直角坐标在软件开发中的应用研究

为简化不同软件开发技术处理界面中组件关系的算法,增强使用数学模型解决软件开发中算法设计的能力,全面分析和总结直角坐标系在界面设计中的应用十分必要。通过对不同开发技术处理界面设计的分析,界面中组件位置关系实质上都可以转化为坐标关系的计算。本文列举了直角坐标系在Python编程、Android编程、Java编程和Unity编程中的应用,以期给相应的算法设计提供借鉴思路。     

A three-dimensional surface measurement system implemented with Gaussian process based adaptive sampling

Self-adaptive surface measurements that can reduce data redundancy and improve time efficiency are in high demand in many fields of science and technology. For this purpose, a system implemented with Gaussian process (GP) adaptive sampling is developed. The non-parametric GP model is applied to reconstruct the topography and guide the subsequent sampling position, which is determined from the inference uncertainty estimation. A criterion is proposed to terminate the GP adaptive measurement automatically without any prior model or data of the topography. Experiments on typical surfaces validate the intelligence, adaptability, and high accuracy of the GP method along with the stabilization of the automatic iteration termination. Compared with traditional raster sampling, data redundancy is reduced and the time efficiency is improved without sacrificing the surface reconstruction accuracy. The proposed method can be implemented in other systems with similar measurement principles, thus benefitting surface characterizations.     

An Improved Torque Sensorless Speed Control Method for Electric Assisted Bicycle With Consideration of Coordinate Conversion

In this paper, we propose an improved torque sensorless speed control method for electric assisted bicycle, this method considers the coordinate conversion. A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling. A DC motor provides assisted power driving, the assistance method is based on the real-time wheel angular velocity and coordinate system transformation. The effect of observer is proved, and the proposed method guarantees stability under disturbances. It is also compared to the existing methods and their performances are illustrated through simulations. The proposed method improves the performance both in rapidity and stability.      

Multisensor data fusion via Gaussian process models for dimensional and geometric verification

An increasing amount of commercial measurement instruments implementing a wide range of measurement technologies is rapidly becoming available for dimensional and geometric verification. Multiple solutions are often acquired within the shop-floor with the aim of providing alternatives to cover a wider array of measurement needs, thus overcoming the limitations of individual instruments and technologies.In such scenarios, multisensor data fusion aims at going one step further by seeking original and different ways to analyze and combine multiple measurement datasets taken from the same measurand, in order to produce synergistic effects and ultimately obtain overall better measurement results.In this work an original approach to multisensor data fusion is presented, based on the development of Gaussian process models (the technique also known as kriging), starting from point sets acquired from multiple instruments. The approach is illustrated and validated through the application to a simulated test case and two real-life industrial metrology scenarios involving structured light scanners and coordinate measurement machines.The results show that not only the proposed approach allows for obtaining final measurement results whose metrological quality transcends that of the original single-sensor datasets, but also it allows to better characterize metrological performance and potential sources of measurement error originated from within each individual sensor.     

AutoCAD平台下不同坐标系图形数据的转换

在建设用地勘测定界及其他测绘工作中,时常遇到不同坐标系图形数据的转换,本文基于赫尔墨特相似变换参数,讨论了在AutoCAD平台下进行不同坐标系图形数据转换的方法、步骤,初步给出了不同坐标系图形数据转换的LISP语言程序.     

川南城镇密集区协调发展的规划对策研究

川南城镇密集区一体化快速、协调发展的规划对策为:促进区域产业协调发展、协同发展旅游业、合理引导城镇群空间发展格局、加强区域空间管制、促进区域基础设施的整体协调建设、合作共建区域环境安全体系.     

地磁坐标系下变姿态空间相机的外热流计算

为了提供准确的空间相机外热流数据,提出一种在地磁坐标系下进行频繁姿态变换的空间相机瞬态外热流计算方法。首先,确定了在J2000坐标系下太阳地球的相对位置及太阳辐照强度;其次,计算相机不同位置的地磁纬度,并采用二分法得到相机在轨运行时进出高磁纬地区(|L|60)的轨道时间;然后,依据其地磁纬度,确定相机不同时刻下的在轨姿态。最后,采用蒙特卡洛法(MCM)计算相机的各环境映射面的轨道视角系数,进而得出整轨周期内各环境映射面接受的瞬时外热流。此方法与IDEAS/TMG软件的外热流结果能够较好的吻合。与姿态稳定的相机相比,空间相机姿态频繁变化会导致外热流数值的明显波动。尤其是入光口所在的+Z面,其波动范围为0~1 245.4 W/m2。     

基于三坐标测量机的非圆齿轮误差测量

为了提高非圆齿轮的测量精度和效率,提出应用三坐标测量机进行测量的思想。从制造工艺上根据非圆齿轮有别于圆齿轮的特点,提出适用于非圆齿轮的误差项目。通过类比圆柱齿轮精度指标公差的计算方法,找到非圆齿轮精度指标公差的计算方法。选取合适的测头、对测量路径进行规划、采用三坐标测量机实现对非圆齿轮的逐齿扫描测量,以获得非圆齿轮的齿廓数据值。在此基础上,对数据值进行曲线拟合和计算,从而得出非圆齿轮的误差。     

A quick deviation zone fitting in coordinate metrology of NURBS surfaces using principle component analysis

Evaluation of the tolerance zone using discrete measured points plays a critical role in today’s manufacturing, metrology, and many industrial applications. The deviation zone is typically evaluated using a fitting method that locates an ideal desired geometry corresponding to a set of measured points while a function of the Euclidean distances of the measured points to the ideal surface becomes minimum. This paper presents a quick and reliable algorithm called Dynamic Principle Component Alignment (DPCA) for fitting complex surfaces to the coordinate metrology measured points using the information that is dynamically generated by Principal Component Analysis (PCA) of the measurement data and the corresponding fitted geometry. The developed algorithm efficiently eliminates the necessity for applying commonly used optimization methods for the fitting (localization) process, which decreases the computational cost and uncertainty of the evaluation process. Moreover, DPCA is very reliable and practical in coordinate metrology with large data sets in processes such as laser scanning and other optical methods. The results show that the proposed methodology more accurately finds fitting parameters in comparison with the other commonly used methods while the computational cost is considerably reduced.     

A practical sampling method for profile measurement of complex blades

Blade is one of the most important parts in turbine machinery. The complex geometry of blades not only makes them difficult to fabricate, but also leads them difficult to inspect. Typically, the surface of blades is measured by using coordinate measuring machine (CMM). Since the measurement time and cost increase proportionally as the increase of measurement points, it is essential to sample measurement points which can represent entire blade with sufficient confidence and accuracy. In order to achieve a certain allowable deviation with a suitable set of points, a practical sampling method for surface measurement of blades was studied. Firstly, the leading edge curve and trailing edge curve were supposed to represent the twisted and bend information of blades. A sampling method based on maximum chordal deviation for leading edge curve and trailing edge curve was researched. Further, a fusion approach for sampling points on both edge curves, which determine the cross-sections, was proposed. Secondly, the inspection points sampling method for sectional curves were investigated. Finally, two simulation and one experimental examples were used to demonstrate the sampling methodology. The results indicated that the approach of this study can ensure the measurement precision at high curvature potion by measuring a small number of points.