Indoor Dead Reckoning Localization Using Ultrasonic Anemometer with IMU

Dead reckoning is an important aspect of estimating the instantaneous position of a mobile robot. An inertial measurement unit (IMU) is generally used for dead reckoning because it measures triaxis acceleration and triaxis angular velocities in order to estimate the position of the mobile robot. Positioning with inertial data is reasonable for a short period of time. However, the velocity, position, and attitude errors increase over time. Much research has been conducted in ways to reduce these errors. To position a mobile robot, an absolute positioning method can be combined with dead reckoning. The performance of a combined positioning method can be improved based on improvement in dead reckoning. In this paper, an ultrasonic anemometer is used to improve the performance of dead reckoning when indoors. A new approach to the equation of an ultrasonic anemometer is proposed. The ultrasonic anemometer prevents divergence of the mobile robot’s velocity. To position a mobile robot indoors, the ultrasonic anemometer measures the relative movement of air while the robot moves through static air. Velocity data from the ultrasonic anemometer and the acceleration and angular velocity data from the IMU are combined via Kalman filter. Finally we show that the proposed method has the performance with a positioning method using encoders on a good floor condition

The Khepera IV Mobile Robot: Performance Evaluation, Sensory Data and Software Toolbox

Taking distributed robotic system research from simulation to the real world often requires the use of small robots that can be deployed and managed in large numbers. This has led to the development of a multitude of these devices, deployed in the thousands by researchers worldwide. This paper looks at the Khepera IV mobile robot, the latest iteration of the Khepera series. This full-featured differential wheeled robot provides a broad set of sensors in a small, extensible body, making it easy to test new algorithms in compact indoor arenas. We describe the robot and conduct an independent performance evaluation, providing results for all sensors. We also introduce the Khepera IV Toolbox, an open source framework meant to ease application development. In doing so, we hope to help potential users assess the suitability of the Khepera IV for their envisioned applications and reduce the overhead in getting started using the robot

Practical investigations in robot localization using ultra-wideband sensors

Robot navigation is rudimentary compared to the capabilities of humans and animals to move about their environments. One of the core processes of navigation is localization, the problem of answering where one is at the present time. Robot localization is the science of using various sensors to inform a robot of where it is within its environment. Ultra-wideband (UWB) radio is one such sensor technology that can return absolute position information. The algorithm to accomplish this is known as multilateration, which uses a collection of distance measurements between multiple robot tag and environment anchor pairs to calculate the tag’s position. UWB is especially suited to the task of returning precise distance measurements due to its capabilities of short duration, high amplitude pulse generation and detection. Decawave Ltd. has created an UWB integrated circuit to perform ranging and a suite of products to support this technology. Claimed and verified accuracies using this implementation are on the order of 10cm. This thesis describes various experiments carried out using Decawave technology for robot localization. The progression of the chapters starts with commercial product verification before moving into development and testing in various environments of an open-source driver package for the Robot Operating System (ROS), then the development of a novel phase difference of arrival (PDoA) sensor for three-dimensional robot localization without an UWB anchor mesh, before concluding with future research directions and commercialization potential of UWB. This thesis is designed as a compilation of all that the author has learned through primary and secondary research over the past three years of investigation. The primary contributions are: 1. A modular ROS UWB driver framework and series of ROS bags for offline experimentation with multilateration algorithms. 2. A robust ROS framework for comparing motion capture system (MoCap) ground truth vs sensor data for rigorous statistical analysis and characterization of multiple sensors. 3. Development of a novel UWB PDoA sensor array and data model to allow 3D localization of a target from a single point without the deployment of an antenna mesh

Experimental Investigation of a MAV-Scale Cyclocopter

The development of an efficient, maneuverable, and gust tolerant hovering concept with a multi-modal locomotion capability is key to the success of micro air vehicles (MAVs) operating in multiple mission scenarios. The current research investigated performance of two unconventional cycloidal-rotor-based (cyclocopter) configurations: (1) twin-cyclocopter and (2) all-terrain cyclocopter. The twin-cyclocopter configuration used two cycloidal rotors (cyclorotors) and a smaller horizontal edge-wise nose rotor to counteract the torque produced by the cyclorotors. The all-terrain cyclocopter relied on four cyclorotors oriented in an H-configuration. Objectives of this research include the following: (1) develop control strategies to enable level forward flight of a cyclocopter purely relying on thrust vectoring, (2) identify flight dynamics model in forward flight, (3) experimentally evaluate gust tolerance strategies, and (4) determine feasibility and performance of multi-modal locomotion of the cyclocopter configuration. The forward flight control strategy for the twin-cyclocopter used a unique combination of independent thrust vectoring and rotational speed control of the cyclorotors. Unlike conventional rotary-winged vehicles, the cyclocopter propelled in forward flight by thrust vectoring instead of pitching the entire fuselage. While the strategy enabled the vehicle to maintain a level attitude in forward flight, it was accompanied by significant yaw-roll controls coupling and gyroscopic coupling. To understand these couplings and characterize the bare airframe dynamics, a 6-DOF flight dynamics model of the cyclocopter was extracted using a time-domain system identification technique. Decoupling methods involved simultaneously mixing roll and yaw inputs in the controller. After implementing the controls mixing strategy in the closed-loop feedback system, the cyclocopter successfully achieved level forward flight up to 5 m/s. Thrust vectoring capability also proved critical for gust mitigation. Thrust vectoring input combined with flow feedback and position feedback improved gust tolerance up to 4 m/s for a twin-cyclocopter mounted on a 6-DOF test stand. Flow feedback relied on a dual-axis flowprobe attached to differential pressure sensors and position feedback was based on data recorded by the VICON motion capture system. The vehicle was also able to recover initial position for crosswind scenarios tested at various side-slip angles up to 30 degrees. Unlike existing multi-modal platforms, the all-terrain cyclocopter solely relied on its four cyclorotors as main source of propulsion, as well as wheels. Aerial and aquatic modes used aerodynamic forces generated by modulating cyclorotor rotational speeds and thrust vectors while terrestrial mode used motor torque. In aerial mode, cyclorotors operated at 1550 rpm and consumed 232 W to sustain hover. In terrestrial mode, forward translation at 2 m/s required 28 W, which was an 88% reduction in power consumption required to hover. In aquatic mode, cyclorotors operated at 348 rpm to achieve 1.3 m/s translation and consumed 19 W, a 92% reduction in power consumption. With only a modest weight addition of 200 grams for wheels and retractable landing gear, the versatile cyclocopter platform achieved sustained hover, efficient translation and rotational maneuvers on ground, and aquatic locomotion

