Descent Control Research Articles

Flow Field Analysis on Critical Feedback Information for UAV Autonomous High Speed Descent in Power Line Scenario

Abstract To improve the UAV efficiency in power line inspection, it must autonomously and rapidly descend to a specific height to complete the charging or landing task. This task requires the UAV to contain a stable control loop to face the specific airflow during autonomous and rapid descent: the vortex ring problem, and this specific airflow will reduce the UAV controllability. To implement the UAV autonomous high-speed descent, a control method must provide feedback information on the affected airflow and output a stable rotational speed. Hence, this paper designs a UAV autonomous high-speed descent control loop and proposes a variable rotor speed method to solve the feedback information in the control loop. This method reveals the relationship between the air movement caused by the rotor rotation and the controllability of the UAV high-speed descent. Therefore, with this method, the UAV control loop can obtain stable feedback on the air movement and achieve autonomous high-speed descent. To solve the UAV feedback information, we built the model to calculate the rotor speed in the autonomous high-speed descent UAV control loop and verified it by the CFD. The verification results showed that the model could reflect the actual fly condition. The proposed method solves the problem of UAV autonomous high-speed descent feedback information, improving the work efficiency of UAVs in power line inspection operations.

IoT based Adaptive Lightning and Hill Descent Control with Accelerometer

IoT based Adaptive Lightning and Hill Descent Control with Accelerometer

MPC motion control of boom descending of unmanned excavator based on regenerative valve

The control precision of the working device has always been a challenging aspect in unmanned excavator research due to the adoption of a triangular drive mode and a complex hydraulic system in the working mechanism. The article focuses on the research of autonomous control for the downward motion of a robotic arm in an unmanned excavator equipped with a regeneration valve. The study aims to achieve precise tracking of fast movement trajectories during operator manipulation, utilizing Model Predictive Control (MPC). Furthermore, the exceptional disturbance rejection capability of the MPC algorithm is demonstrated through interference application. A comprehensive model considering mechanical, hydraulic, and electrical factors is established for the excavator boom. The MPC algorithm is applied to achieve precise control over the boom descent process, providing a foundation for motion control in unmanned excavators. This article presents a theoretical analysis to elucidate the robustness principle of MPC in the descent control of uncertain dynamic arms. By incorporating real parameters, we successfully track predetermined planned paths at different speeds and validate them on a 20-ton hydraulic excavator. The results demonstrate that the MPC control algorithm accurately manipulates the boom descent motion while exhibiting excellent disturbance rejection performance. Compared to PID control algorithms, MPC offers wider target adaptability range and better disturbance rejection performance, making it suitable for rapid application in controlling working devices of unmanned excavators.

Investigation of the Performance of Plugging Braking System as a Hill Descent Control (HDC) for Electric-Powered Wheelchair

Recently, a study on Electric Powered Wheelchairs (EPWs) has become significant because they can enhance the mobility of individuals with disabilities. One of the issues on EPW is during descending on a slope because it is difficult to control the speed and prevent it from slipping. Moreover, the manual braking system is frequently used for speed control by pressing the brake lever. The complexity of the task increases significantly when dealing with elderly or paralyzed users with physical limitations. Consequently, the risk of collisions and injuries is elevated. This research seeks to develop a hill descent control (HDC) system for an EPW to address these challenges. By implementing HDC into EPW, the EPW's speed can be controlled, thus increasing the safety of the EPW while descending on the slope. In this study, the plugging brake system is introduced as a hill descent control (HDC) mechanism to inhibit the acceleration of the EPW and ensure it maintains a constant speed during downhill descents. The plugging voltage will be controlled based on the desired speed of 0.6 m/s. To maintain the speed of the EPW, the PID control is used as a control strategy for HDC. The simulation work in Matlab Simulink has analyzed the performance of the plugging brake system with HDC. The results obtained from the simulation reveal that, despite starting with a high initial braking speed of 2.5 m/s, the Electric Powered Wheelchair (EPW) can consistently maintain its velocity at the desired target value of v_d = 0.6 m/s during the descent on the slope. Furthermore, the amplitude response for the PID control shows the settling time is 2.3 s, and the steady-state error is ±0.05. Based on the simulation results, it can be approved that the proposed HDC in the plugging brake system can prevent the EPW from accelerating while descending on the slope and improve the safety of the EPW.

