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So, how was the meeting?

Proceedings of the San Francisco

Robotics Society of America (SFRSA)

Monthly Meeting at the Exploratorium

Museum of Science, Art and Human Perception

By Cliff Thompson

(email: clifftrobot@home.net)

3 - March - 1997


Tonight’s meeting at the Exploratorium saw a full house populated by quite a few new guests. Tonight was also the date for the first presentation of President Kevin Fahl’s recently proposed new pair of SFRSA Robotics Events, the Robot Art and Robot Survival Contests.

Exploratorium Technical Curator

& SFRSA "Godfather" Larry Shaw

drops in before the start of the meeting

& eagerly peruses the 1st issue of


Tonight’s turnout

Kevin had several items:

Digital Frequency unit

L/C meter

Aade’s Web Site

ROBOTICS DIGEST arrives on Earth

Member Patty Pink passed around several handouts, one titled "Sumo Design Hints and Tips", and another titled "Pentek Wall Walker". The latter described a "Robotic Wall Climber...to deploy surface treatment processes to vertical surfaces like tanks, beams and walls". PENTEK may by contacted at (412) 262-0725 and emailed at pentekusa@aol.com.

Pentek Wall Walker write-up

SFRSA Treasurer Robert McAdams passed around information profiling a Robot FireFighting Contest. The Contest runs a Web Site at http://www.trincoll.edu/~Robot.

Kevin proposed that, if Robotics Digest Magazine picks up this Newsletter and ROBOTS! stops seperate publication, we can still post announcements on the SFRSA Internet Web Site at http://www.robotstore.com/sfrsa. Though some members may not have Internet accounts, a Guest at the meeting noted that the San Francisco BAY GUARDIAN Newspaper is offering free Internet accounts for Web access. The paper runs a Web Site at http://www.sfbg.com/frameset.html and may be contacted at (415)255-3100 and emailed at tim_redmond@sfbayguardian.com

SF Bay Guardian Web Site

I had a couple items:


Gero von Randow



Speersort 1

20079 Hamburg


mailto: randow@zeit.de


Dear Mr. Thompson.

every time ROBOTS! is in my mailbox, nothing can stop me from reading it

immediately. I really like your magazine. I quoted it (and you) in my new book

Gero von Randow

ROBOTER (< ---- in german, sorry)

Unsere nächsten Verwandten

Rowohlt Verlag (< ----- the publishing house)

Reinbek 1997 (< ---- available since two weeks!)

42,- DM

356 pages

Best regards!



Gero, if you’re reading this, let me tell you that your timing was most serendipitous. The very day your mail arrived, I had spent a grueling day on the computer. I was laboriously converting the last 6 articles and a long story covering the last Exploratorium-SFRSA Annual Robot Competition and Exhibition (ARCE) into a form acceptable for publication in the new magazine ROBOTICS DIGEST.

The work involved removing all the article pictures from the story, converting each picture’s format from 8 bit bitmap to 24 bit TIFF and converting the text format from Microsoft Word to ASCII. The work proved quite tedious and by the end of the day I was feeling pretty low. I was wondering if there was really anyone interested "out there" and if all my work was worth the effort. Moments later my wife walked in with your letter. Your kind words really picked up my Spirit and my wife and I spent the evening in a state of elation. Thank you for your praise and support. I look forward to obtaining a copy of your book and running my Language Translator software on the text.

My wife advises me not to place too much hope in the Translator. She was recently contracted by Proctor Jones, the Honorary Consulate General of Tunisia and author of the comprehensive tome NAPOLEON. Proctor asked my wife, a computer consultant, to run a French Translator program on a letter written by Napoleon to one of his Generals. The letter began "My Dear General". The program’s translation read "My Expensive General". Fortunately for the General, the Translator program wasn’t available at the time, otherwise there would have been a dear and expensive price to pay!

