Modeling of centrifugal deployment of three-section minisatellite boom

The aim of the article is to model the processes of centrifugal deployment of a three-section boom and preliminary analyze the feasibility of this deployment method for an Earth remote sensing (ERS) minisatellite (MS). During the research, methods of theoretical mechanics, multibody dynamics, control theory, and computer modeling were used. Centrifugal deployment of multi-section booms have been successfully used on spin stabilized satellites, but not on ERS satellites, which have other features of operation and require additional studies. The main part of the MS is a platform to which a transformable antenna is attached by means of a transformable boom. Before deployment, the stowed boom and antenna are attached to the MS platform. The boom sections are connected by joints with one rotational degree of freedom and deployed sequentially due to centrifugal forces when the MS rotates in the required direction. Each of the boom joints has a locking mechanism that latches when a predetermined deploy angle is reached. To model the processes of the boom deployment, the MS is presented as a system of connected bodies, where the platform and the stowed antenna are absolutely rigid bodies, and the boom consists of three flexible beams of a tubular cross-section. The differential equations of the MS dynamics during the deployment are obtained using the Lagrangian formalism, which are supplemented by algebraic equations describing the constraints from the joints. The scenarios of the boom deployment with a constant control torque and a constant angular velocity of the MS are considered. These scenarios are simulated, and estimates of the control actions needed to ensure full deployment of the boom and the stabilization of the MS after latching of the joints are calculated. Dependences of variations of the loads on the boom structure during deployment are obtained. The simulation results allow us to conclude that it is feasible to implement the method of the boom centrifugal deployment for the MS, which can perform fast rotations about the three axes of the body reference frame. Implementation of this method allows designers to reduce mass of the MS because it does not require any servo drives in the boom deployment system.

Influences of Control Parameters on Reduction of Energy Losses in Electrohydraulic Valve with Stepping Motors

In many heavy machines, the use of high force drives is required. For such tasks, electrohydraulic servo drives with proportional valves are used most often. In these valves, the proportional electromagnets are applied. If high precise control is additionally required, it is necessary to use expensive servo valves or precise stepping motors. In this paper, the application of a valve with one (or with two) stepping motors in the electrohydraulic servo drive is described. Such motors may work in a micro-step mode, which enables the precise positioning of the valve spool with low energy consumption. The control system structure that was used for positioning, consisting of such an electrohydraulic servo drive with a valve having stepping motors, is described. In the investigations, the following control parameters are considered: the number of stepping motors used, proportional gain coefficients, supply pressure, and desired step distance. The simulation model of the servo drive is proposed, enabling the investigations of energy consumption during the positioning process. In the investigations, the drive step responses are recorded and compared, taking into account the rise time and energy consumption. The overshot-free algorithm is used in the following step and tested in positioning tasks. The collected results of energy consumption of the drive during the positioning process are compared with other solutions.

Artificial Intelligence in Predicting Abnormal States in a Robotic Production Stand

The aim of the described study is an engineering solution to the problem of the implementation of artificial intelligence methods in predicting abnormal, extremely emergency states in robotic production stands. This task results from the need to improve the operational reliability of automated and robotic production lines, thus rationalizing the utility and cost values of these lines. The available hardware solutions as well as the existing and newly introduced new procedures and IT platforms are described. In the hardware part of the work, electric servo drives and gears of a multi-chain tripod robot were used, configured with the Festo Automation Suite software, programmed with the KEBA controller and the developed KeStudio application program.

MOVEMENT ALGORITHM OF AN AUTONOMOUS ROBOT-HEXAPOD FOR MOVING IN NARROW CLOSED SPACES

The article proposes the use of a walking robot - hexapod for its use to monitor the technical condition of ventilation shafts, technical dry channels, enclosed spaces, etc. The peculiarity of this type of robots is the increased possibility in comparison with tracked or wheeled machines, due to their design and ability to overcome irregularities. Also, in comparison with existing designs, the hexapod can be fully autonomous and does not depend on a stationary power source. In its turn, construction of walking robots requires development of complex algorithms of motion, which are significantly different compared to wheeled or tracked moving devices, because in addition to the control of limbs, which are set in motion by servo drives, the computer core must process information from sensors that provide information both about the position of the robot itself, and about the surrounding objects, which can be: distance sensors, touch sensors, video cameras, accelerometers, gyroscopes, etc. The paper highlights the developments used to date, but analysis of existing algorithms for walking robots showed a lack of such for the use of the robot in narrow and confined spaces, ventilation shafts, dry technical ducts, etc. In this regard, an algorithm was developed that partially closes this gap. The peculiarity of this algorithm is the simplicity of practical implementation, as well as the safety of the construction of work in progress, because it takes into account the need for increased static stability by modifying the matrix of limb position by a third state, which gives the opportunity to consider the initial position, or memorize the limb state, from which, in the future, you can continue the movement from an arbitrary stable position. In addition, the algorithm can be applied not only to robots with six limbs, but also to other kinds of mobile walking platforms, because the proposed variant allows testing and calibration of any type of gait at each iteration of the step. In the future, it is planned to test the proposed algorithm on the developed prototype not only when moving the work on horizontal surfaces, but also on vertical surfaces, which is an important component for the proposed application area.

Efficient Sensorless Speed Estimation of Electrical Servo Drives Using a Full-Order Nonsingular Terminal Sliding Mode Observer

This paper proposes an efficient sensorless speed estimation approach for electric servo drives based on the full-order nonsingular terminal sliding mode observer (FONTSM) with the application of DC motor drives. In this method, a specific full-order terminal sliding mode manifold is utilised for the observer design which results in the elimination of the chattering and avoiding the singularity phenomenon of conventional and terminal sliding modes. Here, speed and armature back emf can be directly estimated from the relevant observer’s inputs which are continuous instead of being discontinuous high-frequency “switching” signals. The efficiencies and advantages of this approach have been proven and validated in both simulation and experimental results.