Tangential Thrust Research Articles

Autonomous orbit maintenance takeover control of ultra-low orbit spacecraft with event-triggered mechanism

In this paper, the problem of high-precision autonomous orbit maintenance takeover control of ultra-low orbit (ULO) spacecraft with event-triggered mechanism (ETM) and tangential continuous low thrust is addressed. First, the ETM I is proposed to reduce the communication burden between Global Navigation Satellite System (GNSS) cellular satellite and controller cellular satellite. Second, a fuzzy adaptive controller is proposed to maintain the orbit altitude of the ULO spacecraft. Furthermore, the ETM II is provided to ensure that the control thrust changes infrequently to extend the lifetime of electric thrust cellular satellite. In addition, the ETM II can lighten the communication burden between controller cellular satellite and electric thrust cellular satellite. By combining fuzzy adaptive control method and ETMs, the ETM-based fuzzy adaptive controller is established. Finally, the simulation is provided to verify the effectiveness of the developed control method.

Autonomous assembly of multiple spacecraft by tether-aided rendezvous and docking: From theory to experiment

Utilizing the tether-aided rendezvous and docking to realize an on-orbit autonomous assembly of multiple spacecraft is a novel and prospective space mission. The paper presents the dynamics and control of this assembly mission mode in a spinning scenario numerically and experimentally. The system equations in general form are first established. Based on several feasible assumptions, the coupling effects among the chaser spacecraft are eliminated, a set of simplified governing equations described by the tether length and the libration angle are then obtained. By employing the trapezoidal tether retrieval law, an assembly strategy composed of the tangential and normal thrust controllers is proposed. The operation constraints of the tether tension and the libration angle are explicitly considered. Numerical simulation results verify the feasibility and effectiveness of the designed control strategy. In addition, the corresponding tether-aided assembly process is further validated by the air-bearing experiment based on the upgraded system SOOHLS.

Method of SLAS's ground track manipulation based on tangential impulse thrust

Method of SLAS's ground track manipulation based on tangential impulse thrust

Research directions for reducing the resistance force to the movement of a wheeled power vehicle

The article discusses the efficiency of the use of energy means largely depends on the traction properties developed by them, which directly affects the realized traction force on the hook. Studies have established that the tangential thrust force realized by the energy means is spent on overcoming the forces of resistance to movement and overcoming the forces of resistance of the agricultural machine. In turn, the resistance strength of an agricultural machine largely depends on the physical and mechanical properties of the soil, the width of the grip and the speed of movement, especially on clay and heavy loamy soil types. It should be noted that this type of soil has a significant impact on the strength of resistance to movement, which is due to the fact that at the same time there is an additional force associated with overcoming the viscosity forces that arise between the soil particles when they are separated from each other. In addition, when the soil adheres to the propellers of the energy vehicle, there is an additional energy consumption for the promotion of additional flywheel masses with an increase in the mass of the propeller. Research and industrial observations have established that one of the ways to reduce the force of resistance to movement on clay and heavy loamy soils is the timely cleaning of wheel movers from the soil adhering to them. In the presented article, the issue of reducing the force of resistance to movement due to purification (purification) of the tire tread of the wheel mover is considered.

Determination of the value of tangential force for the half-track traction vehicle with rubber tracks

Practice shows that with insufficiently high traction qualities of traction vehicles deteriorate its operational properties. At present, extensive research is under way at home and abroad to find inexpensive but highly effective ways and techniques to improve the traction qualities of vehicles. The design of running systems with reduced resistance to movement and slipping will help to significantly increase the productivity of vehicles and reduce fuel consumption. This, in turn, will contribute to greater operational efficiency for traction vehicles. The authors of this study have developed the design of a traction vehicle with a half-tracked propulsor. The objective of the study is to develop a mathematical model for calculating the efficiency of operating a traction vehicle equipped with a half-tracked propulsior with rubber tracks. The proposed mathematical expression takes into account the deformability of the rubber tracks of the propulsor, the uneven distribution of normal pressure along the length of the track, slipping, geometric parameters of the propulsor and the physical and mechanical properties of the soil. Using numerical methods, calculations were carried out to determine the effect of the tangential tractive force on the slipping of a wheeled traction vehicle with a different layout of the running system. The dependences of the amount of slipping on the tangential thrust force are determined. It has been found that with an increase in the traction force, the slipping increases, however, the intensity of growth of a half-tracked propulsor compared to a wheeled propulsor is much lower.

