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Thread: Using the Serializer with Xbee WiFi

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    Question Using the Serializer with Xbee WiFi

    I am currently working on a robot butler as a part time project during school. I want to use the serializer board for controlling my robot. I thought it would be easier to not physically attach the robot to the computer but to instead have a more powerful desktop computer in another room controlling it. How hard would this be to do with the Xbee WiFi attachment? The computer would need to do all the thinking such as interpreting sonar values and moving the motors. Could this be done reliably with the Xbee? I don't plan on using python anymore because I think it would make things more complex. I hope to use a program with Microsoft .NET framework. What program would be best for a beginner to programing that has the Microsoft .NET framework?
    Dalton Caughell

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    Re: Using the Serializer with Xbee WiFi

    Quote Originally Posted by ROBOTMAN View Post
    I am currently working on a robot butler as a part time project during school. I want to use the serializer board for controlling my robot. I thought it would be easier to not physically attach the robot to the computer but to instead have a more powerful desktop computer in another room controlling it. How hard would this be to do with the Xbee WiFi attachment? The computer would need to do all the thinking such as interpreting sonar values and moving the motors. Could this be done reliably with the Xbee? I don't plan on using python anymore because I think it would make things more complex. I hope to use a program with Microsoft .NET framework. What program would be best for a beginner to programing that has the Microsoft .NET framework?
    Connecting with the XBEE rather than a hard serial cable should be no different (that's the whole design of the interchangeable modules). However, and I realize that the serializer has a DotNET library, I don't think DotNET is going to be any "easier" than Python (the serial protocol for the Serializer is really quite straight forward). Python is about the easiest language out there (that is a real language). I'd suggest rather than jumping around from platform to platform, sitting down and really learning how to use what you have.

    -Fergs

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    Re: Using the Serializer with Xbee WiFi

    I'm going to agree with Fergs here, but I'm going to expand a bit...

    If you _really_ believe you need dotNet, maybe Visual BASIC. BUT - dotNet is a gihugic rat-hole. There are so many levels of inheritance buried so deep in overrides that its rather impenetrable. I find myself gravitating more and more back to the "pure" languages. Python is still relatively pure but powerful. ANSI C with the appropriate libraries. Python with the appropriate libraries. PHP with the appropriate libraries. Easier to learn, easier to move around in, easier to do source and version control in a meaningfully maintainable sort of way.

    You need to do some soul-searching and ask why you _really_ feel you need the dotNet framework. You're asking to lock yourself into a structure that is going to be _very_ hard to break away from later. And later you're going to discover all the reasons why you want to, and you're "going to hate yourself in the morning"

    Yes, driving the Serializer over its serial control from any modern language on any modern operating system with any modern hardware is the ultimate trival programming endeavor. All the hard work is already done within the embedded system. I think you'll find that you bump your head when you start getting into fast wheel encoders and trying to do advanced SLAM, but for today, it should address what you're trying to learn, be it over a hard wire, BlueTooth, or the XBee.
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    Re: Using the Serializer with Xbee WiFi

    You mentioned running into problems with fast wheel encoders? Wheel encoding is why I plan on using this kit. My home made solution with the arduino didn't work because encoder data was getting to my python code to slow. I now plan on using this kit for the base of my robot butler. http://www.trossenrobotics.com/stinger-robot-kit.aspx. Would I run into problems trying to keep the robot from drifting left or right with encoders using serializer. The big problem with my last bot was that it would slowly turn to the left or to the right. My real fear with the serializer is getting encoder or sensor data too slow and either drifting or hitting something; also not being able to send commands back quickly and efficiently.
    Dalton Caughell

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    Re: Using the Serializer with Xbee WiFi

    You need to look at your architecture and code. Thousands of people are effectively using the Arduino and encoders. If your architecture is messed up with such a simple system, trying to move to a non-deterministic PC-based system is going to be a nightmare for you.
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    Re: Using the Serializer with Xbee WiFi

