Department Publications

Flying and handling qualities are substantially dependent on, and this paper is described it, in terms of the stability and control characteristics of UAV. It is essential to be able to describe and quantify the stability and control parameters completely. It is absolutely essential to understand the relationship between the aerodynamics of the airframe and its stability characteristics to prolong the flight endurance and effective deployment. And this paper is described the stability analysis based on the dynamic model of the twin boom double vertical stabilizer UAV.

This paper presents modelling, simulation and implementation of a quadrotor Unmanned Ariel Vehicle (UAV) Focus of this work is to gain in-depth understanding of quadrotor dynamics to develop a simulator and a laboratory platform to facilitate future development of control algorithms, automatic navigation systems, and trajectory planning for quadrotors. Quadrotor dynamics is modeled using Newton-Euler method. The model predicts the effects of the forces and torques generated by the four propellers on the quadrotor motion. Based on the model, a quadrotor simulator was developed in MATLAB® Simulink, on which various control algorithms can be developed and tested. A quadrotor prototype was built on which some of the control algorithms were tested experimentally in different environments to evaluate the stability and controllability of the platform. Experimental flight data and simulation results were …

Congestion in a networked control system (NCS) has many undesirable effects that can make a control system unstable if severe enough. These include delays and packet drops. Therefore, reducing network traffic, including traffic generated by the NCS itself is a necessity. In event based control (EBC) a control signal is generated when a specific event is triggered such as the control error exceeding a predetermined threshold. When the rate of change of a variable is bounded, event triggering reduces the effective frequency in which control signals have to be generated when compared to a system with periodic sampling. This paper proposes a new method of event triggering called event triggered adaptive differential modulation (ETADM) that combines the bandwidth reduction strategies of event triggering and human speech coding techniques. The proposed method can be applied to nonlinear systems with a …

In planetary rover missions, there exist severe communication constraints, which make it difficult to control rovers from a long distance (eg from the Earth). Therefore, there is a need to address the important issue of onboard local autonomy to allow deployed rovers to make their own decisions, which contributes to increased scientific return. To achieve this, robot algorithms should be constantly improved and innovative hardware mechanisms should be sought. In this context, simulators play a major role as they can help researchers develop novel technologies even without having access to expensive hardware components. In this paper, the authors present ongoing work on the planetary rover simulation environment that have been developed for testing and validating autonomous navigation of a planetary exploration rover using opensource tools. The simulation system has been developed using Gazebo, an open source 3D multi-robot simulation framework and ROS. The developed simulator provides an essential tool for visualization of the rover functionality for many state-of-art algorithms.

This paper outlines the problem of outdoor autonomous robot localization for agricultural operations. Vision based outdoor localization system is developed entirely of off-the-shelf components that can accurately guide a field robot in small agricultural fields. Visual odometry using downward faced camera is proposed as a high resolution relative localization system. A stereo vision based range measurement system is also developed and field tested as an absolute localization system that can bound the incremental error caused by the visual odometry system. The extended Kalman filter with measurement gating is implemented using both visual odometry and stereo range measurement data. Field tests demonstrated proposed system is capable of localization of two wheel tractor at a very low cost with acceptable accuracy in small agricultural fields.

This paper details the development of a model for a walking tractor also known as power tiller. A complete model for power tiller is developed considering kinematics, dynamics and engine dynamics for autonomous operation. Inputs to the simulation model are left clutch control signal and right clutch control signal. Data from an Inertial Measurement Unit (IMU) attached to the power tiller enables validation of the model using analogue matching and integral least squares. The result of the validation is that the model is a suitable representation of the power tiller. Developed model is intended to use for development of a controller for the remote and autonomous operation at agricultural fields.

Quad Rotor unmanned aerial vehicle (UAV) is an aerial vehicle platform which has drawn much attention in the recent past due to its simple yet unique design. Despite the simplicity in the hardware, the vehicle is inherently unstable, and many control strategies have been proposed to achieve stability and control of the quad rotor platform. This paper presents a Fuzzy Logic based design to stabilize and control the quad rotor UAV. The fuzzy controller was designed and simulated along with a non-linear dynamic model of the quad rotor UAV. The fuzzy controller was then used to achieve stable hovering of the quad rotor UAV, amidst velocity disturbances. The simulation results show that stable hovering conditions can be achieved with the designed controller.

