Fault Identification in Non-Stationary Systems Based on Sliding Mode Observers

The paper is devoted to the problem of fault identification in technical systems described by non-stationary nonlinear dynamic equations under unmatched disturbances. To solve the problem, sliding mode observers are used. The suggested ap- proach is based on the model of the original system of minimal dimension having different sensitivity to the faults and distur- bances in contrast to the traditional approaches to sliding observer design which are based on the original system. Additionally it is assumed that matrices describing such a model have the canonical form and are constant. The main purpose of using such a model is possibility to take into account the non-stationary feature of the systems. As a result, the model has stationary dynamic and non-stationary additional term that allows to promote sliding mode design. Besides, the new approach to design sliding mode observers is suggested. The peculiarity of this approach is that it does not require that original systems should be minimum phase and detectable. According to the traditional approaches stability of the observer is provided by minimum phase and detectability properties. In our approach, stability of the observer is achieved due to the canonical form of the matrices describing the model. In addition, the matching condition is not necessary. This allows to extend a class of systems for which sliding mode observers can be designed. Theoretical results are illustrated by practical example of electric servoactuator.

A New Approach to Images’ Pespective Transformation in Robotics Telemetry

Remotely controlled robots are the majority of contemporary robots’ population. As a rule such robots are used for inspection, patrolling, mines disposal. This is caused by a fact that today’s level of robots’ autonomy is rather low and autonomous robots can not secure reliable performance. However performance of remotely operated robots depends largely on efficiency of information perception by human-operator. This paper studies images representation to operators on robots’ control pendants. More specifically it studies 3D images representation on flat displays. The goal of this study is to increased reaction rate and decrease errors done by robot’s operator due to image’s uncertainty or poor quality. Our main attention is paid to the development of software that implements the technology of transforming the perspective of images. Matrixes for perspective transformation are studied. Hence application of these matrixes within remotely operated robots is discussed. A novelty of this research is in new knowledge about perspective transformation which is done for a better information perception by human-operator and, as an outcome, to increase efficiency of remotely operated robots. The related technologies in the field of telemetry and technical vision systems have been investigated. Also considered are works in medical fields, in particular, the psychology of perception of images and space. A static software model has been developed. The video camera has been implemented with the introduction of perspective distortions to improve the reliability of the transmission of the necessary areas in the image. Research on the technology is carried out jointly with the Institute of Biomedical Problems of the Russian Academy of Sciences. A special prototype for perspective transformation basing on various scenarios is being developed.

Distributed System for Objects Localization in the Working Area of a Modular Reconfigurable Mobile Robot

The paper proposes a novel approach to the objects localization in the working area of a modular reconfigurable robot (MRR), which implies the installation of stationary monitoring points (SMP), consisting of detachable robot’s modules and in- stalled by robot itself. This approach is based on the architecture of the MRR control system previously proposed by the authors and a new method for comparing information about the speed and position obtained from various sensors. The key steps of the approach are following. Upon arriving in the target area, the MRR places SMPs, which consist of a power source, a computing device, a wireless transceiver and a sensor, detached from the robot. Then SMPs monitor the working area using different types of sensors (cameras, rangefinders, etc.), perform segmentation of the measured data and transfer this information to the robot. Further a sensor fusion is performed using a novel object tracking method, which makes it possible to localize target objects even in those cases when they are not visible by some of the SMPs. One of the key advantages of the new approach is a possibility of implementation in the distributed architecture of a MRR. The simulation results show that proposed method has Multiple Object Tracking Accuracy (MOTA) metric of 86 %, which is higher than the most of its analogues, while the estimated dynamic object localization error in a 8x7 m working area using 2 cameras and 1 rangefinder does not exceed 10 cm.

Estimation of the Accuracy of a Control System with a Fuzzy PID Controller Based on the Approximation of the Static Characteristic of the Controller

The problem of estimating the accuracy of an automatic control system with a fuzzy PID controller is solved. To describe a fuzzy controller, its static characteristic is used, which is approximated by two piecewise-linear and one piecewise-constant sections. This approach makes it possible to study the system as a linear one at each section of the approximated characteristic, and accordingly develop the calculation methods known in control engineering, taking into account the features of the system under consideration. In the article, to calculate the error in the steady state, the theorem on the final value of the original is used. For two different types of second-order control objects — static and astatic — on the basis of this theorem, analytical expressions are obtained that relate the accuracy of the control system with the values of the target and disturbance with a different structure of the controller (P-, PI-, PD-). When conducting experimental studies, the fuzzy PID controller was compared with a linear one tuned by the method of the maximum stability. Research results show that a fuzzy controller ensures the accuracy of the control system is not worse than a linear one, while increasing the dynamics of the system. The analytical expressions presented in the article make it possible to assess the accuracy of a control system with a fuzzy controller and can be used as a technique for adjusting the controller based on the accuracy requirements.

