Minutes of the PARTS meeting on April 5th, 2003
President Pete Skeggs opened the meeting by asking for a show of hands from first-time attendees; about six folks were attending for the first time (although more arrived later in the meeting.)
Pete next asked for members of the PDXBOT.03 event committee to raise their hands and be recognized for their work to date to produce this years robotics exposition and competition. Pete showed the poster advertising the event, and announced that online registration for entrants would appear on the club website soon. PARTS members voted (9 FOR and 6 AGAINST) to purchase a $200 1/9th-page ad in Computer Bits magazine to advertise PDXBOT.03. The Computer Bits website already has an on-line listing for PDXBOT.03; this ad will appear in the print version of the magazine.
Larry Geib, PDXBOT.03 Event Coordinator, reported on various aspects of the planning so far. Rules for all but the sumo events have been posted on the club website; sumo rules will be posted with a table that outlines the differences among the various classes. The line following course will use black tape; Larry had limited success finding a commercially-available tape that would show up as grey in infrared illumination. Larry brought the course for the walking robot event so everyone could see it. He said that we will actively decide at event registration if entrants qualify for the beginner class mini-sumo event. We want the beginner class to be fair, especially for younger builders.
Pete showed a data sheet for a new Parallax color sensor AppMod based on a chip made by TAOS. (Brett Nelson showed single-color versions of these sensors at a PARTS meeting over a year ago.) This new sensor costs $79, and has an 8x8 array of photodetectors, each with a red, green, blue or no filter. Filter colors are evenly distributed throughout the array to minimize detection bias. The sensor has its own built-in white LED illumination.
Pete showed the latest version of his quadrature encoder board. His earlier version had registration holes to aid alignment, but ensuring that the Omron detectors were correctly placed for accurate quadrature output was difficult. Petes new design places the detectors in line, and moves the quadrature offset to the encoder disk itself (a much more precise method of achieving quad outputs). The new board design has a hole through which the servo output shaft passes, and can provide either decoded (from a US Digital chip) or raw output signals. Pete custom-made his encoder disks with a three-layer sandwich of metalized Mylar, an inner double-sided adhesive layer, and a top layer of overhead projector film on which the encoder segments were laser-printed.
Stu Caruk showed his ER1 robotics platform from Evolution Robotics. Stu bought his ER1 at CompUSA, and said that overall it was a well-thought-out product. His only real quibble was with the integrity of the anodized aluminum frame; with plastic connectors and small setscrews, it doesnt have the strength that Stu is used to dealing with (hes a machinist.) You need to provide your own laptop computer, but the ER1 kit provides what is arguably the hard part for most people: dual stepper motors and drivers , a gel cell powered interface box, a command-level interface and a graphical interface. All connections to the laptop are done via the USB port. The ER! Programming interface is based on behaviors that are run one at a time. The laptop can send and receive email while controlling the ER1, so Stu has used it to implement a notification system between his shop and office so he knows when a program has run to completion on his milling machine or lathe. Stu demonstrated the ER1s ability to recognize images. It correctly identified the front and back sides of a 1-, 5- and 20-dollar bill, and was not fussy about orientation; it even recognized the bills when they were held diagonally. Stu reports that the supplied battery will last about 1-1/2 hours while the ER1 is moving, and over a day if the ER1 is stationary.
Ron Nucci brought a tracked robot with an attached CMUCam. Ron was using a BasicX-24 microcontroller because it provides additional processing speed. The robots CMUCam was pointed toward the floor and used to determine if the robot could safely advance. He also had a Devantech text-to-speech board driving an external speaker to provide spoken verification of the operating mode.
Daryl Sandberg brought Boxter 4.0. This fourth version is a 3 kg Japan-class sumo robot with rare earth magnets from disk drive head positioners that provide additional downward force to increase traction. Daryl is using KIA window actuator motors to drive his wheels.
Larry Geib showed his new Crawler Kit for the Parallax BOEBot. This $39 add-on allows the BOEBot to walk. He also showed his efforts to waterproof some Cirrus servos for a robotic fish that he hopes to build soon. Larry had installed an O-ring behind the control horn of the servo to prevent water from entering the case at the output shaft. He also filled one servo with light mineral oil to displace any water that might attempt to enter. He actually ran the servo in a small plastic tub of water.
Ron Laing was attending his first PARTS meeting. He said that he is interested in building a microscope stage with stepper motor positioning, and was seeking information about stepper motor controls that can be attached to a USB port.
Warren Leach reported that there has been interest expressed on another robotics news group about radio frequency identification (RFID) tagging for robots. He has been working on some RFID projects lately and brought in samples of implantable transponders used in Texas Instruments tagging products, and a tag from a Ford automotive ignition switch. The implantable tags are sealed in tiny glass ampoules, and contain a wire loop inductive antenna, a 128-bit serial number chip (a number sufficiently large to hold the number of atoms that make up Earth), and a small capacitor and transmitter. He also showed a Texas Instruments receiver with loop antenna.
Larry Ossowski brought in a line following and a walking robot , along with some RF links that he had hoped to use for remote control. The RF system wasnt reliable enough for controlling a robot. Larrys line follower was modified from a kit he bought from BudgetRobotics.com; Larry has built both 3- and 5-sensor detection boards to follow lines. Pete suggested that line following sensors should be placed in line with the wheels to avoid problems with overshoot. Larry said that doing so introduces problems of its own (no ability to immediately shift sideways when you sense that youre not centered.)
