Drag racing 2025/26
Diary
12/6/2026 Above is a photo of the Moror driver after burning with a LiPo battery . Download
22/5/2026
Here's a video of UKM5 running the Drag race:
Youtube URL
13/1/2026:
UKM4 now has 10:1 high power motors too. It also has encoders.
No software development yet, but I suggest using functions to break down the functionality into understandable parts.
We could have a function each for the 5 stages in a run:
The ** options follow the line
Calibrate(): awaits button press
ReadyToStart() awaits white paper in and then out)
Bat out of hell() ** very fast run to get things started. Runs for about 1/3 of a second.
normal() ** fast run. Runs until stop line seen.
Brake() ** Runs at a negative speed for a little while
Stopped() ** follows the line at zero speed.
9/1/2026:
UKM5 (original drag robot) has had its motors replaced and has a standard 9 volt battery.
It has made reasonably good runs (3.5 seconds at slow test speeds), and we are starting on a 3.5 second auto cutout, to protect the motors.
12/12/2025:
The motor driver in the Fast LiPo racer has been replaced.
It appears that the left motor was damaged causing it to run at random speeds slower than the right motor
To prevent future damage, we will change battery to a standard 9 volt one, but contiue with thesticky weels.
We will have 2 robots (UKM5 and UKM4), identical if possible so we have a spare in any competition.
There is work to be done in the extended fall-off calculation, and the display should tell you what to do in the starting sequence .
We should include features to protect against future damage.
5/12/2025:
The extended fall-off was not implemented in the BackInDrag robot, using a raised speeed of 95 and a reduced proportion.
It produced a stable straight-line run. Unfortunately it wasn't timed. See code
The extended fall-off was used in the calibration phase only, so it is untested in the race itself.
A repeat run resulted in the robot being stopped by the safelty jacket, where it was running with stalled motors for a few seconds.
After that it behaved strangely running slowly in stop-start jerks, until it stopped dead, issuing smoke.
The driver has burnt out (we thinlk). A possible protection would be to make the maximum run length always 4 seconds,
even if the stop line isn't crossed. Mr Clapson will be replacing the motor driver.
28/11/2025:
The paper start mechanism sometimes started the race as you put the paper in.
This was caused (probably) by noise on the sensor reading, meaning that
a value >50 was quickly followed by a value <50.
Solution: Make the paper detection start with >60 and stop at <40.
There was still some instability, even when the proportion waas reduced, and derivative raised,
-a tail skid might be needed.
- Extended fall-off might help
21/11/2025:
Mr Clapson has provided a UKMARS full sized line follower with a Lithium battery and Great soft tyres on special wheels.
This is called Dave but also goes by the name BackToDrag also UKM5.
It has a SSD1306 Display module, but no TV remote or Bluetooth sockets.
Progress:
Code added to start the buggy after calibration by removing a piece of white paper from under the stop sensor.
A run time of about 2 seconds was recorded. (But the timing gate didn't recognize the robot passage until 2 seconds had passed.)
General
Robot needed
- Full width line follower sensor
- 10:1 ratio high power motors
Software
- Calibration
- Proportional control
- Derivative
- start on white paper removal. Stop on second white line seen
Strategies
- start very fast for about 500mm or until it becomes unstable at the high speed.
- Slow down if it falls off
Ideas for Improvement:
- Save calibration numbers as a file each time they are generated
- Use long press to read the file instead of calibrating. Use short press to do normal Calibration.
- use the Display to show what to do next Very important
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