Pseudo Distance Research Articles

A fast and accurate compound collision detector for RRT motion planning

The application of artificial intelligence tools has led to newly developed collision detectors which have better computational efficiency than the kinematics-and-geometry based collision detectors (KCD) to improve robot motion planning strategies. However, new detectors are not very accurate in some cases. To improve the accuracy, a trade-off between efficiency and accuracy is required. We propose a novel compound collision detector (CCD) for collision queries that modifies the planners of rapidly-exploring random tree (RRT) to improve the classical probabilistic collision detector (PCD). It is composed of an exact collision detector (ECD), an inference collision detector (ICD) and a strategy to determine ECD or ICD based on some conditions. In our CCD, we use a sphere-ellipsoidal pseudo distance (SEPD) in the determination strategy to alleviate the problem of highly-frequent outputs of false-positive in narrow passages of PCD, and a node based bounding method (NBB) to increase the speed of data storage and loading for the sub-algorithm ICD. Experiments on a Kinova Jaco assistive robotic arm are taken to evaluate the performance of our CCD, which show an improved accuracy with a small reduction of speed in comparison with PCD. So, it is a promising tool in robot motion planning.

Concatenated Permutation Codes under Chebyshev Distance

Permutation codes are error-correcting codes over symmetric groups. We focus on permutation codes under Chebyshev (ℓ∞) distance. A permutation code invented by Kløve et al. is of length n, size 2n-d and, minimum distance d. We denote the code by φn,d. This code is the largest known code of length n and minimum Chebyshev distance d > n/2 so far, to the best of the authors knowledge. They also devised efficient encoding and hard-decision decoding (HDD) algorithms that outperform the bounded distance decoding. In this paper, we derive a tight upper bound of decoding error probability of HDD. By factor graph formalization, we derive an efficient maximum a-posterior probability decoding algorithm for φn,d. We explore concatenating permutation codes of φn,d=0 with binary outer codes for more robust error correction. A naturally induced pseudo distance over binary outer codes successfully characterizes Chebyshev distance of concatenated permutation codes. Using this distance, we upper-bound the minimum Chebyshev distance of concatenated codes. We discover how to concatenate binary linear codes to achieve the upper bound. We derive the distance distribution of concatenated permutation codes with random outer codes. We demonstrate that the sum-product decoding performance of concatenated codes with outer low-density parity-check codes outperforms conventional schemes.

Anti Interference Clock Error Correction Technology Based on BD3 System

Beidou-3 (BD3) uses the pseudo range transmission method to calculate the clock difference through the pseudo range. However, due to the influence of electromagnetic interference, the clock difference measurement error is too large, which affects the timing accuracy of the power system. This paper first introduces the principle of Beidou timing service; Secondly, it introduces the clock error calculation method; Finally, combined with the clock difference calculation method, this paper presents an anti-interference clock difference correction method based on Least Mean Square (LMS) filter. According to the principle of LMS filter, the influence of electromagnetic interference on pseudo distance can be eliminated, and the clock difference can be calculated. Then the clock difference can be corrected. The simulation results show that the method is feasible and effective.

Evaluating the quality of gnss observables and the positional accuracy of the data collected by xioami mi 8 smartphone’s gnss chipset / Avaliando a qualidade dos observáveis gnss e a precisão posicional dos dados coletados pelo chipset gnss do smartphone xioami mi 8

In May 2016, Google LCC announced that GNSS raw data would be available to Android 07 users, thus allowing them to access GNSS observables data, both from carrier cycle count (phase) and pseudo distance measurements. Since then, several studies have tried to analyze the sources of positioning errors obtained with single and dual frequency GNSS chipsets inserted in different smartphone models. In this sense, the main goal of this study is to analyze the quality of GNSS observables and the positional accuracy of the final coordinates, obtained by processing GNSS raw data collected by the Xiaomi Mi 8 and to compare them to those obtained through conventional dual frequency GNSS receivers. Two processing strategies will be used for both datasets, namely: static relative positioning and IBGE Precise Point Positioning. The GNSS data, obtained by both the Xiaomi Mi 8 and the GRS-1 Receiver, manufactured by Topcon, was collected simultaneously, with a tracking time of 3 hours. The raw data was post-processed in RTKlib software in relative mode and in the IBGE PPP online platform. We realized that the signal quality, indicated by the carrier power-to-noise ratio and the carrier wave phase residuals were on average 10 db-Hz lower and 10 times higher for the satellites detected by the Xiaomi Mi 8 compared to the GRS-1 receiver, respectively. While the coordinate accuracy of the Topcon receiver ranged from 1 mm to 6 mm, those of the Xiaomi Mi 8 ranged from 17 cm to 53 cm.