Amorphous silica glass nano-grooving behavior investigated using molecular dynamics method

This work uses molecular dynamics to simulate the grooving behavior of optical silica glass. The amorphous SiO2 (silica glass) was fabricated using a melting-quenching process, and the critical cut depth, and mechanism of the chip formation, were explored using a molecular dynamics simulation. The analytical results indicated that the tool edge radius affected the critical cut depth and roughness of the machined surface. A larger tool edge radius had a larger equivalent negative rake angle at the same depth of cut, causing a larger critical cut depth, while producing a smoother machined surface. In addition, the uncut chip thickness affected the tangential force and thrust force distribution weighting of the tool. The temperature field analysis revealed that a groove formed by the chip formation mechanism resulted in a higher workpiece temperature, causing the brittle material to exhibit ductile cutting behavior during the nanogrooving process. However, grooves formed by the scratching-indenting mechanism had a lower workpiece temperature.

Математическая модель тягового электропривода колесной пары тепловоза с электрической системой повышения сцепных качеств

A mathematical model of the traction electric drive of a diesel locomotive wheelset has been developed, which allows for theoretical analysis of the increase in coupling qualities when exposed to electric current on the contacts of wheels with rails. For mathematical description of the processes occurring in the electric motor, a classical calculation method is used, which is based on a generalized electric machine. When studying the electric drive, it is not necessary to take into account elastic bonds in the mechanical part, therefore it is presented in the form of a one-mass calculation scheme. The processes occurring in the electric drive system are influenced by various factors. The tangential thrust force, which determines the moment of static load, can have different values determined by resistance to the movement of the train. The greatest traction force depends on reduction of the load on the wheelset in traction mode and on the calculated coefficient of adhesion of the wheels to the rails, which has a non-linear falling character, especially in the zone of low speeds. Contamination of the rolling surfaces of wheels and rails leads to decrease in the physical coefficient of adhesion. The supply of electric current to the contact zones of wheels with rails increases the coefficient of adhesion, the limit values of which in various contact states according to the degree of contamination are described by the corresponding regression mathematical models.

RESEARCH AND REVIEW OF CLAY AND GLASS FIBER REINFORCED POLYESTER NANOCOMPOSITE MATERIALS USING OPTIMIZATION TECHNIQUES

Drilling process plays a vital role in the development of polymer clay nanocomposites. The effects of various parameters, such as tool, feed rate and speed to generate the impact on tangential force, thrust force and delamination factor acting on the material in production are studied during drilling operations in the aerospace and automotive industries. The input variable settings to adjust the speed and feed rate to show the outcomes of tangential force, thrust force and delamination factor of the material according to the consumption of the parts in the next stage of manufacturing are calculated by efficient feed rate optimization. A series of tests are performed by changing tools such as High speed steel (HSS), end mill (HEM), High speed steel (HSS), twist drill (HTD) and carbide twist drill (CTD) on various materials to evaluate the influence on the feed rate and speed. Based on the experimental analysis, mathematical modeling is implemented to study the properties of glass fiber reinforced polyester nanocomposite (GFRPNC; 3[Formula: see text]wt.%). Using the desirability approach, the optimum operating conditions of the selected process variables are considered to minimize delamination. A full factorial experiment design is adopted using the two fundamental concepts of replication and randomization of experimental design to research the relationship between the variables. Based on the analysis of variance (ANOVA), the process model is formulated using the [Formula: see text] statistical kit. It is inferred that the delamination factor is minimal for all tools (CTD, HTD and HEM) at 0.1[Formula: see text]mm/rev feed rate and speed at 852[Formula: see text]rpm.

