Shop OBEX P1 Docs P2 Docs Learn Events
Rf network of 6-10 bs2 boe-bots — Parallax Forums

Rf network of 6-10 bs2 boe-bots

rfman78rfman78 Posts: 12
edited 2007-03-09 21:50 in BASIC Stamp
Hi group,
I'm thinking of using the BS2 boe-bots to implement a sensor network project that I'm working on. My question is if there is enough resources on BS2 board to simultaenously control movement of the boe-bot, monitor the sensors to detect objects, monitor current position using GPS, broadcast coordinates to a PC (using RF), and recieve (using RF) coordinates from a PC. From the little research I've done, it seems like the Javelin is better suited for these kinds of tasks.

Does anyone with RF experience know if I cau use the parallax rf modules to network multiple boebots? Any inputs you could provide would be greatly appreciated. yeah.gif

Comments

  • Andy Lindsay (Parallax)Andy Lindsay (Parallax) Posts: 1,919
    edited 2007-03-08 21:31
    The RF communication will be fine, but the Boe-Bot might need to make brief stops to get the GPS data. If that's allowable, then you might want to take a look at the Bluetooth Boe-Bot robot for Microsoft Robotics Studio. Microsoft Robotics Studio would also allow your PC to function as the base station for·the group of autonomous robots.· By adding a Parallax Servo Controller to each Boe-Bot, you might be able to eliminate the need for brief stops and get back to doing it all on the fly.

    Bluetooth Boe-Bot Robot·for Microsoft Robotics Studio

    Other options for doing it all on the fly (no servo controller required) include switching to either the Javelin Stamp or Propeller Microcontroller. Especially if you want to have all the robots communicate and function autonomously without a PC base station, the Propeller microcontroller is probably your safest bet for a processor.

    Propeller·chip on Boe-Bot forum thread with picture and some code that follows an object with dual PID distance/servo control loops.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Andy Lindsay

    Education Department
    Parallax, Inc.

    Post Edited (Andy Lindsay (Parallax)) : 3/8/2007 9:37:51 PM GMT
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-08 21:38
    Theoretically you could do this. There have been wireless networks using ethernet techniques on a single RF channel. It would be fairly slow. You'd be better off with xBee which allows addressed packet communications. Martin Hebel (www.selmaware.com) has an AppMod adapter board that nicely mounts on a BOE. You might want something that will offload the handling of the servos, like a PWMPAL that can mount under the Stamp. The Stamp can poll the GPS, collision sensors and the xBee interface. I think you'll have a better time with the Javelin or a Propeller (on a Protoboard) since they both can easily do multitasking.
  • rfman78rfman78 Posts: 12
    edited 2007-03-09 00:37
    Thank you both for your replies. At this time, I think that it may be best to switch to the Javelin ! Hopefully Parallax takes returns on USE BOE-BOT! [noparse];)[/noparse]

    It seems like the Javelin is more suited for multi-tasking assignments, plus the Java interface looks a lot neater and considerably more powerful and intuitive than the procedural PBASIC!
  • Martin HebelMartin Hebel Posts: 1,239
    edited 2007-03-09 01:20
    The Javelin is fun, but nothing is going be as much fun as using the Propeller & the boe-bot sized proto-board. It's cutting edge technology, very simple to program and at $19, the best bang for the buck parallax has to offer! ** Prop-Plug required for programming, not included **. Nothing against the Javelin, it just isn't....the Propeller!

    So keep those boe-bot kits and use them with the proto-board instead.

    my 2 cents,

    -Martin

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    StampPlot - GUI and Plotting, and XBee Wireless Adapters
    Southern Illinois University Carbondale, Electronic Systems Technologies
  • Bill ChennaultBill Chennault Posts: 1,198
    edited 2007-03-09 01:35
    Mike--

    Do you have time to expound a bit on wifi's (G) inadequacy in this situation? And, would you say something about 802.11G as the carrier between a PC and a single device, but one with a "lot" of simple I/O? (Joint positions, proximity detection, and collision sensors, mainly.) I know this is vague, but so am I. Your words are valuable to me.

    Thanks!