Анализ баллистических ограничений при отработке возможности установления лазерной связи со спускаемым аппаратом на атмосферном участке спуска

The paper presents the Plasma-SA space experiment to study possibility of establishing a laser communication channel between the descent vehicle of the Soyuz transport spacecraft and ground stations at the atmospheric descent phase, when plasma layer is blocking radio communication. Design limitations associated with safe installation of the scientific equipment onboard the Soyuz spacecraft descent vehicle are briefly considered. Ballistic limitations caused by the descent trajectory and the descent vehicle control at the atmospheric phase determining location areas of the ground-based laser radiation sources were analyzed. Principal possibility to register test signal from the ground source by the equipment installed onboard the descent vehicle is demonstrated. Effect of deviation from the calculated trajectory and of alteration in the roll angle during descent control with its registration is demonstrated, and ways to improve these conditions are proposed.

Design and Implementation of Novel Fault Ride through Circuitry and Control for Grid-Connected PV System

This paper provides a comparison of a designed method of a fault ride through (FRT) circuit, i.e., switch-type fault current limiter (STFCL) and bridge-type fault current limiter (BFCL), to optimize the electrical parameters of grid-connected solar systems (PVSs) under asymmetric single line-to-ground fault and symmetric three-phase fault. The main differences between switch- and bridge-type fault current limiters is the electric component devices such as the bridge rectifier, snubber capacitor, energy absorption bypass and current-limiting inductors. In addition, the designed FRT performance with the inverter control are analyzed in-depth, e.g., a well-adjusted proportional integral (PI) and proposed steepest descent (SD) controller are compared in the fault condition. To compare the proposed method with the conventional method, the AC power and voltage on a common coupling point (PCC) and DC link voltage of the PV system are analyzed with a MATLAB/Simulink model of a 100 kW three-phase grid-connected photovoltaic system. The simulation results of the proposed FRT circuit and SD controller verify the stability improvement and vibration-free and fast and robust responses of electrical parameters on both PV grid sides during asymmetric disturbances.

Fall arrest strategy training improves upper body response time compared to standard fall prevention exercise in older women: A randomized trial

Introduction Exercise can decrease fall risk in older adults but less is known about training to reduce injury risk in the event a fall is unavoidable. The purpose of this study was to compare standard fall prevention exercises to novel Fall Arrest Strategy Training (FAST); exercises designed to improve upper body capacity to reduce fall-injury risk in older women. Method Forty women (mean age 74.5 years) participated in either Standard (n = 19) or FAST (n = 21) twice per week for 12 weeks. Both interventions included lower body strength, balance, walking practice, agility and education. FAST added exercises designed to enhance forward landing and descent control such as upper body strengthening, speed and practice of landing and descent on outstretched hands. Results Both FAST and Standard significantly improved strength, mobility, balance, and fall risk factors from pre to post-intervention. There was a significant time by group interaction effect for upper body response time where FAST improved but Standard did not (p = 0.038). Discussion FAST resulted in similar gains in factors that reduce fall risk as a standard fall prevention program; with the additional benefit of improving speed of arm protective responses; a factor that may help enhance landing position and reduce injury risks such as head impact during a forward fall.

A Robust Control Algorithm of a Descent Vehicle Angular Motion in the Earth’s Atmosphere

A new approach to synthesize a robust controller for the angular motion of the Earth lander by decomposition method of output modal control is proposed. A universal analytical solution for the problem of stabilizing the angular position of the lander is obtained. A comparative analysis of the presented algorithm with the currently used onboard algorithm for descent control of the manned spacecraft Soyuz is carried out. The advantages of the new algorithm relative to the existing algorithm are presented, both in terms of stabilization accuracy and the consumption of the working fluid of the control motors.

Оптимизация формы крыла и выбор рациональных параметров траектории многоразового космического аппарата туристического класса

The article considers solving the interrelated problems of wing shape optimization and synthesis of the re-entry trajectory control law for the reusable spacecraft of tourist class. To ensure a high aerodynamic quality of the wing, increase its bearing properties, as well as improve the maneuverability and controllability of the spacecraft as a whole, the wing shape has been optimized for sub- and supersonic flight modes. The problem of minimizing the wing area is solved for subsonic flight speed while ensuring the level of lift sufficient for landing, with the introduction of restrictions on the minimum wing sweep angle. For supersonic flight speed, maximization of the aerodynamic quality of the wing is used as an objective function. The length and taper of the wing, leading-edge sweep angle, the size of the root and tip chords, and the position of the wing relative to the fuselage were chosen as variables. For the wing shape selected on the basis of the parametric analysis, the calculation of the dependences of the spacecraft aerodynamic coefficients on the Mach number, used for selecting a rational program for the descent control in the atmosphere, was carried out. The choice of a rational control program is made with restrictions on the level of overloads, kinetic pressure and maximum heat flux.

