Object-oriented programming for robotic manipulator simulation

Using an object-oriented programming approach, ROBOOP, a robotic manipulator simulation package which is both platform and vendor independent, compares favourably against a package requiring similar coding effort. Performance tests show that with ROBOOP the class inverse dynamics of a 6-DOF robot can be computed in less than 5 ms with a Pentium 100 MHz computer     

Planning for robotic exploration based on forward simulation

We address the problem of controlling a mobile robot to explore a partially known environment. The robot’s objective is the maximization of the amount of information collected about the environment. We formulate the problem as a partially observable Markov decision process (POMDP) with an information-theoretic objective function, and solve it applying forward simulation algorithms with an open-loop approximation. We present a new sample-based approximation for mutual information useful in mobile robotics. The approximation can be seamlessly integrated with forward simulation planning algorithms. We investigate the usefulness of POMDP based planning for exploration, and to alleviate some of its weaknesses propose a combination with frontier based exploration. Experimental results in simulated and real environments show that, depending on the environment, applying POMDP based planning for exploration can improve performance over frontier exploration.     

Finite element simulation of robotic origami folding

In this paper, we focus on some aspects of the finite element simulations of robotic paper folding and the reconstruction of models from the origami crease patterns by the robot arms. The paper highlights the simulation problems, which should be solved in developing our recent study in mechanical and geometrical design of the origami-performing robot. The basic premise underlying the study is that folding operations with the origami crease patterns are considered as the functions of the mechanical systems such as a robot. Manipulations with the foldable objects, such as a sheet of paper (the origami crease pattern), by the robot arms in the simulation environment lead to understanding the design of the origami-performing robot without testing physical prototypes at each design stage. In this case, dynamic and kinematic behavior of the robot arms in forming the 3D origami objects is modelled by using the finite element method (FEM) in LS-DYNA solver. For simulating, two forms of origami are considered: flexible, if bending is used for paper folding, and rigid, if origami patterns are considered as the kinematic systems. Results of the simulation are presented and provided by the illustrations.     

空间机器人视觉伺服半物理仿真的原理与实现

针对在地面很难对空间机器人目标捕获过程进行微重力环境下的真实实验问题,建立了半物理仿真系统,以对图像处理、路径规划以及控制等关键算法进行验证,该系统的关键在于将"虚拟环境"与"真实环境"结合起来,利用真实视觉对虚拟环境进行3D重构,以计算目标的相对位置和姿态,实现对视觉伺服控制的闭环仿真.从理论上推导了半物理仿真的原理,并提出了等效投影模型的标定方法,仿真结果表明了该方法的有效性.     

用于避障研究的微型仿生机器鱼3维仿真系统

基于VC++6.0开发环境和OpenGL（open graphics library）国际图形标准,在Windows系统下开发了微型仿生机器鱼3维仿真系统。该系统可以降低用实体机器鱼进行机器鱼避障能力研究的成本和减少在研究过程中对实体机器鱼造成的损害。采用多边形建模的方法构建了虚拟微型仿生机器鱼模型,模拟了鱼类尾鳍的摆动。提出了一种模拟红外传感器探测障碍物的虚拟射线方法。并采用实时模糊决策算法设计了基于多传感器信息的复合模糊控制器,决策微型仿生机器鱼的避障行为。仿真实验表明,复合模糊控制器实时性好、效率高;无论是单个任意形状的障碍物还是多个连续障碍物,复合模糊控制器都能有效地引导仿生机器鱼避开障碍物,到达目标点。微型仿生机器鱼3维仿真系统为研究仿生机器鱼的自主避障能力提供了可靠、逼真、便利的平台。     

Control aspects of a robotic haptic interface for kinesthetic knee joint simulation

A new 6 DOF (degrees of freedom) haptic device is presented for display of the dynamic properties of a virtual human knee in orthopaedic training. In order to achieve the high impedance requirements in this application an industrial robot has been selected and extended with a PC-based high performance controller hardware and redundant safety features. Two control architectures—a force-command and motion-command control—are presented and both implemented in a 1 DOF application. With a new method for evaluation and comparison of controller performance in terms of impedance error the experimental results reveal that motion-command provides better accuracy for display of the high impedances specific to the human knee application.     

