Mikhail Medvedev

Control system design for robotic airship

Abstract In this paper control system design for robotic airship is developed. The nonlinear multilinked mathematic model of airship is considered. The results of aerodynamic analysis, parametric and structure disturbances estimation, nonlinear control algorithms, and neural network motion planning are presented. Theoretic results are implemented on experimental robotic mini-airship.

Mathematical model of robot on base of airship

This work is aimed at mathematical model of unmanned robotized airship. An airship can be controlled remotely by pilot or fly autonomously. Nonlinear interrelated model of an airship, considering kinematics and dynamics, main propulsion drives and ballonets is developed. Also mathematical model of external environment is presented. Results of CFD researches for aerodynamics are presented.

Development of Indirect Adaptive Control for Underwater Vehicles Using Nonlinear Estimator of Disturbances

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.

Control Method for Vehicles on Base of Natural Energy Recovery

This paper is devoted to vehicle movement control method based on the natural energy recovery [1] and position-path control approach [2,3,4]. This method ensures the fullest use of kinematic energy of the controlled vehicle. Method is applied for path profile with variable height. Vehicle velocity is changed to minimize kinematic energy losses. The time of the path passage is accounted in the designed method. In this report typical profiles of the controlled vehicle are considered. In general case the vehicle velocity program is developed on base of solutions for typical profiles. The vehicle velocity program is changing while vehicle is moving. The developed method is applied for control of trains implemented with electrical power drives. On base of train model studying it is proved that optimal mode of trains acceleration is maximal traction. The maximal traction ensures minimum energy consumption of train drives. But the traction of trains is extreme function of the speed wheel slip [5, 6]. Therefore the new extreme control for the train drives is developed. This method supports trains traction in extreme value. The developed method is implemented in simulator based on Matlab and Universal Mechanism. Movement of a freight train on a real track section is simulated.

Decentralized Control of a Group of Homogeneous Vehicles in Obstructed Environment

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.

Control Method for Heterogeneous Vehicle Groups Control in Obstructed 2-D Environments

The article considers the problem of distributed control for a group of heterogeneous vehicles. A survey of tasks and group control methods is given. A problem is posed to synthesize a local control algorithm ensuring motion if a heterogeneous group in a 2D environment with nonstationary obstacles. The algorithm is used to calculate the required speed and robot’s heading. A principle is used that allows us to treat all the neighboring objects as repellers. Unlike the known methods, in the proposed approach the repelling forces are formed at the outputs of dynamic units allowing us to perform synthesis in the state space instead of a geometric space. Motion steady state modes analysis of the planned paths is performed and their stability is considered. The presented results allows to improve the operation of the robot safety among human environment.

Basic algorithms of adaptive position-path control systems for mobile units

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.

Implementation of Intelligent Control System for Autonomous Underwater Vehicle

This paper introduces the implementation of intelligent motion control and planning for autonomous underwater vehicle (AUV). Previously developed control system features intelligent motion control and planning subsystem, based on artificial neural networks. It allows detecting and avoiding moving obstacles in front of the AUV. The motion control subsystem uses position-trajectory control method to position AUV, move from point to point and along given path with given speed. Control system was tested in the multi-module simulation complex. Simulation showed good results – AUV successfully achieved given goals avoiding collisions not only with static obstacles, but also with mobile ones. That allows using the proposed control system for the groups of vehicles. Besides simulation, control system was implemented in hardware. AUV prototype passed tests in Azov Sea and proved its efficiency.

Position-trajectory control system for robot on base of airship

This work is devoted to control system of unmanned robotized airship. Mathematical model is analyzed for controllability. Position-trajectory control system on the base of high-order nonlinear interrelated model of airship is suggested. System adaptation is implemented with robust estimation algorithms. Use of redundant control channels is solved on the base of minimum of applied control actions. Experimental results of system functioning are presented.

Positioning Method Basing on External Reference Points for Surgical Robots

This paper proposes an automatic laparoscopic camera tracking for conducting optimal visualization of the required area such as operated field in the minimally invasive surgery. A robotic surgery system was designed and developed to perform the camera handling and tracking task during laparoscopic surgery. The method of positioning and automatic tracking for the surgical instruments during the laparoscopic operations was developed. The significant difference of the method is the usage of the markers and reference points that are placed at the visible area (outside the abdomen). This technique allows us to define the coordinates of the laparoscope and the surgical instruments in the operated field by the usage of the methods of vector algebra and geometric transformations without application of the image recognition. The algorithm of the laparoscope control and automatic tracking for the surgical instruments was offered. Also the conditions for the optimal visualization of the operated field were determined. The field of the required laparoscope position according to the surgical instruments was defined. The experimental research of the offered method was done and its justifiability was confirmed. The offered method of positioning and tracking is universal for the different types of the robotic holders with different number of DOFs.