Precise power descent control of a lunar lander using a single thruster

This paper addresses the problem of powered descent control of a lunar lander during its final landing phase, where soft and precise landing at the target cite is required. In the literature, this problem has been solved considering a fully actuated lunar lander. Recently, landers are designed as complex systems with several onboard payloads and subsystems for completing demanding mission tasks. There are increasing constraints on mass budget and space availability onboard a lander. In order to meet these requirements, a novel controller using a single thruster is proposed. The proposed controller has three control inputs (thrust and two gimbaled angles) to control the six degrees of motion of a lander; these control inputs are non-affine. The proposed controller is designed based on variable structure control technique augmented with a high order filter, an immersion and invariance-based mass estimator and a sliding mode angular velocity observer. The stability analysis using Lyapunov theory and the results of the numerical simulations along with Monte Carlo simulations of the system show that the precise landing of the lunar lander using a single thruster is feasible.

A Gradient-Based Approach for Coordinating Smart Vehicles and Traffic Lights at Intersections

In this letter we consider the coordination of connected and autonomous vehicles (CAVs) with intelligent traffic control signalization to improve the performance of traffic at intersections. We propose a coordination method based on a gradient-based multi-agent system. Specifically, we consider both the traffic light and the approaching vehicles as smart connected agents and we define a suitable edge tension function for each connection between agents. The agents then run a decentralized gradient descent control policy that drives them towards a desirable sequence of intersection crossings. In the literature, the problem of coordinating CAVs at intersections has been widely explored, with different algorithms being proposed. However, the problem of considering both smart traffic lights and smart cars simultaneously is relatively unexplored, especially from a multi-agent system, gradient-based, perspective. The advantages of the edge tension approach lie in its simplicity in terms of computation and in its ability to scale to larger networks. Furthermore, the control framework is applicable under different connected vehicle penetration rates. This flexibility is a desirable advantage given the gradual nature of the implementation of autonomy in real traffic networks. The proposed strategy is evaluated in simulation and significant fuel savings and delay improvements are shown in comparison with fixed-time traffic light control.

Work-related musculoskeletal disorders and injuries among emergency medical technicians and paramedics: A comprehensive narrative review

The aim of this article was to review the current knowledge relating to work-related musculoskeletal disorders (WRMDs) and non-fatal injuries in emergency medical technicians and paramedics (EMTs-Ps). A literature search was conducted in PubMed, Google Scholar, and Clinical Key. The annual prevalence of back pain ranged from 30% to 66%, and back injuries and contusions from 4% to 43%. Falls, slips, trips, and overexertion while lifting or carrying patients or instruments ranged from 10% to 56%, with overexertion being the most common injury. Risk factors were predominantly lifting, working in awkward postures, loading patients into the ambulance, and cardiopulmonary resuscitation procedures. Lack of job satisfaction and social support was associated with WRMDs and injuries. EMTs-Ps had the highest rate of worker compensation claim rates compared to other healthcare professionals. Positive ergonomic intervention results included electrically powered stretchers, backboard wheeler, descent control system, and the transfer sling.

Beever

Paul Beever, an automotive engineer who spent 38 years at Land Rover, recalls the ideas, trials and dangers of creating the Hill Descent Control system

A Fuzzy-PID Scheme for Low Speed Control of a Vehicle While Going on a Downhill Road

We explored a vehicle hill descent control (HDC) system based on an electronic stability program (ESP) and applied this system to brake cars. The experimental results reveal that our system can effectively reduce the workload of a driver during a downhill journey. In the first phase of our work, the control strategy of the HDC system based on fuzzy-PID (Proportion Integral Differential) was built by MATLAB/Simulink. Then, the co-simulation based on MATLAB/Simulink, CarSim and AMESim was carried out. Finally, a real vehicle test was conducted to further verify the feasibility of the strategy. A series of simulation experiments and real vehicle tests show that the HDC system can assist the driver to control the vehicle while driving downhill at low speed, thus effectively improving the safety of the vehicle and reducing the workload of driver.