Formation-Based Odour Source Localisation Using Distributed Terrestrial and Marine Robotic Systems

This thesis tackles the problem of robotic odour source localisation, that is, the use of robots to find the source of a chemical release. As the odour travels away from the source, in the form of a plume carried by the wind or current, small scale turbulence causes it to separate into intermittent patches, suppressing any gradients and making this a particularly challenging search problem. We focus on distributed strategies for odour plume tracing in the air and in the water and look primarily at 2D scenarios, although novel results are also presented for 3D tracing. The common thread to our work is the use of multiple robots in formation, each outfitted with odour and flow sensing devices. By having more than one robot, we can gather observations at different locations, thus helping overcome the difficulties posed by the patchiness of the odour concentration. The flow (wind or current) direction is used to orient the formation and move the robots up-flow, while the measured concentrations are used to centre the robots in the plume and scale the formation to trace its limits. We propose two formation keeping methods. For terrestrial and surface robots equipped with relative or absolute positioning capabilities, we employ a graph-based formation controller using the well-known principle of Laplacian feedback. For underwater vehicles lacking such capabilities, we introduce an original controller for a leader-follower triangular formation using acoustic modems with ranging capabilities. The methods we propose underwent extensive experimental evaluation in high-fidelity simulations and real-world trials. The marine formation controller was implemented in MEDUSA autonomous vehicles and found to maintain a stable formation despite the multi-second ranging period. The airborne plume tracing algorithm was tested using compact Khepera robots in a wind tunnel, yielding low distance overheads and reduced tracing error. A combined approach for marine plume tracing was evaluated in simulation with promising results

Formation-Based Odour Source Localisation Using Distributed Terrestrial and Marine Robotic Systems

This thesis tackles the problem of robotic odour source localisation, that is, the use of robots to find the source of a chemical release. As the odour travels away from the source, in the form of a plume carried by the wind or current, small scale turbulence causes it to separate into intermittent patches, suppressing any gradients and making this a particularly challenging search problem. We focus on distributed strategies for odour plume tracing in the air and in the water and look primarily at 2D scenarios, although novel results are also presented for 3D tracing. The common thread to our work is the use of multiple robots in formation, each outfitted with odour and flow sensing devices. By having more than one robot, we can gather observations at different locations, thus helping overcome the difficulties posed by the patchiness of the odour concentration. The flow (wind or current) direction is used to orient the formation and move the robots up-flow, while the measured concentrations are used to centre the robots in the plume and scale the formation to trace its limits. We propose two formation keeping methods. For terrestrial and surface robots equipped with relative or absolute positioning capabilities, we employ a graph-based formation controller using the well-known principle of Laplacian feedback. For underwater vehicles lacking such capabilities, we introduce an original controller for a leader-follower triangular formation using acoustic modems with ranging capabilities. The methods we propose underwent extensive experimental evaluation in high-fidelity simulations and real-world trials. The marine formation controller was implemented in MEDUSA autonomous vehicles and found to maintain a stable formation despite the multi-second ranging period. The airborne plume tracing algorithm was tested using compact Khepera robots in a wind tunnel, yielding low distance overheads and reduced tracing error. A combined approach for marine plume tracing was evaluated in simulation with promising results

Proceedings of the International Micro Air Vehicles Conference and Flight Competition 2017 (IMAV 2017)

The IMAV 2017 conference has been held at ISAE-SUPAERO, Toulouse, France from Sept. 18 to Sept. 21, 2017. More than 250 participants coming from 30 different countries worldwide have presented their latest research activities in the field of drones. 38 papers have been presented during the conference including various topics such as Aerodynamics, Aeroacoustics, Propulsion, Autopilots, Sensors, Communication systems, Mission planning techniques, Artificial Intelligence, Human-machine cooperation as applied to drones