View Full Version : New to robotics, and trying to build a turret

03-25-2007, 05:53 PM
I've always wanted to get more serious into robotics, ever since I first got one of the first-gen Mindstorms kits. However, I've never really had a project to work on until now. Knowing I'm an all-around geek and interested in robotics, my local paintball field (Another hobby of mine) asked me if I could build a new centerpiece thing for their scenario games-a turret-controlled paintball marker. Well, 4 markers. Since they're funding me, I told them I'd do my best.

So, much research later, I've got an idea for the controls, and I'm presenting it to you, the robotics gurus, to see if it will work before I start shelling out.

The base of the unit will be controlled by 2 stepper motors. Specific models to follow...well, once I figure out what I can use. The markers themselves are all electo-mechanicals, meaning that they use a small chip to fire a solenoid. They'll be fired by some sort of electroic on/off switch. The whole system will be controlled by a Phidgets Sensor Interface Kit 8/8/8 (http://www.robotshop.ca/home/suppliers/phidgets-en/phidgets-1013-sensor-interface.html) hooked into my laptop. That will in turn be controlled via their USB VB Joystick control software (http://www.phidgetsusa.com/demoprojects.asp) (Well, source code, but I can compile it).

Anyways, that's the rough idea. However, like I said, I'm new to anything more complex then simple servos and Mindstorms. I'm sure there's some glaring stupid flaw in the plan, and I hope you guys can tear it apart so I can get this thing running properly.

Also, more specific questions:
1) How powerful a stepper motor can that board control? I'd like to get two motors that can move 40-50 pounds, just to be safe. However, I can scale the project down easily if large enough motors can't be used.
2) Where can I find a electronic on/off switch? The boards on the markers are powered by a simple on/off switch that is pressed when the trigger is pulled. I want to replace them with a switch that I can control from the joystick.

Anyways, please, suggest and correct away!

03-26-2007, 01:06 PM

Thanks for considering Phidgets for your project!

However, as I'm sure you expected, you do have some glaring flaws in your project:(

First of all, there is no Phidget device that can control Stepper motors. If you want to use Stepper Motors, then you might want to have a look at the Step 1 Kit (http://www.trossenrobotics.com/store/p/4886-STEP1-Kit.aspx). Secondly, the VB Joystick control software that you referenced uses Servos and the Phidget Servo Controller (http://www.trossenrobotics.com/store/c/2665-Servo-Controllers.aspx), and also is very old and references old Phidget library files that no longer exist. If you intend to use this project, then there will have to be some updates that you need to make to accommodate the new library.

The most important thing I should ask is do you have any programming experience? I see that you've worked with Lego Mindstorms, which may mean that you've dabbed around with the .NET Interface for Lego Mindstorms.

- Alex

03-26-2007, 03:08 PM
Stepper motors were my first consideration, but I've come across something that might be a bit more useful-power car seat motors. Specifically, the motors used to power the power seats in a Crown Victoria. I'm not sure if they're DC or not, but it looks like I could use them with the board. If not, I'm sure there are some equally powerful motors out there. I just considered steppers because in order to get the precision and stability I want without them, I'd have to buy more powerful motors.

As for the board and controls, I realized soon after that the 8/8/8 works only with their mini joystick controllers. However, judging by their joystick-building tutorial, I could achieve the same result with their mini joystick or build my own.

As for the Mindstorms .NET interface, I've heard of it but never used it. The version I have-or had, I'm not even sure where it is or if it still works-was a first-gen version. I can do some coding in C-I'm minoring in Computer Science at univ, and am currently taking C classes.

Anyways, thanks for the help so far!

03-27-2007, 04:00 PM
The 8/8/8 isn't meant to power/drive things like motors (steppers, servos, DC motors, etc.).

That said, if you want to drive DC motors, and possibly have some encoders for positioning feedback, then I'd recommend the following setup:

Banebot motors:

A Banebot Encoder correctly matched to your DC motor:

The next area you have two choices to choose from.


If you don't mind waiting about 2 weeks (and I highly recommend doing so, you will be quite happy that you did) we're going to have a board that is almost an all in one solution for the rest of this setup. Additionally, there will not only be a really sweet .NET API to work with, but you also have the option to choose from USB, RS-232, and Bluetooth as an Interface:)

This board has the ability to drive up to two DC motors, read data from two encoders, has digital IO ports, analog input ports, and has the ability to drive up to six servos!