    My concern for you is that you are just transferring the problem of a noisy algorithm off one onboard core to an inherently noisier and far less manageable remote core. You're going to amplify the problem instead of resolving it. Have you done any reading into process control, like Kalman Filtering?
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    Re: Using the Serializer with Xbee WiFi

    Quote Originally Posted by ROBOTMAN View Post
    You mentioned running into problems with fast wheel encoders? Wheel encoding is why I plan on using this kit. My home made solution with the arduino didn't work because encoder data was getting to my python code to slow..
    We discussed this is the last thread I thought. If you want to do closed-loop speed control, it really has to be done entirely on the micro. Sending encoder counts up to a PC, and then adjusting the motor output from that PC is likely going to generate way too much lag -- frankly, I'm amazed that you just had gradual drift, rather than the robot breaking into oscillation.

    Maybe you should post up a bit more about your current version, it's almost certainly less work (and definitely less cost) to debug the current implementation, than to jump ship and start from scratch.

    -Fergs

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    Re: Using the Serializer with Xbee WiFi

    The reason for the drift was bad serial communication due to crappy coding on my part and your right it was more like oscillation. Also my encoders where just modified line sensors. Basically the whole setup was bad. I'm looking for a more professional look and feel that a wooden platform, arduino, and phidgets motor controller couldn't give me. Condensing the robot into a smaller factory made platform and getting real encoders seems like a good idea. I have no way of controlling my size and torque motors form an arduino otherwise I would. Also my computer needs to be able to control the motors fully to use the robots full potential something that seems difficult to do with the arduino. Also changing the boards needed to control this robot from four to one makes more sense in my opinion.
    Dalton Caughell

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    Re: Using the Serializer with Xbee WiFi

    Quote Originally Posted by ROBOTMAN View Post
    The reason for the drift was bad serial communication due to crappy coding on my part and your right it was more like oscillation. Also my encoders where just modified line sensors. Basically the whole setup was bad. I'm looking for a more professional look and feel that a wooden platform, arduino, and phidgets motor controller couldn't give me. Condensing the robot into a smaller factory made platform and getting real encoders seems like a good idea.
    I definitely can see reliability being a reason to jump ship (based on the breadboarded pictures I've seen of your bot), but I think a few of your other reasons aren't such a good motivation for jumping ship.

    Quote Originally Posted by ROBOTMAN View Post
    I have no way of controlling my size and torque motors form an arduino otherwise I would.
    Huh? You're using banebots motors and wheels combo, right? You could get a motor driver that interfaces with the Arduino, such as one of the Sabertooth models.

    Quote Originally Posted by ROBOTMAN View Post
    Also my computer needs to be able to control the motors fully to use the robots full potential something that seems difficult to do with the arduino. Also changing the boards needed to control this robot from four to one makes more sense in my opinion.
    Your computer could control the motors -- the PC sends a desired speed to the Arduino, and the Arduino drives the motors and uses the encoders to adjust the motors, trying to keep the desired speed.

    -Fergs

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    Re: Using the Serializer with Xbee WiFi

    An Arduino could control motors large enough to float the Enterprise aircraft carrier, or small enough to brush your teeth. And it has less latency inherently, with an easier to use interface, and is designed and intended to talk to a PC.

    The Serializer is just a PIC 18F452 with a small motor controller and a friendly output to TTL serial (friendly being a couple 2mm headers).

    I hate to say it, because I don't think the Serializer is a bad board used for the right reasons [I'm playing with one on Dora in fact], but the arbotiX does everything it does and a whole lot more - you can't really run code natively ON the Serializer, but you can on the arbotiX. And the arbotiX has two serial ports instead of one. And the arbotiX is a grown-up version of the Arduino intended for robotics. The Arduino could do about everything the arbotiX does, and a Sanguino certainly could, it's just the arbotiX is packaged nicely.
    Last edited by Adrenalynn; 10-24-2009 at 07:18 PM.
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