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Thread: Affordable Robotics Platform - First Proposal

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  1. #1
    Administrator T-1000 vikas's Avatar
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    Default Affordable Robotics Platform - First Proposal

    Hello all

    Affordable Robotics Platform - First Proposal

    Objective : The objective of the platform is to provide a affordable and low cost platform which can be easily built from available components . It will allow an starter to dive straight into robotics and yet be extendable enough for a person with some experience to use it for his own purpose . Libraries for various sensors and functionality ( LCD , light sensors ,IR , sonar etc ) will be available under the GNU GPL license . The total cost of the system is planned to be below < Rs 1000 ( 22 $ )

    Hardware Architecture

    Main Micro controller : I propose of using the x51 core for the system which is widely available and all major companies support the uC and have many other pin compatible alternatives are also available . So 89s8252 uC will be good enough its powerful and has most features of a good uC . I am still not shore about using a 64 K ram - abt 18 IO lines are required for it , Though i plan to use a multitasking core for the system .

    Power supply : Well this will be a simple 7805 based power supply with a simple on and off switch .

    Drive Type : This will be differential drive which will be driven by 2 geared motors . Though stepper motors offer better precision and control small steppers are hard to get and gear sets for them might not be available . Servos also have a similar problem . For dead reckoning we will print white strips on paper and stick it to the wheels and use them as a means to count the rotations .

    Motor driver : This will be a simple H-Bridge driver so we might use L293d or might use the simple homebuilt H-Bridge ( circuit available in the wike section )

    Sensor Details : The various sensors which will be used and what type .
    - Light Sensors : Simple CDS cells based light sensors will allow the robot to perform tasks like finding the brightest light / fire fighting ( 2 will be there )
    - Light Sensors ( for line following ) : These sensors will me mounted below the robot so as to enable it to follow the line ( will give output as 0 or 1 and will use lm234 as the comparator )
    - Light Sensors ( for Dead reckoning ) : These sensors will be near the wheels of the robot they will allow the user to know the approximate position where the robot is .
    - IR Sensors ( 2 IR LED with simple TSOP type detector ) : This will be made up of a simple dual IR LED and a IR Detection system . Will allow the robot to detect obstacles and avoid them .

    Battery : Rechargeable NiCad batteries will be used 6 in total There will be a charger built into the system using the LM 317 IC . Will allow the easy recharging of the circuit . There will be a socket to put in the power supply directly .

    Outputs : The various components which will allow us to know of status
    - LCD interface : There will be an interface for the intelligent LCD controllers ( Can be used to display information )
    - Status LEDs : There will be a set of 2 LED's which will tell of the 4 basic states in a robot . They can be easily switched off to conserve power . It will use up 2 lines on the uC .
    - Battery indicator : This will be a simple indicator telling of the battery status ( use lm234 ) .

    Communication - The communication will be though the UART only which could be easily connected to the serial port communication. There will be three types of extensions for this
    * Simple Serial comm : When connected using a null modem wire .
    * IR based comm : We could use IR modules when connected to communicating to a nearby module .
    * RF Based comm : WE could also use the widely available RF modules ( 433 / 27 / home built ) .

    Software Architecture

    Main core : I propose the usage of a simple multitasking RTOS , but am not so whore right now .

    Modular system : The system will be completely modular so as to allow only the components you wish to use be added . Adding the component for use in the core will be simply including the include files for the components and adding the requisite functions .

    Extendibility and reuse : Users will be easily able to modify the system to suit there own needs . For example to use the system to drive a ripped R/C car . All the user will have to do is change the config in the drive.h
    //proposed orignal config for Diff Drive
    // [00:left][00:right]
    #define FORWARD 0101
    #define RIGHT 0100
    #define LEFT 0001
    #define BACK 1010
    // R/C car config
    // [00:Forward Steering][00:Rear Drive]
    #define FORWARD 0001
    #define RIGHT 0101
    #define LEFT 1001
    #define BACK 0010



    Programming Language : The programming language used will be C ( the all time favorate )
    The syntax for using libraries will be something like

    /************************************************** *************************
    * What the code would should be like ( just thinking ) *
    ************************************************** *************************/

    //simple object avoiding bot

    #include "botconfig.h" // various pin level config of your robot
    #include "core.h" // always
    #include "drive.h"
    #include "irbump.h"

    void main()
    {
    init_core();
    init_drive();
    init_irbump();

    start_thread(object_detect);
    while(1);
    }

    //simple thread
    void object_detect()
    {
    while(1)
    {
    if(irbump_left()==true && irbump_right()=true ) {
    drive(BACKWARD);
    }
    if(irbump_left()==true) drive(RIGHT);
    if(irbump_right()==true) drive(LEFT);
    drive(FORWARD);
    }
    }


    License : All the code and circuit will be under GPL .

