Position Control Method Research Articles

Camera-based sample-position detection and control for microgravity electrostatic levitation.

This paper presents a method for high-speed sample detection and position control in an electrostatic levitator. The algorithm uses images acquired from two charge coupled device cameras and allows for robust and reliable detection of the sample position under various process conditions. The results show improvements over position sensitive detector systems especially under harsh environments and during autonomous operation under microgravity conditions. The position of samples with a radius from 0.6 mm to 1.1 mm is detected in three dimensions with an accuracy of ±40 μm inside a 7 mm × 7 mm × 7 mm levitation area. The two orthogonally arranged cameras, recording images at a resolution of 260 px × 260 px, are used to calculate the position every 5 ms. The control model and the corresponding position controller for the three axes are presented as well. The system was successfully tested in the laboratory and under microgravity conditions at the drop tower, during parabolic flights, and on the MAPHEUS sounding rocket.

Two-satellite formation flying control by cell-structured solar sail

The method of simultaneous relative motion and attitude control by a solar radiation pressure is proposed. The control goal is to stabilize the given closed relative orbit. The principle idea is to use special materials for solar sail that able to change their optical properties. The solar sail consists of a number of rectangular cells. Each of them can change its optical properties. The necessary control force is produced by varying the average reflectivity of solar sail, and the control torque is achieved by the appropriate pattern of black and white cells.

Efficiency improvement of energy storage and release by the inlet position control for seasonal thermal energy storage

Borehole Thermal Energy Storage (BTES) system is considered one of the most practical technologies in the fields of new regeneration energy or energy conversion. The BTES system can store the solar energy in summer or the waste energy from power plant. It is important to store thermal energy in the BTES system before releasing the energy. Generally, the inlet position for heat source injection is fixed in the BTES system. In this study, the inlet position control method according to the temperature distribution between the borehole and the injected heat source is investigated during the thermal energy storage process. It is confirmed that the energy loss of the conventional type could be minimized and the thermal energy storage efficiency could be improved by controlling the inlet position. Also, the thermal energy release efficiency of the inlet control type is compared with that of the conventional type. The ANSYS/Fluent is used for the simulation analysis of the efficiency improvement by the inlet position control method. The coupled heat transfer calculation between fluid and solid is applied. In the BTES system with the radius of 12.5 m and the depth of 33.5 m, the storage efficiency and thermal energy sharing ratio are improved by 24.4% and 69.4% respectively at the end of the third year during the storage period. And the inlet control type could store the low-grade thermal heat source in the low temperature region of the BTES system, leading to the improvement of the release efficiency by the inlet position control.

Design of a Robust Rack Position Controller Based on 1-Dimensional AMESim Model of a Steer-by-Wire System

This paper presents a robust rack position control method based on a disturbance observer to enhance maneuverability and steering robustness during steering situation. It is shown that the rack and pinion system of Steer-by-Wire system with irregular parameters and external disturbance from the tires and mechanical elements can be modelled as a simple second-order system. In control design, robust control method, e.g., two-degree-of-freedom control (2-DOF) with a disturbance observer, is used for improving the steering robustness. Moreover, A friction compensator is designed to eliminate the friction generated by mechanical gear contact that hinders precise position control. The simulation model of the Steer-by-Wire system is designed with a permanent magnet synchronous motor (PMSM) and mechanical parts using AMESim program. The proposed controller was verified through simulation using AMESim and Matlab/Simulink cosimulation with different references.

Comparative analysis of different valve timing control methods for single-piston free piston expander-linear generator via an orthogonal experimental design

This paper presents a single-piston free piston expander-linear generator for small-scale organic Rankine cycle. In order to achieve stable operation, two types of valve timing control methods are developed: time control method (TCM) and position control method (PCM). The orthogonal experimental design is adopted to evaluate the influence degree and significance level of different factors on the prototype performance. Results show that the symmetry motion characteristics are worse when the TCM is used than those of the PCM. Furthermore, such characteristics could be improved by appropriately increasing expansion duration and intake duration tBT. For the PCM, operating frequency gradually increases as external resistance, intake pressure, and intake duration but significantly decreases as theoretical stroke. For the TCM, operating frequency is only related with intake and expansion durations. Intake pressure has the greatest influence on the peak power output, peak velocity, and actual stroke length, followed by intake duration. Theoretical stroke is the dominant factor affecting operating frequency, followed by intake pressure, and then by intake duration and external resistance. Thermal-work, work-electric, and thermal-electric conversion efficiencies can achieve a maximum of 5.4%, 28.8%, 1.4%, respectively.