Nonparametric Method for Predicting the Trajectory of an Actively Maneuvering Vessel for Unmanned Aerial Vehicle Landing

The article is devoted to the development of algorithms for predicting the trajectory of maneuvering objects based on nonparametric systems theory. The analysis of uncertainties affecting the modeling of the movement maneuvering water objects is presented. An overview of parametric, nonparametric and combined methods for predicting maneuvering water objects trajectory is given. The problem of high-precision autonomous control of the landing unmanned aerial vehicles on the landing vessel in the conditions of its irregular movement caused by meteorological conditions and active maneuvering is being solved. The method for predicting the trajectory of a vessel’s movement based on solving direct problems of dynamics using nonparametric systems theory is proposed. The advantages of the proposed method are that it’s not affected by model errors, due to the fact that it is based only on a retrospective analysis of several consecutive values of the spatial vessel coordinates. The proposed method differs from similar nonparametric methods in that it does not require statistical calculations, own training, or time-consuming tuning. The method does not imply the solution of identification model parameters, state and control actions problems and can be applied with any unknown linearizable input control actions, including when the model of the vessel’s motion dynamics is not identifiable. The results of numerical modeling for solution the problem of predicting the trajectory of an actively maneuvering small-sized landing vessel using a full nonlinear dynamic model with six degrees of freedom are presented. The studies carried out confirm the efficiency, adequacy and very fast adjustment of the developed method under conditions of complete parametric and nonparametric uncertainty. The proposed method can be used to predict the trajectory of any vehicle under the condition of linearizability of its model and control signals over the observed time interval.

Fuzzy Model of Situational Control of the Flight Parameters of an Autonomous Unmanned Aircraft under Uncertainty Conditions

The article outlines the main problems of automatic planning of the behavior of an autonomous unmanned aerial vehicle in unstable air conditions. It is shown that the urgency of the problem is due to the fact that an autonomous unmanned aerial vehicle independently forms and implements its flight route without support from a ground control station. There is therefore a need to develop a method for automatic control of programmed movements associated with the implementation of the route constructed by the problem solver. To solve this problem we propose an approach to regulating the parameters of the state of dynamic objects based on the principle of situational control of the goal-directed behavior of complex systems in changing environmental conditions. The expediency of choosing this control principle is due to the fact that the state of an autonomous unmanned aerial vehicle during its flight is characterized by a large number of parameters and disturbing environmental factors. In order to effectively implement this control principle, we introduce the concept of a complete problematic situation, which consists of deviations of the state parameters of an autonomous unmanned aerial vehicle from the required values during flight and disturbing environmental factors. On this basis, a fuzzy model of situational control of the state parameters of an autonomous unmanned aerial vehicle functioning in an unstable environment is developed, in which linguistic variables and functions are used to provide a generalized presentation of reference problem situations, as well as to describe the deviations of the state parameters and disturbing environmental factors. The conditions are determined under which the reference indistinctly presented problem situations generalize the actual problem situations that arise at the control object. This makes it possible to significantly reduce the number of logical-transformational decision rules in the situational control model and to promptly automatically determine effective control actions in problematic situations that ensure the effective implementation of programmed movements of an autonomous unmanned aerial vehicle under conditions of uncertainty. In conclusion, it is shown that for the implementation of control actions which are selected on a situational basis with increased requirements for the accuracy of regulation of the time-varying parameters of the control object and a significant level of possible discrepancies between their actual and specified values in conditions of uncertainty, it is advisable to use indistinctly implemented proportional, integral and differential regulation laws.

