Papers by Keyword: Residual Error

Abstract: Deterministic surfacing technique is an effective method for intelligent control of operation planning of the unmanned construction machine, and its foundation is the accurate modeling of the three-dimensional terrain data. According to the digital elevation model based on regular grid, the modeling of 3D terrain surface data is obtained. The evaluation of residual error is further investigated, which is quite important for the iterated operation in deterministic surfacing. Through revealing flow chart of the deterministic surfacing method, the importance of the modeling of terrain data and that of the evaluation of residual error are emphasized. The study on modeling of terrain data will promote application of the deterministic surfacing in intelligent control of unmanned construction machine.

Abstract: To predict dynamic targets by using tracking gains, an improved adaptive α-β filtering algorithm is presented. First, we introduce the pseudo acceleration to build generalized model for uniform linear and acceleration motions. Then, the tracking gains based on tracking index are adaptively determined. Simulation results demonstrate that the proposed filtering algorithm can track both maneuvering and non-maneuvering targets with good performance.

Abstract: On the basis of the Preston assumption, the removal function of the annular polishing pad with the structure of the dual-rotor movement has been studied. The level of the similarity of the characteristic curve of the annular polishing pad and the Gaussian distribution has been evaluated by the tending factor. The pulse iteration method and the matrix calculation have been used to compute the residual error and the dwell time. The simulation result proved that the residual error (RMS) polished by the annular polishing pad had dropped 8.7% than that polished by the normal polishing pad with the same initial error condition, the surface quality has been improved by the new method.

Abstract: By choosing deferent initial approximation solutions and deferent linear operators, the nonlinear equation of the jamming transition problem (JTP), which is based on the Lorentz system, in traffic flow is discussed. The approximation solutions of the JTP are obtained using the homotopy analysis method (HAM). The method of choosing the linear operators and the initial approximation solutions, the corresponding residual errors and the influence of the boundary condition to the solution are studied respectively. By comparing the present results with the previous related studies, the conclusion is drawn that the HAM is superior to the differential transform method. The correctness of the theoretical analysis is confirmed by numerical simulation and the analysis of the residual errors.

Abstract: A new approach, namely the global residue harmonic balance, was developed to determine the accurately approximate periodic solution of a class of nonlinear Jerk equation containing velocity times acceleration-squared and velocity. Unlike other improved harmonic balance methods, all the forward harmonic residuals were considered in the present approximation to improve the accuracy. Comparison of the results obtained using this approach with the exact one and the existing results reveals that the high accuracy, simplicity and efficiency of the presented solution procedure. The method can be easily extended to other strongly nonlinear oscillators.

Abstract: This paper presents a method improving accuracy for evaluating S-parameters (Scattering-parameters) of MCP (Microwave Coplanar Probe). This method may be named one-port two-tier Multi-TRL (Thru-Reflect-Line) calibration method. It measures two-port devices only at one port of VNA (Vector Network Analyzer). It decreases the random errors caused of cable movements and connecting times. This method is implemented with coaxial OSL (Open-Short-Load) and on-wafer TRL calibration kit. It directly calculates and removes the residual errors caused of coaxial OSL calibration kit imperfection. It significantly reduced system errors by using on-wafer TRL calibration kit. To verify the effectiveness of the proposed method, the measured S-parameters up to 50GHz of MCP configured with GSG-100 are given and discussed.

Abstract: The influence functions action orientation of the Bonnet Polishing (BP) process is perpendicular to the contact zone. So the normal error of the aspheric surface should be used as the residual error to calculate the dwell time. But the Z axis direction error is generally adopted as the residual error and few papers on the normal error have been reported hitherto. Its necessary to pay attention to this issue. In this paper, two algorithms which are Asphericity Subtraction (AS) algorithm and Z Axis Direction Error Transformation (ZADET) algorithm are presented to calculate the normal error of the large aspheric surface. Simulations in three different cases are organized to utilize these two algorithms, together with the comparison of them. And the comparison of the normal error and the Z axis direction error is also organized. Its found that there exists difference between AS algorithm and ZADET algorithm. Both of them can be used to calculate the normal error of the aspheric surface when the ratio value of the width to radius is small. And the difference between the normal error and Z axis direction error is considerable. So the normal error should be used as the residual error to calculate the dwell time in BP process.

Abstract: Ultrasonic-magnetorheological combined finishing (UMCF) is a new technique for the ultra precision machining of aspheric surfaces, especially for high quality work pieces with small curvature radius concave surfaces. The goal with UMCF is to minimize surface figure errors by optimizing the dwell time and tool path, and the current approach typically results in low amplitude form errors. However, discrepancies exist between the predicted and observed form errors. The major sources of such errors are machine axes positioning errors and unpredicted variations of the removal function. Errors that can produce discrepancies between actual and predicted removal profiles were modelled. A diagnostic method was developed to determine the residual error induced by two types of error. Their effects were examined with numerical simulations and the simulation result was presented. Finally, UMCF experiments are performed on a variety of optical surfaces. The final residual error after polishing is less than 2.6 nm PV values. The successful figuring results prove the validity and advantages of UMCF.

Abstract: A compensation method was proposed for correcting wheel setting error and residual form error in nanogrinding of axisymmetric surfaces. In this method, profile data from on-machine measurement were used to obtain the setting error of grinding wheel, as well as the normal residual form error. Compensation model of single-point inclined-axis grinding was built up for generating new compensation path. Grinding test of aspheric tungsten carbide mould was conducted to evaluate performances of the compensation method. A profile error of 182 nm (peak to valley) and average surface roughness of 1.71 nm were achieved. These results indicated that the form error compensation method may significantly improve form accuracy of ground surface.

Abstract: In order to keep the stability of tool’s removal function, it is required that the anastomosis be tight between the tool and workpiece surface in Computer-controlled Optical Surfacing (CCOS). In this paper, the influence of tool’s character on anastomosis status is firstly studied. The relation model on the ratio of radius to thickness, Young's modulus of the tool, normal asphericity and normal arc height of workpiece surface is established, and the macroscopical condition of tight anastomosis is derived in aspheric optics machining. According to the microcosmic distribution of surface error, the mathematical relation between anastomosis error and removal rate is researched. In the end, the influence rule of anastomosis status on the convergence ratio of residual error is analyzed in machining zone. Based on the conclusion of machining instance, it is found that workpiece material would be fast removed in middle contact zone when the peak value of tool’s removal function locates in its center position.