如果你想在机器人上工作，但是没有时间从无到有去建立，那就请考虑买一台iRobot公司的Create机器人。这个机器人混合了若干自定义的特性，包括一个为板上编程的设计的命令模型，一个用来发送独立命令的串口线，10个内置演示程序，超过30个内置传感器和一个25针的扩展接口。Build on an Existing Robot PlatformIf you want to work on a robot but dont have to time build one from scratch, check outiRobots Create. The robot incorporates several customizable features, including a commandmodule for on-board programming, a serial cable to send individual commands,10 built-in demos, over 30 built-in sensors, and a 25-pin expansion port.Occasionally, I get dragged to the nearest mall,especially around Christmas time. Few of thestores interest me. But Brookstone is different. It is anation-wide specialty retailer with an assortment of consumerproducts that are functional in purpose, distinctivein quality and design, and not widely available fromother retailers. Years ago, I was drawn in by a Frisbeeshapedgizmo wandering around on the floor near thestores entrance. It was an iRobot Roomba vacuumingrobot. iRobots literature described it as the first practicaland affordable home robot. You may have heard of iRobot,which developed robots like the PackBot that wasused to search the rubble of the World Trade Center inNew York after the September 11 terrorist attacks. It isnow used by the U.S. military overseas.Apparently, iRobot quickly sold more than 1 millionRoomba units. This success led to a line of similar roboticappliances used for vacuuming, sweeping, washingfloors, and cleaning pools and gutters. As you can imagine,when the robots started becoming popular, hackingsites sprang up with information about ways to use theseplatforms for unintended purposes.iRobot took advantage of this growingfrenzy and developed an offshoot basedon the Roombas proven technology. The Create was born with two basicmodels. In this article, I will discusswhat iRobot provides as a system andhow you can use the technology.PROGRAMMABLE ROBOTThe Create mobile robot platformis for educators and developers alike.Its mobile out of the box. There is noneed to assemble the drive system orworry about low-level code. Thebasic unit includes a serial cable forsending individual commands from aPC or writing basic scripts of up to100 open-interface commands, whichcan be stored on the robot. Ten builtindemos perform various preprogrammedbehaviors. More than 30built-in sensors enable the robot toreact to both internal and externalevents (see Photo 1). In addition to aserial communications port, there isa 25-pin expansion port, to which youcan connect your own electronics(sensors, actuators, wireless connections,computers, cameras, or otherhardware). The cargo bay has variousthreaded holes for securely mountingyour own brand of hardware. You canadd a fourth wheel to improve thestability of larger payloads, but thisslightly reduces its ability to adapt tochanges in grade.Photo 1The Creates Power, Play, and Advance buttonsand LEDs (a) and wall sensor and IR receiver (b) along withevery other sensor can be disconnected from the interfaceboard (c). Motor gearboxes with optical encoders (d) givethe Create (e) a movement resolution of 1 mm. Angle isdetermined to 1 of rotation based on the left and rightencoder values.The advanced unit includes theiRobot Command Module for onboard(autonomous) programming. The Create is fully compatible with all iRobot Roomba accessories, including rechargeable batteries, apower supply, a home base, a remotecontrol, and virtual walls. The Command Module screws onto the 25-pin expansion port at the front of the cargo bay. It contains an Atmel ATmega168 microcontroller that communicates with the Createthrough a serial connection in the expansion port. It is programmed viaa USB port. Lets begin with a look atthe basic units array of peripheral I/O devices.UNDER THE HOODThe Create is preprogrammed with an operating system that enables access to all of its input and output devices by passing commands via a serial communications port (default speed of 57,600 bps). Commands include an opcode (128 159) followed by a number of data bytes, depending on the opcode. Table 1 lists the opcodes and data requirements of each. I color-coded the table so you can see the groups. Five commands place the Create into special modes.The Create begins in Off mode and remains there until a Start command is received. The Start command places the Create into passive mode ready for additional commands. From the passive mode, the Create accepts only the Baud, Safe, or Full commands.Safe and Full are similar commands that give you complete control using any of the other commands.Safe mode, as its name implies, has some automatic selfpreservation actions, which prevent it from falling off an edge, for instance. In Full mode, if you don t pay attention to its cliff sensor, for instance, it would attempt to fly right off a ledge (thereby needlessly testing its poor aerodynamic characteristics).The built-in demo programs can be called through the o