The Walking Robot Control System that is Adaptive to Changes in the Kinematics

The walking mobile robots (WMR) have recently become widely popular in robotics. They are especially useful in the extreme cases: search and rescue operations; cargo delivery over highly rough terrain; building a map. These robots also serve to explore and describe a partially or completely non-deterministic workspace, as well as to explore areas that are dangerous to human life. One of the main requirements for these WMR is the robustness of its control system. It allows WMR to maintain the operability when the characteristics of the support surface change as well as under more severe conditions, in particular, loss of controllability or damage of the supporting limb (SL). We propose to use the principles of genetic programming to create a WMR control system that allows a robot to adapt to possible changes in its kinematics, as well as to the characteristics of the support surface on which it moves. This approach does not require strong computational power or a strict formal classification of possible damage to the WMR. This article discusses two main WMR control modes: standard, which accord to a serviceable kinematics, and emergency, in which one or more SL drives are damaged or lost controllability. As an example, the structure of the control system of the WMP is proposed, the kinematics of which is partially destroyed in the process of movement. We developed a method for controlling such robot, which is based on the use of a genetic algorithm in conjunction with the Mealy machine. Modeling of modes of movement of WMR with six SL was carried out in the V-REP program for two cases of injury: absent and not functioning limb. We present the results of simulation of emergency gaits for these configurations of WMP and the effectiveness of the proposed method in the case of damage to the kinematic scheme. We also compared the performance of the genetic algorithm for the damaged WMR with the standard control algorithm.

To the Anniversary of the Department of "Robotic Systems and Mechatronics" of the Bauman Moscow State Technical University

This year we celebrate the 70-th year of the chair founded in BMSTU in 1951 which name today is "Robotic Systems and Mechatronics". Evolution of the chair during the last 70 years is completely reflected the technical progress in the field of automation. From automatic drives to autonomous robots. Again with the improvement of the educational programs in accordance with the vital demands the chair managed to keep the basic traditions of the Russian engineering school based on the combination of the fundamental scientific background with the practical competence in the new technical systems design. The prominent scientists and engineers made a major contribution to the content and methods of training of future specialists in robotics and mechatronics which are acknowledged both in Russia and abroad. Nowadays robotics is transforming from perspective direction to urgent needs. The chair "Robotic Systems and Mechatronics" is completely ready to reply the new challenge of time.

Multi-Level Control System for an Intelligent Robot that is Part of a Group

The article is devoted to the application of a group of robotic complexes for military purposes. The current state of control systems of single robotic complexes does not allow solving all the tasks assigned to the robot. The analysis of methods of controlling a group of robots in combat conditions is carried out. The necessity of using a multi-level control system for an intelligent combat robot is justified. A multi-level control system for an intelligent robot is proposed. Such a system assumes the possibility of controlling the robot in one of four modes: remote, supervisory, autonomous and group. Moreover, each robot, depending on the external conditions and its condition, can be in any control mode. The application of the technique is shown by the example of the movement of a group of robots with an interval along the front. The problem of the movement of slave robots behind the leader is considered. When forming the robot control algorithm, the method of finite automata was used. The algorithm controls the movement of the RTK in various operating modes: group control mode and autonomous movement mode. In the group control mode, the task is implemented: movement for the leader. For the state of "Movement in formation", an algorithm for forming the trajectory of the movement of guided robots was implemented. An algorithm for approximating the Bezier curve was used. It allows you to build a trajectory for the slave robot. On the basis of the obtained trajectory, the angular and linear velocity were calculated. In the autonomous control mode, two tasks are solved: moving to a given point and avoiding obstacles. Vector Field Histogram was used as an algorithm for detouring an obstacle, which determines the direction of movement without obstacles. The state of "Movement to a given point" is based on Pure Pursuit as a simple and reliable algorithm for solving such problems. A computer model of the movement of a group of robots was developed. The model is implemented in the MATLAB program using the Simulink and Mobile Robotics Simulation Toolbox libraries. Several different variants of the movement of the RTK group are modeled, which differ from each other in the initial location of the robots and the position of obstacles. The conducted computer simulation showed the efficiency and effectiveness of the proposed method of RTC control.

Application of Distributed Robotic Systems in Earthquakes: Search, Planning and Control Abstract

In order to search and rescue injured during earthquake, we proposed a method for multi-robots motion planning and distributed control in this paper. At first, we have created two probabilistic search models to considering the search area and the characteristics of sensors, which we used to search the injured targets. And after finding the targets, they are assigned to the mobile robots on the land to afford emergency rescue. In order to reach to the targets, a path planning method based on map matching is proposed. There are three parts here. Firstly, to obtain the global and local map: continuous ground images are first collected using the UAV’s vision system, and subsequently, a global map of the ground environment is created by processing the collected images. The local map of the ground environment is obtained using the 2D laser radar sensor of the leader (UGA). Established the coordinate conversion relationship between UAV and UGV, unknown values during map matching are determined via the least square method. Secondly, our robots moved by group (leader-follower). The leader’s path was planned globally and locally. The other multi-robots moved along the path planned by the leader. Thirdly, in order to plan and coordinate the robots in the group, the finite state machine is used to describe the logical level of control system for each robot in the group. After that, at the tactical level of the control system, the movement control law of formation maintaining mode and formation switching mode is designed.