Keywords: virtual prototype; industrial robot; robot
1. Introduction
Virtual prototyping (VP) is an emerging technology in the field of design and manufacturing. This technology integrates product information into a computer-provided visual virtual environment using CAD/CAM/CAE technologies, enabling product simulation, analysis, and optimization before actual manufacturing. Robot simulation is a crucial aspect of robotics research, applicable to robot kinematics and dynamics analysis, trajectory and path planning, robot-work environment interaction, and offline programming. With the development of advanced manufacturing technologies such as virtual manufacturing and digital manufacturing, robot simulation has become an essential component of the entire digital design, verification, and manufacturing environment surrounding the product lifecycle. Researching and developing robot virtual prototyping systems allows for the completion of these research tasks within a virtual environment, providing new tools for robotics research and the development of advanced manufacturing technologies.
2. Virtual prototyping technology
Virtual prototyping technology involves the kinematics and dynamics modeling theory and its technical implementation for multibody systems. It is a comprehensive application technology based on advanced modeling techniques, multi-domain simulation techniques, information management techniques, interactive user interface techniques, and virtual reality techniques. Virtual prototyping technology allows for a complete analysis of the entire system in the early stages of design—the conceptual design phase—allowing for observation and experimentation of the mutual motion of each component. Through system simulation software, the motion of the system is realistically simulated in a corresponding virtual environment. Design flaws can be easily modified on a computer, different design schemes can be simulated, and the system can be continuously improved until the optimal design is obtained, after which a physical prototype is created.
The design methodology of virtual prototyping embodies the concepts and ideas of concurrent engineering. It represents a future direction for advanced manufacturing technology. Compared to traditional methods, it offers numerous advantages, including the ability to determine key parameters during the design phase, update the product development process, shorten development cycles, reduce costs, and improve product quality. Key technologies of virtual prototyping include the following:
1) System integration virtual prototyping solutions involve multiple technologies. The virtual prototyping execution environment needs to be converted between different systems. Its integration includes the following aspects:
● Create a 3D model of the mechanical system in a CAD environment and perform simple motion performance analysis;
● The geometric model is converted into a geometric model in the CAD system and imported into the virtual prototype analysis system for kinematic and dynamic analysis;
● The loads in the virtual prototype are transmitted to the finite element analysis software, and the analysis results of the latter are transmitted back to the virtual prototype;
●The standardization of the production line model and its control system, and the integration with the virtual prototype.
2) System parameterization: Establishing a parameterized virtual prototype system allows for repeated testing of the virtual prototype system under multiple simulation parameters. It also enables analysis and comparison of simulation output results under various conditions, laying the foundation for further system optimization.
3) The system optimization virtual prototype solution selects the solution required by the designer under the premise of multiple system parameters and virtual verification, and provides optimized system parameters and design results.
4) System Visualization and Interactivity: The system provides an excellent model display environment, giving operators a highly realistic sense of immersion. Due to its visualization advantages, designers can interactively explore the functions of the virtual mechanical system during the design process, repeatedly debug the virtual prototype in a simulated real environment, and fully integrate their own experience and abilities into the design process of the computer-generated virtual prototype.
3. Virtual Prototype of Industrial Robot
3.1 Robot Digital Virtual Prototyping System The robot virtual prototyping system combines robot research with virtual prototyping technology. It focuses on researching and developing systems for kinematic and dynamic analysis, trajectory and path planning, and the interaction between the robot and its working environment during the robot design and manufacturing process. The system enables the design, analysis, and virtual production process of the robot to be realized in a virtual environment. The specific structure of the system is shown in Figure 1.
3.2 Functions and Technical Characteristics of the Robot Virtual Prototyping System The core function of the robot virtual prototyping system is to provide a virtual environment for robot design and development on a computer. Its main functions include the following:
1) Visualizing a Robot Virtual Prototype System: Establishing a visualization environment is the foundation of a virtual prototype system, and CAD geometric modeling is the core. The visualization environment for a robot virtual prototype has the following characteristics:
● A visual environment for robot manipulators is created on a computer, allowing operators to design and develop robots intuitively and efficiently. A good environment also allows operators to easily integrate their own experience and knowledge into the system at any time.
● Extract geometric data from CAD models and utilize it in further processes of the virtual prototyping system, such as motion analysis and dynamic simulation;
●The robot CAD model differs in structure at different stages of virtual prototype development. In the initial conceptual design stage, the robot CAD geometric model may be relatively rough, only meeting the current design needs, and some detailed geometric structures may not need to be modeled; in the detailed design stage, after repeated verification and improvement, the system obtains optimized geometric data, and detailed geometric modeling of the prototype can be performed to form the robot simulation result of the entire virtual prototype.
