Visual Servoing for a Quadcopter Flight Control

In this thesis the potential of visual servoing techniques for vertical take-off and landing(VTOL) UAV platforms is explored. An overview of UAV applications and state-of-the-art quadrotors is provided, backed up by the necessary theoretical background. Visualservoing based solutions of the important flight tasks (such as vertical take-off and land-ing, obstacle avoidance and attitude estimation) are presented.A novel vision based autopilot for vertical take-off and landing is developed, exper-imentally verified and implemented on a medium-size outdoor quadrotor platform pro-vided by Dr. YangQuan Chen from Utah State University, Center for Self-OrganizingIntelligent Systems.Validerat; 20120723 (anonymous

An Evolutionary Approach to Tuning a Multi-Agent System for Autonomous Adaptive Control of a Flapping-Wing Micro Air Vehicle

Biomimetic flapping wing vehicles have attracted recent interest because of their numerous potential military and civilian applications. In this paper, we describe an evolutionary approach to tuning a Multi-Agent System for autonomous adaptive control of a Flapping-Wing Micro Air Vehicle. The wings of the vehicle are controlled by a split cycle oscillator, which combined with non-linearities and differences between each vehicle, brings significant challenge for selecting the proper parameters for the control system. Adopting a Neo-Darwinistic evolutionary approach, where solutions are evolved in a similar manner as in nature, allows us to precisely learn control parameters for each vehicle. After describing the evolution algorithm and evolving the control parameters, we utilize these values for autonomous waypoint following by the micro air vehicle

An open-source real-time UAS flight control prototyping and testing platform with fractional-order horizontal controller example

Safety and reliability are key if unmanned aerial systems (UAS) are to move from research and become an everyday part of our lives. How can safety and reliability be maintained when cost and timeliness are such pressing factors in small UAS development? In this paper, it is shown that with open-source flight control software (provided by the authors), sophisticated testing practices (hardware-in-the-loop) can provide rapid pre-flight verification of experimental control system designs. Using these methods increases the reliability of flight control software developed in many ways if tested properly Both PID and auto-generated PIλD control schemes are compared as examples of flight software under test, and simulated flight performance is shown

Improving communication security of open source UAVs: Encrypting radio control link

Safety and reliability (also referred to as airworthiness) are well-known factors of Unmanned Aerial Vehicle (UAV) operations, and significant effort has been put into maintaining and improving them for everyday UAV users. Cyber-security, on the other hand, gained attention only recently. Currently, a malicious user can relatively easily disturb operation or even seize control of the most popular open-source UAVs, as a result of their poor communications security (COMSEC). Even though solutions to improve UAV\u27s COMSEC are known, they have not been fully implemented in a user-friendly way. The contribution of the paper is an implementation of an encrypted Radio Control (RC) link that can be used with a number of popular RC transmitters. We use Galois Embedded Crypto library, an ArduinoLibs Crypto library together with openLRSng open-source radio project. We provide some lessons learned during development, implementation, and testing so users wishing to use their own encrypted link can leverage our work

Battery State-Of-Charge Based Altitude Controller for Small, Low Cost Multirotor Unmanned Aerial Vehicles

Small unmanned aerial vehicles (UAV) are typically driven by Lithium polymer batteries. The batteries have their own dynamics, which changes during discharge. Classical approaches to altitude control assume a time-invariant system and therefore fail. Adaptive controllers require an identified system model which is often unavailable. Battery dynamics can be characterized and used for a battery model-based controller. This controller is useful in situations when no feedback from actuators (such as RPM or thrust) is available. After measuring the battery dynamics for two distinct types of batteries, a controller is designed and experimentally verified, showing a consistent performance during entire discharge test and a consequent flight verification

Battery State-Of-Charge Based Altitude Controller for Small, Low Cost Multirotor Unmanned Aerial Vehicles