TOSHIBA Pipe ‘bot


Member and ZAXIS TELEROBOTICS, INC President Bob Nelson brought in the latest addition to his company’s line of Telerobotic Manipulator Grippers, along with mockups of the kit’s box cover and side panel artwork. The new low-end unit, a Robotic Starter Gripper kit, features a 42 ounce-inch servo, high resolution servo controls, 3¼" capacity parallel gripper and costs $69.95. Bob also mentioned that his larger table-top model was upgraded to heft loads of 5 lbs. Bob noted that the various models are inter-modular and that a system may be built-up incrementally. One can begin with the Starter kit and build up to the table-top model using components from the Starter. Currently the Telerobotic kits operate by remote joystick control, while the next set of enhancements will include closed-circuit video and a PC interface. Bob added that the kits start out as CAD/CAM designs on a computer that then drives a cutting machine to punch out the parts. Though the current prototype cutting machine costs around $3000, ZAXIS is planning a future kit for the cutting machine costing about $2000, to be followed by an eventual hobby market version for roughly $400.


ZAXIS’ newest Gripper

ZAXIS’ box cover art shows larger desktop

model Gripper

ZAXIS’ President Bob Nelson explains

Gripper engineering

I asked Bob if it’s possible to automate the Manipulator movements through motion training or programming. Bob replied that a motion training feature is coming and that even now it is possible to record individual joint positions because the system uses cylindrical coordinates. Additionally, the PC interface will be able to record and playback motion scripts. Bob added that this technology is heading towards high-end systems that utilize Inverse Kinematics (IK), where the operator specifies an end-point and the system calculates all the in-between positions. IK runs in robust 3D modeling animation software to produce realistic model and creature movement. Among Intel platform products that use IK are 3D-STUDIO, (from the original PC CAD and VR company AUTODESK), and LIGHTWAVE, (from NEWTEK, creators of the Video Toaster desktop television studio), used exclusively for special effects in the Television Sci-Fi series BABYLON 5.

I wondered if a search of the Internet Web might help locate IK technical papers and possibly even some plug-in software for Bob. I entered the keywords "inverse kinematics robot software" into the Internet Search Engine at http://www.yahoo.com. The query returned a page from which I have copied and pasted below a few entries from an astonishing list of "Search Results":


Found 43240 matches containing inverse kinematics robot software. Displaying matches 1-20.

•Inverse Kinematics - Inverse Kinematics. Updated 26 Jan 1996. Finding a set of joint variables for a given manipulator position. Gripper position is known all we need to do is...


•No Title - A Combined Optimization Method for Solving the Inverse Kinematics Problem of Mechanical Manipulators. Author: Li-Chun Tommy Wang ; Chih-Cheng Chen....


•No Title - Inverse Kinematics for Robot Manipulators. Efficient Inverse Kinematics of General 6R Manipulators (10 pages PostScript, 94K) D. Manocha and J. Canny,...



Yahoo Search Results screen

Kevin played a video from the NEXT STEP Television series. The tape included the following clips:


shows forms of Artificial Muscle


shows Mr. Bony


shows Artificial Muscle powers robot insect



Muscle Wires powers the ANT

Member Ryan Light demonstrated a remote controlled car whose servo is a potentiometer and whose DC motors output pulse width. By the way, Ryan just landed a job working at the Exploratorium as an Explainer. Congratulations, Guy! You’ve joined an unique group of science trail guides, in which my wife and I were members in the early days of the Exploratorium.

Ryan’s car

Car closeup


Car controller


Robot Art Contest

As SFRSA’s youngest members Hans Barnum and Nils Bailey, both age 6 (!), set-up their Robot Artists, their mother Patty Pink passed around the following Robot Art Experiment Report on the lads’ project:


San Francisco Robotics Society Meeting

at the Exploratorium in San Francisco March 8, 1997

Hans Barnum and Nils Bailey Age 6

Robot Art Experiment

Goal: Robot that makes Art on 8.5 x I I inch paper

Hans and Nils are using alike robots that are bipedal humanoid shaped battery powered toy robots with sound, flashing lights 360 degree rotating upper torso with arms that move up and down. The following is a description of attempts to get the robots to create "art" within the confines of the paper.

