Study and Development of Robust Control Systems for Educational Drones

This paper considers the problem of attitude and altitude control of quadrotors using the sliding mode control theory. The mathematical model of the quadrotor is derived using the Euler-Newton formalism. The sliding-mode is applied to the Parrot Mambo minidrone, which is a strong example of bringing educational robotics to formal (MATLAB, Python, JavaScript), non-formal (Tynker, Blockly, Swift Playground) and informal education. The control considered shows good performance and enhanced robustness.

Synthesizing robust control systems for mechatronic objects with digital state controllers and observers

Currently, digital controllers with state observers are widely applied in automatic control systems for mechatronic objects, which great potential abilities are caused by structural flexibility and developed methods of synthesis. However, during design and practical implementation of the systems there is problem of robustness, associated with parametrical uncertainty of typical mechatronic objects. Most methods for synthesis of robust control systems are based on application of continuous mathematical models and do not take into account specific of digital realization of controllers with state observers. Methods of state space, modal control, digital system design, numerical optimization algorithms and simulation in MatLab environment were used. We propose a method of synthesizing robust digital modal control systems with state observers based on generating dynamic system characteristics within the areas of parametric robustness. Further, low sensitivity of the system to changes in controlled object parameters is ensured by the minimal phase character of the complex controller transfer function, while low sensitivity to changing parameters of the controller itself is ensured by excluding positive feedback in both control and adjustment circuits. Developed recommendations of choosing dynamic characteristics of state controller with observer loops within robustness areas and of forming rational state observer structure allow us to synthesize digital automatic control system with low sensitivity for variation of both control object parameters and inherent controller parameters.

The Effects of Weighting Functions on the Performances of Robust Control Systems

An important stage in robust control design is to define the desired performances of the closed loop control system using the models of the frequency sensitivity functions S. If the frequency sensitivity functions remain within the limits imposed by these models, the control performances are met. In terms of the sensitivity functions, the specifications include: shape of S over selected frequency ranges, peak magnitude of S, bandwidth frequency, and tracking error at selected frequencies. In this context, this paper presents a study of the effects of the specifications of the weighting functions on the performances of robust control systems.

Synthesis of a robust control system for two-mass electric drive by H∞-theory

The practice of designing and operating control systems for industrial facilities has shown that systems synthesized according to the criteria of modular and symmetric optima, as well as by quadratic quality criteria, are sensitive to changes in the parameters of the controlled object, incoming characteristics, disturbing influences, the structure and parameters of the object model changing, which used in control loops. Such systems can lose optimality as well as productivity, if information about the object and operating environment is known with some probability or uncertainty. For an industrial electric drive, changes in load torque, moment of inertia of rotating parts, supply voltage and environmental characteristics (temperature, vibration) are especially significant. These changes affect both the mechanical characteristics rigidity and the transients’ quality. Robust control systems provide a required quality of work when changing the characteristics of impacts and instability of the control object parameters in a wide range. In the presence of uncertainties, a robust controller provides robust stability and quality for all admissible uncertainties. The synthesis of robust control systems with an H∞-speed controller of a two-mass electric drive by methods of H∞-theory is presented in order to prove the possibility of using algorithms for a given stabilization and speed control, as well as providing the necessary degree of sensitivity to parametric and coordinate disturbances acting on the control object. Application of the method of robust controllers’ synthesis taking into account the requirements for the quality of a controlled coordinate transient processes in the control system. The analysis of the operation of a synthesized robust system with an H∞-speed controller using digital modeling on mathematical models in the MATLAB / Simulink environment is carried out. The possibility of the speed independent control, the steady-state error and the nature of the transient processes of the controlled coordinate in the synthesized electric drive control system is shown.