Graphic-based analysis of robot motion economy principles

Performance of robotic systems depends on the robot design, its motions and the workcell set-up. Robot motion economy principles can provide important design guidelines to optimize the overall automation in robotic work systems. This work presents graphic-based analysis of the performance of 10 different robots in four classes and three group sizes for 27 different bin locations (positions and orientations). This extensive analysis and evaluation lead to several conclusive results concerning motion economy principles related to design of robotic workcells.     

表征空间中的机器人分层运动规划

由于对机器人的任务要求日趋复杂和多变,如何使机器人具备灵活的配置和运动规划能力,以适应复杂任务的需求,成为了目前运动规划领域所研究的核心问题.传统的基于任务空间和配置空间的建模方法虽然在机器人运动规划领域得到了非常广泛的应用,但在用于解决复杂规划任务时无法对不可行任务进行进一步地处理.本文在表征空间模型的基础上,提出了一种分层的运动规划算法,一方面借助于表征空间维度的扩展,使对运动规划任务的描述更为灵活;另一方面通过任务层与运动层的循环交互,使生成的路径满足更高层次和更丰富的任务要求.在仿人机器人和多机器人系统上的应用结果表明了本文所提算法的有效性.     

On the development of a robotic workcell for sanitary ware spray glazing

This paper describes planning activities that need to be undertaken before the implementation of robotic workcells for sanitary ware spray glazing operations. An existing economic justification model that can be used to evaluate the economic feasibility of these workcells is also modified.     

A welding task data model for intelligent process planning of robotic welding

Nowadays, as an efficient and automatic welding machine that accepts and executes human instructions, welding robots are widely used in industry. However, the lack of intelligence in process planning makes welding preparation complex and time-consuming. In order to realize intelligent process planning of robotic welding, one of the key factors is designing a welding task data model that can support process planning. However, current welding task models have some drawbacks, such as inaccurate geometry information, lacking information on welding requirements, and lacking consideration of machine-readability and compatibility. They cannot provide sufficient information for intelligent process planning. In this paper, a welding task data model, which includes information on accurate geometry, dimension and welding requirement, is presented to solve these problems. Firstly, through requirement analysis, necessary information items of a welding task data model are analyzed and summarized. Then the welding task data model is designed in detail by using EXPRESS. The feasibility of proposed welding task data model is demonstrated through creating the welding task file of an automobile front door subassembly. Moreover, an application framework of the welding task file is presented. Results show that proposed welding task data model is feasible for supporting intelligent process planning and information integration of robotic welding.     

A risc approach to sensing and manipulation

This article describes sensing and manipulation strategies that use simple, modular robot hardware. To bridge the gap between automation and robotic technologies, we suggest that traditional automation hardware, such as parallel-jaw grippers and optical beam sensors, can be combined with geometric planning and sensing algorithms. The resulting systems should be cost-effective, reliable, and easy to set up and reconfigure. They should also be flexible enough to support small batch sizes and rapid changes in part design needed in forthcoming flexible/agile manufacturing systems. The RISC acronym, borrowed from computer architecture, suggests the parallels between the two technologies. RISC robots perform complex operations by composing simple elements. The elements may be individual light beam sensors, grouped together to form an array for recognition. Or a complex manipulation task may be performed via a sequence of grasp steps by different grippers specialized for acquisition and placement. This article emphasizes three areas: (i) RISC sensing, primarily optical beam sensing, (ii) RISC manipulation using simple parallel-jaw grippers or minimal configurations of fingers, and (iii) Computer-aided design of RISC workcells. © 1995 John Wiley & Sons, Inc.     

A Ground Experiment System of Free-floating Robot For Capturing Space Target

Technology for the capturing of space target is very important for on-orbit servicing. In order to assure the task is accomplished successfully, ground experimentations are required for the verification of the planning and control algorithms of space robotic system before it is launched. In this paper, an experiment concept is used, which is a hybrid approach, i.e. it combines the mathematical model with the physical model. The key issues of the concept are dynamic emulation and kinematic equivalence, in which the behaviors of the space robotic system are calculated by its dynamic equations. The motion of its end-effector and the space target is realized by two industrial robots. According to different observation spots, two modes of capturing process are emulated: one is observed from the inertial frame, the other is from the space base. Based on the concept proposed above, a ground experiment system is set up, which is composed of two industrial robots, a set of global visual system and five industrial computers. Using the system, algorithms of space robot of any geometry and mass properties can be tested. As an example, the autonomous trajectory planning algorithm is verified by the experiment of capturing a moving target. Moreover, a real-time 3D simulation system is developed to emulate the capturing process in 3D space. Numeric simulation and experiment results show that the ground system is effective in evaluating the planning and control algorithms of space robot.     

Parametric Planning for Multiple Cooperative Robots

A novel planning strategy, parametric planning, is proposed to negotiate the task-oriented object manipulation of multiple coordinated robots. The approach provides an advantage to improve flexibility of robotic cooperation, in which the desired trajectories in Cartesian space derived from task requirements are converted into the trajectories of robots in joint space for a fixed-coordinated multi-robot system. For this purpose, a parametric cooperative index matrix is introduced to handle the relationship of the input desired Cartesian trajectories and the position of robots. A case study of 2-dimension object-motion trajectory tracking using four robots is presented in the end. It proved that the proposed approach effectively delivers trajectory task requirements to the joint trajectories of robots.     

Generic development methodology for flexible robotic pick-and-place workcells based on Digital Twin

Together with the trends of mass personalization, flexible robotic applications become more and more popular. Although conventional robotic automation of workpiece manipulation seems to be solved, advanced tasks still need great amount of effort to be reached. In most cases, on-site robot programming methods, which are intuitive and easy to use, are not applicable in flexible scenarios. On the other hand, the application of offline programming methods requires careful modeling and planning. Consequently, this paper proposes a generalized development methodology for flexible robotic pick-and-place workcells, in order to provide guidance and thus facilitate the development process. The methodology is based on the Digital Twin (DT) concept, which allows the iterative refinement of the workcell both in the digital and in the physical space. The goal is to speed up the overall commissioning (or reconfiguration) process and reduce the amount of work in the physical workcell. This can be achieved by digitizing and automating the development, and maintaining sufficient twin closeness. With that, the operation of the digital model can be accurately realized in the physical workcell. The methodology is presented through a semi-structured pick-and-place task, realized in an experimental robotic workcell together with a reconfiguration scenario.     

Moving Personal Robots in Real-Time Using Primitive Motions

Personal robotics is a new and attractive use of robotic technologies. In this paper we study one of its important topics—real-time motion planning of personal robots. We propose to use primitive motions and their combinations to make this possible. The primitive motion has a unified pattern and is borrowed from the motion pattern of human hands observed by previous researchers. The pattern is simple yet powerful and can form complex trajectories. A reflexive motion control scheme is proposed to activate appropriate primitive motions for a desired motion. As a result, real-time motion planning of personal robots becomes possible by using discrete and sparse human commands. Experiments results are presented to show the effectiveness of the proposed scheme.     

BIM-based task-level planning for robotic brick assembly through image-based 3D modeling

The application of robotics in the assembly of building bricks has become a popular topic, while the planning of construction robots is still lagged far behind the manufacturing industry. New robotic assembly task with manual teaching–planning method is always time consuming. A task-level planning method was proposed, and the implementation details were described to improve the planning efficiency of robotic brick assembly without affecting accuracy. In this work, a BIM (Building Information Model)-based robotic assembly model that contains all the required information for planning was proposed. Image-based 3D modeling was utilized to help the calibration of the robotic assembly scene and building task models. The placement point coordinates of each assembly brick were generated in the robot base coordinate system. Finally, three different building information model tasks of modular structures (e.g., wall, stair, and pyramid) were designed. The feasibility and effectiveness of the proposed method were verified by comparing the efficiency and accuracy of three models through manual teaching and task-level planning.     