    --Bill

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    You are what you write.
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-09 02:12
    Bill,
    I don't think WiFi is in any way inadequate. It's kind of complicated for the task and pretty much any implementation will take more power than you're probably spending on everything else except motors even if it is only 1-2W. If you were using embedded Linux or a similar system on an appropriate processor, I'd think WiFi would be a preferred wireless link, but you're not. Bluetooth is a nice single master, multiple slave system with good range, reliability, and addressability and would fit in with your network. xBee is, to my mind, better because it has an addressable packet-based mode, it's low power, reliable, and less complicated than WiFi. If needed, the BOE-BOTs can communicate with each other as well as with the "base station". To the "base station", the I/O looks like a serial port which is usually easier to manage in most high level languages than multiple network connections.

    I'd second Martin's suggestion about using the Propeller. The Javelin is still a single processor even though it can do certain I/O "in the background" using interrupt routines. The Propeller really is a multiprocessor. You will use one processor for talking to the network, one for bit-level serial I/O, another for servo control, maybe do most of the sensors with one processor. That still leaves a couple.
  • Bill ChennaultBill Chennault Posts: 1,198
    edited 2007-03-09 03:17
    Thank you, Mike.

    --Bill

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    You are what you write.
  • Martin HebelMartin Hebel Posts: 1,239
    edited 2007-03-09 19:59
    Since last semester, my·electronics technology students in their club have been working on an interface & code to control and monitor multiple Boe-Bots at once, using XBee's and StampPlot.· The plans were to write-up an article for Nuts and Volts.· I'm not sure it'll ever get done, so I asked if I could post what they had going on my web site.

    It's a nice illustration of being able to monitor and control 3 bots, switch them to autonomous mode, or control all as a group using broadcast address.· I posted the code, macro and a short discussions at:

    http://www.selmaware.com/stampplot/xbee/xbee_bots.htm

    -Martin




    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    StampPlot - GUI and Plotting, and XBee Wireless Adapters
    Southern Illinois University Carbondale, Electronic Systems Technologies

    Post Edited (Martin Hebel) : 3/9/2007 8:04:06 PM GMT
  • rfman78rfman78 Posts: 12
    edited 2007-03-09 20:59
    Wow, I like that xbee interface a lot. Your suggestions have been so helpful. I've decided to go with the Javelin controller and the xBee for the communcations. The propellor looked to be quite a bit of overkill for what we're going to try to accomplish. The main focus of this project is the sensor network, not really the robots, so the propeller will have to wait until I decided to focus on a purely robotics project!

    I'll definetely keep you guys posted with my testing, and the code as it progresses along.
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-09 21:14
    If you've familiar with Java and would prefer using it, then the Javelin is for you. If it doesn't make a difference, I'd go with the Propeller. It's also cheaper, particularly in the Protoboard configuration.
  • rfman78rfman78 Posts: 12
    edited 2007-03-09 21:28
    I studied the propellor, but something about the Javelin keeps drawing me to it. I think its the chance to work on my Java skills while simultaneously working on this project that excites me. But do you see any possible problems with using the Jav instead of the Prop? If you dont mind Mike, I'd like to ocnsult with you as I start prototyping and putting this network together. Seems like you've got a lot of experience with a lot of the parallax microcontrollers and products!

    Also, isn't java more in line with what industry uses (C++ for embedded software industry) ?
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-09 21:50
    rfman78,
    There's no problem in using the Javelin. Do keep in mind that there's no dynamic memory allocation, particularly an issue with string use.

    As you start prototyping and putting this together, do post your progress and problems that you run into. There's a tremendous amount of experience among the various members of this forum. If you do go with the Javelin, use the Javelin forum and the Sandbox since this particular forum is specific to the Stamp processors.

    In terms of industry use of Java, there's very little use in microcontrollers and Java requires a lot of processor "horsepower" to support. About the smallest platform I've seen with wide usage of Java is the Palm and PocketPC. I imagine you'd find some support with the ARM type larger embedded processors. It's rare to see Java on something like the SX processor (the Javelin).

    Post Edited (Mike Green) : 3/9/2007 9:55:42 PM GMT
Sign In or Register to comment.