Deceleration Method Research Articles

Dynamic look-ahead feedrate scheduling method based on sliding mode velocity control

In the feedrate scheduling of complex curve direct interpolation, dynamic constraints such as axis acceleration and jerk are related to the actual state of the tool. Most existing methods convert dynamic constraints to velocity constraints at sampling points. However, it cannot guarantee the dynamic constraints are satisfied between sampling points. Addressing the issue, this paper proposes a dynamic look-ahead feedrate scheduling method based on sliding mode velocity control, which generates the motion command considering dynamic constraints in every interpolation cycle. To dynamically generate commands based on the current tool state, the acceleration and deceleration method based on sliding mode velocity control has been proposed, which can control tool state to transition to the command state with any initial state. To ensure sufficient distance for acceleration and deceleration, this paper uses braking distance to dynamically estimate the look-ahead distance. Then the minimum value within the look-ahead interval is selected as the command velocity for this scheduling cycle and the actual motion command is determined based on the dynamic constraints of each axis. Simulation and experiment results prove that compared with the existing method, this method effectively reduces the overshoot of dynamic constraints without significantly increasing the machining time. The analysis of real-time computation time has demonstrated the potential of the method proposed in this paper for real-time applications.

Prescribed-time integrated guidance and control for bank to turn reentry vehicle

In this paper, a novel prescribed-time integrated guidance and control (IGC) with spiral maneuvering deceleration (SMD) method is developed for bank to turn (BTT) reentry vehicle with the consideration of elevation angle and terminal velocity constraints. First, a strict feedback form IGC model is established for BTT reentry vehicle under multiple constraints. Second, a prescribed-time sliding mode controller (SMC) based on prescribed-time extended state observer (ESO) is designed to hit the ground fixed target with the desired line of sight (LOS) elevation angle. Then in order to make the reentry vehicle achieve a better strike effect, it is necessary to constrain the terminal velocity of the reentry flight, a SMD scheme is proposed to achieve the desired terminal velocity. Finally, the efficiency of the proposed scheme is verified by six–degree–of–freedom (6DoF) numerical simulations.

New Technique of Injecting Radioactive Ions into Charge Breeding ECR Ion Source

Cyclotron Institute at Texas A&M University started a project to develop the reacceleration of radioactive ions using the two operational cyclotrons and a Charge Breeding ECR ion source. The radioactive ions are produced primarily via (p,n) reactions using the IGISOL technique. The reaction products are transported into a Charge Breeder ECR ion source where their charge state is boosted from 1+ to higher charge states. The transport of the radioactive products and the injection into the ion source are very important for the efficiency of charge breeding. Two techniques have been used: acceleration–deceleration method (classic) and low - energy RF-only sextupole ion guide transport and injection method (innovative technique). The last method appears to be very efficient and great charge breeding efficiency was observed. The presentation of the entire project, the new injection technique, experimental results, and future plans will be discussed.

Energy-saving strategy and method of spindle deceleration during no-load operation of machine tools for energy lean management

Computer Numerical Control (CNC) machine tools undergo periods of no-load motion, such as tool feeding, tool withdrawing, and tool changing, during workpiece processing. These intervals result in energy wastage as the machine tools remain idle without performing cutting operations. To address this issue, we propose a novel energy-saving strategy and method involving spindle deceleration during the no-load operation of machine tools for energy lean management. Specifically, we conducted three tasks: (1) analyzed the energy consumption characteristics of the CNC machine tool during no-load operation; (2) established a theoretical decision-making model for the energy-saving method of spindle deceleration; (3) discussed the energy-saving critical time for energy savings and the energy-saving effect of the deceleration strategy for the machine tool spindle through three machining cases. Furthermore, we conducted a case study using the CK6153i lathe to verify the effectiveness and feasibility of the proposed method. The results demonstrated significant energy savings of 1826.65 J, 2948.85 J, and 7650.05 J, along with reductions in energy waste of 14.99 %, 20.43 %, and 53.01 %, respectively, in the three machining cases through the implementation of the spindle deceleration strategy. We believe that the outcomes of this research can better assist engineers in the energy lean management of machine tools.