Selection of parameters of machines for collection of logging waste

The article presents a methodology for a reasonable choice of parameters of a machine for collecting of logging waste, which allows to determine the possibility of the machine’s movement depending on various design parameters and natural-production factors when performing technological operations based on an assessment of the traction and coupling properties of the base chassis. A relationship has been established to determine the resistance force to dragging of logging waste, which takes into account the taxation characteristics of the plantation (liquid stock, species composition and density of wood), the parameters of technological equipment (its width) and the peculiarities of the location of the shafts of logging waste through the average distance of passes. The results of determining the resistance force of overcoming a stump with a tooth of technological equipment of a rake type are also given. The proposed nomograms allow, based on the specified operating conditions, to determine the total force of resistance to movement from technological equipment and branches. From this value, using the graphical-analytical method, based on the type of soil, the considered layout of the base chassis and the expected speed of operations, the minimum required engine power, tangential force thrust and weight of the base chassis are established. Based on the results obtained, recommendations are given on the use of various types of base chassis, depending on the type of soil.

Low-thrust transfer to the Earth-Moon triangular libration point via horseshoe orbit

This paper proposes a novel method for the low-thrust transfer to the triangular libration points in the Earth-Moon system. Horseshoe orbit is explored as the coasting arc in this transfer scenario. By tangential thrust control strategy, the low-thrust transfer from the Earth to the short-period orbit around L4 point is realized. The pseudospectral method is used to obtain another Earth-L4 transfer trajectory by solving an energy-optimal low-thrust trajectory optimization problem. Interestingly, these two kinds of Earth-L4 low-thrust transfer trajectories both share similar geometric configuration and velocity trend with a natural Horseshoe orbit, which evokes the main contributions of this paper that leveraging Horseshoe orbit as the coasting arc. The complete transfer trajectory is divided into three phases: Earth spiral phase, Horseshoe coasting phase and L4 point insertion phase, where the first and the third are powered phases. The tangential thrust control strategy is used in the first phase to generate the transfer from the Earth to the Horseshoe orbit, and the pseudospectral method is utilized in the third phase to enable the transfer from the Horseshoe coasting arc to the L4 point by solving a time-optimal transfer problem. Then, by patching these two powered segments with the unpowered Horseshoe coasting arc, the Earth-L4 low-thrust transfer is constructed.

Fixed-time terminal sliding mode control of spinning tether system for artificial gravity environment in high eccentricity orbit

In this paper a new strategy is introduced to produce an artificial gravity environment by spinning tether system (STS) in high eccentricity transfer orbit. Compared with other common artificial gravity environment methods, spinning tether system has simple structure, light weight and suitable spin velocity, which is more favorable for the spacecraft to generate the artificial gravity in the weightless space. The mathematical model of the spinning tether system is established by the second type of Lagrangian equation firstly. Then, the tension control law and the tangential thrust control law of tether system are designed. Through the mutual coordination of both control law, a method of Variable Moment-of-Inertia and Angular Momentum is realized which makes the tether system spin along the expected spinning velocity in most of the processes of uniform velocity development by constant tangential thrust. With the end of development, the artificial gravity environment level on the spacecraft also met the expected requirements, and the nominal trajectory curve of STS under the high-eccentricity transfer orbit was obtained. Finally, considering the rapidity of convergence time, a fixed time terminal sliding mode controller is designed to control the closed-loop trajectory curve of the tether system.

In vivo evaluation of machining forces, torque, and bone quality during skull bone grinding.

This study investigates neurosurgical bone grinding with varying parameters on skull bone using a miniature grinding burr. Three process parameters, namely, rotational speed, feed rate, and depth of cut, have been investigated at three different levels in the terms of tangential force, thrust force, and torque generated during grinding. The results revealed that as the rotational speed is increased, the cutting forces and torque showed a decreasing trend. Nevertheless, the increase in feed rate and depth of cut leads to the escalation in response characteristics. The best parametric combination for minimum cutting forces and torque is as follows: rotational speed = 55,000 r/min, feed rate = 20 mm/min, and depth of cut = 0.50 mm. Morphological analysis reveals cracks in the bone's surface at a higher feed rate. Furthermore, delamination and cutting streaks are also visible on the surface of the bone after grinding. Energy-dispersive spectroscopy and elemental mapping of the tool after bone grinding indicate the accumulation of the bone chips in the successive diamond abrasives. The outcomes of the study will be beneficial for the neurosurgeons in understanding the effect of various process parameters on cutting force, toque, microcracks, and bone's regeneration ability during surgical bone grinding.

