Tilt slew issue

Discussion in 'Radian' started by Remy Dehaan, Aug 19, 2015.

  1. Remy Dehaan

    Remy Dehaan New Member

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    Hi all,
    First post and time setting up Radians i had laying around and having an issue with the slew on the tilt axis. My simple needs are to be able to tilt the camera to look straight down (leave it there) using a 2 position switch and return it to upright. Just taking photos with a scientific camera.

    Aircraft Type: Cinestar 8
    Gimbal Type: Cinestar 2-axis

    Controller: DJI Wookong
    Radian Type 2-axis
    Gimbal Power source: powered through S-bus from Futaba receiver R6208SB
    Gimbal Radio Type: Futaba 18MZ (single operator)
    Radian Communication Protocol (S.Bus): Futaba

    Connections:
    Roll Sensor:
    Port
    1. SBUS - including Power from RX
    2.
    3. To Tilt sensor
    4. To Roll servo

    Tilt Sensor:
    Port
    1. From Roll sensor
    2.
    3.
    4. Tilt servo

    Mode setup to channel 12 for both units and in Stabilized Slew on start up.
    Roll axis slew off
    Tilt axis Slew Channel 13.

    The problem: I can get the system to do exactly what i want using the assigned switch and adjusting endpoints for Channel 13 connected to the tilt via USB. Once done dosconnect USB and system is still fine and working until i power down. As soon as i power down the Wookong/RX and restart again the CH13 slew switch won't work. If i adjust the endpoints on the radio to a different value the slew works again. Power down and power on again no longer works. Adjust endpoints to different values works again. Driving me mad.

    Anyone got any ideas? I know i haven't provided pictures etc but wondered if anyone has encountered this before?
    Also is it ok to only power the radians with a single sbus lead on port 1 of the roll? Everything seems to work fine and camera is light and stabilization is fine. I will keep trolling the forum in case i can find something.
    Cheers,
    Remy
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

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    Remy:
    1. Are you saving the changes back to the Radians? It's been a long time since I worked with one, but I recall that you have to save the changes once you've made them if you want them to be permanent.

    2. I would provide separate power to the servos (with a common ground connection) as the servos pull about 1.5 Amps each and also emit a fair amount of DC noise back down their power lines.
    Hope this helps
    Andy.
     
  3. Remy Dehaan

    Remy Dehaan New Member

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    Thanks Andy. I have worked out the problem and thought i would tell others in case anyone is still using a servo driven gimbal for photo work or like me trolls this forum to find a solution. Cannot believe i left these on the shelf for so many years and just used the wookong even though it is good enough for taking Nadir photos the radians do so much better stabilisation even for this.

    Most people setup the radian on a second radio and use a stick to command input of the slew. The stick is usually at the neutral position (0) when they set it up and has 2 directions outside center where it can move the camera up or down. I made the mistake of using a switch which is fine but you won't get any slow slew as your fixed end positions are essentially commanding the fastest slew rate (like pushing your stick to max deflection) when you flick the switch rather than a slow slew as you move the stick slowly through its axis. The radian just sees you have reached your max endpoint and therefore gets to the min or max angle that you have defined as fast as it can when you apply the switch. My mistake was to use a 2-postion switch as you are at one end or the other with no neutral. It seems the radian assumes one position is neutral or zero and the other is maximum in one of the directions.

    So when you flick the switch because you don't go pass neutral it doesn't receive the command to go back in the other direction. Hence why i could adjust endpoints later and get it to move back as i past the zero position by adjusting the endpoints in the radio. Changed it to a 3 position switch and it works as i would expect. Importantly you must write the channel/switch in the radian software while it is in the neutral or middle position so you have a down and up in the other positions otherwise the effect is the same and the radian won't recognise you have gone pass zero and hence won't return the camera back in the opposite direction when you flick the switch. All makes sense now that i think about it.

    Thanks for the info on power. I will run signal and ground from the main copter sbus and tap into the main power loom with a 5v castle bec. The system is working fine and the sbus receiver is only providing a signal to the wookong and is rated to handle higher than the two servos loads but better to be safe rather than sorry.

    Thanks again for your reply.
     

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