Coupled Simulation of Passive Aerodynamic Stabilisation of a Nanosatellite During Orbital Decay

Small satellites are opening radical new possibilities for space utilisation, especially in low-Earth orbit (LEO). Due to their compactness, many small satellites have no active attitude control systems. A method for passive stabilisation would be useful to regulate attitude without requiring the mass and volume of powered sensors and actuators. In this paper, passive aerodynamic stabilisation of a 3U nanosatellite is investigated using an in-house coupled orbit-attitude simulation platform. The objective is to evaluate the robustness of satellite stabilisation in the 200-400 km altitude range, including in the presence of a perturbing magnetic torque, and initial spin motion. The results show that at 400 km altitude, aerodynamic stabilisation is not a realistic method for attitude control, but that its potential increases lower in the atmosphere.

Attitude control of fixed-wing UCAV based on adaptive fuzzy PID

Aiming at the nonlinear and strong coupling characteristics of the fixed-wing UCAV’s rigid body six-degree-of-freedom model, an adaptive fuzzy PID attitude control method was designed based on expert experience. The nonlinear model of UCAV was linearized with the principle of small disturbance, thus the state space expressions of longitudinal and lateral channels were obtained and the decoupling of the longitudinal and lateral channels was achieved. To verify the designed adaptive fuzzy PID controller, the simulation was carried out aiming at the pitch angle and velocity of the longitudinal channel and the roll angle of the lateral channel. The result showed that the designed controller had faster responsive speed and higher stability, and it could control the UCAV to achieve the desired attitude effectively.

Actuator modelling for attitude control using incremental nonlinear dynamic inversion

Recently, the concept of incremental nonlinear dynamic inversion has seen an increasing adoption as an attitude control method for a variety of aircraft configurations. The reasons for this are good stability and robustness properties, moderate computation requirements and low requirements on modelling fidelity. While previous work investigated the robust stability properties of incremental nonlinear dynamic inversion, the actual closed-loop performance may degrade severely in the face of model uncertainty. We address this issue by first analysing the effects of modelling errors on the closed-loop performance by observing the movement of the system poles. Based on this, we analyse the neccessary modelling fidelity and propose simple modelling methods for the usual actuators found on small-scale electric aircraft. Finally, we analyse the actuator models using (flight) test data where possible.

Tolerance dataset: mating process of plug-in cable connectors for wire harness assembly tasks

In this research, we studied the mating tolerance of various plug-in cable connectors and provide a mating tolerance dataset of 70 different connectors. This dataset will be highly advantageous to industries for wire harness assembly tasks using robots. Understanding the mating tolerance is crucial for automating the mating process because it is closely related to the control specifications of a robotic manipulator. Our system uses a 2-finger Robotiq adaptive gripper attached to a 6 degree-of-freedom industrial robot (ABB Robotics) to test the mating process of wire harness assembly tasks. In addition, we use 70 types of wire harness connectors with different numbers of pins widths, lengths, and thicknesses, and various shapes, to test the mating tolerance. The results indicate that the connector mating tolerance of our dataset is more generous than the repeatability of conventional industrial manipulators, and further demonstrate the suitability of the position control methods to wire harness assembly tasks.

Quaternion-based position control of a quadrotor unmanned aerial vehicle using robust nonlinear third-order sliding mode control with disturbance cancellation

In this paper, we propose a robust nonlinear position and attitude control method for quadrotor using higher order sliding mode control concept. The control of quadrotor is realized in an inner- and outer-loop structure. Both inner- (attitude control) and outer (position control)-loop controllers are synthesized using third-order sliding mode control. The attitude control is designed in a quaternion framework to avoid gimbal lock and for better computational efficiency. A low-pass filter is used to reduce the effect of chattering in higher order sliding mode. A disturbance observer is designed for disturbance estimation. The robustness of proposed control method is ensured by providing the disturbance compensation term in the control law. Lyapunov stability analysis is provided for both inner- and outer-loop controls. Numerical results show that the proposed method provides effective control solution under continuous disturbance/uncertainties due to unmodeled dynamics, parameter variations, and external disturbance with high position accuracy.

