27404 Parallax Inc, 27404 Datasheet - Page 21

• Manufacturer Part Number: 27404
• Description: COMPETITION RING FOR SUMOBOT
• Manufacturer: Parallax Inc

Specifications of 27404

• Accessory Type: Hobby and Education
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: SumoBot®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Figure 1-6 Top Speed vs. Low Time
As mentioned earlier, taking too much time between pulses to check sensors can cause
the servos to slow down. IR object detectors don't take a very big bite out of the low time
between servo pulses. Each one only takes a couple milliseconds to read. QTI line
detectors, on the other hand, can take up to 20 milliseconds each. The time it takes a QTI
to complete its measurement depends on ambient light and how reflective the surface is.
The problem is, if both QTIs take 20 ms to read, that pushes the low time into the 40 ms
range, which means the servos will slow down, which may put your SumoBot at a
disadvantage.
In this activity, you will determine just how much time you can take between servo
pulses before the servos start to slow down. This will be an important consideration in
the sensor management chapter. One of the goals of sensor management will be to figure
out how to read as many sensors as possible between each servo pulse without exceeding
the time limit. By making a note of the maximum low time before servo slowdown in
this activity, you will have a key piece of information for the sensor management chapter.
Testing Speed vs. Low Time - How Much Does it Matter?
A SumoBot race is a good way to examine the speed difference a longer low time can
make. Simply program both SumoBots to travel forward at full speed, with different low
times. Both programs should deliver pulses in an infinite loop. Each program should
also make use of the same initialization routine from Activity #1 so that you can use the
Reset button to start and stop the race.
Chapter 1: Mechanical Adjustments · Page 17
53 RPM
47 RPM