Tool wear and cutting force investigations during turning 15 wt% SiCp-Al 7075 metal matrix composite

Al 7075 metal matrix composite (MMC) augmented with 15 wt% SiC particles (SiCp) of mean particle size (MPS) 8 µm was fabricated through vortex stir cast method, followed by T6 thermal treatment. The thermal treated MMC ingot was dry turned using multiple titanium nitride coated tungsten carbide (WC) tools to investigate the tool flank wear (Fw) and cutting force components (tangential component-Pz, thrust component-Py and feed component-Px). Turning parameters were optimized and regression model was generated for Fw. Also parametric significance on Fw was determined through Analysis of Variance (ANOVA) at the confidence level of 95%. Results revealed that Fw increased on enhancing speed of cutting (Vc), feed (s) and cutting depth (t); however, optimal parametric combination for Fw was 40 m/min (Vc), 0.05 mm/rev (s) and 0.2 mm (t). Vc was the most significant for Fw, taken after by s; but t was insignificant. Pz was of highest magnitude among all the three force components during turning the MMC. Consistent rise of all the force components was observed either on increasing t at different levels of s or on increasing s at different levels of t, while turning the MMC at constant Vc of 45 m/min.

General Perturbation Method for Satellite Constellation Reconfiguration Using Low-Thrust Maneuvers

A general perturbation solution to a restricted low-thrust Lambert rendezvous problem, considering circular-to-circular in-plane maneuvers using tangential thrust and including a coast arc, is developed. This provides a fully analytical solution to the satellite reconnaissance problem. The solution requires no iteration. Its speed and simplicity allow problems involving numerous spacecraft and maneuvers to be studied; this is demonstrated through two case studies. In the first, a range of maneuvers providing a rapid flyover of Los Angeles is generated, giving an insight to the trade space and allowing the maneuver that best fulfills the mission to be selected. A reduction in flyover time from 13.8 to 1.6 days is possible using a less than velocity change. A comparison with a numerical propagator including atmospheric friction and an 18th-order tesseral model shows 4 s of difference in the time of flyover. A second study considers a constellation of 24 satellites that can maneuver into repeating ground track orbits to provide persistent coverage of a region. A set of maneuvers for all satellites is generated for four sequential targets, allowing the most suitable maneuver strategy to be selected. Improvements in coverage of greater than 10 times are possible as compared to a static constellation using 35% of the propellant available across the constellation.

Thrust and flow characteristic of double synthetic jet actuator underwater

In this paper, underwater thrust vectoring method based on double synthetic jet actuator is studied. The thrust characteristic of the system under different nozzle distances and phase lags are numerically investigated. The numerical method is validated using data in the literature. The average normal thrust increases when nozzle distance increases. The average tangential thrust decreases when nozzle distance increases. The jet interacts with each other strongly under small nozzle distances. When the two actuators are far enough, the interaction between adjacent jets is negligible. The average normal thrust keeps nearly invariant when phase lag varies. The average tangential thrust increases when phase lag increases from 0 to π and decreases when phase lag increases from π to 2π. The variation of the thrust vectoring angle has the same tendency with the average tangential thrust. The velocity vector and the vorticity contour are given. The mathematical model of the average normal and average tangential thrust is also established.

Calculation of the parameters of the corrector section of the speed characteristics tractor engine

One of the main indicators of the corrector section of the high-speed characteristics of the tractor engine is its torque adaptability factor. The article describes the method of General solution of the problem of calculation of this coefficient. The method is to minimize the difference between the two functions (optimality criterion): the first - the dependence of the denominator of the geometric series of gears on the coefficient of adaptability, the second-the dependence of the denominator on the tractor power range, that is, the ratio of the tangential thrust force in the last gear to the same force in the first gear. Taking into account the found coefficient of adaptability by the moment, the rotation frequency of the motor shaft at the maximum torque, the coefficient of adaptability of the engine by the shaft speed, the traction and speed ranges, the theoretical speed in the last gear are determined. The speed of the shaft at the maximum torque is determined from the condition that the engine load factor by power at the maximum torque is equal to 0,85. The power range is determined by the results of minimization of the optimality criterion, the speed range is equal to C-low. The speed of the tractor in the last gear is determined taking into account the given speed in the first gear and the found speed range. The generally accepted range of minimum values of the coefficient of adaptability, based on the time increase in traction resistance, is 1,15...1,20. In some modern tractor engines, this co-efficiency is greater than 1,2. The aim of the article is to optimize the interval of adaptability coefficient values greater than 1,2. The object of study - the engine of a wheeled tractor traction class 3. The initial material-nomi-nal traction and weight of the tractor, its traction range, the interval of theoretical speed in first gear. Research methods-nel programming using the minimization of the convex function; approximation of the linear function of the torque dependence on the current speed of the shaft. The main conclusion: given the accepted criterion of optimality, constraints, and the coefficient of variation moment of resistance of the optimum the coefficient of adaptability at the twisting mo-ment of tractor engines comply with the interval of 1,27 to 1,45.