Digital twin-driven deep reinforcement learning for adaptive task allocation in robotic construction

In order to accomplish diverse tasks successfully in a dynamic (i.e., changing over time) construction environment, robots should be able to prioritize assigned tasks to optimize their performance in a given state. Recently, a deep reinforcement learning (DRL) approach has shown potential for addressing such adaptive task allocation. It remains unanswered, however, whether or not DRL can address adaptive task allocation problems in dynamic robotic construction environments. In this paper, we developed and tested a digital twin-driven DRL learning method to explore the potential of DRL for adaptive task allocation in robotic construction environments. Specifically, the digital twin synthesizes sensory data from physical assets and is used to simulate a variety of dynamic robotic construction site conditions within which a DRL agent can interact. As a result, the agent can learn an adaptive task allocation strategy that increases project performance. We tested this method with a case project in which a virtual robotic construction project (i.e., interlocking concrete bricks are delivered and assembled by robots) was digitally twinned for DRL training and testing. Results indicated that the DRL model’s task allocation approach reduced construction time by 36% in three dynamic testing environments when compared to a rule-based imperative model. The proposed DRL learning method promises to be an effective tool for adaptive task allocation in dynamic robotic construction environments. Such an adaptive task allocation method can help construction robots cope with uncertainties and can ultimately improve construction project performance by efficiently prioritizing assigned tasks.     

关节型工业机器人轨迹规划研究综述

关节型工业机器人凭借其良好的灵活性和高效率的工作模式被广泛地应用于现代工业自动化生产之中,例如搬运、码垛、焊接、切割等。轨迹规划是工业机器人运动控制的基础研究领域,决定着其作业效率和运动性能。工业机器人的轨迹规划是指综合考虑作业需求和机器人性能,在笛卡尔空间或关节空间内得出指导机器人末端执行器运动的轨迹。阐述了工业机器人轨迹规划的概念及其分类,就各个领域的轨迹规划算法进行了全面综述,包括基本轨迹规划和最优轨迹规划,指出了各类轨迹规划算法中所存在的问题和未来的发展方向。     

Optimum motion planning in joint space for robots using genetic algorithms

The optimum motion planning in joint space (OMPJS) for robots, which generally consists of two subproblems, optimum path planning and optimum trajectory planning, was considered as a whole in the paper. A new method for optimum motion planning problem based on an improved genetic algorithm is proposed, which is more general, flexible and effective. This approach incorporates kinematics constraints, dynamics constraints, and control constraints of robotic manipulator. The simulation results for a two and a three degrees of freedom robots are presented and discussed. The simulations are based on genetic algorithm class library WGAClass 1.0 developed by us with Borland C++ 3.1.     

A PSO-based algorithm designed for a swarm of mobile robots

This paper presents an algorithm called augmented Lagrangian particle swarm optimization with velocity limits (VL-ALPSO). It uses a particle swarm optimization (PSO) based algorithm to optimize the motion planning for swarm mobile robots. Considering problems with engineering constraints and obstacles in the environment, the algorithm combines the method of augmented Lagrangian multipliers and strategies of velocity limits and virtual detectors so as to ensure enforcement of constraints, obstacle avoidance and mutual avoidance. All the strategies together with basic PSO are corresponding to real situations of swarm mobile robots in coordinated movements. This work also builds a swarm motion model based on Euler forward time integration that involves some mechanical properties such as masses, inertias or external forces to the swarm robotic system. Simulations show that the robots moving in the environment display the desired behavior. Each robot has the ability to do target searching, obstacle avoidance, random wonder, acceleration or deceleration and escape entrapment. So, in summary due to the characteristic features of the VL-ALPSO algorithm, after some engineering adaptation, it can work well for the planning of coordinated movements of swarm robotic systems.     