1) Robot did not stay on paper so rubber bands were put around the legs to restrict movement.

Hans' and Nils' observations: "It didn't work. It was damaging the inside gears from the sound we could tell that."

2) Put tape over one of the wheels on the bottom of the robot's foot to restrict movement.

H&N: "It still moves too far and goes off paper."

3) Put tape over wheels on bottom of both robot feet.

H&N: "The robot slowed down and stayed on the paper pretty good."

4) Taped felt tip pen to one robot leg.

H&N: "That worked ok and it drew on the paper. It's kinda boring with only one color. We had to tape the pen where it didn't get bumped by top of robot turning around and the arms moving.

5) Taped pencil on other leg.

H&N: "We couldn't see the pencil's mark very good so we took it off."

6) Taped felt tip pen to tinker toy extension and taped to moving up and down rotating robot hand to make another color and an interesting design.

H&N: "The art went off the paper too far. The robot's arm is too long.

7) Taped felt tip pen to robot arm at bent elbow.

H&N: "When the arm went up, and then down, it pushed the robot over. We had to give up on putting a pen on the arm."

8) Taped 3 felt tip pens on each leg for more color variety in art.

H&N: "The robot made art on paper real nice, but after a long time robot still

moves off the paper."

H&N Conclusions:

"Maybe a battery that is half dead would make robot go slow enough not to go off paper very soon. It would go so slow that it would stay on the paper a real long time and still make good art.

It would probably take a lot of time to figure out how to get robots to do this


You might need a different kind of robot than we used."


As the young robotics engineers started up their trio of machines, the robots proved quite entertaining as their gyrations seemed to include pauses for reflection & pacing for inspiration between bold pen strokes. One machine quite deftly drew a series of congruent perfect circles. I thought the idea of using existing walking toy robots with pens attached was ingenious. At the end of the demonstration the audience burst out with several rounds of applause.

Robot Artist is quick on the draw

and holds audience hostage for Art’s sake

Robot Artist uses circular logic. To quote the lads,

"Beautiful, huh!"

The team of Barnum and Bailey and Pink.

"How Robotic Thou Art!"

Nils’ Robosurrealistic work

draws critical acclaim

Young member David Ruben showed a Spirograph Robot work-in-progress featuring a Motorized Pen. Noting a requirement that the system "push out while rotating", David explained how he implemented a solution using a spring to push out the pen as the motor rotates. We wish David success in overcoming the hurdles to completion of the project. I think the application of a robotic manipulator to a Spirograph to produce Mathematical Art is an inspired, and potentially lucrative, idea.

David Ruben explains "Spirobotics"



At the end of the Contest, the team of Barnum and Bailey were declared the winners. A number of attendees offered suggestions to improve the event, such as breaking it down into a number of Categories including "Novice Class" to make the event a little less intimidating to younger members.

Robot Survival Contest

Kevin brought in the 3’ square Pen he is building for the Contest. The Pen features a wall upon which contains two metal plates backed by electronics that create a circuit between the plates and an LED. The idea is that a robot placed in the Pen must find the plates and touch both of them to short them out and cause the LED to light. A later Pen enhancement will include infra-red beacons and an actual wall-plug. The robot, using the beacons, must find and plug-into the wall-plug, then light-up to indicate that charging is taking place. Kevin plans to regularly bring the Pen to meetings so enthusiasts can readily test their mettle.