2) Pre-demonstration of robot operation process: Based on the robot's manipulator body structure, including the geometry and parameters of each part, the number and type of joints, etc., the robot's motion analysis is achieved through forward and inverse kinematic equation solving. Simultaneously, the motion analysis process can also perform simulation studies on the robot's motion space analysis, trajectory planning, collision and interference checks, etc.
3) Dynamics Analysis of Virtual Robot Prototypes: By incorporating physical information, such as the type and mass of the manipulator material, moment of inertia, and joint friction, into the virtual prototype system, dynamics analysis is performed. During the dynamics analysis, the actual working conditions of the robot manipulator can be simulated by pre-loading the virtual prototype or applying gravity, thereby analyzing the stress on various parts of the prototype under various working conditions, studying key aspects, and optimizing the system structure.
4) Robot Control System Simulation: Virtual robot prototypes provide a simulation environment for control systems, allowing for testing. In this respect, virtual prototypes have a significant advantage over physical prototypes. Various control methods can be directly applied to the physical prototype, which is efficient and time-saving, and eliminates concerns about damage to the prototype caused by incorrect control methods.
The robot virtual prototyping system has the following technical features:
1) Provides an integrated system for robot simulation research and a digital robot design and verification environment. The robot virtual prototype system provides a unified data platform that includes digital modeling, visualization of motion process realization, kinematic analysis, and control system simulation, enabling timely and efficient utilization of simulation and analysis results between different parts, and providing a digital research environment.
2) Industrial robots are the basic working units in a manufacturing system and constitute an integral part of a digital virtual manufacturing environment. The robot virtual prototype system can be effectively integrated into the higher-level digital processing and manufacturing environment, meeting the requirements of production line simulation and digital factory at the upper level of the robot working unit in the virtual manufacturing environment, and forming the foundation and integral part of the digital robot production line.
3.3 Technical means for implementing the robot virtual prototype system
3.3.1 Employing High-Level Geometric Modeling Tools With the development of software technology, commercial 3D modeling software such as Pro/E, UG, and SolidWorks can now run smoothly on microcomputer platforms without the need for a dedicated graphics workstation. These software programs can create highly realistic geometric models of virtual robot prototypes and also offer various geometric data conversion formats such as IGES, STEP, and Parasolid to provide the geometric data required for the design and testing of robot virtual prototypes, making them suitable geometric modeling development tools for robot virtual prototypes.
3.3.2 Development Tools for Robot Virtual Prototype Systems Development tools for robot virtual prototype systems mainly fall into two categories: general-purpose software development tools and specialized virtual prototyping or robot development software. Currently, C++ is commonly used for the former, with Fortran and Pascal being earlier options. The characteristic of robot virtual prototype systems developed using general-purpose software is its strong software specificity, addressing the designer's specific problems. However, establishing detailed and accurate models necessary for kinematic and dynamic studies of the prototype requires significant time and effort, and the resulting system lacks flexibility and is difficult to adjust.
Adams, Envision, and others are commercial virtual prototyping development tools…1. These software programs can create simple geometric models or import pre-existing robot geometric models from external CAD software. The systems provide simulation functions for kinematics and dynamics, establishing a virtual prototype design and optimization environment for robots, and possess comprehensive simulation result data processing capabilities. This software frees designers from the tedious process of dynamic robot modeling, allowing them to focus more on the virtual design and verification of prototypes.
4. Conclusion <br /> Applying virtual prototyping technology to the field of robot simulation research and developing virtual robot prototypes expands the research and application scope of virtual prototyping technology. Furthermore, the design and analysis of robot products in a virtual environment represents a future direction for digital design and manufacturing. By applying virtual prototyping technology in robot simulation research, designers can be freed from tedious calculations and focus their energy on the analysis and optimization of the virtual prototype system, effectively conducting system evaluation and providing optimized design products before actual production.
References:
[1] Xiong Guangleng. Virtual prototyping technology [J]. Journal of System Simulation, 2001, 13(1): 114-117.
[2] Zhao Dongbo, Xiong Youlun. Research on offline programming system for robots [J]. Robot, 1997, 19(4): 314-320.
[3] Robotics Society of Japan (ed.). Robotics Technology Handbook [M]. Science Press, 1996.
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