Jay Atkins showed his 3 kg remote control sumo robot. Hes using the Solutions Cubed Motor Mind B drivers, and one started smoking yesterday when he fired it up for the first time. Jays front scoop will slide up and down along the sloping front face of the robot to adjust his bottom clearance. His robot will be powder coated black in an attempt to make it less detectable in IR light. He hopes to sell kits for his design some day.
Dan Gates showed the latest addition to Little Johnny: blue glow wires surrounding the eyes. Dan needed to be careful not to affect the sensitivity of the IR sensors mounted in Johnnys "eyes". Dan also showed the HC11 board he is selling for the Mark III mini-sumo kit. His board has the same capabilities as the MIT Handy-Board, and it works with Interactive C when the expansion board is attached. Dan uses non-volatile RAM in his design so that programs arent lost when power is removed.
Tim Weaver took advantage of the free PCB offer from Advanced Circuits, and designed a controller board for his new mini-sumo robot. Tim will use three 9-volt batteries for power; one will power the controller, and the other two will deliver 18 volts to his Swiss gear motors. It should be pretty zippy; Tim thinks his biggest control problem this year will be preventing his robot from overrunning the black stripe surrounding the ring.
Monty Goodson announced that he had a generous supply of last years Parallax catalogs, and encouraged anyone interested to get one or more from him following the meeting. He showed the micro-sumo competition ring that he had printed at Kinkos; the material isnt durable enough, but hes looking into getting one printed on (or overlaid with) Lexan. Monty accepted the Advanced Circuits offer, too. His micro-sumo controller board was barely larger than a penny, and was designed around the Atmel AVR ATmega8 processor. He included two h-bridge drivers, and diagnostic SMT LEDs. He also included a couple of line sensor designs with 2- and 3-sensor capability. Monty uses Eagle pcb layout software.
John Roach showed his Stiquito walking robot. It uses Nitinol wire "muscles" to flex spring steel wire legs. Tying the small wires onto the legs proved to be a good challenge. He hopes to have a controller built for it soon.
Dana and David Weesner showed their Japan-class robot. Theyre using Craftsman electric screwdriver motors (rated for 3.6-volt nicad power) at 6 volts. David said that these motor include a very nice planetary gear reduction unit; he was able to bypass the torque-limiter by reversing one of the clutch disks. David has machined a very nice aluminum chassis, and custom aluminum wheels with a milled zigzag pattern to prevent tire slippage. He made a tire mold out of Delrin for casting polyurethane tires. Dana said theyll use Rick Farmers PIC evaluation board.
Josh Triska attended PDXBOT.02 last year and knew he had to build a mini-sumo robot of his own. His robot uses the Devantech SRF04 Ultrasonic Ranger and two Single Line Detectors from Lynxmotion. Josh modified the line sensors and front scoop of his robot to detect the outer sumo ring.
Mikhail Pivtoraiko showed his walker robot with Intel Xscale processor and USB camera. His robot is set up for robotic soccer, and uses a Mini-SSC II to control the two servos that drive the leg mechanism. Mikhail is working on wireless network connectivity that would allow him to control the walker at the same IP address no matter where it is located. He has been thinking about adding a USB audio device to provide speech output.
Steven Minichiello reported that he has seen Poo-Chi and Poo-Chi Max toys at the Goodwill store in Beaverton. These toys are a good source of motors for robotic projects.
Mark Medonis has added ultrasonic ears to Maxwell. Theyre intended to allow Maxwells head to turn to face a sound source. Unfortunately, when Maxwells other servos operate, noise (electric, or acoustic, or both) causes his head to shake somewhat spastically. Mark is working on this. Also, Mark has created a mold that hell use to vacuum-form a more natural-looking movable jaw for Maxwell.
Andrew Greenberg reported that the eCos operating system from RedHat is an open source, royalty-free, real-time operating system intended for embedded. It will run in 10-100K of flash memory, and has been ported to several platforms, including the Intel Xscale and PowerPC. He said it may be suitable for robotics projects that require more horsepower than a PIC can provide.
Tim Brandon passed around a sample of solvent-bonded polycarbonate ("in the brown bottle from Multicraft Plastics"). Tim urged everyone not to try to accelerate the bonding process by heating the plastics to be joined either in the microwave or in a conventional oven. This simply drives the solvent out of the joint, preventing a good bond.
John Hurley showed the Lexan base he had made for his 3 kg Japan-class robot. John cut the pieces on a table saw, and will solvent-bond them. Hell be ready for next year when the Japanese sumo champs visit again.
Shawn Marshall showed the replica PKE meter (from the movie GhostBusters) that he is building. He is attempting to drive two servos at the same time, and his servos are twitching (somehow interacting with each other). His first PKE meter looked quite nice, and this one promises to be even better.
Mark Gross showed his Viper and Predator robotic platforms from Lynxmotion. Mark said the kits include the plastic chassis, motors, and wheels. Everything else needs to be purchased separately. Mark has also been working on writing JAL code for the Mark III mini-sumo robot kit.
The next PARTS meeting will be Saturday, May 3rd, 2003.