• aditya mehrotra.

drone updates: main and tail blades are off - ESC setup PART 2 [updates]

So as of this afternoon we realized that taking the main and tail blades off allows us to not need to have the landing gear on to do the next part of the setup. At least video 3 I think.



So here we are, in the backward, with the helicopter, and we have the blades off and we need to do the helicopter's ESC calibration and RSC setup.



As usual, we're going to follow the video and take Chris' works like the word of the universe. This is TWO separate videos. This video - the 20 min one, is the electric configuration. And in the next video it's GAS helicopters. So we only have this one video left.

  • First there's a setting Chris says we need to go back to and that's H_LAND_COL_MIN which actually we need to get right but we didn't last time. That's NOT on 1000-2000 that's on 0-500 --? that means the number of pulses above the 1000 minimum to set it to. And they've limited it to 50% of the range because above that the Heli should be flying. Remember we set this lower than we think we will need to so let's leave it at the 100PWM.

  • So interestingly we do not have that parameter: https://discuss.ardupilot.org/t/arducopter-4-0-heli-summary-of-changes/48291 and now we see why because in ArduCopter 4.0 that was deprecated. So let's not worry about that.

  • The problem is this means H_COL_MID must be set VERY accurately. So we'll test this on the field before doing any autonomous flights and such.

Now it's time to look at HELI_RSC.

  • There are three modes: mode 1, mode 2, and mode 3.

  • MODE 1 - "ch_8" is RC passthrough it just takes the command from channel 8 on the radio and sends it to the system.

  • MODE 2 - is a literal set point it just sends that ONE value (this is used with helicopters with governors only).

  • The thing is we have a governor. And MODE 1 is also designed for electrics with a governor. Chris does not recommend using it as simple passthrough and a throttle curve on the radio. Because then the autopilot has absolutely NO control over the throttle which is not ideal. Basically the failsafe will not work properly.

  • MODE 1 - let's us change head speeds so we're going to try to use that.

  • The reason we want to use governors is as the voltage sags the ESC still tries to hold the speed of the motor. So we need to do two things here. We need to setup the governor on the talon 90, and we need to setup ardupilot. The problem is we don't have an ESC programmer. Which means I don't think we can do it but let's watch the video.

  • So correction - I think with the talon 90 - we can actually do the governor setup from ardupilot itself and not need to put the ESC in governor mode. I'll have to verify that.

  • Okay so FIRST - we need a channel 8 switch that turns the throttle signal on/off. So we're going to make that SWITCH F and at some point re-calibrate the radio.

  • NEVER USE H_RSC_IDLE parameter. = 0 for electric.

  • SO according to the website: https://www.thundertiger.com/products-detail.php?id=28 the ESC was pre-programmed at the factory so let's see what the settings were.

ESC setup:

  • They said it's already programmed I don't know to what speed the head will be rotation at we can assume like 2000 RPM I think is a good assumption. But I do want to set the switches correctly in ardupilot.

  • We'll have switch F be the throttle switch and we'll have the knob be the speed control.

  • Let's read the manual for the helicopter... which is unfortunately utterly useless since its a thunder tiger.

Okay so here's what I'm gathering. We should use the ardupilot governor because I don't know how the ESC governor works and I don't know how the transmitter is sending a signal. So what I think we're going to do is not use VRB as the throttle signal instead use the switch. Now let's setup the governor in ardupilot.

  • So let's try the switch with the 1500 RPM governor in-built. Okay so that didn't do anything. Let's switch the pilot to governor mode and see what happens.

  • Okay so the copter won't go into governor mode - likely because we don't have a speed sensor. What we're going to do now. Is set CH8 to the knob so we have very fine control over the head-seed. Set the governor to pass-through. And fly like this for now. I think it'll be okay but let's figure out how high we really need to go on the PWM.

  • The motor need about ~17.3913043478 V to maintain a headpseed of 2000 RPM.

  • What this means is we roughly set the PWM to 70% - 80% of it's max throttle range which is about 3/4 of the way on the VRB knob. So as long as we know where about 2000 RPM is we should be fine and I think that concludes the Heli's throttle setup. Nothing fancy just a knob and RC passthrough.

What I do want to do now though, is basically go through the original parameters and see if we got everything and then do the things like SAFETY setup.

  • H_RSC_MODE covering later when we do RSC setup

  • H_RSC_RAMP_TIME is the amount of time it takes for the helicopter blades to SPIN UP. (we need to measure this or set it HIGH)

  • H_RSC_RUNUP_TIME is the amount of time for the head to actually reach the speed ~1s longer than ramp.

Let's just double check these parameters.

  • H_RSC_MODE - OK

  • H_RSC_RAMP_TIME - let's make that 10 seconds

  • Let's make the sunup time 11 seconds

So that's ALL OK - now what we want to do is go through each tab of the system and setup things like SAFETY checks and etc.

  • So we've set it to go though all the arming checking including battery which seems to be working even though it isn't displaying on the ground station.

  • I think we're going to switch to power_1 and try to see if it come up on the ground station. And if this does not work we'll try the cube ORANGE setting. So it does the check and ENABLES but it doesn't display the voltage :(

  • Change the mode to normal startup so we don't recalibrate the ESC every single time.

  • Ah yes, switching to analog voltage and current DID IT! It says 23.87V and 1mah. YES!

  • We're doing all the pre-arming checking btw.

  • Now let's turn on ESC CAL ON STARTUP is OFF and now that the props are disconnected I'm going to hit calibrate on the ESCs one more time.

  • Now let's fix that GPS -- and we can now automatically calibrate ESCs on startup. Let's re-boot the vehicle.

  • So now we have battery monitoring, and 13 GPS satellites!

  • We can now arm in ALL modes.

I think, now on the software side, we're all done! I just want to double check the GPS parameters. There might be one last thing to do which is compass motor interference calibration.

  • It doesn't seem to be working with out helicopter at the moment. Whatever - it would have sensed no interference and the compass will be ok.

  • The motor interference compensation type is disabled so it's ok.

The LAST change we're going to make is the channel 12 switch as AUTOTUNE which means we will no longer have control of the helicopter which means that switch is RED. We're going to table all the switches here for reference. It won't enable on the ground but maybe in the air. We can leave it for now. Okay let's table the transmitter!



So we have all that for the record and now. The helicopter should be fully re-setup. What are the next steps?

  • First, we need to 3D print the new landing gear for the helicopter and maybe a new tail blade guard.

  • Then we can start learning to fly in loiter mode.

#updates #omgrobots #yaysetup

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