Using simulation to test the feasibility of robotic assembly

In this paper we address the use of simulation to test the feasibility of robotic assembly. It is shown that three factors are important in modeling an assembly problem: the geometry of the mating parts, the tolerance of assembly components, and the repeatability of the robot system. The process of developing a simulation model is demonstrated using two generic classes of assembly geometries. Simulation programs are presented and the implications for computer-aided design are discussed.     

Process modeling,simulation, and paint thickness measurement for robotic spray painting

An algorithm and a computer program are developed for modeling of the spray painting process, simulation of robotic spray painting, and off‐line programming of industrial robots for painting of curved surfaces. The computer program enables the user to determine the painting strategies, parameters, and paths which will give the desired paint thickness. Surface models of the parts that are to be painted are obtained by using a computer‐assisted design (CAS) software. Models of relatively simple surfaces are formed by using the surface generation tools of the CAD software. For parts with more complex surfaces, point data related to the part is collected by using a laser scanner, and this data is used to form the CAD model of the part surface. The surface is then divided into small triangular elements and centroid coordinates, and unit normals of the elements are determined. Surface data together with the spray distance, painting velocity, and paint flow rate flux are used for simulation of the process and paint thickness analysis. Paint flow rate flux is determined experimentally by using different spray gun settings and painting parameters. During the experiments flat surfaces are painted by using a single painting stroke of the gun. Then, paint thickness measurements are made on the surfaces. It is observed that besides the technical specifications of the spray gun, air and paint nozzles, and paint needle, basic settings like paint tank pressure, spray air pressure, and gun needle‐valve position affect paint cone angle and paint flow rate, which finally characterize the spray painting process. For that reason, settings and parameters should be changed and the painting process should be simulated until an acceptable paint thickness distribution is obtained for the part that is going to be painted. The robot program is then generated in the robot's programming language. Paint thickness distribution on the painted surface is determined by measuring the thicknesses using the robot and the CAD model of the part surface. The thicknesses are measured at the centroids of the surface elements. A measurement probe of the coating thickness measurement gauge is attached to the wrist of the robot by using a feedback/safety adapter designed and manufactured for this purpose. © 2000 John Wiley & Sons, Inc.     

PLC梯形图编辑功能的仿真软件

可编程序控制器(Programmable Logic Controller，简称PLC)近年来在各厂矿企业得到了广泛的应用。但是PLC的生产厂家众多，各种机型互不兼容，学习和操作没有统一标准。该文利用VisualC 开发PLC梯形图编辑功能的仿真软件，模拟PLC编程器的功能。该软件能够实现梯形图符号的编辑、语法检测、逻辑错误检查等功能，为PLC的学习和使用者提供一个友好的编程环境。     

Software selection for simulation in manufacturing: a review

The selection of appropriate simulation software is discussed in journals, conferences and simulation textbooks. Many introductory papers contribute a section to the subject, too. This paper reviews relevant material in this area and considers methodologies for simulation software selection, techniques of evaluating simulation software, criteria used in evaluation and recommendations on the subject. A criticism of the literature searched is outlined and conclusions drawn.     

Software framework concept with visual programming and digital twin for intuitive process creation with multiple robotic systems

With the progressive digitalization in industrial manufacturing, the usage of complex robotic systems in both intralogistics and production is expected to increase. This proposes a challenge for planners and shop floor workers, as programming and interacting with these various systems leads to a high cognitive load. Especially the broad range of different manufacturer specific software leads to a number of problems, e.g. the program-synchronization between different systems and the often necessary workshops for workers. These problems can lead to inefficient programming and planning operations, bad worker satisfaction and human errors. In this paper, we present a modular, system agnostic and human centered software framework that unifies the programming of different systems, to enable centralized and intuitive system programming for non-expert operators. Our software framework utilizes visual programming concepts together with an integrated digital twin of the factory and a novel graph-based programming interface. We explain our concept in detail and describe our validation through integration into a realistic industrial setup with three different systems. In addition, we provide an evaluation of our concept's usability with an experimental user study and discuss the results of the study and the software implementation. Our study results show that even non-technical users are able to use our software after a brief introduction to create complex processes that involve multiple machines working in parallel. All users reported high usability and expert users reported that the visual process editor has enough features to create processes for industrial applications. Finally, we conclude this paper by providing an outlook on future work and use-cases of our software.     

Software components for parallel multiscale simulation: an example with LAMMPS

Multiscale simulation is a promising approach for addressing a variety of real-world engineering problems. Various mathematical approaches have been proposed to link single-scale models of physics into multiscale models. In order to be effective, new multiscale simulation algorithms must be implemented which use partial results provided by single-scale software. This work considers aspects of software design for interfacing to existing single-scale simulation code to perform multiscale simulations on a parallel machine. As a practical example, we extended the large-scale atomistic/molecular massively parallel simulator (LAMMPS) atomistic simulation software to facilitate its efficient use as a component of parallel multiscale-simulation software. This required new library interface functions to LAMMPS that side-stepped its dependence on files for input and output and provided efficient access to LAMMPS’s internal state. As a result, we were able to take advantage of LAMMPS’s single-scale performance without adding any multiscale-specific code to LAMMPS itself. We illustrate the use of LAMMPS as a component in three different modes: as a stand-alone application called by a multiscale code, as a parallel library invoked by a serial multiscale code, and as a parallel library invoked by a parallel multiscale code. We conclude that it is possible to efficiently re-use existing single-scale simulation software as a component in multiscale-simulation software.     

面向TSP的软件过程仿真模型

描述了一种面向小组软件过程TSP(Team Software process)的仿真模型,根据TSP的特点,采用将离散和连续建模思想结合的一种混合模型。这种模型分为两层建立,外层体现软件开发过程的阶段性,内层体现软件开发过程的连续性,从两个层次上详细说明模型的结构和原理;给出了模型的形式化描述;并用一个例子来说明模型的执行过程及结果。此模型能够从不同角度模拟软件的开发过程,并能够对软件开发过程进行监督和预测。     

Coloured Petri nets and graphical simulation for the validation of a robotic cell in aircraft industry

This paper proposes a mixed validation approach based on coloured Petri nets and 3D graphic simulation for the design of supervisory systems in manufacturing cells with multiple robots. The coloured Petri net is used to model the cell behaviour at a high level of abstraction. It models the activities of each cell component and its coordination by a supervisory system. The graphical simulation is used to analyse and validate the cell behaviour in a 3D environment, allowing the detection of collisions and the calculation of process times. The motivation for this work comes from the aeronautic industry. The automation of a fuselage assembly process requires the integration of robots with other cell components such as metrological or vision systems. In this cell, the robot trajectories are defined by the supervisory system and results from the coordination of the cell components. The paper presents the application of the approach for an aircraft assembly cell under integration in Brazil. This case study shows the feasibility of the approach and supports the discussion of its main advantages and limits.     

An efficient planning technique for robotic assemblies and intelligent robotic systems

An efficient planning algorithm for the organization and formulation of complete plans applicable to both robotic assemblies and intelligent robotic systems is proposed. The constraint of task precedence and the concepts of the criticality of tasks-events and valid repetitive orderings are introduced to facilitate and optimize the formulation of every complete plan capable of executing a user-requested job. Two examples demonstrate the applicability of the proposed algorithm to both robotic assemblies and intelligent robotic systems.     

Software toolkit for modeling,simulation, and control of soft robots

The technological differences between traditional robotics and soft robotics have an impact on all of the modeling tools generally in use, including direct kinematics and inverse models, Jacobians, and dynamics. Due to the lack of precise modeling and control methods for soft robots, the promising concepts of using such design for complex applications (medicine, assistance, domestic robotics, etc.) cannot be practically implemented. This paper presents a first unified software framework dedicated to modeling, simulation, and control of soft robots. The framework relies on continuum mechanics for modeling the robotic parts and boundary conditions like actuators and contacts using a unified representation based on Lagrange multipliers. It enables the digital robot to be simulated in its environment using a direct model. The model can also be inverted online using an optimization-based method which allows to control the physical robots in the task space. To demonstrate the effectiveness of the approach, we present various soft robots scenarios including ones where the robot is interacting with its environment. The software has been built on top of SOFA, an open-source framework for deformable online simulation and is available at https://project.inria.fr/softrobot/.     