Kevin hooks up the Survival Pen

while Barnum & Bailey take it in the shorts

Club Focus

Kevin noted he was having some difficulty getting in touch with members and FRONTIER MACHINE CONTROL founders Carlo Bertocchini and Stuart Davis. Their interactive PC-ROVER Robot is a candidate for the joint Exploratorium-SFRSA Internet Robot Exhibit. In the event PC-ROVER was unavailable, a search for alternatives and a backup plan seemed a good idea. A discussion followed, reviewing project requirements and restrictions, such as the lack of museum floor space. Kevin, recalling that Bob Nelson’s robotics company ZAXIS also makes a line of monorail robots that are likewise candidates for the project, prompted an intriguing suggestion from member Ron Brown. Ron noted that the rooms in which SFRSA meets stand alone like an island in the middle of the museum. Along the roof of the rooms runs a guardrail, and Ron’s idea is to attach a monorail track to the guard rail. A monorail robot, sporting a camera and gripper, could them move along the rail to take pictures of the museum. Later, add a telescoping swing-down arm to lower a camera or perhaps the whole robot to visit and possibly operate exhibits on the ground floor.

To address the issue of Internet remote operation of the robot, I hastily sketched on a felt-marker board a diagram, reproduced below, showing the requirements. Moving across the diagram from left-to-right to show the flow of control in input-process-output fashion, robot command data is first gathered by a Web Page Command Input Forms screen. When the Form is filled out and Entered, the command data is converted into a comma-delimited ASCII text command data file. The Form then saves the file to the Exploratorium Web Server, which queues the command strings are and processes them in round-robin fashion. For example, if the Form were filled out for the robot to M(ove) R(ight) 10", then M(ove) L(eft) 3", then O(pen) G(ripper) 2", the resulting command data file might read MR10, MR03,OG02. The Exploratorium would then utilize their radio transmitter facility to beam the command file from the Web Server to the robot, which the robot would receive via an on-board antenna. To greatly simplify the problem of tracking command results and conflicts, Bob had a great idea. Limit the command set to a fixed set of specific operations. For example, have the robot visit a certain select set exhibits and perform a particular group of camera operations.

My sketch of the Web-driven

Internet Robot requirements

New Attendee Round Table Introductions

R Olivarez was visiting from the Homebrew Robotics Club. The Club meets regularly on the last Wednesday of the month at 7:30 at the Main Library in Cupertino. R noted their Club members are largely Engineers. The Club follows the activities of SFRSA and is interested in discussing the possibility of attaching their newsletter as an add-on to this newsletter. We responded positively to the idea, as we’re always on the lookout for additional articles, and also suggested looking into getting their material INTO ROBOTICS DIGEST magazine. R added the Club is setting up standardized programs of weekend workshops to build basic devices, and has a number of on-going robotics projects.

Stan Darlak noted he is putting together a robot described in the MOBILE ROBOTS book. Stan first read of the SFRSA in ROBOT PRACTICIONER magazine (taken over by, and folded into, the new ROBOTICS DIGEST). Stan added he works at the Sunnyvale FRY’S Electronics store on Kern Ave. on weekends. Stan offered himself as a resource to SFRSA Members to help with parts at the giant electronics emporium.

Kurt Meyers and Amy Sun introduced themselves as Purdue Univ. graduates in Computer Electrical Engineering who like to build robots. They’ve entered college competitions and taken first place at the University of Illinois AMD Engineering Open House Design Competition. Last year they entered POKEY in the Middle Weight Class at ROBOT WARS and this year will enter a second machine in the Heavy Weight Class. Kurt mentioned his machines can handle 40 commands over a single channel. For this year’s ROBOT WARS , Kurt added that is currently looking at a $250 9600 Baud UHF Transceiver with a 20 mile range that requires an FCC license. Currently Kurt works on test equipment in San Jose while Amy works at Lockheed.

David Anders mentioned he has worked with Carlos Bertocchini, (FRONTIER MACHINE CONTROL co-founder, reigning SUMO Robot World Champion and creator of THE BEAST). With David was Greg Farnum, who mentioned he is working on a 6811 microprocessor-based radio-controlled vehicle. Greg proposed adding a scaled-down version of a Fire-Fighting Competition to the SFRSA ARCE Event - have the robot blow out a candle.

Scott Brady described his interest in RC vehicles and an additional hobby in building Ultra-Light Plane kits. Scott is currently working on a Middle Weight entry for ROBOT WARS.