Robotic Helicopter Research Articles

Robot Pilot: A New Autonomous System toward Flying Manned Aerial Vehicles

The robot pilot is a new concept of a robot system that pilots a manned aircraft, thereby forming a new type of unmanned aircraft system (UAS) that makes full use of the platform maturity, load capacity, and airworthiness of existing manned aircraft while greatly expanding the operation and application fields of UASs. In this research, the implementation and advantages of the robot pilot concept are discussed in detail, and a helicopter robot pilot is proposed to fly manned helicopters. The robot manipulators are designed according to the handling characteristics of the helicopter-controlling mechanism. Based on a kinematic analysis of the robot manipulators, a direct-driving method is established for the robot flight controller to reduce the time delay and control error of the robot servo process. A supporting ground station is built to realize different flight modes and the functional integration of the robot pilot. Finally, a prototype of the helicopter robot pilot is processed and installed in a helicopter to carry out flight tests. The test results show that the robot pilot can independently fly the helicopter to realize forward flight, backward flight, side flight, and turning flight, which verifies the effectiveness of the helicopter robot pilot.

Passive Fault-Tolerant Control of a 2-DOF Robotic Helicopter

The presence of faults in dynamic systems causes the potential loss of some of the control objectives. For that reason, a fault-tolerant controller is required to ensure a proper operation, as well as to reduce the risk of accidents. The present work proposes a passive fault-tolerant controller that is based on robust techniques, which are utilized to adjust a proportional-derivative scheme through a linear matrix inequality. In addition, a nonlinear term is included to improve the accuracy of the control task. The proposed methodology is implemented in the control of a two degrees of a freedom robotic helicopter in a simulation environment, where abrupt faults in the actuators are considered. Finally, the proposed scheme is also tested experimentally in the Quanser® 2-DOF Helicopter, highlighting the effectiveness of the proposed controller.

AMADEE-18: Vision-Based Unmanned Aerial Vehicle Navigation for Analog Mars Mission (AVI-NAV).

As a part of the AMADEE-18 analog Mars mission, designed to study challenges associated with human-based exploration of the Red Planet, we focused our team efforts on testing means to localize an unmanned aerial vehicle (UAV) on Mars. Robot helicopters, such as the one selected for a technology demonstration as a part of NASA's Mars 2020 mission, are small and their performance is computationally limited. An essential aspect of navigation and path planning of an autonomous helicopter is accurate localization of the robot. In the absence of a global positioning system, a computationally efficient localization technology that can be applied on Mars is visual-inertial odometry (VIO). The AMADEE-18 mission provided an opportunity to test the feasibility of a state-of-the-art VIO algorithm and the camera in a Mars-like analog environment. The flight datasets included different terrain structures that challenged the functionality of VIO algorithms. The experiment has yielded valuable insights into the desired surface structure, texture, and mission times for surface relative navigation of UAV on Mars.

Research on the Operating Mechanicals of the Helicopter Robot Pilot

The requirements for the quantity and quality of pilots are getting more and more demanding. The helicopter robot pilot was put forward as a new autonomous driving scheme which can achieve fast switch between pilot driving and autonomous driving without modifying helicopters. The overall design of the robot was determined and the actuators of the robot was demonstrated in detail according to the handling characteristics of helicopter manipulation mechanism. Based on the detailed design scheme, the robot pilot was processed and assembled. In order to test the control performance of the robot pilot, the robot was installed in the flight simulator to carry out helicopter flight simulations. The test results illustrated that the robot pilot is able to accomplish basic flight control of helicopter.

A Trimming Methodology for a New Coaxial Rotor Configuration of Robotic Helicopter Based on Rotor's Thrust Ratio

A Trimming Methodology for a New Coaxial Rotor Configuration of Robotic Helicopter Based on Rotor's Thrust Ratio

STRUCTURE AND ALGORITHMS OF THE WORK FLYING ROBOT FOR TAKING AWAY AND ANALYSIS OF THE SOIL AGRICULTURAL FIELDS

To conduct soil sampling it was decided to use a system based on mobile robot helicopter type - quadrocopter. To calculate the system we took maximum critical conditions, when the maximum amount of soil and it loose. After the calculation drive of sampling model was created with a conical drill with a cutting edge.