基于处理器仿真的发动机控制软件平台

为提升商用航空发动机控制软件的效率、节省验证成本,数字仿真技术被广泛采用,在仿真平台保证功能逻辑正确的前提下,再进行电子控制器硬件（EEC）的集成。商用航空发动机控制软件在满足发动机的功能和性能要求,还需要满足适航安全的目标,由于仿真平台与真实硬件平台的差异,在仿真平台获得的验证结果往往不被适航所采纳,因此提高仿真度,使得仿真平台能作为控制软件开发平台被适航所认可,是进一步节省成本的有效方法;基于通用仿真运行平台SIMICS,通过采用模拟硬件处理器的寄存器、指令集以及存储器、外设等,使得在目标平台上运行的代码可以直接运行在仿真平台,在仿真平台达到目标码级别的验证;通过软件时间行为的分析与模拟,使得系统和硬件的仿真程度进一步提高,更接近真实硬件,在仿真平台所获取的验证数据,更容易被适航所采纳。     

Collision: Modeling,simulation and identification of robotic manipulators interacting with environments

The performance of many robotic tasks depends greatly on their dynamic collision behavior. This article presents a simple method for modeling and simulating collision behavior in manipulators. The main goal in this task is to provide informative contact models. The proposed models encompasscollision attributes which comprise not only (local) contact surface properties but also structural properties of the environmental object and the manipulator. With this method, the entire dynamic and interactive motion of the manipulator with the environmental object can be simulated effectively. This is verified by our simulation results. To facilitate our investigation, a 2 DOF planar elbow manipulator with PD control is considered in the simulations as well as theoretical analysis. The simulation results are used to highlight the collision attributes which affect collision behavior and to study the effects of these attributes on the manipulator-work environment safety and performance. On the other hand, the reliable operation of intelligent robotic systems in unstructured environments requires the estimation of collision attributes before the prediction of the collision behavior can be completed. For this purpose, we introduce the notion ofcollision identification. The present paper introduces a framework for collision identification in robotic tasks. The proposed framework is based on Artificial Neural Networks (ANNs) and provides fast and relatively reliable identification of the collision attributes. The simulation results are used to generate training data for the set of ANNs. A modularized ANN-based architecture is also developed to reduce the training effort and to increase the accuracy of ANNs. The test results indicate the satisfactory performance of the proposed collision identification system.     

Symbolic modeling and dynamic simulation of robotic manipulators with compliant links and joints

The explicit, non-recursive symbolic form of the dynamic model of robotic manipulators with compliant links and joints are developed based on a Lagrangian-assumed mode of formulation. This form of dynamic model is suitable for controller synthesis, as well as accurate simulations of robotic applications. The final form of the equations is organized in a form similar to rigid manipulator equations. This allows one to identify the differences between rigid and flexible manipulator dynamics explixitly. Therefore, current knowledge on control of rigid manipulators is likely to be utilized in a maximum way in developing new control algorithms for flexible manipulators.

Computer automated symbolic expansion of the dynamic model equations for any desired manipulator is accomplished with programs written based on commercial symbolic manipulation programs (SMP, MACSYMA, REDUCE). A two-link manipulator is used as an example. Computational complexity involved in real-time control, using the explicit, non-recursive form of equations, is studied on single CPU and multi-CPU parallel computation processors.     

A cyber-physical robotic mobile fulfillment system in smart manufacturing: The simulation aspect

Incorporating mobile robots into the production shop-floor helps realize the concept of smart production, and it is considered one of the approaches to enhance manufacturing and operational efficiency and effectiveness by academics and industrial practitioners. This paper develops a cyber-physical robotic mobile fulfillment system (CPRMFS) for tool storage in smart manufacturing. The purpose is to enable Just-in-Time material transfer on the production shop-floor during manufacturing. A decentralized multi-robot path planning adopts graph neural networks (GNN) in the new proposed CPRMFS. We compare multiple classification algorithms for the mobile robots' action prediction, including proposing a spatial-temporal graph convolutional network (ST-GNN) under these circumstances. We also extend the research with the enhanced conflict-based search path planning algorithm. Compared with the existing literature, ST-GNN, under the enhanced conflict-based search, could obtain higher accuracy with an average value of 90% under different scenarios. The practical applicability of the proposed system with the further consideration of ST-GNN is further explained as a reference for manufacturing practitioners who looked out on a confrontation of introducing the mobile robot solutions in their manufacturing site with the goal of enhancing the operation processes.