Moving from RCX to NXT, TLG integrated the rotation sensor into the motors and did away with the stand-alone angle sensor. I have a need for such functionality, but do not want to use a motor for (1. too bulky, 2. not free-rotating). What are options out there for stand-alone rotation sensor on EV3/NXT? Idealy, with pass-through axle hole of course.

Edited October 11, 201311 yr by DrJB

Using an old sensor with the adapter or making your own with a touch sensor?

Using an old sensor with the adapter or making your own with a touch sensor?

That's an idea, but I need continuous reading of the angle value (will be used as feedback signal for a closed-loop control system).

Would the old RCX rotation sensor 9756-1 be compatible with EV3? Reason I'm asking is I just updated my EV3 installation to handle all sorts of sensors, and such rotation sensor is NOT amongst the list.

Per Philo's page http://www.philohome.com/sensors/legorot.htm , I just found out such sensor 9756-1 is really not suitable for my application as it has rather poor angular resolution. I need resolution to within 5 degrees. One option would be to use gears with the sensor but then that brings in its own issues. I'm contemplating preloading the gears with this part x928cx1.

Anyone tried to preload gears so as to remove backlash?

Edited October 10, 201311 yr by DrJB

http://www.hitechnic.com/cgi-bin/commerce.cgi?preadd=action&key=NAA1030

Should work well I think!

If it doesn't need to be a continuous rotation one, you could also use this:

http://www.brickengineer.com/pages/2009/10/05/interface-a-potentiometer-to-the-nxt/

http://www.hitechnic...ion&key=NAA1030

Should work well I think!

If it doesn't need to be a continuous rotation one, you could also use this:

http://www.brickengi...ter-to-the-nxt/

Thank you. The HiTechnic seems to be the solution ... but it is rather &^%$@# pricey!

Edited October 11, 201311 yr by DrJB

That is why I included the other option which is rather do-it-yourself-but-very-cheap ;)

Thank you. That sounds like the more 'reasonable' path.

Edited October 11, 201311 yr by DrJB

HiTechnic sensors are great! They work properly and they match the Lego form factor. However, they are rather pricey.

Anyone tried to preload gears so as to remove backlash?

I have used the caster ball from the EV3 educational set as a weight to "preload" the gears. However, this will only work if you can use gravity as a force vector.

The title says EV3 but your opening sentence says NXT. Are looking for NXT or EV3?

Either way... this mindsensors sensor should do what you are after: http://www.mindsensors.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=173

Totally forgot about the Mindsensors rotation sensor. Nice suggestion!

Make sure you either buy a new one from Mindsensors with EV3 firmware or have a NXT brick around to flash an older one to EV3... I bought one that had no EV3 fw, but I have no NXT brick to flash it...

Thank you, that is more affordable than other options. I'll be using it with EV3. The photo on mindsensors's web page shows the sensor only, but not the connector end of the cable. Is it safe to assume that the cable has the right connector and thus, the sensor is ready

to use out of the box?

Yes, it's ready.

From the manual:

Connections and Placement

Connect GlideWheel-AS connector to Sensor Port of your NXT.

The website (link above) states it is compatible with NXT, EV3, and Arduino and can be programmed in NXT-G, RobotC, NXC, and EV3 (whatever it is called). On the link provided above you can download NXT-G blocks, EV3 blocks and see sample EV3 programs. The ribbon cable going into it has the plug on it to go into your sensor ports straight out of the box.

This link: http://www.mindsensors.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=192&MMN_position=32:32

...explains which Mindsensors need firmware upgrades and how to upgrade them. The Glidewheel-AS requires a firmware upgrade.

Edited October 11, 201311 yr by TasV