Development of Virtual Factory Using Supervisory Control Theory

设想一个有六条腿的机器人在泥滩上行走，收集环境数据。在PARI（港口和机场研究所），这样的机器人已经开发了3年。我们也实现了它的原型使用MINDSTORMS与六个cpu如图所示。在控制系统的设计中，我们需要两种控制器，一种是伺服控制器，用于对每条腿的每个关节执行给定的指令，另一种是步态控制器，用于对六条腿发出协同指令。在本文中，我们关注后一种情况。众所周知，用三脚架法可以平稳地实现步态。然而，在紧急情况下，为了避开一些障碍物，一条腿可能会与另一条腿发生冲突。由于存在许多由意外事件驱动的复杂情况，用普通的三脚架法生成运动数据的方法不能很好地解决这一问题。在我们看来，这个问题应该被视为一个DES（离散事件驱动系统）控制问题。从上面的讨论中，我们被激励将DES控制理论应用于机器人系统（上面的腿）的监督控制器设计，即由机器组成的制造系统。然而，一般来说，通过手工计算计算DES控制器是困难的，这意味着需要开发计算机辅助设计工具。本文介绍了基于C.G.Cassandras和s.l lafortune的教科书，我们使用MATLAB开发的DES分析和合成工具箱，作为我们原始m文件的集合，并展示了它在两个机器在狭窄空间中工作的避碰问题中的应用。利用MINDSTORMS和Real-Time Workshop嵌入式编码器成功地完成了实验实现。

Consider a robot with six legs to walk around a mudflat for collecting environmental data. In PARI (The Port and Airport Research Institute), such a robot has been developed for the last 3 years. We have also realized its prototype using MINDSTORMS with six CPUs as shown. In the control system design, we need the two kinds of controllers, which are (1) servo controller for following a command given for each joint in each leg, and (2) gait controller to give the command to collaborate the six legs. In the paper, we are concerned with the latter case. It is well known that the gait is smoothly realized by the tripod method. However, in an emergency case to avoid some obstacle, there is a possibility that the one leg would get into a hassle with the next legs. The problem could not be solved very well by the ordinary way of generating the motion data of tripod method for several cases because there are a number of complicate cases driven by unexpected events. In our opinion, the problem should be treated as a DES (Discrete Event-driven System) control problem. From the above discussion, we are motivated to apply DES control theory to supervisory controller design for a system of robots (legs in the above), that is, a manufacturing system consisting of machines. In general, however, it is hard to calculate DES controllers by hand calculation, which means the necessity to develop a computer-aided design tool. In the paper, we present DES Analysis and Synthesis Toolbox that we developed as a collection of our original M-files using MATLAB based on the textbook by C.G.Cassandras and S.Lafortune, and show its application to a collision avoidance problem related to two machines working in a narrow space. The experimental implementation was successfully done by utilizing MINDSTORMS and Real-Time Workshop Embedded Coder.