If you cannot wait that long and really need a solution now, then you do have a more modular but also more expensive option available:

The digital inputs on the 8/8/8 will not be able to read the data coming back from encoders, so you'll either need to find a microcontroller, or what I would personally recommend is picking up the Phidget High Speed Encoder:


Which is really sweet, because it you can use the Phidget API environment, which makes it simple (given that you know a little high-level programing) to read data coming from an encoder.

A DC motor (Speed) Controller:

and a servo controller if you plan on purchasing a PWM Speed Controller:


03-28-2007, 02:09 PM
Ooh, that new board sounds awesome-and I can wait, I can't make any purchases until I have a concrete plan down and my income tax receipt back anyways. As for the motors, I'll definitely check out the BaneBots stuff. Thanks!

03-30-2007, 12:37 PM
This board has the ability to drive up to two DC motors, read data from two encoders, has digital IO ports, analog input ports, and has the ability to drive up to six servos!

Alex..This sounds like a great product-How many amps will the motor controller handle?
Any more intriguing details you'd care to share?
bill in scenic Florida

03-30-2007, 02:49 PM
It is a sweet product BillBlack! I just finished testing it last week, and I LOVE it! It's called the Serializer by Robotics Connection. The onboard DC controller can handle up to 5A each and with a simple switch of a jumper, you can connect your own motor controller if you'd like. Also has I2C ports.

Robotics Connection put together one hell of a board here! I can go on and on with the details, but you probably would want to check out all the details on the following in-depth PDF:


The PDF also mentions some way to control a bipolar stepper motor on page 7.

Our product pages for it and all the modules hardly have any information on them yet because they're brand new, but we have the board and all of it's modules available in our serializer section:


It comes with the serial port module, the Bluetooth and USB modules are sold seperately. Or, you can purchase the board with all of the various modules available:


03-30-2007, 04:54 PM
VERY nice...I think this is going to simplify my project. I'll post it in another thread so as not to hijack this one.
Thanks, Alex!

04-07-2007, 10:01 AM
Hey, can that serializer handle motors bigger then 4 amps?

04-09-2007, 10:34 AM
Hey, sorry about the double-post, but I think I've found exactly what I need: the Roboteq AX1500 (http://www.roboteq.com/ax1500-folder.html). It doesn't require much/any programming, can be set up to use an analog joystick and can power motors big enough. Has anybody tried using one of these?

04-09-2007, 11:34 AM
Hey, can that serializer handle motors bigger then 4 amps?
4 A is the limit for the Serializer's built-in motor drivers. You can use the Serializer to control external motor drivers, though. This is one of the features that I find really cool. You can use the Serializer's internal control signals to control external motor drivers, and you can also use an external control signal to control the Serializer's built-in motor drivers. Long story short, they built everything you need into one board, but maintained an impressive level of modular flexibility.

04-09-2007, 11:39 AM
That controller looks pretty sweet! Thanks for the link:) If you don't want to deal with the programming, then this might be better suited for your needs.

To answer your question about the serializer though, the onboard h-bridge cannot handle motors over 4A, but with a change of a jumper on the board, you can drive external h-bridges capable of driving well over 4A.

From page 7 of the Serializer User Guide (http://www.roboticsconnection.com/multimedia/docs/SerializerWL_UserGuide_v2.0.pdf):

Flexible H-Bridge Control:

Not only can you use the onboard h-bridges to drive two DC motors (up to 4A each), but you can also drive external h-bridges (with a higher or lower capacity) with the change of a jumper. If that's not enough, you can drive the onboard h-bridges from an external controller. This flexibility allows the customer to use the Serializer™ in many applications.
Using the Generic I2C command, you can ALSO easily interface up to 8 Gamoto PID Motor Driver boards, without tying up the onboard h-bridges. This allows you to use the onboard h-bridges to control two motors (or a bipolar stepper motor), and use the Gamoto PID Drivers to control extra motors.You can also check out the Serializer discussion going on here (http://forums.trossenrobotics.com/showthread.php?t=963)

04-09-2007, 12:37 PM
Hey, sorry about the double-post, but I think I've found exactly what I need: the Roboteq AX1500 (http://www.roboteq.com/ax1500-folder.html). It doesn't require much/any programming, can be set up to use an analog joystick and can power motors big enough. Has anybody tried using one of these?

I haven't tried that particular one, but we've got a few motor drivers that can be set up for analog control, if that's what you're looking for. Check out the Sabertooth and Syren controllers:

05-10-2010, 05:54 PM

I was wondering what became of your project. I am trying to do something similar with a Tippman A5. replaced the grip/trigger with 2 pieces of machined aluminum and looking to make a turret to mount to a tripod.