This paper presents an algorithm for synthesizing the desired «flexible» kinematic trajectory, designed to ensure a «soft» landing of a quadcopter on a stationary horizontal landing platform. The algorithm is based on the integration of PID controllers with a dynamic mechanism for the formation of adaptive kinematic trajectories, which are adjusted at each iteration of the control cycle. Quantitative and qualitative requirements for the landing maneuver are formulated, including strict restrictions on the final values of vertical and horizontal speeds, as well as the orientation angles of the quadcopter. Control is based on feedback on the current state of the system, which ensures stable trajectory adaptation to changing flight conditions. The proposed algorithm is aimed at minimizing the vertical component of velocity at the moment of contact with the surface, which significantly reduces dynamic loads during landing. For realistic modeling of external disturbances, an adapted Dryden model was used, implemented through first-order aperiodic filters with parameters corresponding to lowaltitude flight conditions in an urban environment. The efficiency of the developed algorithm is confirmed by numerical modeling in conditions of severe atmospheric turbulence. The results obtained demonstrate the high accuracy of achieving the specified final motion parameters, which indicates the effectiveness of integrating «flexible» kinematic trajectories with classical controllers in the task of automatic «soft» landing of a quadcopter.
This paper proposes an innovative non-contact approach to the determination of vibration parameters of technical objects — frequency, amplitude, and phase — based on computer vision methods. The relevance of this work strongly stems from the fact that conventional vibration diagnostics using contact accelerometers face significant limitations in high-temperature environments, on rapidly rotating elements, and in chemically aggressive atmospheres. In such conditions, mechanical fixation of sensors is impossible or compromises measurement reliability. As an alternative, the authors propose a method based on dense optical flow estimation between high-speed video frames combined with Fast Fourier Transform (FFT) spectral analysis. An algorithm has been developed and implemented using the OpenCV library, employing the Farneback method with optimisation of its key parameters: analysis window size, approximating polynomial degree, number of Gaussian pyramid levels, and smoothing parameter. Experimental validation was performed on a test rig equipped with an electromagnetic shaker generating a frequency of 142.3948 Hz and a peak displacement amplitude of 3.0 3.2 mm; video registration was carried out at 2000 fps. Four typical parameter configurations were investigated, each independently repeated ten times. High stability of frequency estimation has been explicitly demonstrated: absolute error did not exceed 0.004 Hz, relative error did not exceed 0.0025 % the amplitude coefficient of variation lay in the target range of 2.9 5.0 %. The obtained results are fully comparable with those of professional accelerometric systems in accuracy and substantially superior in deployment simplicity, absence of mechanical fixation requirements, and overall cost. The method is perfectly applicable to equipment diagnostics in inaccessible and hazardous environments.
The adaptive control task of an onboard space flying robot model with grasped payload in virtual environment systems is considered. The proposed solution to this problem is based on the manipulator links small masses assumption, which allows us to consider the robot as a system with his base link and payload. As part of this task, using the Newton-Euler method, a mathematical model of the robot’s motion was obtained, which linearly depends on the payload’s unknown mass estimation. This model is used to adaptive control synthesis to ensure the robot motion along a given trajectory with a given speed, as well as its rotations and stabilization. The robot control law is formed using the sliding mode theory and feedback by a continuous hyperbolic tangent function with respect to residuals. In addition, to implement of flying robot’s adaptive control synthesis, a differential equation was obtained in terms of the payload’s unknown mass. The methods and approaches proposed in the paper were implemented in the VirSim virtual environment system, developed at the NRC «Kurchatov Institute» — SRISA. Their approbation in this software package was carried out using the example of training person task to interact with onboard flying robots using voice interface. For these purposes, the Oculus Rift CV1 virtual reality headset was used for human immersion in a virtual environment and head tracking, Oculus Touch controllers and Manus Prime II VR gloves for tracking human hands and fingers. As part of this task, a training situation was simulated in which operator hands over the virtual payload with unknown mass to virtual flying robot, which then grasps it and moves with it to another part of the space station. Simulation results in VirSim showed the adequacy of the methods and approaches proposed in the paper for adaptive control of an onboard space flying robot with payload.
Existing algorithms for the direct compensation of unknown disturbances in multivariable systems typically employ a single adaptive controller for the entire system. As a result, only one adaptive gain is available to adjust the overall convergence rate of all control channels. This paper presents a novel adaptive control algorithm for a class of unstable linear time-invariant (LTI) multi-input multi-output (MIMO) systems subjected to unknown disturbances, allowing the adaptive gain of each control channel to be selected independently in order to adjust the convergence rate of the processes. Knowledge of the exact number of harmonic external disturbances is not required. It is assumed that a priori information regarding the upper bound on the number of disturbance harmonics is available. The canonical form of the disturbance description is used, which allows also to consider the case of harmonic components of the same frequency. The control problem is solved by combining a state-feedback decoupling approach with a direct disturbance compensation method based on the internal model principle. As a result, the adaptive algorithm can be designed independently for each control channel. Consequently, the proposed method eliminates the adverse effects caused by the interactions of the control inputs on the system outputs. Furthermore, it reduces the number of parameters that must be tuned in the adaptive algorithm, thereby decreasing the overall complexity of the adaptive control scheme.
The object and purpose of the study is to develop a generalized method for determining the boundaries of the working zone of manipulator mechanisms (PMMZ) on the example of the given model of the kinematic chain of the anthropomorphic robot AR-600E. The method of constructing a work zone allows for a given orientation of the hand (gripper axis) in relation to the horizontal plane. А mathematical model is constructed that allows, on the basis of input parameter setting, to determine the boundary contour lines of RZMM for arbitrary models of kinematic chains of manipulator mechanisms with provision of axis orientation of gripping within specified limits. The developed mathematical model is based on the definition of a plurality of configurations using implementations of instantaneous states, in which the specified positioning accuracy of the center of the output link (UP) is ensured. For these purposes, a private transfer ratio matrix is used to establish a linear relationship between generalized speeds and HV speeds. One of the sections of the RLMM is built on top. The research carried out has made it possible to establish the shape and position of the limiting curve of the external boundary RZMM of an anthropomorphic robot in a given horizontal plane. Similarly, the errors of linearization are inves tigated when the HV center is in the studied plane at a given module of its linear velocity. Research results can be used in the design of technological processes performed by robots, based on computer modeling of executive mechanism movements with constraints set to the orientation axis of the hand (gripper axis).