Design and Simulation of Double-loop Sliding Mode Controller for Missile Attitude

Sliding mode control has the advantages of simple controller design, short control time, strong anti-interference ability and easy physical implementation, so it is widely used in missile control. Combining the attitude dynamics and attitude kinematics of the missile, this paper designs two missile attitude control methods by using sliding mode control. The two controllers using the two-loop sliding mode control scheme can well track the expected inputs of the angular velocity and angle. And the controllers can work normally under small disturbance torque. So they have good traceability performance and robustness. In this paper, the missile attitude simulation is used to verify the accuracy, track performance and robustness of the two controllers, and compares the control effects of the two control methods.

Concurrent attitude and orbit control for Deorbiter CubeSats

This paper details a concurrent attitude and orbit control method for a debris-removing nanosatellite, called deobriter CubeSat, during the rendezvous and synchronization maneuver with an uncontrollable tumbling debris object. The CubeSat is designed based on the utilization of an eight-unit form factor and commercially-available components with substantial space heritage, and is intended for the removal of sizable debris objects in low-Earth orbit. In particular, a low-thrust propulsion system is used for orbit control, as well as three reaction wheels allowing for a three-axis attitude control. Since the thruster can only produce force in one direction in the body frame, the spacecraft is considered to be underactuated. The controller employs the reaction wheels and the thruster to simultaneously rendezvous and synchronize the attitude of the CubeSat with the tumbling debris object, allowing for a concurrent attitude and position tracking. Detailed derivation of the concurrent controller is discussed, the effects of high-order derivatives are analyzed, and the stability of the system is proved. Simulation scenarios are created for two different thruster operation modes, namely, unsaturated thrust force and continuously-saturated thrust force, in order to verify the performance of the controller, as well as its robustness against gravity gradient disturbance torque and gravitational perturbation force.

Fuzzy intelligent control method for improving flight attitude stability of plant protection quadrotor UAV

At present, the attitude control method of plant protection UAV is the classical PID control, but there are some imperfections in the PID control, such as the contradiction between speediness and overshoot, the weak anti-jamming ability and adaptability. The physical parameters of plant protection UAV are time-varying, and the airflow also interferes with it. The control ability of classical PID is limited, and its control parameters are fixed, and its anti-jamming ability and adaptability are not strong. Therefore, a fuzzy adaptive PID controller is proposed in this paper. Fuzzy logic control is used to optimize the control parameters of PID in order to improve the dynamic and static performance and adaptability of attitude control of plant protection UAV. In the process of research, the mathematical model of UAV is established firstly, then the fuzzy adaptive PID is designed, and then the simulation is carried out in Simulink. The simulation results show that the fuzzy adaptive PID controller has better dynamic and static control performance and adaptability than the traditional PID controller. Therefore, the proposed control method has excellent application value in the attitude of plant protection UAV. Keywords: quadrotor UAV, attitude control, plant protect, fuzzy adaptive PID, Simulink DOI: 10.25165/j.ijabe.20191206.5108 Citation: He Z H, Gao W L, He X K, Wang M J, Liu Y L, Song Y, et al. Fuzzy intelligent control method for improving flight attitude stability of plant protection quadrotor UAV. Int J Agric & Biol Eng, 2019; 12(6): 110–115.

A General Position Control Method for Planar Underactuated Manipulators With Second-Order Nonholonomic Constraints.

The study on the stabilization of planar underactuated manipulators without gravity is well recognized as a major challenge since the system includes a second-order nonholonomic constraint when the passive link is not located at the first link. It is important to solve this difficulty for applications such as systems working in aerospace or underwater. This article presents a position control method based on bidirectional motion planning and intelligent optimization for this kind of system. The control objective is to move the end effector of the manipulator from its initial position to a given target position. The differential evolution algorithm is applied to solve the target angles of all links corresponding to the target position of the end effector. Then, bidirectional motion planning is performed, which consists of forward and backward motions. Each motion is planned by designing a trajectory for every active link based on their initial and target angles. During the forward motion, all active links except the first one are moved to their target angles, and the first active link and the passive link to the intermediate angles. For the backward motion, the first active link is moved to its target angle, the other active links remain at their target angles, and the passive link will be moved to its target angle at the same time. The planned trajectories are chosen based on the time-scaling method and differential evolution algorithm to make sure that the forward and backward planned motions can be connected smoothly. Finally, the trajectory tracking controllers for all active links are designed based on the sliding-mode control method. The proposed control method is verified on planar four-link underactuated manipulators with different passive joints. This strategy has the advantage that it works for planar underactuated manipulators with a second-order nonholonomic constraint whose passive link can be at different positions. Meanwhile, by combining intelligent optimization with bidirectional motion planning, the control process becomes simpler and more effective.

A novel anti-swing and position control method for overhead crane.

