In this paper, a new approach is proposed for the smooth path planning of mobile robot based on a new quartic Bezier transition curve and an improved particle swarm optimization (PSO) algorithm. ...First, a dedicatedly constructed quartic Bezier transition curve with three overlapped control points is developed to fulfil the G3-continuity of the smooth path at the joints of the path segments, so as to guarantee the high-order smoothness of the path for the movement of mobile robot. Then, the smooth path planning of mobile robot is formulated mathematically as an optimization problem under several criteria and constraints of the smooth path, e.g. length, smoothness, safety and robot kinematics. Furthermore, an improved PSO with adaptive weighted delay velocity (PSO-AWDV) algorithm is presented for the optimization problem of smooth path planning, where the parameter relationship to ensure the convergence of PSO-AWDV is derived through the stability analysis of the algorithm. Finally, several simulation experiments are carried out to confirm the effectiveness and superiority of the proposed new approach combined with the new quartic Bezier transition curve and the improved PSO-AWDV algorithm.
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•The ice I-liquid phase transition curve of surimi gel was successfully acquired.•The curve of gel temperature with pressure during adiabatic compression was plotted.•Adjusting ...supercooling as a parameter to regulate sample quality is beneficial for enhancing sample quality.•PSF treatment can enhance the strength and water-holding capacity of surimi gel.•Higher degrees of supercooling mean formation of smaller ice crystal sizes, resulting in less mechanical damage to the gel.
In this study, the phase transition curve of grass carp surimi gel in the ice I region was mapped and fitted. Additionally, the average adiabatic compressibility of surimi gel was calculated to be 2.7℃/100 MPa in the range of 0–320 MPa. Building upon this, the study further investigated the impact of pressure-shift freezing (PSF) treatment based on supercooling and pressure coupling on the gel strength, texture profile analysis (TPA), and water-holding capacity of surimi gel. Compared with the low level of supercooling (supercooling value > -15℃) treatment, the PSF treatment with a higher supercooling degree (supercooling value ≤ -15℃) could enhance the strength and water-holding capacity of surimi gel. The morphology and distribution of ice crystals suggested that the diameter and size distribution of ice crystals in the sample were dependent on the combination of pressure level and supercooling. The combination of precise control of supercooling and pressure parameters is beneficial in improving the mechanical properties and water-holding capacity of surimi gel. This is of great value for developing high-quality surimi gel products and also offers a new research thread in the realm of high-pressure freezing.
Aiming at the problems of insufficient modeling accuracy and low efficiency of design verification and calculation in the current parametric design and development of internal gears, a parametric ...design system of internal gears based on accurate tooth profile modeling is developed by using Matlab GUI. According to the principle of gear generating machining theory, the involute tooth profile of internal gears is generated. The tooth profile-normal method is used to establish the tooth root transition curve equation of internal gears, realizing the accurate modeling of the whole tooth of internal gears, and the pressure angles αM and αN at the transition point of the internal gear profile are calculated. The geometric calculation and interference verification of the design parameters of internal gear pairs are completed through the parametric design program. In the transition curve interference verification part, using the pressure angles αM and αN of the tooth profile transition point, the verification formula
Aiming at the problems of insufficient modeling accuracy and low efficiency of design verification and calculation in the current parametric design and development of internal gears, a parametric ...design system of internal gears based on accurate tooth profile modeling is developed by using Matlab GUI. According to the principle of gear generating machining theory, the involute tooth profile of internal gears is generated. The tooth profile-normal method is used to establish the tooth root transition curve equation of internal gears, realizing the accurate modeling of the whole tooth of internal gears, and the pressure angles αM and αN at the transition point of the internal gear profile are calculated. The geometric calculation and interference verification of the design parameters of internal gear pairs are completed through the parametric design program. In the transition curve interference verification part, using the pressure angles αM and αN of the tooth profile transition point, the verification formula
According to the parameters and geometric dimensions of the gear, the parametric equations of the transition curve and involute line of the root cutting gear are established based on the principle of ...machining the gear with the generating method, the tooth shape diagram of the root cutting gear is accurately drawn, and the minimum chord tooth thickness and maximum root cutting radius are accurately calculated with the Matlab software. It provides a reliable basis for establishing the finite element model of the root cutting gear, quantifying the relationship between the bending fatigue strength and the displacement coefficient of the root cutting gear, determining the best displacement coefficient of the root cutting gear, and studying the feasibility of the use of the root cutting gear in the industrial production.