Pheno-Copter: A Low-Altitude, Autonomous Remote-Sensing Robotic Helicopter for High-Throughput Field-Based Phenotyping

Plant breeding trials are extensive (100s to 1000s of plots) and are difficult and expensive to monitor by conventional means, especially where measurements are time-sensitive. For example, in a land-based measure of canopy temperature (hand-held infrared thermometer at two to 10 plots per minute), the atmospheric conditions may change greatly during the time of measurement. Such sensors measure small spot samples (2 to 50 cm2), whereas image-based methods allow the sampling of entire plots (2 to 30 m2). A higher aerial position allows the rapid measurement of large numbers of plots if the altitude is low (10 to 40 m) and the flight control is sufficiently precise to collect high-resolution images. This paper outlines the implementation of a customized robotic helicopter (gas-powered, 1.78-m rotor diameter) with autonomous flight control and software to plan flights over experiments that were 0.5 to 3 ha in area and, then, to extract, straighten and characterize multiple experimental field plots from images taken by three cameras. With a capacity to carry 1.5 kg for 30 min or 1.1 kg for 60 min, the system successfully completed >150 flights for a total duration of 40 h. Example applications presented here are estimations of the variation in: ground cover in sorghum (early season); canopy temperature in sugarcane (mid-season); and three-dimensional measures of crop lodging in wheat (late season). Together with this hardware platform, improved software to automate the production of ortho-mosaics and digital elevation models and to extract plot data would further benefit the development of high-throughput field-based phenotyping systems.

Re-sampled inheritance search: high performance despite the simplicity

This paper proposes re-sampled inheritance search (RIS), a novel algorithm for solving continuous optimization problems. The proposed method, belonging to the class of Memetic Computing, is very simple and low demanding in terms of memory employment and computational overhead. The RIS algorithm is composed of a stochastic sample mechanism and a deterministic local search. The first operator randomly generates a solution and then recombines it with the best solution detected so far (inheritance) while the second operator searches in an exploitative way within the neighbourhood indicated by the stochastic operator. This extremely simple scheme is shown to display a very good performance on various problems, including hard to solve multi-modal, highly-conditioned, large scale problems. Experimental results show that the proposed RIS is a robust scheme that competitively performs with respect to recent complex algorithms representing the-state-of-the-art in modern continuous optimization. In order to further prove its applicability in real-world cases, RIS has been used to perform the control system tuning for yaw operations on a helicopter robot. Experimental results on this real-world problem confirm the value of the proposed approach.

Dependable Low‐altitude Obstacle Avoidance for Robotic Helicopters Operating in Rural Areas

This paper presents a system enabling robotic helicopters to fly safely without user interaction at low altitude over unknown terrain with static obstacles. The system includes a novel reactive behavior‐based method that guides rotorcraft reliably to specified locations in sparsely occupied environments. System dependability is, among other things, achieved by utilizing proven system components in a component‐based design and incorporating safety margins and safety modes. Obstacle and terrain detection is based on a vertically mounted off‐the‐shelf two‐dimensional LIDAR system. We introduce two flight modes, pirouette descent and waggle cruise, which extend the field of view of the sensor by yawing the aircraft. The two flight modes ensure that all obstacles above a minimum size are detected in the direction of travel. The proposed system is designed for robotic helicopters with velocity and yaw control inputs and a navigation system that provides position, velocity, and attitude information. It is cost effective and can be easily implemented on a variety of helicopters of different sizes. We provide sufficient detail to facilitate the implementation on single‐rotor helicopters with a rotor diameter of approximately 1.8 m. The system was extensively flight‐tested in different real‐world scenarios in Queensland, Australia. The tests included flights beyond visual range without a backup pilot. Experimental results show that it is feasible to perform dependable autonomous flight using simple but effective methods. © 2013 Wiley Periodicals, Inc.