An optimization method of acceleration and deceleration time of feed system based on load inertia

The acceleration and deceleration time is usually a constant value in the process of computer numerical control (CNC) machine tool processing, which cannot adapt to the change of external load and greatly affects processing efficiency. This paper proposes an optimization method for the acceleration and deceleration time of the feed system based on load inertia, which provides the basis for the adaptive adjustment of the acceleration and deceleration time of the feed system. Firstly, by establishing the dynamic model of the servo system, the acceleration and deceleration method is used to identify the external load inertia under different working conditions. The prediction model of the current variance based on load inertia and acceleration and deceleration time parameters is established by using the response surface method, and then the multi-objective particle swarm optimization algorithm is used to build the acceleration and deceleration time optimization model based on the load inertia. At the same time, the inertia identification part is compared with the model reference adaptive system method and the empirical formula estimation method based on current and velocity, the simulation and cutting experiment results show that the inertia identification method based on acceleration and deceleration optimizes the other method. Finally, the machining experiments are carried out on three-axis and five-axis machine tools with the same machine tool type, and by adding different counterweight blocks to change the external load. The test proves that the acceleration and deceleration adaptive adjustment strategy based on load inertia can effectively improve processing efficiency and reduce the fluctuation of the processing load.

Research on Deceleration Technology of Rocket Sled Double Track Sled

Aiming at the shortcomings of water brake in the deceleration recovery test of double-track sled, the reverse rocket deceleration was applied to the recovery of double-track sled. A deceleration scheme of rocket sled double track sled car is designed to improve the safety of double track sled car. Firstly, according to the requirements of sliding distance and water entry speed of sled, the deceleration resistance is designed and calculated, and the reverse rocket is selected. However, the sled car is designed according to the dimensions of the reverse thrust rocket, and the installation position and way of the reverse thrust rocket are determined. At last, according to the deceleration trajectory and the parameters of recoil rocket, the control mode and ignition position of recoil rocket are designed. The simulation results show that the deceleration effect of reverse rocket is obvious. This control method is simple and feasible. The reverse rocket deceleration method can be applied to the recovery of double track sled.

Laboratory Measurement of Rolling Resistance Coefficient under Different Conditions

The aim of our research was to design and construct a measuring device that can determine the rolling resistance coefficient (RRC) under laboratory conditions. The measuring device has a drum arrangement, and the RRC was measured on two different model surfaces. The deceleration method was used to investigate the dependence of RRC on compression force, velocity, and surface temperature on steel and rubber surfaces. The measured RRC values (0.010 – 0.025) were similar in magnitude to the values characteristic for asphalt-covered roads. By increasing the model road surface temperature up to T = 60 ◦C the RCC dropped by ~13% compared to the values at T = 22 ◦C

Automatic Deceleration and Braking Research for Driverless Vehicles in Rail Transit based on Internet of Vehicles

With the development of vehicle networking, driverless technology has also seen great progress. In this paper, we mainly study the automatic deceleration and braking method of driverless vehicles in rail transportation. Firstly, Radio Frequency Identification (RFID) technology was briefly introduced. Then, based on RFID, a graded deceleration and braking scheme was designed to position driverless trains through RFID and control the deceleration of vehicles when they reach different subintervals, so that the speed of the vehicles was 0 when they reached the stopping point. The experimental results showed that the reading distance of the system met the requirements of practical use even when the transmitting frequency was small. In the simulation experiment, the system operated stably and the errors of actual speed and the target speed between different sub-intervals were small, which ensured that the vehicle stopped precisely at the stopping position. The experimental results verify that the proposed method is effective. The method can be further promoted and applied in practice.

Adaptive Deformation Control of a Flexible Variable-Length Rotary Crane Arm With Asymmetric Input-Output Constraints.

This article constructs two adaptive control laws to achieve deformation reduction and attitude tracking for a rotary variable-length crane arm with system parameter uncertainties and asymmetric input-output constraints. Two auxiliary systems are given to deal with the input constraints, an asymmetric-logarithm-barrier Lyapunov function is established for achieving the asymmetric output constrains, and five adaptive laws are constructed to handle system parameter uncertainties. Besides, the control design is based on a partial differential equation model, and the S-curve acceleration and deceleration method is used for regulating the arm extension speed. Both the system stability and uniform ultimate boundedness of the controlled crane arm are analyzed. Simulation results validate the effectiveness of our established control laws.