In this study, the bifurcation phenomenon of natural convection at a Prandtl number of 0.3 is analyzed for a circular magnetic field applied to an annulus of a diameter ratio of 2. Flows in the ...annulus have been categorized as upward and downward flows according to the flow patterns observed near the upper stagnation region of the annulus. In previous studies on the bifurcation of natural convection without magnetic effects, no bifurcation was observed at very low (<7000) or high (>45,000) Rayleigh conditions. However, the results presented here indicate the bifurcation can occur even at high Rayleigh conditions (>45,000) under specific magnetic conditions. A bifurcation map was thus created over a range of Hartmann numbers from 0 to 20 and Rayleigh numbers from 3000 to 80,000 and the inflection of the transition lines was studied. As a result, the transition Rayleigh and Hartmann numbers and the critical Rayleigh and Hartmann numbers were redefined.
This paper presents a method of utilizing a transition curve in planning the movement trajectory of agricultural machinery during the headland turns. The approach involves using the transition curve, ...whose curvature and tangent angle are described by the trigonometric function. For the designed course, the kinematic quantities, wheel turning angles, and their rates of change were determined for two models of agricultural tractors. The algorithm proposed in this study ensures continuity and smooth changes in the kinematic quantities and can be applied to the trajectory planning of agricultural implements and machines, autonomous vehicles, mobile robots, manipulators, and CNC machines.
Sharp curves are vulnerable sections for rollover accidents. This study was conducted to investigate the effects of transition curve and superelevation on the critical speed and critical braking ...distance of truck rollovers. Using different transition types (spiral, Bloss and Grabowski curve) and different superelevation values (6%, 120 m transition length and 8%, 160 m) as variables, experiments of constant speed driving and hard braking were simulated and conducted by Trucksim. Conclusions regarding the influence of these road design factors on the stability of vehicles were then proposed. Grabowski curve allowed for the maximum critical rollover speed. The difference in critical rollover speed between different transition types was only determined by the length of the transition section. Simply extending the length of the transition section increased the critical rollover speed of spiral curve, at the same time decreasing the critical speed of Bloss and Grabowski curve. Hard braking experiments showed completely different characteristics. As the initial speed increased, only spiral curve became safer. Increasing superelevation made the braking behaviour of the vehicle more dangerous and fraught with uncertainties due to different target speed, starting curvature and changing superelevation. Based on these findings, a number of useful recommendations for drivers and road designers were put forward.
Track geometry measurements (TGMs) are a critical methodology for assessing the quality of track regularities and, thus, are essential for ensuring the safety and comfort of high-speed railway (HSR) ...operations. TGMs also serve as foundational datasets for engineering departments to devise daily maintenance and repair strategies. During routine maintenance, S-shaped long-wave irregularities (SLIs) were found to be present in the vertical direction from track geometry cars (TGCs) at the beginning and end of a vertical curve (VC). In this paper, we conduct a comprehensive analysis and comparison of the characteristics of these SLIs and design a long-wave filter for simulating inertial measurement systems (IMSs). This simulation experiment conclusively demonstrates that SLIs are not attributed to track geometric deformation from the design reference. Instead, imperfections in the longitudinal profile’s design are what cause abrupt changes in the vehicle’s acceleration, resulting in the measurement output of SLIs. Expanding upon this foundation, an additional investigation concerning the quantitative relationship between SLIs and longitudinal profiles is pursued. Finally, a method that involves the addition of a third-degree parabolic transition curve (TDPTC) or a full-wave sinusoidal transition curve (FSTC) is proposed for a smooth transition between the slope and the circular curve, designed to eliminate the abrupt changes in vertical acceleration and to mitigate SLIs. The correctness and effectiveness of this method are validated through filtering simulation experiments. These experiments indicate that the proposed method not only eliminates abrupt changes in vertical acceleration, but also significantly mitigates SLIs.
A non-parametric, distribution-free, statistical assessment of 5 large Charpy transition curve data sets is used for the optimum fitting equations for smaller data sets. The assessment makes use of a ...combination of rank probability and binomial probability analysis of the data. The original non-parametric assessment method is improved by combining upper and lower bound binomial estimates, thus removing a bias that exists in the original method. The non-parametric assessment is not suitable as a standard method because it requires too many data points to give a reliable result. It is, however, ideal as a research tool to examine transition curve shape and scatter. Based on the assessment several recommendations for transition curve fitting can be made.
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•A non-parametric, distribution free, fitting algorithm for CVN data is presented.•CVN transition curve data is better fitted against temperature than energy.•Symmetrical functions are not optimum for the analysis of larger CVN data sets.•Too flexible functions can lead to “overfitting” for small data sets.
