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    SoR Biped Engine

    Axon controlled Brat biped robot

    image: provided by airman00

    The SoR Biped Engine is simple to use software to get your robot biped walking within ~30 minutes by PC control.

    How Does it Work?
    All biped motion patterns are called 'gaits'. A gait is a stored list of motions that the biped can perform. A timer of sorts is used to control each motion.

    The SoR Biped Engine sets up these gaits in software for you, and gives you the ability to control the speed at which these gaits are performed.

    You simply start with the default Axon software, install the Biped Engine files, then you tweak the gait to do what you want. Almost zero coding is required.

    This video shows my ERP using v2 of the Biped Engine:

    How to Install
    Read *ALL* instructions start to finish before following them.

    1) First, install your Axon software if you haven't already.

    2) Download the SoR Biped Engine v2.1 files into your Axon software folder. It will ask to overwrite both the default control.c and hardware.c files. Say yes, but make sure you backed up your older files first. You'll also see a gaits_ERP.c file, useful for commanding robot arms instead of legs.

    SoR Biped Engine v2.0

    3) hardware.c defines which servo goes to which port. You will probably like the current configuration as is, but its super easy to change if you want to. Open up the file, and attach your biped servos as shown. For example, if you see:

    #define left_foot(position)	servo(PORTH,6,position)
    
    That means you attach the servo for the left foot into H6.

    4) gaits.c defines gaits. Open up this file. First, you need to set home position, so modify where you see 'initialize home variables' and 550 to tweak the servos into the right positions. Then right after you will see 'define walking forward gait' with a huge matrix after it. That matrix you will have to tweak until your biped is walking. You do not need to modify any other part of this file.

    5) control.c is your 'main'. Currently its set up that if you use HyperTerminal with USB, pushing the letter 'h' brings the robot to home position, and letter 'w' for walking forward. My Axon tutorial explains how to use HyperTerminal. 'o' and 'p' toggle the green LED, useful to verify a working connection. You do not need to modify this file.

    6) In control.c you will see this line of code:

    walk_forward(10);
    
    The number represents speed of the gait, as higher numbers mean slower motions. You probably want to set it really slow while you develop and tweak your gait, say 100.

    7) Before compiling your code, you need to add this line to Axon.c at the top with all the other includes. Make sure you add it before control.c. For example:

    #include "gaits.c" //biped gait engine
    #include "control.c" //your code goes in here
    

    8) Future versions of this software will help you incorporate sensors for balance. Please check back for updates!

    9) For a simple test of all your servos and PC connection, upload the Biped_Engine_Test.hex and see what happens. This file is just the compiled version of the default software, so it's guaranteed to work. (hint, useful for debugging)





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