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Using steppers in antenna tracker

Posted by George Myers on January 12, 2016 at 9:53am

Not sure where to post this as I have seen "antenna tracker" in a few different places. 

I would like to reuse a piece of equipment that has steppers to move the pan and tilt axis. I have had no luck in finding antenna tracker electronics that would drive steppers. Or if I did I missed its meaning.

I can hack the equipment to use servos but the current setup with steppers is something I rather not hack up as it is a pretty nice piece of equipment.

My quest is:  Is there antenna tracker hardware that drives steppers instead of servos?

Thanks for any suggestions.

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Replies

  • John Fitter August 30, 2017 at 3:33am

    Nothing can drive a steeper motor, but you are correct - BGC cannot drive stepper motors. It can however drive BLDC motors in micro-stepping mode, and BLCD motors are "dirt" cheap. I did not offer a solution to George's problem of driving stepper motors. Such a solution is TRIVIAL but because low cost steppers have a step angle of 1.8deg some mechanical gearing is likely to be needed and this makes the tracker complex. I offered a cheap and fast solution to the problem of having a tracker that will work with light loads, such as a single small antenna. Refer to the first sentence in my reply "here is an idea".

    I have set this up and it works just fine with really cheap eBay gymbals and BGC. You need to rearrange the motor arms to get the motion required for a tracker - something like a Chinese puzzle - and setup the BGC to output Yaw on the Roll motor and input Yaw from from the Roll RC input.The main limitation I found is the IMU code - BGC cannot cope with the IMU inverting itself so deflections of even a small amount beyond 90 degrees cause chaos.

    It would be interesting to use the IMU as an external IMU to the FC and let BGC be no more than a micro-stepping driver. That would work, but I am too busy with radar software to code this. It's certainly a cheap solution to a small tracker and could be a good project for someone.

    Who are you???



    OG said:

    BGC CONTROLLERS! Can not drive steeper motors ! This what you recommend right? BGC and stepping are different motors are also different.




    John Fitter said:

    This is a technical forum, not Facebook. You can't make unsubstantiated claims. Tell us exactly WHY it will not work.

    OG said:

    This most definitely will not work !!! What you need is adrduino and stepper shield or steeper drivers code already out there that convert Between languages so you do not need to know how to code .


    John Fitter said:

    Here is an idea. Get any gymbal controller. There are cheap clones on eBay. These are designed to run two stepper motors in micro-stepping mode. The micro-stepping mode gives you less torque but finer resolution and is ok if you balance your tracker.

    The controllers have a serial connection as well as servo inputs designed to take pwm signals from the autopilot to drive the gymbal to a set position. It also has a motion sensor input which you can use if you want.

    I use one of these with a small bluetooth dongle connected to its serial port for comms. 

    A BGC 3.1 Control Board is under $10 and will handle 10A peaks and -8 motors.

  • OG August 29, 2017 at 8:07pm
    BGC CONTROLLERS! Can not drive steeper motors ! This what you recommend right? BGC and stepping are different motors are also different.




    John Fitter said:

    This is a technical forum, not Facebook. You can't make unsubstantiated claims. Tell us exactly WHY it will not work.

    OG said:

    This most definitely will not work !!! What you need is adrduino and stepper shield or steeper drivers code already out there that convert Between languages so you do not need to know how to code .


    John Fitter said:

    Here is an idea. Get any gymbal controller. There are cheap clones on eBay. These are designed to run two stepper motors in micro-stepping mode. The micro-stepping mode gives you less torque but finer resolution and is ok if you balance your tracker.

    The controllers have a serial connection as well as servo inputs designed to take pwm signals from the autopilot to drive the gymbal to a set position. It also has a motion sensor input which you can use if you want.

    I use one of these with a small bluetooth dongle connected to its serial port for comms. 

    A BGC 3.1 Control Board is under $10 and will handle 10A peaks and -8 motors.

  • John Fitter August 29, 2017 at 6:24pm

    This is a technical forum, not Facebook. You can't make unsubstantiated claims. Tell us exactly WHY it will not work.

    OG said:

    This most definitely will not work !!! What you need is adrduino and stepper shield or steeper drivers code already out there that convert Between languages so you do not need to know how to code .


    John Fitter said:

    Here is an idea. Get any gymbal controller. There are cheap clones on eBay. These are designed to run two stepper motors in micro-stepping mode. The micro-stepping mode gives you less torque but finer resolution and is ok if you balance your tracker.

    The controllers have a serial connection as well as servo inputs designed to take pwm signals from the autopilot to drive the gymbal to a set position. It also has a motion sensor input which you can use if you want.

    I use one of these with a small bluetooth dongle connected to its serial port for comms. 

    A BGC 3.1 Control Board is under $10 and will handle 10A peaks and -8 motors.

  • OG August 28, 2017 at 11:32pm
    This most definitely will not work !!! What you need is adrduino and stepper shield or steeper drivers code already out there that convert Between languages so you do not need to know how to code .



    John Fitter said:

    Here is an idea. Get any gymbal controller. There are cheap clones on eBay. These are designed to run two stepper motors in micro-stepping mode. The micro-stepping mode gives you less torque but finer resolution and is ok if you balance your tracker.

    The controllers have a serial connection as well as servo inputs designed to take pwm signals from the autopilot to drive the gymbal to a set position. It also has a motion sensor input which you can use if you want.

    I use one of these with a small bluetooth dongle connected to its serial port for comms. 

    A BGC 3.1 Control Board is under $10 and will handle 10A peaks and -8 motors.

  • John Fitter August 28, 2017 at 10:53pm

    Here is an idea. Get any gymbal controller. There are cheap clones on eBay. These are designed to run two stepper motors in micro-stepping mode. The micro-stepping mode gives you less torque but finer resolution and is ok if you balance your tracker.

    The controllers have a serial connection as well as servo inputs designed to take pwm signals from the autopilot to drive the gymbal to a set position. It also has a motion sensor input which you can use if you want.

    I use one of these with a small bluetooth dongle connected to its serial port for comms. 

    A BGC 3.1 Control Board is under $10 and will handle 10A peaks and -8 motors.

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