Hybrid Low Thrust Propulsion Trajectory Design and Optimization Using Virtual Gravity Method

a novel spacecraft trajectory design method using hybrid low thrust system is proposed in this paper. The hybrid system is constituted with a solar sail propulsion thruster and a solar electric propulsion thruster. In proposed method, the former one provides radical thrust and circumferential thrust to from a virtual gravity, while the later one provides a tangential thrust. In this way, the spacecraft is virtually motioned by constant tangential thrust in a virtual gravity field. Using proposed method, the thrusting trajectory can be parameterized, and a large number of feasible trajectories for circle to circle rendezvous problem can be obtained. To the end the steering law to minimize the fuel cost is found using Matlab optimization tools Fmicon function, and the result is compared with traditional pure solar electric propulsion method in terms of payload mass fraction. The simulation results show that the proposed method can reduced propellant consumption significantly compared with the pure SEP system.

Exploring Filling Law of Small Fillet of Dual Clutch Hub

In extruding the dual clutch hub with small fillet gear, the filling of small fillet gear is not complete due to the large forming resistance. A method of preforming the blank into a concave shape is proposed. The mechanical analysis and finite element simulation are used to analyze the principle that the blank of concave shape can promote the filling of small fillet gear, stamping and extruding are both used to form the dual clutch hub and the preform is used to simulate the fillet gear’s extruding to analyze the influence of the geometric parameters of the preform on the forming quality. The mapping relationship between the geometric parameters of the preform and the size of unfilled fillet gear is established by using the BP neural network. The multi-objective genetic algorithm is used to optimize the geometric parameters of the preform. From the results we can see that the frictional resistance decreases due to reduced contact area between the blank and the mold when the section shape of the blank is concave, and at the same time, the tangential thrust is generated on the blank, so the filling of small fillet gear is better; BP neural network combined with genetic algorithm can reliably optimize the geometric parameters of the preform. The filling performance of the fillet gear is better under the optimal preform, and the forming quality of the dual clutch hub is improved. The experimental result verified the feasibility of the method and the accuracy of the simulation.

Magnetic Field and Force Calculation in Linear Permanent-Magnet Synchronous Machines Accounting for Longitudinal End Effect

This paper presents an improved analytical method for predicting the magnetic field and forces in linear permanent-magnet synchronous machines (LPMSMs) accounting for both the primary end effect and secondary end effect. So far, the magnetic field calculation of LPMSM in most studies is conducted in Cartesian coordinate, whereas the end effect is neglected by applying periodic boundary. In this paper, to implement the analytical model, a polar presentation of the machine geometry is proposed and the subdomain method is applied to calculate the magnetic field. Then, according to the developed model, the tangential thrust and normal forces are calculated based on the Maxwell stress theory. Numerical results are subsequently obtained by finite-element method and employed to validate the analytical model. Finally, an LPMSM prototype is manufactured and experiments are conducted. The results show that the developed analytical model has high accuracy for predicting the magnetic field and forces.

Empirical modeling of rotating thruster for underwater robotic platform

A rotating thruster model is needed for the design and control of an underwater robotic platform. Thruster rotation is used to generate an additional degree of freedom for reducing the number of thrusters. The rotation of a thruster during thrusting generates an additional reaction force and torque. A rotating thruster model is required to analyze the dynamic model of a robotic platform by considering rigid body dynamics and hydrodynamics simultaneously. We considered the empirical dynamic modeling of a rotating thruster using frequency and impulse response analysis. A rotating thruster model is derived as a transfer function of longitudinal and tangential thrust forces and rotational torque during the rotation. Simulation is performed using the proposed transfer functions, and the validity of the model is verified by comparison with simulations and the results of experiments. The proposed empirical model can be applied to control an underwater robotic platform with rotating thrusters.