One Case of Shock-free Deceleration of a Supersonic Flow in a Constant Cross Section Area Channel

Air flows with supersonic speeds are used in many cases, for example, as aircraft air intakes, wind tunnels, and energy separation devices. In many cases it is necessary to decelerate the flow to sonic speeds. Traditionally the deceleration realized through the shocks system, which leads to total pressure losses. The article considers the method of deceleration of supersonic flows using permeable surfaces. In this case, the deceleration process occurs without shocks and, therefore, with lower total pressure losses. We have considered the flow in a tube with permeable wall located behind a supersonic nozzle. One-dimensional and axisymmetric mathematical models of such a device are developed. The calculation results are compared with experimental data. It is shown that, depending on the ratio of pressure inside the tube and the ambient pressure, different flow regimes inside the tube are possible: pure subsonic, transitional from supersonic to subsonic, and pure supersonic. The transition from supersonic to subsonic flow occurs without shocks due to the suction and friction combined effects.

競走艇用2ストローク火花点火機関における機関摩擦の計測と機関の加速運転特性に及ぼす影響

A deceleration method was employed to measure the friction loss in a 2-Stroke spark-ignition engine for a racing boat. In order to reveal the effect of the friction loss on the acceleration operating characteristics, a transient operation test system was developed in a usual performance test setup. By adjusting the input current into the field coil of the eddy-current dynamometer, the acceleration operation behaviors were mostly simulated except for the initial rapid acceleration. Two kinds of pistons having different skirt dimensions were applied to the deceleration test to obtain the friction loss. These pistons were also applied to the acceleration operation test, and it is shown that the engine friction effect could appear in the acceleration operation characteristics according to that predicted from the friction measurement results on the whole.

Main patterns of stress corrosion forming the basis for control, evaluation and deceleration methods

The most effective methods of control during incubation of development and cracking were systematized and proposed on the basis of the developed physical model of corrosion cracking of main gas pipelines under stress. It was established that this is one of the most advanced methods for testing gas pipelines for stress corrosion cracking – this is a magnetic location method.

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

• The flow dynamics of the gas phase and gas-melt two-phase fields, and the break-up process were illustrated. • The particle size distributions of simulated results were consistent with the powder experimental tests. • The Fe-based alloy powders with diameters in the range of 25–45 μm were found to be a fully amorphous phase. Gas atomization is now an important production technique for Fe-based amorphous alloy powders used in additive manufacturing, particularly selective laser melting, fabricating large-sized Fe-based bulk metallic glasses. Using the realizable k-ε model and discrete phase model theory, the flow dynamics of the gas phase and gas-melt two-phase flow fields in the close-wake condition were investigated to establish the correlation between high gas pressure and powder particle characteristics. The locations of the recirculation zones and the shapes of Mach disks were analyzed in detail for the type of discrete-jet closed-coupled gas atomization nozzle. In the gas-phase flow field, the vortexes, closed to the Mach disk, are found to be a new deceleration method. In the two-phase flow field, the shape of Mach disk changes from “ S ”-shape to “ Z ”-shape under the impact of the droplet flow. As predicted by the wave model, with the elevation of gas pressure, the size of the particle is found to gradually decrease and its distribution becomes more concentrated. Simulation results were compliant with the Fe-based amorphous alloy powder preparation tests. This study deepens the understanding of the gas pressure impacting particle features via gas atomization, and contributes to technological applications.

Research on the acceleration phenomenon of projectile leaving the target when penetrating thick concrete target

Based on the theoretical analysis of penetrating thick concrete targets, a model of converting friction into heat and then into high-pressure gas thrust at the bottom of the projectile is proposed. Furthermore, an analysis and calculation method of deceleration after perforation is given by using thermodynamic theory. In the off-target stage of penetrating the thick concrete target, the projectile has a short-term acceleration movement, and the calculation equation of acceleration in this stage is given. The calculated value is in good agreement with the penetration experiment data. It is of great significance to determine whether the projectile body penetrates thick concrete targets and whether it is necessary to control the projectile body's detonation.

A Study on acceleration / deceleration methods considering the ride quality of senior cars

A Study on acceleration / deceleration methods considering the ride quality of senior cars

Improvement of type-I method for observing magnetic contrast using scanning electron microscope under tilting-deceleration condition

We developed a method of observing SEM images with a clear magnetic contrast without anisotropy using a scanning electron microscope (SEM). Directional-selective detection of secondary electrons (SEs) is needed to obtain SEM images with a clear magnetic contrast using a type-I method that utilizes changes in the number of detected signals due to a deflection of SEs by the stray magnetic fields of specimens. By combining beam deceleration and specimen tilting (hereinafter “tilting deceleration”), we achieved a directional-selective detection condition for SEs that is preferable for the type-I method. We found that the tilting deceleration method has high sensitivity for fine magnetic domain structures and can visualize submicron-sized magnetic domain structures in a vertically magnetized region of Nd2Fe14B specimens. Furthermore, we synthesized two SEM images with different directional information to reduce the anisotropy of magnetic contrast obtained by the asymmetric detector configuration. As a result, we obtained SEM images with isotropic magnetic contrast, which is similar to that of an SEM image acquired by a spin-SEM equipped with a Mott-type spin-polarization detector.