Probing the PIP2 dependence of the ASAP1 PH domain membrane binding by NMR and MD simulations

Association of the ASAP1 Pleckstrin homology (PH) domain with multiple PI(4,5)P2 at the membrane surface participates to the regulation of the small GTPase Arf1 activity. However, the effect of local PI(4,5)P2 enrichment at the membrane is unclear beyond an increased affinity of ASAP1 PH for the membrane. In particular, how PI(4,5)P2 concentration affects the docking geometry of ASAP1 PH is unknown. To determine the orientation of ASAP1 PH at the membrane interface, we explored the use of pseudo distance constraints obtained from NMR Paramagnetic Relaxation Enhancement (PRE) experiments.

An Obstacle Avoidance and Trajectory Tracking Algorithm for Redundant Manipulator End

An obstacle avoidance algorithm was suggested in this study to handle the redundant manipulator’s end trajectory planning problem, with the accuracy of the end trajectory guaranteed to be within the projected error. To accomplish this goal, the calculation method of vector pseudo distance is used instead of the traditional Euclidean distance to express the minimum proximity between the robot arm and the obstacle. This method can express the constraint conditions between the obstacle and the robot arm more clearly and improve the obstacle avoidance efficiency. The virtual repulsion force is generated to make the end of the manipulator far away from the obstacle through the relationship between the velocity vector and the angle vector of the end motion, and the end recovers to the desired trajectory quickly and stably after avoiding the obstacle through the adjustment of the tangent velocity function. The error adjustment coefficient e K is intended to communicate back the actual trajectory of the end obstacle avoidance to the tracking function in real time, and to adaptively change the velocity and acceleration of the end-executor to reduce the end trajectory tracking error. The simulation results show that when an envelope body obstacle appears unexpectedly on the end executor’s expected mission locus, if the expected distance between the endeffector r and the obstacle is greater than or equal to 0.02m, the end of the actuator can avoid the obstacle and return to the expected track quickly and smoothly.

Research on Satellite Positioning Based on Total Least Squares Algorithm

In the technology of satellite positioning, positioning observation equation is constructed by measuring pseudo distance between the satellite and the receiver and the satellite position coordinates from navigation message, then the equation is solved and positioning results are obtained. The algorithm proposed in this paper is to use total least squares method to calculate initial value, and then someone carry out the Taylor series expansion on the basis of it, and then use weighted least squares in the iterative process to get the calculation results. Finally, user positioning is achieved. The algorithm is simulated by using observation series of Fangshan GNSS station in Beijing, and the simulation results are compared with the results obtained by the least squares algorithm. The results show that the satellite positioning algorithm based on total least squares is more accurate and faster in positioning calculation.

Fractional Order of Evolution Inclusion Coupled with a Time and State Dependent Maximal Monotone Operator

This paper is devoted to the study of evolution problems involving fractional flow and time and state dependent maximal monotone operator which is absolutely continuous in variation with respect to the Vladimirov’s pseudo distance. In a first part, we solve a second order problem and give an application to sweeping process. In a second part, we study a class of fractional order problem driven by a time and state dependent maximal monotone operator with a Lipschitz perturbation in a separable Hilbert space. In the last part, we establish a Filippov theorem and a relaxation variant for fractional differential inclusion in a separable Banach space. In every part, some variants and applications are presented.

A Pseudo-Distance Algorithm for Collision Detection of Manipulators Using Convex-Plane-Polygons-based Representation

• A pseudo-distance algorithm for collision detection of manipulators is proposed. • Convex-Plane-Polygons-based representation is firstly introduced. • Results show the algorithm can largely improve the efficiency of collision detection. • This algorithm are applicable to both convex and nonconvex objects. Robots have become indispensable parts for the industrial automated workshop. The distance calculation between the industrial robot and obstacles is a fundamental problem for the robotic collision-free motion control. But existing methods for this problem have the disadvantage that the accuracy and execution efficiency cannot be guaranteed at the same time. In this paper, a pseudo-distance algorithm is presented based on the convex-plane-polygons-based representation to solve this problem. In this algorithm, convex plane polygons (CPPs) and cylinders are utilized to represent obstacles and the manipulator, respectively. The spatial relationship between each CPP and each cylinder is discussed through defining condition parameters, and is divided into six conditions including three special conditions when the contact happens, and the other three conditions when there exists a certain distance between the CPP and the cylinder. The distance is modelled under different relations based on the theory of mathematics and geometry. The pseudo distance is determined through selecting the smallest value from distances between CPPs and cylinders. The numerical experiment is performed based on the proposed and two previous algorithms to estimate the shortest distance between an industrial robot and a groove-shape obstacle. And an application example is performed to show the significance of this work on the robotic motion control. Results indicate that the proposed algorithm is more efficient than previous algorithms under a certain precision requirement, and can be effectively applied in the robotic motion control.

