneu-tired, diesel engine driven, hinged frame steer with 2 1/2 cubic yard multi-purpose bucket, (Allis-Chalmers model 645M), FSN 3805-051-9359.

Includes index.