REAL-TIME UAV BASED GEOSPATIAL VIDEO INTEGRATED INTO THE FIRE BRIGADES CRISIS MANAGEMENT GIS SYSTEM

Abstract. During a fire incident live airborne video offers the fire brigade an additional means of information. Essential for the effective usage of the daylight and infra red video data from the UAS is that the information is fully integrated into the crisis management system of the fire brigade. This is a GIS based system in which all relevant geospatial information is brought together and automatically distributed to all levels of the organisation. In the context of the Dutch Fire-Fly project a geospatial video server was integrated with a UAS and the fire brigades crisis management system, so that real-time geospatial airborne video and derived products can be made available at all levels during a fire incident. The most important elements of the system are the Delftdynamics Robot Helicopter, the Video Multiplexing System, the Keystone geospatial video server/editor and the Eagle and CCS-M crisis management systems. In discussion with the Security Region North East Gelderland user requirements and a concept of operation were defined, demonstrated and evaluated. This article describes the technical and operational approach and results.

Low Power Greenhouse Gas Sensors for Unmanned Aerial Vehicles

We demonstrate compact, low power, lightweight laser-based sensors for measuring trace gas species in the atmosphere designed specifically for electronic unmanned aerial vehicle (UAV) platforms. The sensors utilize non-intrusive optical sensing techniques to measure atmospheric greenhouse gas concentrations with unprecedented vertical and horizontal resolution (~1 m) within the planetary boundary layer. The sensors are developed to measure greenhouse gas species including carbon dioxide, water vapor and methane in the atmosphere. Key innovations are the coupling of very low power vertical cavity surface emitting lasers (VCSELs) to low power drive electronics and sensitive multi-harmonic wavelength modulation spectroscopic techniques. The overall mass of each sensor is between 1–2 kg including batteries and each one consumes less than 2 W of electrical power. In the initial field testing, the sensors flew successfully onboard a T-Rex Align 700E robotic helicopter and showed a precision of 1% or less for all three trace gas species. The sensors are battery operated and capable of fully automated operation for long periods of time in diverse sensing environments. Laser-based trace gas sensors for UAVs allow for high spatial mapping of local greenhouse gas concentrations in the atmospheric boundary layer where land/atmosphere fluxes occur. The high-precision sensors, coupled to the ease-of-deployment and cost effectiveness of UAVs, provide unprecedented measurement capabilities that are not possible with existing satellite-based and suborbital aircraft platforms.

Efficient Planning under Uncertainty with Macro-actions

Deciding how to act in partially observable environments remains an active area of research. Identifying good sequences of decisions is particularly challenging when good control performance requires planning multiple steps into the future in domains with many states. Towards addressing this challenge, we present an online, forward-search algorithm called the Posterior Belief Distribution (PBD). PBD leverages a novel method for calculating the posterior distribution over beliefs that result after a sequence of actions is taken, given the set of observation sequences that could be received during this process. This method allows us to efficiently evaluate the expected reward of a sequence of primitive actions, which we refer to as macro-actions. We present a formal analysis of our approach, and examine its performance on two very large simulation experiments: scientific exploration and a target monitoring domain. We also demonstrate our algorithm being used to control a real robotic helicopter in a target monitoring experiment, which suggests that our approach has practical potential for planning in real-world, large partially observable domains where a multi-step lookahead is required to achieve good performance.

Improved nonlinear trajectory tracking using RBFNN for a robotic helicopter

AbstractThis paper presents a backstepping control method using radial‐basis‐function neural network (RBFNN) for improving trajectory tracking performance of a robotic helicopter. Many well‐known nonlinear controllers for robotic helicopters have been constructed based on the approximate dynamic model in which the coupling effect is neglected; their qualitative behavior must be further analyzed to ensure that the unmodeled dynamics do not destroy the stability of the closed‐loop system. In order to improve the controller design process, the proposed controller is developed based on the complete dynamic model of robotic helicopters by using an RBFNN function approximation to the neglected dynamic uncertainties, and then proving that all the trajectory tracking error variables are globally ultimately bounded and converge to a neighborhood of the origin. The merits of the proposal controller are exemplified by four numerical simulations, showing that the proposed controller outperforms a well‐known controller in (J. Robust Nonlinear Control 2004; 14(12):1035–1059). Copyright © 2009 John Wiley & Sons, Ltd.