Optimal transport at finite temperature.

Optimal transport (OT) has become a discipline by itself that offers solutions to a wide range of theoretical problems in probability and mathematics. Despite its appealing theoretical properties, solving the OT problem involves the resolution of a linear program whose computational cost can quickly become prohibitive whenever the size of the problem exceeds a few hundred points. The recent introduction of entropy regularization, however, has led to the development of fast algorithms for solving an approximate OT problem. The successes of those algorithms have resulted in a popularization of the applications of OT in several applied fields such as imaging sciences and machine learning, and in data sciences in general. Problems remain, however, as to the numerical convergence of those regularized approximations towards the actual OT solution. In addition, the physical meaning of this regularization is unclear. In this paper, we propose an approach to solving the discrete OT problem using techniques adapted from statistical physics. Our first contribution is to fully describe this formalism, including all the proofs of its main claims. In particular we derive a strongly concave effective free energy function that captures the constraints of the optimal transport problem at a finite temperature. Its maximum defines a pseudo distance between the two set of weighted points that are compared, which satisfies the triangular inequalities. The temperature dependent OT pseudo distance decreases monotonically to the standard OT distance, providing a robust framework for temperature annealing. Our second contribution is to show that the implementation of this formalism has the same properties as the regularized OT algorithms in time complexity, making it a competitive approach to solving the OT problem. We illustrate applications of the framework to the problem of protein fold recognition based on sequence information only.

A Path Optimization Technique with Obstacle Avoidance for an 8-DOF Robot in Bolt Looseness Detection Task

In the bolt looseness detection task of the locomotive system, the robot could be used to highly improve the working efficiency and reliability, but faces the complex static obstacles while planning the path for the robotic motion. In this paper, a path optimization technique is proposed to obtain an optimal path with obstacle avoidance for a redundant robot in the static complicated environment. There are three main contributions in this technique. The first is the solving of the inverse kinematics problem for a redundant robot based on the screw theory and the geometric description, which is general to all robots with rotational joints. The second is the modeling of the spatial constraint, where the pseudo distance is defined based on the plane description of the obstacles and calculated using the spatial analytic geometry knowledge. The third is the presentation of the whole path-planning framework based on the above two contributions, which could largely improve the generality of the presented technique. In this framework, the minimum-time path could be obtained while guaranteeing both the motion stability and obstacle avoidance. Moreover, a real setting that includes an obstacle environment and an 8-DOF robot, is taken as an example to better present the technique. Finally, the simulation experiment was performed in Isight software to verify the effectiveness of the path optimization technique.

Target Cooperative Location Method of Multi-UAV Based on Pseudo Range Measurement

Based on the locations of several unmanned aerial vehicles (UAVs) and the pseudo ranges to a target, a target cooperative location method is proposed in this paper. The nonlinear equation about real pseudo distance information is transformed to another equation by using Tayloy formula. By solving the above equation, position information of the target can be obtained. Meanwhile, the certain equation's variables are the measured results of pseudo distances, location errors of UAVs and distance-measuring errors of range sensors. Besides, an online enumeration method is applied to search for the best formation, whose objective is to enhance the location accuracy, and the mentioned formation is mapped to the minimal GDOP. The simulations verify the validity and adaptability of the proposed method.

Pseudo Kobayashi hyperbolicity of subvarieties of general type on abelian varieties

We prove that the Kobayashi pseudo distance of a closed subvariety $X$ of an abelian variety $A$ is a true distance outside the special set $\operatorname{Sp}(X)$ of $X$, where $\operatorname{Sp}(X)$ is the union of all positive dimensional translated abelian subvarieties of $A$ which are contained in $X$. More strongly, we prove that a closed subvariety $X$ of an abelian variety is taut modulo $\operatorname{Sp}(X)$; Every sequence $f_n:{\mathbb{D}}\to X$ of holomorphic mappings from the unit disc ${\mathbb{D}}$ admits a subsequence which converges locally uniformly, unless the image $f_n(K)$ of a fixed compact set $K$ of ${\mathbb{D}}$ eventually gets arbitrarily close to $\operatorname{Sp}(X)$ as $n$ gets larger. These generalize a classical theorem on algebraic degeneracy of entire curves in irregular varieties.

