On the MINDSTORMS website, the NXTLOG team “froze” submissions of robots at 4999 and then proceeded to determine a robot “that best demonstrates the true LEGO MINDSTORMS NXT creative spirit.” That 5000th robot is now chosen: Mars Explorer Mk1 by user mezzauk (see below). Click here to see the robot, and click here for a full list of winners: second place, third place, and honorable mention.
Dave Parker’s website, nxtprograms.com, is an absolutely outstanding resource. On his website, you’ll find a multitude of projects with building and programming instructions. The pictures for the building instructions are very clear and well done. He has several categories of creations:
The “Rattlesnake” creation under the “Animals” category is one of my favorites. Sometimes when I’m showing kids my robots, I’ll say, “Don’t worry–it doesn’t bite.” I couldn’t say that with this robot!
The official MINDSTORMS website reports that there were nearly 100 entries in the Winter Wonderland Building Challenge, and the results are now in! The Champion’s Award went to the robot Dancing Snowman (shown below) by Mini_Man176. You can find all the winners and see their robots here.
The official MINDSTORMS website is hosting yet another “challenge” or contest: the Camera Bot challenge. Can you guess what this challenge is about? I thought so. The website has this to say about the contest:
Lights, camera, action!
The MINDSTORMS NXT Camera Bot Building Challenge is asking you to create the NXT spy bot, paparazzi bot, photojournalist bot, or even a robotic fashion photographer.
We are looking for robots that can take still photos (not video), and we want you to also share the pictures taken from your robots point of view.
Get building! The deadline is February 29th. You can read the complete rule set here.
A reader (Nathan G.) of The ULMN Inventor’s Guide recently wrote me about an NXT-G program he was working on for Tag-Bot. The program’s purpose was to solve Tag-Bot’s inability to determine its steering position. In the book, I simply instruct readers to always center the robot’s steering before starting a program—the robot then assumes that its steering has been centered. The reader used an unofficial NXT-G block, the Motor Power Meter block, to fix the problem.
What does this enormously helpful block do? The repository on nxtasy.org reports the following:
This block is a sensor which allows you to monitor the actual power sent to the NXT servo motor. In a single motor mode (Motor block) with Motor Power enabled the firmware automatically increases the power to keep constant speed. Monitoring the Actual Power allows detecting stall conditions as well as slip conditions (e.g. when your robot hits the wall, its motors might still be able to slip in place but the robot does not move).
I modified Nathan’s program some, but the basic idea remains the same. Using the Power Meter option within the standard Wait block to determine a stall condition, Tag-Bot first steers to the rightmost position and then resets the built-in rotation sensor of the steering motor (Motor A). Next, it steers to the leftmost position and then divides the current value of Motor A’s rotation sensor by 2. The quotient is the number of degrees that the steering motor should turn to center the steering. Voilà! Automatic steering. You can start the program with Tag-Bot’s steering in any position, and it should always be able to center it.
If you’d like to download the mini-program shown below, click here. Remember that you have to download the Motor Power Meter block if you want to use this program.
The basic Zippy-Bot model from Chapter 11 of The ULMN Inventor’s Guide allows you to create a number of unique robots by adding on different subassemblies. I included two robots in the book—Bumper-Bot and Claw-Bot—based on Zippy-Bot, but I had wanted to include a third: a simple line-follower. Well, I’ve finally created that line-follower and named it Line-Bot. The robot uses one additional subassembly, the Light Sensor subassembly, and an extremely simple NXT-G program.
You can build Line-Bot by downloading the LEGO Digital Designer (LDD) file of the Light Sensor subassembly. (If you haven’t downloaded the LDD software yet, you can do so at http://ldd.lego.com/.) Once you’ve opened my file, clicking the Building Guide Mode button or hitting F7 on your keyboard takes you to the building instruction for the model. Follow the instructions to build the subassembly, and then attach it to Zippy-Bot by pushing its bushed friction pegs into the angled beams on the front as shown in the image below. Use a small or medium size cable to connect the light sensor to input port 1 on the NXT.
After construction, download the NXT-G program Line-Bot.rbt, and after you’ve loaded the program into Line-Bot, place the robot on the outside of the black line on the NXT test pad. Run the program, and that’s it! Line-Bot steers left when it detects the black line, steers right when it detects the white surface, and goes straight when it reads an “in between” value. Note that, depending on the lighting in your room, you may need to modify the trigger values used by the two Switch blocks in the program. In addition, depending on the NXT’s current battery level, you may need to adjust Line-Bot’s speed (if the robot goes too fast, it’ll “get lost”).
Feel free to experiment with the program and the robot’s design, and let me know what you can come up with!
Ive added video of Claw-Bot, the robot from Chapter 13 of The Unofficial LEGO MINDSTORMS NXT Inventors Guide, to the Pages section of the blog. You can also watch the video below.
Claw-Bot is based on the Zippy-Bot model from Chapter 11, adding a claw-like subassembly with an ultrasonic sensor and a light sensor. Claw-Bot moves toward the center of the NXT test pad, spins in a circle until it detects an object with its ultrasonic sensor, and then drives forward to push the object until its light sensor detects the black line. The robot is programmed to find three objects, but it’s easy to change the number to more (or less) than three. Go Claw-Bot!
Ive added video of Bumper-Bot, the robot from Chapter 12 of The Unofficial LEGO MINDSTORMS NXT Inventors Guide, to the Pages section of the blog. You can also watch the video below.
Bumper-Bot is based on the Zippy-Bot model from Chapter 11, adding a bumper built around a single NXT touch sensor. Bumper-Bot is content to explore its surroundings by randomly running into objects and then changing its path. Fortunately, robots don’t get headaches from bumping into objects—unless they’re programmed to get headaches, of course.
I’ve added video of Golf-Bot, the robot from Chapter 16 of The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide, to the “Pages” section of the blog. You can also watch the video below. Have you ever seen a LEGO robot golf? This bot scans its surroundings for a special LEGO target, places a ball on the ground (a LEGO ball, of course), and then hits the ball into the target. Despite its size and complexity, Golf-Bot can be created from the pieces in a single NXT set. There’s just not that many pieces left over by the time you’re finished building!
I recently added a funny video of Tag-Bot, the robot from Chapter 14 of The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide. Check it out below. For one part of the video, I stuck my camcorder (which is very small) onto Tag-Bot’s “head” with the aid of some special “glue dots.” Using this approach, I was able to get some video of what it looks like from the robot’s perspective!
The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide
