I have a newer 3dr iris+ and recently had a flight where the Mission stated an altitude of 200meters. It flew most of the way at the correct altitude, but towards the end it started to get low, to around 50 meters. I was watching and I switched it into loiter mode and put the throttle high up and it had no problem gaining altitude.The battery voltage was fine as well, as it was a short mission.What could cause this? I was using the droidplanner2 android software....I can provide logs if needed....Thanks in advance for your help!
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Thanks for the file Michael. Performance doesn't appear to be that different, although your motors are running at slightly lower PWM values than Adams; not significantly though.
Adam,
Was it windy the day you had this flight? In the images below you see a plot of Altitude vs. Speed, and Motors 1 + 4.
During the climb you can see that Motor 1 maxes out at full throttle. Once it reaches altitude the throttle drop as expected and it maintains the 200m requested. Next I believe you reach the next WP and commanded X number of turns, during which time speed is obviously decreased, but you are losing altitude. Next it proceeds to the next WP and struggles to climb, again maxing out throttle on Motor 1. Again at the next WP you ask for X turns I believe and there is a loss of altitude followed by proceeding to the next WP and another attempt to regain lost altitude. I believe we change directions here and we see Motor 1 become more stable while Motor 4 maxes out the throttle and stays there (this is why I ask if it was windy). Your really losing altitude rapidly here and finally you attempt to regain control by switching to loiter.
I don;t have a concrete answer for why, or what to do; but as Michael suggested you might try reducing WPNAV_SPEED a bit. Also running your mission at a lower altitude might help as well. Your voltage dropped quite a bit during the climb to 200m and might be having some effect on performance.
Try these changes on a small mission at a lower altitude of say 100m or less and see what happens. Be sure you have a freshly/fully charged battery. Do you have a way to check the pack voltage (individual cells if possible). A fully charged pack should be between 12.5-12.6 volts with each cell being between 4.15-4.2 volts.
I have an IRIS with a Gopro Tarot gimbal and have flown several missions with no issues with power. Flight times where in the 10 minute area. I have flown at 100 meters but not at 200 which for the most part is counter productive as this makes the items being photographed become to small to be important. I find flying at 20 meters to be to high as well but useable.
The IRIS does not use the same ESC's as the other copters from 3DR. It has a 4 in 1 ESC.
The other batteries do not fit in the space provided by the IRIS. The 5100 IRIS+ battery is a great option as it is light weight and has lots of power. Other batteries add too much weight. With the IRIS battery you can get about 4000mah which leads to about 20 minutes of flight time and over 10 minutes with gimbal. You can't use 5100 mah from your battery as it would be dead and rendered useless. You need to leave about 20% in the tank when you get it on the ground.
I also used Droid Planner to watch as my copter flew over the target area and was able to track its movement more closely then with the naked eye.
Great Suff. Love it.
Adam S > Michael BurmeisterDecember 29, 2014 at 2:26pm
Hi Michael,
Do you know if there's a way to make it so if during a mission it sees itself losing altitude, it will lower the speed?
I do love using the Iris+! Telemetry to my android phone is amazing as well!
Sorry, have not had that issue and I would think that it would try to maintain that altitude by slowing down. It is in auto mode so it should be trying to stay at that altitude as one of the parameters. You could lower the waypoint speed as well.
Nathaniel Caner > Michael BurmeisterDecember 30, 2014 at 6:18am
Hey Michael,
Thanks for the link, I hadn't seen that site before. I had hoped to be able to download the log file so I could compare some things like motor output levels climb rates etc., but I couldn't find a way to download the file. Any chance you could post it here?
Correct me if I'm wrong with this, but here's my logic as to potentially why it was flying so low:
When I'm flying straight up, with no forward/reverse velocity 100% of the available power is going towards holding or increasing the altitude.
When I'm flying forward, the quadcopter is tilted at an angle. This would (brings me back to statics class) share the amount of thrust with vertical AND horizontal. Thus is would need to increase thrust to maintain the current altitude. Faster I'm flying, more thrust needed.