Analysis of the Deceleration Methods of Fatigue Crack Growth Rates under Mode I Loading Type in Pearlitic Rail Steel

The paper presents a comparison of the results of the fatigue crack growth rate for raw rail steel, steel reinforced with composite material—CFRP—and also in the case of counteracting crack growth using the stop-hole technique, as well as with an application of an “anti-crack growth fluid”. All specimens were tested using constant load amplitude methods with a maximum loading of Fmax = 8 kN and stress ratio R = σmin/σmax = 0.1 in order to analyze the efficiency of different strategies of fatigue crack growth rate deceleration. It has been shown that the fatigue crack grows fastest in the case of the raw material and slowest in the case of “anti-crack growth fluid” application. Additionally, the study on fatigue fracture surfaces using light and scanning electron (SEM) microscopy to analyze the crack growth mechanism was carried out. As a result of fluid activity, the fatigue crack closure occurred and significantly decreased crack driving force and finally resulted in fatigue crack growth decrease.

Вычислительные эксперименты с методикой AUSM

In this paper, we discuss computational experiments based on the “AUSM” stream splitting methods. The efficiency of using various pressure approximations for flow splitting according to the original AUSM method is shown. The proposed use of splitting is tested on one-dimensional and three-dimensional problems. Partial use of the flow splitting method, only in terms of pressure, is proposed to be used in the calculations of the Euler system on unstructured grids. A variant of the application of the method of strong deceleration of the flow in the calculations of the flow around obtuse bodies is considered. The algorithm of the method for calculating flows with an extended stagnation zone, within which the Mach numbers decrease to about ~ 0.1, is investigated. Comparison with high-precision methods based on the solution of the Riemann problem is given.

A Novel Moment of Inertia Identification Strategy for Permanent Magnet Motor System Based on Integral Chain Differentiator and Kalman Filter

In a motor control system, the parameters tuning of speed and position controller depend on the value of the moment of inertia. A new moment of inertia identification scheme for permanent magnet motor system was proposed in this paper. This is an extension of the existing acceleration deceleration methods, which solves the large moment of inertia identification error caused by variable angular acceleration, large calculation error of inertia torque, and large measurement noise in the acceleration process. Based on the fact that the angular acceleration is not constant and the sampling signal is noisy, the integral chain differentiator was used to calculate the instantaneous angular acceleration at any time and suppress the sampling signal noise at the same time. The error function with instantaneous angular acceleration and inertia torque as parameters was designed to estimate the moment of inertia. In order to calculate the inertia torque accurately, viscous friction torque was considered in the calculation of inertia torque, and Kalman filter was used to estimate the total load torque to solve the problem of under rank of motor motion equation. Simulation and experimental results showed that the proposed method could effectively identify the moment of inertia in both noisy and noiseless environments.

Efficient Planning and Solving Algorithm of S -Shape Acceleration and Deceleration

S -shape acceleration and deceleration are the most widely used flexible acceleration and deceleration method in the current CNC system, but its velocity solution equation contains irrational terms, which create a more complicated solution process. When analyzing the solution process of the S -shape acceleration and deceleration directly, using a traditional numerical solution method, the phenomenon of “solving the interval jump” arises, which is the main reason for low efficiency and poor stability of the solution. According to the S -curve profile and solution, the concept of separating the curve profile recognition from the velocity solution was proposed, and a method of quickly identifying the interval of the solution location was introduced. Through the method mentioned above, the complete acceleration and deceleration curve parameters can be obtained through a one-time plan and a one-time solution, and the solution efficiency and stability are guaranteed; solving the Newton problem depends too much on the initial value of Newton velocity, which not only retains the speed advantage of the Newton method but also uses the downhill factor to ensure its convergence. Through the simulation comparison and analysis, the efficiency, stability, and universality of the method are verified.