Based on Takagi-Sugeno fuzzy modeling and linear matrix inequality with decay rate, this article presents a novel anti-swing and position control scheme for overhead cranes. First, the simplified nonlinear dynamic model is proposed by adopting a virtual control variable method to reduce the number of nonlinear terms. Then, the Takagi-Sugeno fuzzy model is constructed using sector nonlinear technique, and the anti-swing and position controller of overhead crane is designed based on a linear matrix inequality with decay rate. Finally, the proposed control method is compared with the traditional Takagi-Sugeno fuzzy control method, and robustness of the system is discussed. The simulation results demonstrate that the proposed method is feasible and effective.

Nanoparticle Positioning on Liquid and Polymerized Faceted Droplets

Nanoparticle (NP)-decorated emulsion droplets are widely employed in science and technology. Yet, no method for a precise positional control of individual NPs on the droplet’s surface has been hith...

Deep-Reinforcement-Learning-Based Distributed Vehicle Position Controls for Coverage Expansion in mmWave V2X

In millimeter wave (mmWave) vehicular communications, multi-hop relay disconnection by line-of-sight (LOS) blockage is a critical problem, especially in the early diffusion phase of mmWave-available vehicles, where not all the vehicles have mmWave communication devices. This paper proposes a distributed position control method for autonomous vehicles to make long relays connecting to road side units (RSUs) by avoiding blockages to communicate with each other via LOS paths. Even though vehicles with the proposed method do not use the whole information of the environments and cooperate with each other, they can decide their action (e.g., lane change and overtaking) to form long relays using only information of its surroundings (e.g., surrounding vehicle positions). The decision-making problem is formulated as a Markov decision process so that autonomous vehicles can learn a practical movement strategy of making long relays by a reinforcement learning (RL) algorithm. This paper designs a learning algorithm based on a sophisticated deep reinforcement learning algorithm, asynchronous advantage actor-critic (A3C), which enables vehicles to learn a complex movement strategy quickly by its deepneural-network architecture and multi-agent-learning mechanism. Once the strategy is well trained, vehicles can distributedly move to positions where the long relay to the RSU is established. Simulations results confirm that the proposed method can increase the relay length and coverage even if the traffic conditions and penetration ratio of mmWave communication devices in learning and operation phases are different.

Intelligent Attitude Control of Aircraft Based on LSTM

The flight attitude control is the core part of the maneuvering process in air combats. Traditional flight attitude control methods have high computational complexity, low flexibility and poor ability to learn sequential feature. This paper proposes a flight attitude control model based on long short term memory network, which utilizes its special gates structure to memorize historical information, and acquire the variation law of the attitude control variable from the time sequential data including the battlefield situation and flight parameters automatically. Moreover, the basic framework and training methods of the model are also introduced, and the influence caused by various LSTM network parameters is deeply discussed. The experiment results show that the proposed model has better prediction accuracy and convergence performance than the traditional recurrent neural network.

Novel finite-time attitude control of postcapture spacecraft with input faults and quantization

This paper investigates a novel finite-time attitude control method for the postcapture spacecraft with an unknown captured space target in the presence of input faults and quantization. First, a quasi fixed-time convergent performance function is developed to quantitatively characterize the attitude tracking performance. Then, a backstepping prescribed performance attitude controller is devised via using integral barrier Lyapunov function. Compared with the existing works, the fractional state feedback and discontinuous controller is directly avoided to achieve the fixed-time convergence rate. Namely, the proposed fixed-time controller is easily achieved online. Finally, two groups of illustrative examples are organized to validate the effectiveness and robustness of the proposed control method.

A New Method for Positional Accuracy Control for Non-Normal Errors Applied to Airborne Laser Scanner Data

A new statistical method for the quality control of the positional accuracy, useful in a wide range of data sets, is proposed and its use is illustrated through its application to airborne laser scanner (ALS) data. The quality control method is based on the use of a multinomial distribution that categorizes cases of errors according to metric tolerances. The use of the multinomial distribution is a very novel and powerful approach to the problem of evaluating positional accuracy, since it allows for eliminating the need for a parametric model for positional errors. Three different study cases based on ALS data (infrastructure, urban, and natural cases) that contain non-normal errors were used. Three positional accuracy controls with different tolerances were developed. In two of the control cases, the tolerances were defined by a Gaussian model, and in the third control case, the tolerances were defined from the quantiles of the observed error distribution. The analysis of the test results based on the type I and type II errors show that the method is able to control the positional accuracy of freely distributed data.