    This is just the first proposal , I want you to point the mistakes , make suggestions , give ideas and help us improve it . With your suggestions and help we might even start seeing the initial prototypes within a month or two . Please let us know though the mailing list or the forums at Robotics India .

    Be apart of the ARP TEAM
    Also anyone interested in the testing or development can also let us know through this thread .
    Also in case of the work being h/w oriented Robotics India will provide you with the requisite capital and components required free of cost ( in India only ).

    Vikas Patial

    http://www.roboticsindia.com

  2. #2
    Senior Member Cyborg
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    Default

    Hi Vikas,

    We (KRAIG, IIT Kharagpur) have been working on the development of a general purpose platform using the x51 for quite some time....first the idea came to my mind a few months ago, the design was prototyped using 89C2051 (pretty low capability, but good for testing) and now it is being improved upon.

    The current design has the following features:
    1. Two PWM motor drives capable of driving upto 1A motors in both directions
    2. IR communication with PC at 38Khz 300bps
    3. One Analog Comparator (2051 has inbuilt comparator)
    4. Five gen purpose Digital I/O pins
    5. Toy car with differential drive
    6. Power supply provided with 4 NiCd (700mAH) & 4 NiMH (2100 mAH)cells

    I'll soon be improving the design to extend it's capabilities.

    It would be very nice, if I could contribute to the design of the "Affordable Robotics Platform" as proposed by you.
    Sumandeep Banerjee
    M.Tech, IIT Kharagpur,
    B.Tech, IIT Kharagpur,
    http://www.robotix.in

  3. #3

    Default

    still in the non-existent world of x51 .. crap

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    Default

    well then whats there in the Existing world???
    Bhargav

  5. #5

    Default

    atmega128
    16 bit micrcontrollers
    and u can always go up the climb

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    hmmmm............ well most of the guys in India prefer x51 core uC.Easy to learn,easy to program and i dont think theres much which an x51 chip cannot do.Is there anything.Even if theres something there are alternatives.Btw this is like a group work and i think only vikas is familiar with the AVRs.
    Bhargav

  7. #7
    Administrator T-1000 vikas's Avatar
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    Default well

    I know that x51 is pretty old , I dont like it either ... But its damn cheap , major vendors support it ( intel, atmel ,pic ) . Lots of doc on the web .

    BTW i prefer x51 in this case becuse of the way it handles interrupts ( unlike avr or pic ) and also how the program memory is accessed and also becuase of its high avalibility ( most colleges have it too ) and affordability .

    Anyway for me AVR will be always better .

  8. #8
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    I have worked with AVR Atmega series but only through engineering samples. I am still waiting for good source of purchase of AVR in India and want to know approx. cost. The availability of MCU is the major factor to be considered before going for project of common interest. In India we have major limitation over availabilty. So its useless to use MCU having very good features but not available to common man for experimentation.
    Sunil Jha
    I.I.T. Kanpur

  9. #9
    Senior Member Cyborg
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    I strongly agree with sunil, whatever uC is considered, it's availablility in the common Indian market is to be thoroughly considered.

    and 'robodorylus' atmega 128 is good, but is not available everywhere, atleast not where I live !
    Sumandeep Banerjee
    M.Tech, IIT Kharagpur,
    B.Tech, IIT Kharagpur,
    http://www.robotix.in

  10. #10
    nirvanicgeek
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    Default

    Yeah even i agree with it. Mega128 is hardly available everwhere except the metros. So it is always better to use X51 series.Moreover as vikas said , there isnt a thing that x51 cant do, it is really powerfull chip. And support is also very high in case of x51.

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