Recently I have been asked to develop a timing registration system for the IUF Slalom (a discipline) in the Dutch Unicycling Championships (nkeenwieleren.nl). After searching the internet, the main thing I found is that there is a lack of information about such a system, or even individual components. There are suppliers of complete race timing system (for professional races), suppliers of main building blocks (such as beam breakers and timing software or devices), and suppliers of small hardware components. Only the latter share design parameters, other manufactures seem to keep their secrets in a vault.
As the event is low cost (so even younger children can afford to attend), I'll be doing it Pro Deo, and any ready made, off the shelf, systems are way above budget. The event is 84 days from now, and as there are also holidays planned, the time is on a tight budget too.
In the coming weeks I will attempt to design a timing device, and share the knowledge and insights gained in that process to you, the internet community.
Crossing the line
In general, a race is started on a signal, and ends when the competitor crosses the finish line. For the IUF Slalom this is slightly different: the time starts after the competitor crosses the start line, so a detector is needed at the start line too. The exact definition of “crossing a line” is defined in the IUF rulebook; for the Slalom there is some flexibility in the rules. But how does a timing system detect “crossing a line”?
A few options:
- Touch – the line itself is sensitive for touch. This could be a pressure sensitive plate (with switches or PIR-elements), capacitive or resistive touch (in a plastic layer; much like older touch screens), SAW-devices (surface acoustic wave) etc.
- Trip wire – a wire hanging over the line which is pulled slightly when a wheel crosses the line
- Detection loops – a loop (usually buried under the surface) detecting the presence of metal
- Beam breaker (or Light barrier) – a visible or non-visible light beam which is interrupted when the competitor crosses the line
I’ll discard touch and trip wire systems, as they seem either very complex, vulnerable for damage, not very reliable or sensitive to dirt and rain. The detection loops are physically large and therefore not accurate, and they require the presence of metal (which is not guaranteed). Most ready-made systems seem to use beam breaker systems, so for me that’s a clue this is a feasible route.
Should this not work for whatever reason, I'll come back to this point and reconsider.
Other posts on Timing: