Welcome to 16×62: Robot Programming Laboratory. This manual is your guide to the Nomad Scout robots that you will be programming this semester. This guide details the robot hardware, operation, communication, and user software. Robot Hardware Description Mechanical System The Nomad Scout mobile base is a differential direct drive, non-holonomic system (can’t go sideways) with zero gyro-radius (can turn on a dime). A dedicated 68332 board performs all the hard work, with help from an hc6811 that controls the 16 sonars. The base has a maximum translational speed of about 30 inches per second (approximately) and a maximum rotational speed of 50 degrees per second. Electrical System Each robot uses two large and heavy sealed 12-volt batteries. We estimate the maximum running time of a robot with fully charged batteries to be about 12 hours. This is based on the fact that the processors use a total of only 500 milliamps. But the batteries are sealed lead-acid batteries. If they are fully depleted (deep-cycled), they won’t last through this semester. Avoid using a robot for more than six hours straight.

The batteries can last hundreds of shallow cycles. Do not remove the batteries from the scouts and/or swap batteries between scouts. Ever. The scout has a very nice feature: a built-in charging unit. To charge the scout, simply plug it into the wall. There is one huge catch: THE ROBOT MUST BE ON FOR THE CHARGING CIRCUIT TO WORK . This means no matter how long you leave it plugged in, if the scout is off, charging will not happen. So, at night, when you tuck the scouts in, leave them plugged in and on. Like R2D2, the scouts communicate with you by beeping. When you plug them in (and they’re on!), they will emit two short beeps. Then, if the batteries are half-full, you’ll hear two long beeps. If the batteries are totally full, you’ll hear 4 short beeps. If you hear a continuous beep during operation, that’s the low battery warning beep. Plug the robot in (don’t turn it off!!!) immediately. Of course, the Toshiba notebook housed on top of the robot runs off its own battery (or ac adaptor). The Toshiba battery only lasts about 3 hours. In a cruel twist of fate, the Toshiba batteries are Lithium, which means deep-cycling them is good! One really nice feature of the Toshiba’s is, if you close the lid, the monitor turns off (after a high-pitched 2 squeal) but your program keeps running! To preserve your notebook battery, close the lid whenever you don’t need to see what’s on the screen This makes a huge difference to the battery’s discharge rate.

Also, whenever you and your robot aren’t moving, plug that portable into the wall.There are extension cords for this purpose awaiting you in the Lab. Important points to remember: ALWAYS leave the portables in the Lab overnight (they really, really don’t want to go home with you) . The Sonar System The round gold ‘coins’ are the robots’ only range sensors: sonars. These transducers provide surprisingly accurate range information from 6 inches to 255 inches. Each Polaroid Tranducer has a beam width of about 25 degrees, although there may be variation in this beam width, or half cone, from sonar to sonar. A single sonar unit works as follows: The transducer emits a series of 16 pulses at a frequency of 49.4 KHZ. The echo receiver circuitry is disabled…

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