Small unmanned aerial vehicles (UAV) are typically driven by Lithium polymer batteries. The batteries have their own dynamics, which changes during discharge. Classical approaches to altitude control assume a time-invariant system and therefore fail. Adaptive controllers require an identified system model which is often unavailable. Battery dynamics can be characterized and used for a battery model-based controller. This controller is useful in situations when no feedback from actuators (such as RPM or thrust) is available. After measuring the battery dynamics for two distinct types of batteries, a controller is designed and experimentally verified, showing a consistent performance during entire discharge test and a consequent flight verification

Battery Model-Based Thrust Controller for a Small, Low Cost Multirotor Unmanned Aerial Vehicles

Small Unmanned Aerial Vehicles (UAV) are typically driven by LiPo batteries. The batteries have their own dynamics, which changes during discharge. Classical approaches to altitude control assume time-invariant system and therefore fail. Adaptive controllers require an identified system model which is often unavailable. Battery dynamics can be characterized and used for a battery model-based controller. This controller is useful in situations when no feedback from actuators (such as RPM or thrust) is available. After measuring the battery dynamics for two distinct types of batteries, a controller is designed and experimentally verified, showing a consistent performance during whole discharge test. Unmanned Aerial Vehicles (UAV), Vertical Take-Off and Landing (VTOL), quadrotor, hexarotor, multirotor, altitude control, battery monitoring and modelling

Experimental evidence for the role of Brissopsis lyrifera (Forbes, 1841) as a critical species in the maintenance of benthic diversity and the modification of sediment chemistry

The effects on infaunal diversity and sediment chemistry of bioturbation/feeding activity by different densities of the heart urchin Brissopsis lyrifera are quantified in an experiment conducted in the benthic mesocosm facility of the Norwegian Institute for Water Research at Solbergstrand, Norway. Using sediment from Bjørnhordenbukta, a small, sheltered bay in Oslofjørd, areas were subjected to 20 weeks of continuous disturbance from urchins at densities equivalent to 28 and 71 individuals m−2, whilst other areas remained undisturbed. Low density treatments, reflecting the natural field densities observed during collection of the sediment, produced higher infaunal β diversity than the heavily disturbed or control treatments and this could be attributed to a decrease in competitive exclusion. This is consistent with the predictions of the intermediate disturbance hypothesis (Connell, 1978). Bioturbation also caused a significant change in the chemistry of the surface sediment increasing oxygenation, decreasing the rates of denitrification and increasing the precipitation of phosphate. It is concluded that the disturbance activity of Brissopsis lyrifera may play a vital role in the maintenance of regional diversity and in the mediation of geochemical processes

CompartOS: CHERI Compartmentalization for Embedded Systems

Existing high-end embedded systems face frequent security attacks. Software compartmentalization is one technique to limit the attacks' effects to the compromised compartment and not the entire system. Unfortunately, the existing state-of-the-art embedded hardware-software solutions do not work well to enforce software compartmentalization for high-end embedded systems. MPUs are not fine-grained and suffer from significant scalability limitations as they can only protect a small and fixed number of memory regions. On the other hand, MMUs suffer from non-determinism and coarse-grained protection. This paper introduces CompartOS as a lightweight linkage-based compartmentalization model for high-end, complex, mainstream embedded systems. CompartOS builds on CHERI, a capability-based hardware architecture, to meet scalability, availability, compatibility, and fine-grained security goals. Microbenchmarks show that CompartOS' protection-domain crossing is 95% faster than MPU-based IPC. We applied the CompartOS model, with low effort, to complex existing systems, including TCP servers and a safety-critical automotive demo. CompartOS not only catches 10 out of 13 FreeRTOS-TCP published vulnerabilities that MPU-based protection (e.g., uVisor) cannot catch but can also recover from them. Further, our TCP throughput evaluations show that our CompartOS prototype is 52% faster than relevant MPU-based compartmentalization models (e.g., ACES), with a 15% overhead compared to an unprotected system. This comes at an FPGA's LUTs overhead of 10.4% to support CHERI for an unprotected baseline RISC-V processor, compared to 7.6% to support MPU, while CHERI only incurs 1.3% of the registers area overhead compared to 2% for MPU