Institute for Personal Robots in Education Blog

Parallax Scribbler Robot: First Impressions

For $79.95 you can purchase a preassembled, ready-to-run, personal robot called, Scribbler, made by the folks at Parallax Inc. for ages 8+.

The Scribbler is a programmable robot whose dimensions are approximately 6(W) x 8(L) x 3.5(H) inches. The shipped package contains the robot (no assembly required), a 26-page Start-up Guide, software CD, and a serial cable (for downloading programs from a PC). The software runs on a PC only (Windows 200/XP). If your PC does not have a serial port, you can additionally purchase a USB-to-serial adapter ($14.95) that will enable the connection over the provided serial cable.

Now for the robot itself, it comes in an industrial looking molded plastic, greyish-blue, shell with two large black plastic wheels (one on each side) and a small plastic tail wheel. Here is what it has:

  • 2 IR emitters (one on each side in front) and 1 IR detector
  • Three light sensors (photoresistors) mounted on the front
  • a speaker
  • 3 programmable LEDs
  • A pair of IR emitters and detectors mounted on its base facing down to detect lines
  • a reset button
  • 2 programmable motors (DC, PWM) with sufficiently high torque
  • an internal stall sensing capability
  • a "pen port" for inserting a Sharpie pen (hence the name!)
  • controller is a BASIC Stamp2

The robot requires 6 AA batteries (not included). Also not included is the pen itself (:-) There is also an ON/OFF swith, a RESET switch, an indicator red LED, and the serial port.

The robot comes pre-loaded with 8 demo programs that are ready to run after you've installed the batteries. The programs demonstrate light sensing, light seeking behavior, object detection, obstacle avoidance behavior, line sensing, line following behavior, scribbling behavior (draws a cricle and a square), and an "ambulance" behavior. All of these are accessible through the light sensors (3 sensors, 8 behaviors, get it? You'll see.). The CD contains a PDF file to print out already drawn sengments of black lines on your printer (nice!) which you can then combine to form whatever path you like (sort of like those whacky trains/engines which fit together like puzzles), except the sheets do not glue or fit.

The CD also contains two options for programming the Scribbler. A Scribbler GUI for kids that contains "action blocks" one can piece together (like the LEGO Mindstorms GUI) to construct new control programs that can then be dowloaded on the Scribbler. Alternately, you can program the robot using PBASIC (did I mention that this is a Stamp2 based robot). Both environments are available for installation from the CD. The CD also contains a PBASIC Manual, a short crib sheet of variable-port assignments for the robot's programmable parts for use in PBASIC programs, and the manuals and books for some of Parallax's other robot products.

I opened the package and tried all the demos. Took me all of 10 min to do all of them except the shape drawing since I did not have a Sharpie at hand (Note to Parallax: if you're going to call it a Scribbler, please, provide the pen). All worked as expected. Nicely designed. You do have to be careful when you are covering light sensors with your fingers. All in all a very pleasant first experience.

I then downloaded the GUI software and played around with the interface a little. The look and feel is kind of unpolished and clunky and it requires extra clicks for things you'd expect just 1 or 2 clicks. The HELP section of the GUI contains a reference manual for the GUI action blocks (or computation tiles, as they call them). You can also caliberate and monitor sensors through the GUI. The action tiles include standard programming constructs: sequencing, conditions, loops, and subroutines.

I am quite impressed with this little robot especially for what you get for the price. I also know of at least one instance where Scribblers were used in an undergraduate course: Sanjeev Arora's course The Computational Universe at Princeton University. A great non-majors course offered at Princeton, which BTW requires all students to fullfill a science and technology requirement(!!). They developed their own GUI (based on .NET?) that students used to carry out their lab exercises. They seemed to have enjoyed the experience (see the course blog).

Compared to the LEGO MIndstorms NXT, you get a robot that you do not have to worry about assembling. Of course, LEGO's philosophy is exactly the opposite. With NXT you get the freedom to design the robot as you wish. With the Scribbler, you get everything already preassembled and you can then experiment with behaviors that are possible. Both approaches allow for creativity and both provide ample room for learning programming and problem solving. Except, for the price of one NXT kit, you can buy 4 Scribblers.

For using the Scribbler in an undergraduate CS course, there is still a need for providing a programming lanaguage interface that is better than PBASIC. If that becomes available (for free?) we will have ourselves a solid, basic, programmable robot with potential for use in CS1 courses.

More to come...


Wed, 2007-08-15 23:57
Anonymous (not verified)


The robots are 99.99 if you

Fri, 2009-03-06 16:36

The robots are 99.99 if you buy 1. They are only 79.95 if you buy 20.

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