total noob questions.

Rontopia

Hi all,

It’s a long long story, but I have not used any of my parallax stuff in several years. so long in fact that the last time I was at the web site there was no activity bot and spin was still the language used for propeller, if I remember correctly.
I am looking to start up again. I have a propeller education kit and several basic stamps and an older boebot. I was thinking I would just order a propeller activity board and fit it to my existing boebot. There are 2 or 3 things that I see that I would want in addition and that is making be thing that perhaps I should scrape up the extra cash for and activity bot.. so here are the questions.. and thanks in advance.

The servos on the activity bot are faster and quitter?

The wheels have slots for encoding?

And how does the wheels/servos encode on the activity bot. I see in the description on the website but could not find by what method this is done?

Also, given that I do want the ability to know how far the bot has traveled should I just go ahead and buy the activity bot? or just buy the parts to retrofit my old boebot?

Thanks in advance

Courtney Jacobs

Hi Rontopia,

I'm happy to answer these questions for you, and hopefully it'll help you decide the path forward (retrofitting vs. the ActivityBot kit).

1) Yes, the servos that come with the ActivityBot rotate faster than the traditional Boe-Bot servos. The Boe-Bot servos have a rated maximum speed of about 50 RPM, whereas the high-speed continuous rotation servos used by the ActivityBot have a rated max of about 180 RPM. Because the ActivityBot uses encoders, however, a calibrated ActivityBot won't normally exceed 96-128 RPM when running navigation programs. This limit was set to ensure that the robot is executing precisely-measured speeds and distances.

2) The ActivityBot's wheels do have slots for taking its encoder readings that allow it to go precise distances and speeds. These types of wheels are also now included with the newer Boe-Bot kits, though the encoders are not.

3) It's easier if you read through this page of the ActivityBot tutorials to get a sense of how its encoder/wheel system works. You could read the following page on Setting Speeds to go more in depth. The encoder reads the passage of wheel spokes (the series of plastic spokes vs. open holes), which are a set distance apart, and through basic calculations your robot can use that information to determine or set distance and speeds with high precision.

Whether you want to retrofit is definitely your choice, but we have compiled a list of what is traditionally necessary to upgrade a Boe-Bot to an ActivityBot to help people choose the best path for their needs or budget. The cost is roughly the same if you have an older robot that you're considering upgrading.

Rontopia

thank you courtney, that is exactly the information I was looking for.

Mike Green

You can also just get an Activity Board for now and install it on your old BoeBot chassis in place of your Stamp Board of Education. There's a version of FemtoBasic that has built-in statements for servo control and a PING))) sensor (and its mounting bracket servo). You can add an xBee module and program it wirelessly if you want. This is the configuration I use.

Electrodude

Rontopia wrote: »

and spin was still the language used for propeller

Many people, if not most, still use Spin. You can still get great support for it here. If you do switch to C, don't let thoughts of Spin is old, outdated, etc. be the only reason for your switch, because none of those reasons are true.

Rontopia

thanks guys.

I did or do not think of spin as bad or outdated.. just that C was not availible when last I looked. so that was a while ago.