Timing system for bicycle races
I am involved in a recumbent racing team that is trying to set new records from time to time.
For these attempts we need a timing system something we like to own ourselves to be able to take it anywhere and also use it during tests.
During testing we now mostly measure the time using a stop watch, or even worse by just counting seconds on my watch. This method does not work, we either don't pay attention because we are also working on getting other things fixed or we lost count ... Time to make something that is a bit less error prone.
I have had a number of ideas to make something I could use during training on the track in the velodrome. What if I place a ultrasound transmitter next to the track. With a receiver on my bike I could do a dopler sound measurement; a dip means I am closest to the transmitter (the finish line) so then I can calculate my lap time and show it on my bike.
Too complex and not good enough to be used during races so I decided to not even investigate this further.
QuTi107: A quick version of a timing system
Then the question arose again; can we have our own timing system? Something simple just using a tape switch so we can keep track of lap times during our tests.
The requirements were simple: just something so we do not have to type in, or write down, the time on each lap.
A tape switch is available so I just have to make some kind of a recording stop watch - an easy task with one of my microcontroller boards.
QuTi107 was born.
A standard LPCXpresso 1343 microcontroller board with a USB cable attached is all I need. The controller is just a very advanced stop watch that sends the time over the USB cable to the PC. It just behaves like an automatic keyboard; on each lap it seems to type in the time (in hh mm ss.mmm) followed by the enter key.
All that is needed is a PC or laptop that is not being used for anything else during the race. Take a program like excel (or OpenOffice.org Calc) and you get a nice list of times. There are actually tabs in between the hh mm and ss field so that each value is placed in a separate column for easy calculations. Add your own columns with some math and during the event there is a nice list with current time, lap time, lap speed and the average speed.
The mechanical design was kind of an accident. I had a piece of 80x80 aluminum extruded profile that was exactly 107 mm long. The top and bottom are formed by some scrap glassfibre board and the controller board is padded with some foam. An almost unbreakable box.
When I showed this to the team they only had one extra request; an option to remove an event from the list in case someone accidentally stepped on the tape switch.
QuTi2xx: a stand alone timing system
There was a request to remove the need for a PC in this system. we don't always have mains power available and laptops tend to stop when their battery is empty ...
This automatically adds some extra requirements. I do like to have data like lap time, lap speed and avarage speed available during the attempt.
We also added some extra (optional) requirements to look at a transponder system. Using RFID tags we can then have multiple attempts with automatic logging of the racer/bicycle. With a good system it should even be possible to do the timing for normal races with multiple riders crossing the finish line next to each other.
This is all still under development. Nothing is fixed yet.