A lattice-type reconfigurable robotic system for achieving gaits of chain-type robots

Traditional lattice-type reconfigurable robots can only achieve the flow-style locomotion with low efficiency. Since gaits of chain-type robots are proved to be efficient and practical, this paper presents a novel lattice distortion approach for lattice-type reconfigurable robots to achieve locomotion gaits of chain-type robots. Using this approach, the robotic system can be actuated by local lattice distortion to move as an ensemble. In this paper, a rule that makes the lattice distortion equivalent to joint rotation is presented firstly. Then, a kind of module structure is designed according to requirements of the lattice distortion. Finally, a motion planning for achieving locomotion is developed, which works well in physics-based simulations of completing a serpentine locomotion gait of a snake-like robot and a tripod gait of a hexapod robot.     

多移动机器人分布式智能避撞规划系统

研究在同一工作环境中多移动机器人的运动规划问题 ,提出将原来比较复杂的大系统问题转化为相对简单的子系统,由各智能机器人依据任务要 求和环境变化,独立调整自身运动状态,完成任务的分布式智能决策体系结构,并给出相应 的模型和算法．     

Service Platform for Robotic Disassembly Planning in Remanufacturing

Remanufacturing is being paid much attention due to environmental protection and resource re-utilization. Disassembly is an inevitable step of remanufacturing and it is always finished by the manual labor. Robotic disassembly helps to improve the automation of disassembly process, while robotic disassembly planning helps to improve the efficiency of robotic disassembly. However, the existing research on robotic disassembly planning seldom integrates the physical industrial robots and then provides convenient services for the users. In this paper, the framework of service platform for robotic disassembly planning in remanufacturing is studied. The database of the service platform is designed, and the data communication method between the software system and KUKA industrial robots is studied. After that, based on the physical facilities, this service platform is implemented using MyEclipse software. The developed service platform is convenient for the users to access the methods of robotic disassembly planning and the connected industrial robots can also execute the optimal disassembly solutions through the data communication method after the optimal disassembly solutions are obtained. Finally, case study based on an idler shaft is conducted to verify the developed service platform for robotic disassembly planning.     

Rapid response manufacturing through a rapidly reconfigurable robotic workcell

This article describes the development of a component-based technology robot workcell that can be rapidly configured to perform a specific manufacturing task. The workcell is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable “plug-and-play” robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components are facilitated by a workcell-wide TCP/IP network and device-level CAN-bus networks. An object-oriented simulation and visualization software for the reconfigurable robot is developed based on Windows NT. Prototypes of the robot workcells configured to perform the light-machining task and the positioning task are constructed and demonstrated.     

High-level motion planning for CPG-driven modular robots

Modular robots may become candidates for search and rescue operations or even for future space missions, as they can change their structure to adapt to terrain conditions and to better fulfill a given task. A core problem in such missions is the ability to visit distant places in rough terrain. Traditionally, the motion of modular robots is modeled using locomotion generators that can provide various gaits, e.g. crawling or walking. However, pure locomotion generation cannot ensure that desired places in a complex environment with obstacles will in fact be reached. These cases require several locomotion generators providing motion primitives that are switched using a planning process that takes the obstacles into account. In this paper, we present a novel motion planning method for modular robots equipped with elementary motion primitives. The utilization of primitives significantly reduces the complexity of the motion planning which enables plans to be created for robots of arbitrary shapes. The primitives used here do not need to cope with environmental changes, which can therefore be realized using simple locomotion generators that are scalable, i.e., the primitives can provide motion for robots with many modules. As the motion primitives are realized using locomotion generators, no reconfiguration is required and the proposed approach can thus be used even for modular robots without self-reconfiguration capabilities. The performance of the proposed algorithm has been experimentally verified in various environments, in physical simulations and also in hardware experiments.