This paper presents a real time non linear automatic UAV simulation test-bed and autonomous control implementation with way point navigation. This UAV simulator is an integrated product that combines a vehicle operator station with a synthetic environment to support UAV research, training and operations while providing the operators (Internal Pilot) with a consistent interface. the simulated air vehicle operates against simulated terrain, weather, and computer generated forces In the synthetic mission space. External pilot also interact into synthetic simulation test-bed. The autonomous control system is based on the Aerosonde UAV and major considerations of controller performance and minimum instability within manual and autonomous switching have been evaluated with full software simulation. Major requirements for the good control system are minimum overshoot, minimum setting time without undesirable …

Three-wheelers are popular in Sri Lankan roads as a convenient mode of transportation. Presently there are about 500,000 registered three-wheelers. The range of commercially available electric vehicles are limited due to their battery weight and hence used mostly as neighbourhood vehicles. Three-wheelers are used mostly as neighbourhood vehicles and hence ideal for electrification. But no successful commercial electrically powered three-wheeler is available yet. Aerodynamic drag coefficient and rolling resistance coefficient are two basic parameters needed to determine the motor capacity of an electric vehicle. Accurate values of aerodynamic drag coefficient and rolling resistant coefficient are important to calculate accurate power estimate in electric vehicle design. In this paper we present an accurate method to determine the aerodynamic drag coefficient and rolling resistance coefficient of commonly …

Research & Development of an Autonomous Mobile Robot "Transformer '08 to '09"for Tsukuba Challenge - Shibaura Institute of Technology Skip to main navigation Skip to search Skip to main content Shibaura Institute of Technology Home Shibaura Institute of Technology Logo English 日本語 Search content at Shibaura Institute of Technology Home Profiles Research units Research output Activities Press/Media Prizes Research & Development of an Autonomous Mobile Robot "Transformer '08 to '09"for Tsukuba Challenge Peshala Gehan Jayasekara , Shimon Ajisaka , Sousuke Nakamura , Takeshi Sasaki , Hajime Tamura , Hideki GHashimoto Functional Control Systems Research output: Contribution to journal › Article › peer-review Overview Original language English Pages (from-to) 1382-1384 Journal Default journal Publication status Published - 2009 Dec 26 Cite this APA Standard Harvard Vancouver Author …

Research on outdoor autonomous mobile robots has received much attention in the past decade. Outdoor autonomy meets with many challenges due to unpredictable dynamic environments, hard to control lighting and unavailability of resources. Nevertheless, such robots find a wide variety of potential applications in exploration, surveillance, agriculture, rescue missions and self-driven vehicles. This paper presents the authors’ approach to achieve long distance autonomous navigation with a mobile robot on outdoor cluttered pedestrian paths. The expected outcome was to finish “The Real World Robot Challenge”, an event held in the City of Tsukuba in Japan, by navigating a 1km course autonomously in a real environment with pedestrians and cyclists. Utilized hardware components and software architecture are illustrated. Furthermore, the strategies and other tactics to overcome context-based complexities are explained. The experimental results demonstrate the effectiveness of the system for outdoor autonomous navigation. Finally, the problems the authors faced in the real event are discussed.

This paper presents non linear automatic unmanned aerial vehicle (UAV) control simulation with high maneuverability and precise tracking. Major considerations of flight performance and precise tracking have been evaluated with software simulation by aerosonde UAV. The autonomous control system is based on the Aerosonde UAV with control theory previously developed and implemented into aircraft. Major requirements for the high maneuverability are good path following with minimum overshoot, settling time without oscillation and low coupling between high level commands. High maneuverability leads to precise tracking for any kind of application. A MATLAB reg standard configuration environment and the Aerosim reg Aeronautical Simulation Block Set are utilized for simulation studies and presented through a Flightgear reg interface.

A new type of force-position compliant control is proposed, where hyperbolic tangent function is used to dynamically adjust the gain of the position feedback loop so that to control the contact force safely and according to a given pattern. The proposed compliant controller uses a high gain in the position control loop when the robotic device is in free space motion, and as and when it comes into contact with the environment, the gain of the position loop is lowered according to the roll-off of inverse tangent function. The controller is tunable with only one parametery, and is capable of mimicking a wide range of force control behaviors. In this paper we apply the proposed controller to mimic human compliant motion in gripping and lifting objects. And, we have verified that the human compliant behavior can be satisfactorily realized by the proposed compliant controller.

The optimum distribution of treated pipe-borne water is a critical requirement in countries which have a deficit production in comparison with the demand. However, in 3rd world countries, it is not feasible to design the entire water distribution network as a whole, to enable near-optimized delivery, due to economic constraints. The current practice in such countries is to operate the nodes of the water distribution network, such as pump houses and water towers, in isolation, based on ad hoc criteria. Improper co-ordination of these nodes leads to wastage and inefficiencies in the utilization of the scarce resource of treated water. Hence the challenge lies in improving the water distribution process via a network that has not been inherently designed to support optimum distribution. The proposed system presents a solution to this predicament by centrally monitoring and controlling the functionality of these points of …

This paper describes a baby sitting robot system, which has the capabilities of baby tracking , cry signal processing, map building and obstacle avoidance, path planning, entertain the baby or alarm the guardian if any defined anomalies found and voice interaction. For that purpose, the baby sitting robot system has a capability to track and follow the baby with obstacle avoidance. It is also potential enough to identify when the baby cries, or reach near to any defined anomalies. Further more it provides a convenient voice interface for easy usage and various entertainment services for the baby. Rather than just notify the parents that the baby is approaching anomalies, it will try to prevent it from reaching the anomalies by either blocking or distracting with music. In this paper, the overall system is introduced and the detailed subsystems and functions are presented. Baby tracking, cry detection and step detection have …

A data-driven adaptive neurofuzzy controller is presented for the water-level control of U-tube steam generators in nuclear power plants. This neurofuzzy controller is capable of learning the control action principles from the data obtained using other methods of automatic or manual control. There are four inputs in the neurofuzzy system, yet only eighty fuzzy rules involved. Therefore, the fuzzy system is versatile and moderately compact. The versatility is due to the higher input space dimension that helps to learn more control principles. The compactness is due to the number of rules being not too many. A 10-h evaluation trial of the trained fuzzy controller demonstrated its capability in regulating the water level under random disturbances and reference level changes.