Numerical comparison of adaptive optics correction based on stochastic parallel gradient descent and phase conjugate in scintillation conditions

Adaptive optics (AO) systems with wavefront sensors are based on the phase conjugate (PC) principle. These systems do not work effectively when the scintillation intensity in the receiver aperture becomes significant. AO correction technique based on stochastic parallel gradient descent (SPGD) control algorithm is an alternative approach which does not depend on wavefront sensor but optimizes the performance metric directly. In this study, we established a simulation model for an SPGD–AO system in which the SPGD optimisation algorithm was applied to control the tip-tilt and the deformable mirrors to correct the aberration in several turbulence scenarios. The performances of the SPGD–AO and the PC–AO correction schemes were tested in different scintillation conditions based on numerical simulations of dynamic turbulence. In weak scintillation conditions, the effects of the SPGD–AO correction were as accurate as those of the PC–AO correction, but upon scintillation increasesσR2>1, the SPGD–AO yielded a significant correction effect compared to PC correction. The results also showed that SPGD did not require any wavefront phase information, but it was very effective for discontinuous phase correction.

Stair Descent Control of a Single-wheeled Inverted Pendulum Robot

Stair Descent Control of a Single-wheeled Inverted Pendulum Robot

Modification of the Terminal Control Algorithm for Descent from Near-Earth Orbit Applied to “Enhanced” Disturbances

The problem of reentry vehicle control during its descent from a near-Earth orbit is considered under conditions of “enhanced” disturbances. The earlier developed terminal descent control algorithm is considerably improved to satisfy constraints on landing accuracy, load factor, and propellant consumption. A method for automatically shifting the deorbit point, adaptating to actual motion conditions, and modifying the reference bank function is proposed, which ensured the satisfaction of the specified constraints under action of an aggregate of enhanced disturbing factors.

Control of Directed Formations Using Interconnected Systems Stability

This paper deals with the problem of rigid formation control using directed graphs in both two-dimensional (2D) and three-dimensional (3D) spaces. Directed graphs reduce the number of communication, sensing, and/or control channels of the multi-agent system. We show that the directed version of the gradient descent control law asymptotically stabilizes the interagent distance error dynamics of minimally persistent formation graphs. The control analysis begins with a (possibly cyclic) primitive formation that is grown consecutively by Henneberg-type insertions, resulting at each step in two interconnected nonlinear systems, which are recursively analyzed using the stability of interconnected systems. Simulation and experimental results are presented for the directed formation controller in comparison to the standard undirected controller.

Dynamic Simulations of Adaptive Design Approaches to Control the Speed of an Induction Machine Considering Parameter Uncertainties and External Perturbations

Recently, the Indirect Field Oriented Control (IFOC) scheme for Induction Motors (IM) has gained wide acceptance in high performance applications. The IFOC has remarkable characteristics of decoupling torque and flux along with an easy hardware implementation. However, the detuning limits the performance of drives due to uncertainties of parameters. Conventionally, the use of a Proportional Integral Differential (PID) controller has been very frequent in variable speed drive applications. However, it does not allow for the operation of an IM in a wide range of speeds. In order to tackle these problems, optimal, robust, and adaptive control algorithms are mostly in use. The work presented in this paper is based on new optimal, robust, and adaptive control strategies, including an Adaptive Proportional Integral (PI) controller, sliding mode control, Fuzzy Logic (FL) control based on Steepest Descent (SD), Levenberg-Marquardt (LM) algorithms, and Hybrid Control (HC) or adaptive sliding mode controller to overcome the deficiency of conventional control strategies. The main theme is to design a robust control scheme having faster dynamic response, reliable operation for parameter uncertainties and speed variation, and maximized torque and efficiency of the IM. The test bench of the IM control has three main parts: IM model, Inverter Model, and control structure. The IM is modelled in synchronous frame using d q modelling while the Space Vector Pulse Width Modulation (SVPWM) technique is used for modulation of the inverter. Our proposed controllers are critically analyzed and compared with the PI controller considering different conditions: parameter uncertainties, speed variation, load disturbances, and under electrical faults. In addition, the results validate the effectiveness of the designed controllers and are then related to former works.

Variable Geometry Stair Ascent and Descent Controller for a Powered Lower Limb Exoskeleton

This paper describes a control approach for a lower limb exoskeleton intended to enable stair ascent and descent of variable geometry staircases for individuals with paraplegia resulting from spinal cord injury (SCI). To assess the efficacy of ascent and descent functionality provided by the control approach, the controller was implemented in a lower limb exoskeleton and tested in experimental trials on three subjects with motor-complete SCI on three staircases of varying geometry. Results from the assessments indicate that subjects were able to capably ascend and descend step heights varying from 7.6 to 16.5 cm without changing control settings; the controller provided for step time consistency highly representative of healthy subjects (9.2% variation in exoskeleton step time, relative to 7.7% variation in healthy subjects); and the exoskeleton provided peak joint torques on average 110% and 74% of the healthy-subject peak joint torques during stair ascent and descent, respectively. Subject perceived exertion during the stair ascent and descent activities was rated between “light” and “very light.”