Common or uncommon sensors used in FRC

[aryker]

From what I heard, this can be accomplished easier by plugging the limit switch directly into a Jaguar, and using jumpers to determine which directions the motor can rotate when the switch is activated. You will have to consult the Jaguar information sheet for this, though, as I have never attempted this.

I implemented one of those in 2011 for a soft stop on our robot's elevator--it wasn't too bad, although if I remember correctly I had to solder a few transistors onto a proto board and stick it between the switch and the Jag jumper to step down the voltage.

Also, our team tried out a Hall Effect(magnetic) sensor this year to work was a soft stop for the cam that pushed our Frisbees into our shooter, and it worked perfectly--all the convenience and functionality of a limit switch, but with no physical contact involved, so it never wore out!

[aryker]

Originally Posted by aryker

I implemented one of those in 2011 for a soft stop on our robot's elevator--it wasn't too bad, although if I remember correctly I had to solder a few transistors onto a proto board and stick it between the switch and the Jag jumper to step down the voltage.

Also, our team tried out a Hall Effect(magnetic) sensor this year to work was a soft stop for the cam that pushed our Frisbees into our shooter, and it worked perfectly--all the convenience and functionality of a limit switch, but with no physical contact involved, so it never wore out!

Oops, forgot to include the link to the Hall Effect sensor we used:
https://www.sparkfun.com/products/9312

[Ginto8]

We used a hall-effect sensor (put together by the team) to measure wheel speed -- two opposite-facing neodymium magnets in a bracket on the axle let us use the Counter class's getPeriod() (implemented in the cRIO's FPGA) to determine how fast it was spinning.

We also used IR bounce-back sensors (also team-constructed) for no-contact limit switching, similar to how aryker used a hall-effect sensor.

After our district competitions, we also added a string-potentiometer, which in our case we used to keep our tilter from going too high and pulling out our lead screws -- yes, there were mechanical alternatives, but we didn't want to risk dismantling the system on the first day of MAR champs. Also, our drivers ended up using it as an alignment system when our camera died (that is, never worked on the field).

[jasp]

Our team generally uses

• ir
• encoders
• limit switchs
• camera/ircamera

generally we use IR instead of ultrasonic because IR works better for the ranges we need, and generally the ultrasonics we have are too short a range.Also limit switchs are nice, the problem with them is that they break easly.

last year one of the mechanical teams made us put on a Hall Effect Sensor to know the rpm for shooter wheel. We never used it because it was to much work with little benift. Not sure if they realized it wasn't pluged in.