Asymptotic Results for Goodness-of-Fit Tests Using a Class of Generalized Spacing Methods with Estimated Parameters

A class of pseudo distances is used to derive test statistics using transformed data or spacings for testing goodness-of-fit for parametric models. These statistics can be considered as density based statistics and expressible as simple functions of spacings. It is known that when the null hypothesis is simple, the statistics follow asymptotic normal distributions without unknown parameters. In this paper we emphasize results for the null composite hypothesis: the parameters can be estimated by a generalized spacing method (GSP) first which is equivalent to minimize a pseudo distance from the class which is considered; subsequently the estimated parameters are used to replace the parameters in the pseudo distance used for estimation; goodness-of-fit statistics for the composite hypothesis can be constructed and shown to have again an asymptotic normal distribution without unknown parameters. Since these statistics are related to a discrepancy measure, these tests can be shown to be consistent in general. Furthermore, due to the simplicity of these statistics and they come a no extra cost after fitting the model, they can be considered as alternative statistics to chi-square statistics which require a choice of intervals and statistics based on empirical distribution (EDF) using the original data with a complicated null distribution which might depend on the parametric family being considered and also might depend on the vector of true parameters but EDF tests might be more powerful against some specific models which are specified by the alternative hypothesis.

Non-contraction of intermediate admissible discontinuities for 3-D planar isentropic magnetohydrodynamics

We investigate non-contraction of large perturbations around intermediate entropic shock waves and contact discontinuities for the three-dimensional planar compressible isentropic magnetohydrodynamics (MHD). To do that, we take advantage of criteria developed by Kang and Vasseur in [6], and non-contraction property is measured by pseudo distance based on relative entropy.

Mapping the time. Method for logistics management software: Application in Spain

The usual form to represent a point in a map is based in its geographical coordinates, establishing their relationship with other points in terms of distances and angles, usually azimuths. However, sometimes, the distance is not the most crucial factor when we want to represent certain relations. Thus, it may be important to represent jointly the travel time between two cities and the distances between them. In this representation greater distances are not always associated with longer times to drive. These maps, which also represents the time as a pseudo distance, would be useful for decision-making related to logistics management. This occurs in distribution logistics, where companies must meet delivery times, making prompt deliveries and timely deliveries. A software to perform comparative mapping from a source to a destination of distances and times between different geographical areas for road, rail and flight transport, would be useful for making decisions about what transport type should be used in order to minimize travel time between two points. This article shows method for joint representation of both magnitudes, which has been implemented in CHRONAS-MAP an initial version of software that implements this method in Spain.

근접한 두 GPS 수신기의 의사거리 차 분석

의사거리는 GPS 수신기의 위치를 결정하기 위한 오차를 포함해 측정된 GPS 위성과 수신기 사이의 거리이다. 재방송 재밍기는 GPS 수신기에 가까이 있을 때 효과적으로 동작한다. 본 논문에서는 재방송 재밍의 원리를 효과적으로 이해하기 위해 근접한 GPS 수신기의 의사거리 차를 분석한다. Pseudorange is the pseudo distance between a GPS satellite and a GPS receiver to determine the receiver's position. The closer the distance between jammer and victim receiver is, the more effective a repeat-back jamming is. In this letter, we analyze the pseudorange difference between adjacent GPS receivers using real GPS pseudorange data to understand the effects by the repeat-back jamming.

Pseudo Distance for Trellis Coded Modulation in Overloaded MIMO OFDM with Sphere Decoding

Pseudo Distance for Trellis Coded Modulation in Overloaded MIMO OFDM with Sphere Decoding

Stability and Persistent Excitation in Signal Sets

Persistent excitation (PE) conditions have been widely used to analyze stability properties of various parameter identification algorithms and to establish uniform global asymptotic stability (UGAS) for a large class of nonlinear time-varying systems. In order to generalize such conditions to a more general setting, a new PE condition is proposed with three basic ingredients: a signal set to represent a family of time functions (e.g., trajectories); a pseudo distance measure to describe the convergence; and some binary relations (e.g., state-to-output relations). Closely related to detectability, this PE condition is a necessary condition to guarantee UGAS. Under uniform global stability and an integral inequality, it becomes a sufficient condition of UGAS. A novel concept: M-pair, which aims at simplifying the checking of the PE condition, is introduced. By using M-pair, it is possible to simplify the structure of the referred signal set (in the spirit of the classic Krasovskii-LaSalle theorem) and to extend the dimension of the reference signal set (similar to the Matrosov theorem). Thus, the framework of M-pair not only unifies these well-known results, but also generates more flexibility in checking the PE conditions. When applied to nonlinear switched systems, three new tools to verify the PE condition are obtained. Finally, an example illustrates that a nonlinear time-varying switched system with arbitrary switching can be shown to be UGAS without using a common Lyapunov function.

К вопросу исключения систематической ошибки за дальность

Abstract: In practice of geodesic observations with the use of space navigation systems it is important not only to estimate the precision of surface points’ spatial coordinates determination but also to eliminate possible errors if possible. The method of calculating and exception of bias errors at pseudo distance is worked out in-process, it is based of that fundamental equalization of satellite navigation at presence of errors, and the real results over of treatment of the satellite measuring the GLONASS system are given.