Does this firmware support coaxial/coax copter? if anyone successfully tested the coaxial or coax copter using Pixhawk Cube Orange on the mission planner. Please share with me the link to refer them.
thanks.
Hi, you are asking about a coaxial helicopter? It has cyclic and collective pitch and a constant rotor speed? Just want to be sure because there is a multirotor configuration called Coax copter that uses variable speed fixed pitch props.
If you are referring to a helicopter then yes, we have had users successfully fly coaxial helicopters with this firmware.
Regards,
Bill
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Swashplate mechanisms with four servos are employed in my design, which I am relatively new to. I believe Arducopter’s Heli firmware can accomplish this. When I test the motors and servos with this firmware, I occasionally get the error Prearm: Motors Interlock Enabled. I cannot change it on the parameters list because it is not there.
And when I start giving throttle, one motor will sometimes start, and when I reach 100 percent throttle, another motor will start spinning; it is kind of the opposite. and it returns to normal without changing anything on the mission planner.
Concerning the Servos, what settings should I alter with four servos to get flawless swashplate movements?
Yes, the software is capable of handling swashplates wirh 4 servos. Are you using a Ganged swashplate setup where both rotors are connected for tilting the swashplate or do you have independent swashplate control (4 servos on each swashplate)
Did you follow the wiki for your swashplate setup. Here is a link to the wiki for swashplate setup.
https://ardupilot.org/copter/docs/traditional-helicopter-swashplate-setup.html
For 4 servo swashplates, you need to use the linear servo feature. Follow the set up procedure for linear servo to get flawless swashplate movement.
Motor interlock pre-arm message is common for those that haven’t set up the transmitter properly. The flight controller requires that an RC channel be used to enable motor interlock. The controller defaults to using channel 8. Put channel 8 on a switch on your transmitter. Set the switch low before arming. The pre arm message should disappear. Then arm the controller and when you are ready to start the motor, you would flip the switch to that high position. Then the motor will start. You can read more about the motor interlock and the rotor speed controller in the wiki.
Yes, my swashplate is driven by four servos in the H4_90 configuration.
Neither my RadioLink transmitter nor the mission planner allowed me to change the motor interlock.
Ch8 also increases as the throttle is increased. I tried adjusting it on the transmitter, but I don’t know why Ch. 8 isn’t modifiable.
Please post your param file. You can save it in mission planner by connecting to your heli and then go to config tab and on the left select full parameter tree. On the right of that screen, you will see a button that says save file. Use that to save the Params and then post them here.
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Dual_Heli.param (17.4 KB)
Please see the above param file.
And about the motors, is it normal for one motor to start running at 5% throttle and the other to run at 30% throttle?
Please describe the physical set up. Since you have two motors i’m assuming that you have two swashplates, one for each rotor and a motor driving each rotor independently?
My design is almost identical to this model RC helicopter. We use two motors with two spooling shaft swashplates and four servos to drive the swashplate. No tail rotor or flybars are used.
Just to be clear about your set up, you only have four servos total. I believe three of them control the lower, swashplate, tilting and movement up and down. The fourth controls the movement of both swashplates in opposite directions, which actually controls the yaw motion of the aircraft. The only way you could control both swashplates independently would need to have three servos connected to each swashplate. Which, from what I can tell here is not the case.
If you only have four servos total, then you wouldn’t use a dual heli frame type in Ardupilot. you would use a traditional helicopter frame type (frame type 6). The servo arrangements for the lower swashplate appears to be a H3–120 reversed swashplate. It could be an H3–140 swashplate but I can’t tell from the picture. Use the diagrams from the Swashplate set up wiki to determine what type of swashplate this is. The servo that controls the opposite movement of the swashplates on the shaft, would be connected to the tail rotor control for the traditional helicopter frame type.
Hopefully this makes sense and matches what you see with your helicopter.
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All four servos control the lower swashplate to move it up and down. It is an H4-90 swashplate type.
@Md_jln please provide pictures from other angles showing me the servos that are connected to the swashplates. You only have 4 servos to control the heli. How do you control yaw? Please provide a drawing or explanation.
Yes, you’re correct; we use four servos like helicopter swashplates. And it’s a coaxial Model, so the yaw can be controlled by adjusting both propellers.
@Md_jln I can’t help you determine the proper set up unless you provide pictures or a video to show how each of the axes (pitch, roll, yaw and collective) are controlled. Based on what I have seen and what you have told me, the dual heli frame is not the correct frame to use for this setup.