Tuesday, August 12th, 2008
Can Robots Mindstorm? - Day 2
Lecture
We attended a presentation on "Sensors for Mobile Robots" concerning mainly the position measurements and the related odometry errors (systematic and non-systematic).
Practical Assignments
Today we had to do the following tasks:
Exercise 1
Take 5 measurements from 5-30 cm with 1 cm resolution and another 5 measurements from 30-150 cm with 5 cm resolution using a cardboard box as a target and make a plot of actual versus measured distance.
We made a program that helped us measure the distances after every centimeter (prog. names: worknr2, worknr3) and we looped it for 5 times to get all the data for the diagrams. After completing the tests we compared the diagrams (on the picture below). We could conclude that the difference between the actual and measured distance is bigger when resolution is smaller (1 cm) (the original pictures are on the computer).
Exercise 2
-> Calculate cm for your tribot:
Our tribot wheel diameter is D=5.6cm and C=360 ticks. Based on formula for 1 full turn cm=pi*D/C=0.048869
-> Measure the distance between wheels: b = 11.3 cm
-> Measure cm by making the robot go forward 2m:
programming the code for the robot to move 2m (worknr4) wheels made 4917 ticks and cm=200/4417=0.045279
-> Try to check b by calculating n for a 90-degree turn and compare with what the robot actually does:
After 6 tests we calculated the average number of clicks that the wheels did while turning the robot for 90 degrees.
Based on formula: b = (ΔUr-ΔUl)*2 /pi = 11.0954
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