Search

in this report a method of trajectory planning for a mobile robot with maneuver restrictions is developed. The maneuver restrictions depends on robot's velocity. Restrictions are represented by virtual obstacles that close up the inaccessible to the robot sectors when it moves at specific velocity. The proposed method is compatible with any path-planning algorithm. The paper describes trajectory planning system of mobile robot based on rapidly exploring random trees method. Dijkstra's algorithm searches the shortest path in the tree. Motion control system calculates the desired yaw angle and velocity of the robot and automatically reduces the velocity when approaching obstacles and while turning. Simulation results for the wheeled robot in obstructed environment are presented.

In article it's made the analytical review of articles in which methods and algorithms of terminal control are considered. Terminal control - coordinated movement of a mobile robot (MR) in time and space. The purpose of the terminal control problem solution is searching of such movement control of the mobile object, which provides achievement of the target position from the initial point in a given time with the given tolerance. Since the environment is uncertain, a heuristic approach to solving the problem of terminal control together with automatic motion control of the MR is applied. This paper proposes the application of intelligent evaluation of the terminal state of MR. This is the difference between solving the problem of terminal management with the proposal to introduce into the environment of movement of control (reference) areas (points). At each control point, the parameters of the further movement of the MR are calculated. The method of key areas definition in the motion environment allowing to lower the indeterminacy degree during the solution of the terminal control problem is developed. Empirical researches of the proposed method that showed the effectiveness of the proposed approach to the solution of the terminal control problem are conducted.

The article is devoted to the development of algorithms for terminal control of mobile objects. A moving object of multicopter type described by a nonlinear model of motion of a solid body in three-dimensional space is considered. A three-stage procedure for solving the problem of terminal control of a moving object when it moves to a given point is proposed. The main difference of the proposed procedure is the correction of the desired trajectory so that it passes through the current position of the moving object at each moment of time. This method of constructing the desired trajectory allows you to automatically adjust the speed when moving to a given point. The need for correction of the desired trajectory can be caused by the presence of obstacles, differences between the model and the real object, and the influence of external disturbances. At the first stage, the desired trajectory taking into account a given finite time of motion is constructed. The motion trajectory represents the desired velocity and orientation angles of a moving object of multi-copter type. At the second stage, the method of position-trajectory control is used to synthesize feedback, which provides stabilization of the moving object relative to the calculated desired trajectory. The result of the second stage is the thrust and torque generated by the motors, which are then recalculated in the speed of rotation of the rotors. At the third stage, the desired trajectory is corrected depending on the current position of the moving object. As a result of the correction, a singularity occurs at the target point. In order to eliminate the singularity at the target point, the problem is solved in the formulation of weak terminal control. Before the target point hits the given neighborhood, the velocity of the moving object is calculated based on the remaining distance and time of movement. When a given neighborhood of the target point is reached, the speed of movement becomes constant. The analysis of the closed-loop system is carried out, as a result of which the asymptotic stability of the desired trajectory and the hit of a moving object in a finite given neighborhood of the target point at a finite time are shown. The results of numerical modeling, confirming the performance of the proposed algorithms in the example of hexacopter, are presented.

In this article, development of glider control system for movement in a three-dimensional based on position-trajectory control laws is considered. To ensure control, a model of spatial motion of the glider is used, taking into account the component of the variable buoyancy. As a result of the simulation, the trajectories of the glider were obtained at points set in the horizontal plane, considering the parameters of the trajectory for movement in the vertical plane. The results obtained make it possible to evaluate the adequacy of the developed control system. The deviation of the system when the glider reaches the set point is minimal, and using the trajectory parameters in the vertical plane, it is possible to control the depth of immersion and speed. The presented results of the simulation of coating elements prove the possibility of practical use of the control system when planning glider-type AUV missions.

In this paper, authors propose a new method of disturbance estimation that can be used for marine and air vehicles. As stability area for nonlinear systems is connected with performance of estimation, indirect measurement is proposed to estimate the error. The base for calculation is vehicle accelerations provided by navigation system. New algorithms were tested in simulation for which authors developed a block diagram of indirect adaptive control system that features independence of estimator from controller. Analysis of results showed that the error of the developed estimator in transient mode is 30-40% less than error of the linear estimator. In steady state mode, gain of the proposed estimator is equal to gain of the linear estimator and output noise is the same. Simulated system was implemented in mini motor boat, and showed good results in experiment. New estimator allowed to increase the accuracy of moving along the paths.

Testing and debugging of real equipment is a time consuming task. In particular, in the case of marine robots, it is necessary each time to carry out the transportation and deployment of a robot on the water. Experiments with not yet fully functional prototype of marine robot equipped with expensive hardware is in the meantime very risky. Therefore, the use of simulators is affordable way to accelerate the development of robotic systems from the viewpoint of labor effort and cost of experiments. This paper presents a simulator specifically designed for autonomous unmanned underwater vehicles.

We present a design method used to develop an extrapolating multidimensional neural network planner for mobile object with intelligent position-trajectory control system. The modeling results of a modified neural network neural network planner used for a robotic mobile object are presented. The design method is based on the bionic environment sensing in undefined conditions with stationary and mobile obstacles in a multidimensional space. The main design principal of the neural network planner structure is the hierarchical principle of information-processing systems. Based on this we present a hierarchical structure of a complex extrapolating multidimensional neural-alike network. Such network contains separate layers used on different stages to process the environment plan received from a robotic object's technical vision system. The hierarchical structure of a complex multidimensional neural-alike network is based on the following principles: object-oriented parametric synthesis, synthesis of weighted object position features with time sampling, and direction vector plans used to extrapolate such features. These plans with a certain probability determine the spatial position of related objects in future. We present the modelling results of selected methods used to detect round or spherical mobile obstacles based on technical vision system data and to predict their trajectories in two-dimensional and three-dimensional space. We present the results of software-based modelling of this approach to design neural network planner for the intelligent position-trajectory control system of mobile objects in two-dimensional space and in the simulation software package in three-dimensional space.

Recently we can see significant increase in consumer demand for autonomous mobile robots that are used for a wide range of functional tasks in a not completely determined environment. The actual task that we consider is solution problem of development of an effective situational planning subsystem for the behaviour of autonomous mobile robots. The purpose of writing this article is a brief coverage of basic principles (proposed by the authors) of functional and modular organization of situational planning subsystem, that is included in system of position trajectory control for mobile robots. The situational planning subsystem is designed to determine the values of the parameters of the safest movement in environment with moving and stationary obstacles to the goal. Designed situational planning subsystem structural is differed from others by using of neural network basis in the construction of a situational planning subsystem functional kernel. The presence of built-in detection means and short-term auto-tracking trajectories of movable obstacles with considering a priori to certain limitations, the calculation of the spatial and velocity zones where collisions with the obstacles are the most possible are differed our planning subsystem too. Also we determinate parameters of mobile robot manoeuvre on the plane, which in this case should be perform. In the basis of functional and modular organization for situational planning subsystem was put situational planning method that was developed by the authors. We designated it CDVH-NN (distance vector histogram — neural network complex method). Integration of algorithmic means of short-term forecasting of the external environment with the formal-logical basis of direct distribution neural networks are different CDVH-NN method from others. The productivity and the efficiency of the functional and modular organization of situational planning subsystem are confirmed by the results of software simulation in MatLab and executed natural experiments. In the article, we present results of modelling of CDVH-NN kernel in basis on FPGA for family Altera Cyclone IVe. We note that the implementation of situational planning subsystem using SOPC technology increase on several times of situational planning subsystem performance with comparison to its full program implementation. It allows freeing up resources of mobile robot board computer for other important operational task.

The paper presents an automatic control system for autonomous surface vehicle. The system is designed to organize autonomous performing of mission defined from ground control station. Structure, hardware and software implementation of autonomous surface vehicle and its navigation and control system as well as experiment results are described.

This paper presents homing and docking autopilot design for the autonomous underwater vehicle (AUV). A nonlinear interrelated dynamic model of the underwater vehicle is considered. The AUV autopilot is designed on base of a position-trajectory control method. Adaptation of the control system is based on robust disturbances estimation. Modeling and hardware results approved feasibility of the proposed methods.

The problem of decentralized control of group of robots, described by kinematic and dynamic equations of motion in the plane, is considered. Group performs predetermined rectangular area passing at a fixed speed, keeping the line and a uniform distribution. The environment may contain a priori unknown moving or stationary obstacles. Decentralized control algorithms, based on the formation of repellers in the state space of robots, are proposed. These repellers form repulsive forces generated by dynamic subsystems that extend the state space of robots. These repulsive forces are dynamic functions of distances and velocities of robots in the area of operation of the group. The process of formation of repellers allows to take into account the dynamic properties of robots, such as the maximum speed and acceleration. The robots local control law formulas are derived based on positionally-trajectory control method, which allows to operate with non-linear models. Lyapunov function in the form of a quadratic function of the state variables is constructed to obtain a nonlinear closed-loop control system. Due to the fact that a closed system is decomposed into two independent subsystems Lyapunov function is also constructed as two independent functions. Numerical simulation of the motion of a group of five robots is presented. In this simulation obstacles are presented by the boundaries of working area and a movable object of a given radius, moving rectilinear and uniform. Obstacle speed is comparable to the speeds of the robots in a group. The advantage of the proposed method is ensuring the stability of the trajectories and consideration of the limitations on the speed and acceleration at the trajectory planning stage. Proposed approach can be used for more general robots’ models, including robots in the three-dimensional environment.

This paper is part of a series that describe the development and setup of intelligent underwater vehicle. Here we focus on the implementation tests for the identification of the actuating device parameters. An energy efficient type of glider is chosen with its block diagram presented. The assembled model is placed in a mini pool for movement tests with the objective of setting up the motors and pump. When put in neutral, its immersion and surfacing position show that there is interdependent between pump operation time, ballast bag maze, displacement of weight and glider attitude angle. These dependencies are described by linear equations and coefficients which are then identified.