OATS: Oxford Aerial Tracking System

Small robot helicopters are becoming a popular research platform due to the availability of off-the-shelf components and their suitability for useful applications. We describe the Oxford Aerial Tracking System (OATS) that we are commissioning, which takes a commercial airframe and low-level flight controller, and adapts these for use in applications requiring the visual tracking of ground targets. This uses a camera on a two-axis gimbal feeding images into an on-board processing system, which communicates summary information to a ground station. So far we have tested the system off the aircraft using laboratory targets and canned image sequences; we have also developed in simulation a variety of high-level algorithms for the platform, including those for target area scanning, geo-localisation, 3-D path planning, and target trajectory prediction; this paper focuses on the hardware, system software, and object tracking sub-systems. Testing on the airframe is now underway.

Insect Behaviour: Controlling Flight Altitude with Optic Flow

Insects can smoothly control their height while flying by adjusting lift to maintain a set-point in the ventral optic flow. The efficacy of this simple flight-control mechanism has been demonstrated using a robot helicopter.

AN EXPERIMENTAL STUDY OF AERIAL STEREO VISUAL ODOMETRY

Unmanned aerial vehicles normally rely on GPS to provide pose information for navigation. In this work, we examine stereo visual odometry (SVO) as an alternative pose estimation method for situations in which GPS in unavailable. SVO is an incremental procedure that determines ego-motion by identifying and tracking visual landmarks in the environment, using cameras mounted on-board the vehicle. We present experiments demonstrating how SVO performance varies with camera pointing angle, for a robotic helicopter platform. Our results show that an oblique camera pointing angle produces better motion estimates than a nadir view angle, and that reliable navigation over distances of more than 200 meters is possible using visual information alone.

Design and Flight Testing of an H00 Controller for a Robotic Helicopter

Although robotic helicopters have received increasing interest from university, industry, and military research groups, their flight envelope in autonomous operations remains extremely limited. The absence of high-fidelity simulation models has prevented the use of well-established multivariable control techniques for the design of high-bandwidth control systems. Existing controllers are of low bandwidth and cover only small portions of the vehicle's flight envelope. The results of the synergic use of high-fidelity integrated modeling strategies and robust multivariable control techniques for the rapid and reliable design of a high-bandwidth controller for robotic helicopters are presented. The project implemented and flight tested an H ∞ loop shaping controller on the Carnegie Mellon University (CMU) Yamaha R-50 robotic helicopter. During the flight tests, the CMU R-50 flew moderate-speed coordinated maneuvers with a level of tracking performance that exceeds performance reported in the publicly available literature. The authors believe that the results open the road to the implementation on robotic helicopters of full-flight-envelope control systems for complex autonomous missions.

A new generation of military robots

US military branches are undergoing a shift in the structure and missions that's designed to help them become lighter and more agile, able to move easily and quickly to hot spots. Long-range planning to prepare for modern warfare includes developing robotics for military use. For instance, the Army's Future Combat Systems program plans to make a third of its ground forces robotic within about 15 years. The army's 20-year plan envisions 10 steps of robotic development, starting with completely human-controlled systems and ending with autonomous, armed, cooperative robots. The Robotics Institute has developed a small, unmanned ground vehicle called a "throwbot" that can be tossed into buildings to gather and relay information back to soldiers before they enter the building. The institute is also developing larger robotic vehicles that can do reconnaissance and breaching missions, including a robotic helicopter that can generate 3D models from the air.

Mathematical Modeling and Experimental Identification of an Unmanned Helicopter Robot with Flybar Dynamics

AbstractThis paper presents a mathematical model for a model‐scale unmanned helicopter robot, with emphasis on the dynamics of the flybar. The interaction between the flybar and the main rotor blade is explained in detail; it is shown how the flapping of the flybar increases the stability of the helicopter robot as well as assists in its actuation. The model helicopter has a fast time‐domain response due to its small size, and is inherently unstable. Therefore, most commercially available model helicopters use the flybar to augment stability and make it easier for a pilot to fly. Working from first principles and basic aerodynamics, the equations of motion for full six degree‐of‐freedom with flybar‐degree of freedom are derived. System identification experiments and results are presented to verify the mathematical model structure and to identify model parameters such as inertias and aerodynamic constants. © 2004 Wiley Periodicals, Inc.