The velocity dipole field method is presented for real-time collision avoidance of mobile robots. The direction of motion of the obstacle is used as the axis of the dipole field, and the speed of the obstacle is used to proportionally strengthen the dipole field. The elliptical field lines of the dipole field are useful to skillfully guide the robot around obstacles, quite similar to the way humans avoid moving obstacles. Field modulation coefficient is also introduced to weaken the field effect as the obstacle recedes. The real-time algorithm of the velocity dipole field has been devised and experimentally tested on the robot soccer test-bed. The results show the capability of the new real-time collision avoidance strategy and how it can overcome the weaknesses in the conventional potential field method. The new method makes an explicit and proactive action of collision avoidance, unlike the conventional method, which forces the robot merely away from the obstacle aimlessly. The proposed method delivers greater capability with no considerable computational overhead

Effective training is essential for human teleoperators to deliver satisfactory performance in actual tasks. Teleoperation is naturally a very difficult task due to the absence of naked-eye vision that cripples the cognitive behavior of the remote operator. Camera vision somehow is not a satisfactory substitution. However, training with naked-eye vision feedback may help human teleoperators to learn how to deliver satisfactory performance when they actually interact with camera vision. This study was carried out to further investigate this hypothesis, and to quantitatively supplement it with experimental proofs. For this cause, the recently built telerobotic test-bed between KAIST (Korea) and Saga University(Japan) was reshaped to a telerobotic mini-golf system, which is the trial experiment in this study. The performance of the players with and without naked-eye training was compared and quantitatively evaluated. The …

This paper discusses the safety assurance, capability features, and user-friendliness of Internet-based telerobotics, in the sense that how these features could be incorporated in order to enhance teleoperator performance. A comprehensive set of safety features are incorporated to the interface to screen and accept only the safe commands from the remote operator while discarding risky commands. A laser pointer is used to help remote operator in perceiving self-location and navigation, whereas orientation control has been completely automated and synchronized to the position commands of the teleoperator. The effectiveness of these features has been demonstrated by playing telerobotic mini-golf.

This paper describes the design and implementation techniques of a generic Internet-based telerobotic system. The purpose is to make available the precious technical information and hands-on experience of the authors for the research community. The paper is based on the telerobotics system that the authors recently implemented between KAIST, Korea and Saga University, Japan. In its current functionality, two control modes: high-level supervisory control and low-level supervisory control are explored demonstrating their merits and demerits.

Focus of attention is often attributed to biological vision system where the entire field of view is first monitored and then the attention is focused to the object of interest. We propose using a similar approach for object recognition in a color image sequence. The intention is to locate an object based on a prior motive, concentrate on the detected object so that the imaging device can be guided toward it. We use the abilities of the intelligent image analysis framework developed in our laboratory to generate an algorithm dynamically to detect the particular type of object based on the user's object description. The proposed method uses color clustering along with segmentation. The segmented image with labeled regions is used to calculate the shape descriptor parameters. These and the color information are matched with the input description. Gaze is then controlled by issuing camera movement commands as …

A telerobotic test-bed has recently been built between KAIST (Korea) and Saga University (Japan). This paper presents its first research work on investigating the interactive learning performance of human teleoperators. For this purpose, the telerobotic test-bed was re-shaped to a telerobotic golf system. Eleven players were participated, and their interactive performance with the telerobot was carefully analyzed for the errors and skills that they demonstrated. It was observed that human teleoperators first try to avoid errors that they did in the previous trials, and then make efforts to explore new skills. It was also experienced that simple task oriented design features and their coordination could significantly improve telerobotic system performance without making it to an excessively sophisticated shape. Interactive learning with naked-eye vision was compared with that of camera vision, and an effective training procedure for human teleoperators was revealed. Some simple, yet appropriate techniques have also been identified that significantly enhance the performance of human teleoperators.

A new pole selection method for feedforward compensators of mechatronic servo systems is presented in this paper. It is necessary to have the system poles located at desirable positions on the s-plane in order to realize better servoing performance. However, selection of new poles is not a straightforward problem and in most industrial mechatronic systems, it has been a mere cut-and-dry procedure. In this research, feedforward compensator poles are related to the control input, and a criterion was developed to determine the desirable poles that improve the control input within its limits. This method was developed for the second-order model and it was simulated and experiments were performed with the Performer MK3s articulated industrial robot manipulator. Some attractive results have been obtained with the new method.