Building Smaller Robots

[Wendy Holladay]

We are going to build this summer a small drive only robot for our cheerleaders to use at pep rallies.

I would like to use the Andy mark kit chassis and CIMS if we can, we have a lot of stock and gives students more practice with FRC hardware.

We are looking for a lesser controller than the crio. I have looked at the VEX kit from Andy mark and it looks good but still pricey.

Any suggestions for a cheaper, easy to use, etc alternative that will drive CIMS?

thanks

[waitwhat?]

Another option is the Arduino, which usually retails for around $50 online. You could purchase one of these boards and then interface it with the robot open. This should allow you to control a driving chassis with a relatively low cost control system. One thing to consider is that to program the arduino, you will probably have to generate new code as the libraries are different. Also, there is a limit of 8 digital input/outputs. But for a driving base, I think this would be fine.

Here's the link for the arduino:
http://www.arduino.cc/

And for the robot open module:
http://www.team221.com/robotopen/


Hope this helps!

[IndySam]

Try Ebay for the older radio Vex controllers. You should be able to pick one up much cheaper than a VEXnet setup.

[techhelpbb]

Another option is the Parallax Propeller which is the microcontroller, sort of like the Arduinos use Atmel microcontrollers. Here's a sample of a robot controller made from a Parallax Propeller.

http://mikronauts.com/roboprop/

These Parallax Propeller microcontrollers are extremely powerful and support simultaneous operations in their cog infrastructure.

The can be programmed in spin (assembler), pBASIC (like the BASIC Stamp) and C.

The 40 pin DIP chips themselves are basically $15 each.

The only real draw back is that the Propeller is natively 3.3V. So if you plan on interfacing lots of custom 5V logic be prepared to use 2N7000s or level translators (SparkFun sells premade level converter modules).

[thefro526]

Originally Posted by IndySam

Try Ebay for the older radio Vex controllers. You should be able to pick one up much cheaper than a VEXnet setup.

This is a great suggestion. Entire V.5 kits pop up on eBay for less than $100 every so often.

Here's another option if you're just looking for a simple bare bones signal driver (Still requires an older vex radio setup, check ebay for these if you don't want to spend $130 on a new one): http://www.vexrobotics.com/products/.../276-2217.html

[dtengineering]

If you are planning to use CIMs, then you are likely using an FRC battery... so your robot is likely going to weigh more than 50 pounds. It is also likely to be able to move pretty quickly, and its frame will likely be able to inflict damage on whatever it hits.

I'm pointing this out because the commercial robot kits, such as the VEX controller, have failsafe systems where the robot will stop if it loses a signal from its controller.

I really like PICs, Arduinos and all the other low cost options, but there are some good reasons to pay for the layer of engineering that wraps a commercial robot control solution.... particularly if you aren't 100% sure how to program a safe, reliable, control system on your own.

Just a thought. The old VEX PIC controller works great on one of our old FRC robots.

Jason

[gixxy]

Hey Mrs. Wendy:

I also suggest the Arduino platform. Its fairly inexpensive and simple. I never really liked the OpenRobot Platform and prefer to use the Tinkerkit Senor Shield.

Arduino Uno Rev3: $29.96
http://store.arduino.cc/ww/index.php...du cts_id=195
TinkerKit Sensor Shield V.2: $16.33
http://store.arduino.cc/ww/index.php...odu cts_id=89

Arduino Mega2560 Rev3: $58.42
http://store.arduino.cc/ww/index.php...du cts_id=196
TinkerKit Mega Sensor Shield V.2: $29.81
http://store.arduino.cc/ww/index.php...du cts_id=147

And There is also the Wireless Shield: $22.32
http://store.arduino.cc/ww/index.php...duc ts_id=145
Which you can purchase a couple of XBees (one for the Arduino, one for a Controller) and I believe you can make a controller that sends the digital and analog signals directly over to the Bot wirelessly.

This is what my Dad and I are using for a small robot (testing a drive train system that will have the traction of traditional wheels and move-ability of mechanum), as well as what the Team is using for a T-shirt Launcher.

a few downsides however: 1) You program in Arduino (and C++ for the Libraries) 2) Stacking Shields can be annoying

[slijin]

Cross the Road also offers the CANipede, which for $200 will replace a cRIO. Whether the additional cost is worth it or not is, however, your decision. Can anyone who's used it chime in on its ability? (We're specifically curious about its quadrature encoder counting capabilities).

[daniel_dsouza]

If you still have some/most of your IFI era control systems, then those will work like a charm! There are also many recent threads detailing how to use them...

[ajlapp]

Our RobotOpen Shield for Arduino and the associated controls protocol was specifically designed for projects like this. The protocol has built in examples for basic drive code.

The wifi comms part of the puzzle is the hard part. RobotOpen takes the guess work out and has safety features built in that disable the outputs should the bot lose communications data.

As I stated in a different thread, you can skip the RO board and build your own DIY system using Arduinos...details can be found on our website.

Good luck with your project.