I was cruising at about 10 m/s, so maybe the quadcopter didn't have enough thrust to both fly at 10m/s and hold the altitude?
Wouldn't the only way to increase thrust be to increase the motor speed? (Or change props). But the motor speed is based off the voltage, and I'm not going to a 4s battery.
Does raising the C rating on the battery change the motor speed?
Replies
Thanks for the file Michael. Performance doesn't appear to be that different, although your motors are running at slightly lower PWM values than Adams; not significantly though.
Adam,
Was it windy the day you had this flight? In the images below you see a plot of Altitude vs. Speed, and Motors 1 + 4.
I don;t have a concrete answer for why, or what to do; but as Michael suggested you might try reducing WPNAV_SPEED a bit. Also running your mission at a lower altitude might help as well. Your voltage dropped quite a bit during the climb to 200m and might be having some effect on performance.
Try these changes on a small mission at a lower altitude of say 100m or less and see what happens. Be sure you have a freshly/fully charged battery. Do you have a way to check the pack voltage (individual cells if possible). A fully charged pack should be between 12.5-12.6 volts with each cell being between 4.15-4.2 volts.
Regards,
Nathaniel ~KD2DEY
It was pretty windy, which would make sense. I might try:
https://www.cloud-surfer.net/2014/10/10/improving-lift-on-iris-with...
to increase thrust. I don't want to change to 4s batteries and risk my warranty.
I am trying to see how I can reduce the weight as well.
I want to add a FPV kit/goggles to the copter at some point, if you have any recommendations!
Can't thank you (everyone else who responded) for all your help! It's all been extremely helpful to me.
I have an IRIS with a Gopro Tarot gimbal and have flown several missions with no issues with power. Flight times where in the 10 minute area. I have flown at 100 meters but not at 200 which for the most part is counter productive as this makes the items being photographed become to small to be important. I find flying at 20 meters to be to high as well but useable.
The IRIS does not use the same ESC's as the other copters from 3DR. It has a 4 in 1 ESC.
The other batteries do not fit in the space provided by the IRIS. The 5100 IRIS+ battery is a great option as it is light weight and has lots of power. Other batteries add too much weight. With the IRIS battery you can get about 4000mah which leads to about 20 minutes of flight time and over 10 minutes with gimbal. You can't use 5100 mah from your battery as it would be dead and rendered useless. You need to leave about 20% in the tank when you get it on the ground.
I also used Droid Planner to watch as my copter flew over the target area and was able to track its movement more closely then with the naked eye.
Great Suff. Love it.
Hi Michael,
Do you know if there's a way to make it so if during a mission it sees itself losing altitude, it will lower the speed?
I do love using the Iris+! Telemetry to my android phone is amazing as well!
Sorry, have not had that issue and I would think that it would try to maintain that altitude by slowing down. It is in auto mode so it should be trying to stay at that altitude as one of the parameters. You could lower the waypoint speed as well.
Michael,
Thanks for the clarification. Do you by any chance have a log file you could share for comparison?
Regards,
Nathaniel ~KD2DEY
Sure do: http://exmaps.com/uploads/4322
Here is a link to the actual recording. Please not this is for an IRIS and not the IRIS+.
337.bin
Hey Michael,
Thanks for the link, I hadn't seen that site before. I had hoped to be able to download the log file so I could compare some things like motor output levels climb rates etc., but I couldn't find a way to download the file. Any chance you could post it here?
Regards,
Nathaniel ~KD2DEY
When I'm flying straight up, with no forward/reverse velocity 100% of the available power is going towards holding or increasing the altitude.
When I'm flying forward, the quadcopter is tilted at an angle. This would (brings me back to statics class) share the amount of thrust with vertical AND horizontal. Thus is would need to increase thrust to maintain the current altitude. Faster I'm flying, more thrust needed.
I was cruising at about 10 m/s, so maybe the quadcopter didn't have enough thrust to both fly at 10m/s and hold the altitude?
Wouldn't the only way to increase thrust be to increase the motor speed? (Or change props). But the motor speed is based off the voltage, and I'm not going to a 4s battery.
Does raising the C rating on the battery change the motor speed?
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