The presented solution is a decentralized control system with a minimal informational interaction between the objects in the group. During control and path planning the obstacles are transformed into repellers by the synthesized controls. The main feature distinguishing the developed approach from the potential fields method is that the vehicle moves in the fields of forces depending not only on the mutual positions of a robot and an obstacle but also on the additional variables allowing solving the problem of robot’s path planning using a distributed control system (Pshikhopov and Ali, 2011). Unlike the work by Pshikhopov and Ali, 2011, here an additional dynamic variable is used to introduce stable and unstable states depending on the state variables of the robot and the neighboring objects. The local control system of each vehicle uses only the values of its own speeds and coordinates and those of the neighboring objects. There is no centralized control algorithm. In the local control algorithms the obstacles are represented as vehicles being a part of the group which allows us to unify the control systems for heterogeneous groups. An analysis was performed that proves existence and asymptotic stability of the steady state motion modes. The preformed simulation confirms the synthesis and analysis results.

Today, mobile objects are finding increasing usage in a wide variety of applications. Robots have been put to use in the air, on the ground and under the sea. Along with this expansion in robot technology, the problem of control and autonomous decision making is an ongoing concern, especially in light of the increasing difficulty of tasks. This study is focused on the algorithms of adaptive control system for mobile objects. The authors examined the application of direct adaptive control with reference to model approaches, in particular the position-path method. Point positioning is discussed, and the authors propose a method for efficiency improvement. Parametric uncertainty and influence of immeasurable disturbances are expected. Basic algorithms for the calculation of controlling forces and moments are synthesized using the position-path control method. The authors propose a structure and algorithms of an adaptive position-path system with a reference model. The synthesis of adaptive regulator and stability analysis of closed-loop system is performed, and an example of regulator synthesis is given. Finally, the authors present simulation results for an autonomous unmanned underwater vehicle equipped with a main engine, nose and hydrodynamic rudders on the tail. Along with this, horizontal and vertical maneuvering devices are presented.

Authors consider problem of maintenance and service of underwater vehicles. Usually, underwater station or accompanying ship is required for such operations. Docking is one of the most difficult tasks on the vehicle path from the outer space to the servicing bay. Algorithms allowing docking were presented in the earlier paper, and in this paper authors prove their stability. Movement control is based upon the path regulator. The stability of the closed-loop system according to Liapunov with the given control and limitations is proven. Equations, showing that vehicle will complete the positioning task with account to given limitations and staying stable are given. The criterion for switching movement and “positioning to point” algorithms is proposed. Achievement of the developed criterion was researched theoretically and in computer simulation. Experiments provide deviation of actual coordinates and velocity from the required ones and proved that achieving of criterion is enough to claim that system will be stable while performing algorithms with limitations for controls.

the paper substantiates the necessity of the CFD analysis of the underwater vehicle. Algorithm of hydrodynamic coefficients computation is presented. The initial conditions and environment model for computation are defined. Authors discuss results of simulation and propose the approach of hydrodynamic coefficients analysis.

This paper presents adaptive control system for the autonomous underwater vehicle. A nonlinear interrelated dynamic model of the underwater vehicle is considered. The novelty of developed control system is in use of positional-trajectory control method. This means feasibility of Autonomous Underwater Vehicle in complicated trajectories with relatively small computational resources. Adaptation of the control system is based on robust disturbances estimation. Modeling results validate proposed methods.

The paper shows approach of unmanned surface vehicle motion planning in an environment with obstacles. The structure of the control system hardware, software architecture, based on client-server model with the loose coupling in ROS software environment, is presented. Global planner is designed using the method of Generalized Voronoi Diagrams. Local planner is implemented using the unstable regimes of control to bypass obstacles near USV. The results of simulation, which showed the efficiency of the proposed approaches, are presented.

In this paper authors develop and research system for motor boat control, that allows to move along the stated paths with the given speed. It is assumed, that boat is equipped by the measuring system that provides current coordinates, linear and angular velocities. Control system is based upon the mathematical model, presented earlier (see references). In order to analytically find the necessary controls, all equations were transformed to Jordan controllable form. Besides solution this transformation also allows to handle model nonlinearities and get required quality of movement along the stated paths. Control system includes algorithms for control of longtitudal velocity and boat course. Research of the proposed control system according to boat design limitations for the values of control variables was performed by simulation in MATLAB. Results of two experiments, different in value of the required velocity are discussed.

This paper considers design of the control system for prototype of stratospheric airship, that is distinctive for its hybrid shape, leading to essential aerodynamic moments in flight. Mathematical model of the airship is presented. Control system implements remotely controlled by pilot flight and autonomous flight. Algorithm of automatic distribution of controlling forces and moments in actuators is presented. Adaptation of control system is provided with robust estimator of disturbances as indirect robust control. Control system is experimentally tested with hardware and software complex for HIL-simulation and pilots training.