Reader Question Submission #2

We received this question: "If I want my tribot to turn 90 degrees, how come I have to code the motors to spin in opposite directions each for 180 (or a bit more) degrees? I mean, why 180 degrees if I am turning the robot 90 degrees?"

Click on the image at left. If you take the NXT stock wheels (2.25 inches in diameter) and calculate their circumference, you get approx. 7 inches. Now, assume those wheels are mounted on a bot as shown, with a distance of 5 inches between them and you want the bot to spin a quarter-turn in place (left wheel spins one direction, right wheel spins the opposite direction).

When the Bot makes a quarter turn, each wheel has traveled 3.925 inches (along the path indicated by the red circle). If 7 inches = 360 degrees, then a simple calculation shows that 3.925 inches is approx 201 degrees - not 90.

The bot as a whole has made a 90 degree turn, but the wheels have turned substantially more.

Did this help? Can someone verify my math and that I've done this correctly?

Jim

Celebrating MINDSTORMS with a Remix - Part 3

The ROBOTMAK3RS continued their celebration of the 25th Anniversary of MINDSTORMS through these Fall and Winter remix projects. Each ROBOTMAK3R was tasked with selecting one LEGO set of their choice and combining it with a MINDSTORMS set. Below are the five amazing models they came up with. Braill3 by Jerry Nicholls Braill3 is an EV3-based LEGO Braille bricks reader. This robot uses its fingertip, made from three touch switches, to read messages written using the LEGO Braille bricks and will speak out what it detected. If it sees a simple maths problem it will attempt to solve it and give the answer as well. To learn more about the process of creating this machine, read Jerry's blog . Braill3 can be viewed here . Set Review: The Braille Bricks set is well thought out. The ratios of the letters is suitable for general use and the addition of some punctuation and arithmetic operators is excellent. There is a card showing what bricks there are and their quantities, but no form of sort...

Celebrating MINDSTORMS with a Remix - Part 2

The ROBOTMAK3RS continued their celebration of the 25th Anniversary of MINDSTORMS through these summer and fall remix projects. Each ROBOTMAK3R was tasked with selecting one LEGO set of their choice and combining it with a MINDSTORMS set. Below are the five amazing models they came up with. Remote controlled material handle r by Jozua van Ravenhorst (aka Mr Jo) This remix combines the LEGO Technic Material Handler (42144) with MINDSTORMS EV3 (31313) It uses the power of pneumatic cylinders to move objects around. By using a bluetooth remote control, very precise movements can be made with this model. Touch sensors in the base chassis prevent the turret twisting the cables that go through the turntable to much. The program has several protections to prevent over pressurizing the system for each of the 3 individual pumps and valves that control the 2 booms and claws. The real version of this machine is mostly used in waste material sites to bring the material to machines that sort and...

Celebrating 25 Years of MINDSTORMS

In celebration of the 25th Anniversary of MINDSTORMS, we take a trip through history. Please also visit ROBOTMAK3RS Community every week as we highlight different projects all through 2023 in celebration of the anniversary. Some of the early history is based on the content shared by Coder Shah in our MINDSTORMS EV3 Community Group . Some of the text and links may have been edited from his original posts for consistency and clarity. 1984 - Kjeld Kirk Kristiansen watched a TV program called "Talking Turtle," where MIT professor Seymour Papert demonstrated how children could control robot "turtles" using LOGO, a programming language he developed. 1988 - The collaboration between MIT and LEGO resulted in LEGO TC Logo in 1988, which allowed students to control LEGO models using computer commands. The video shows Papert demonstrating TC Logo. 1990 - LEGO TC Logo was hampered since the robots you built had to be tethered to a personal computer. LEGO and MIT...

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