Will the H allow itself to crash into the ground?

[Skeets]

Hi folks!
I was using UAV Toolbox and created a CCC mission that was mostly 100 feet up. I then wanted it to descend to 10 feet, then rise back up to 100 feet. It seemed like it was descending pretty fast and I thought maybe it would hit the ground, so I chickened out at about 20 feet and put into RTH.
So my question is will the bottom sensors keep it from hitting the ground whether it is a GPS issue or operator input error (i.e mistakenly putting in 1 ft altitude when you actually wanted 100 ft, or something like that)

Thanks!

 

[ricmitch]

I would not program it to do that. I am not sure how it detects the ground level. So if the ground was higher then your start point I would think it would crash. That for me is way too close for comfort.
I have used uav tool box to as well but my flights are at a high altitude here is the site I have been using it on.

 

[Tuna]

In short - yes, it is possible to crash during CCC flights - which is why both Yuneec and UAV Toolbox have warnings about being prepared to stop a flight if it looks like you might hit something.

The Typhoon, like all drones of this type, does not know where the ground is. It only knows where it took off from. It's possible to fly below that height (for instance, if you took off over a ravine and flew down into it), so it will not stop you (or the CCC route) from going below the takeoff point. All altitudes in CCC routes are relative to your takeoff point, not the height of the ground that the Typhoon flies over.

Height is measured using an air pressure sensor (again, like all drones of this type), which is fairly stable, but can drift. It's not unusual for the altitude reading to be off by +/- 10 ft at the end of a flight.

Finally, CCC routes are not exact - the Typhoon 'smooths out' the motion so you get a nice curve rather than jerky robotic motion. That means that it may fly below the heights of waypoints so the path is a smooth curve.

For these reasons, UAV Toolbox restricts the minimal height you can have in a CCC route so that there is reasonable clearance during flight. It's still possible to come up with a route that exceeds those limits, and flying over uneven ground or near obstacles will increase the risk. You should always fly a CCC route with care and be prepared to abort it if it looks like things are getting too close.

I hope that helps a little.

 

[Tuna]

I would not program it to do that. I am not sure how it detects the ground level. So if the ground was higher then your start point I would think it would crash. That for me is way too close for comfort.
I have used uav tool box to as well but my flights are at a high altitude here is the site I have been using it on.

Love that video - what an excellent site to fly around!

 

[PatR]

A brief story about GPS altitude. There's a lot of small, military grade UAV's that use a combination of GPS and abro altimeters to establish their flight altitude. Some of them use GPS as the primary means of display and broadcasting their altitude through their telemetry and used GPS reported altitude as the reference source for their altitude encoding transponders.

Quite a few manned military aircraft were seeing UAV's at altitudes that were considerably different from what the UAV was reporting via transponder to military ATC. They were off hundreds of feet, which caused conflicts with manned aircraft. The military aircraft were using baro pressure to set their altimeters based upon known weather conditions obtained from certified weather stations. The field elevations were extremely well documented and provided an accurate means of double checking initial altitude settings. The altimeters used in manned aircraft are much more sensitive and accurate than what is used in our small flight control systems. After a lot of investigation it was established that GPS reported altitude was not accurate so the UAV's were required to develop a mathematical offset formula to correct for GPS altitude errors that had to be coded into the UAV auto pilots and used before the data reached the altitude encoding transponders for transmission.

The real short version is that our multirotor altitude reports are not accurate and those that trust the reported altitude to be accurate will likely have problems if they use that information to construct very low altitude flight plans. If you want to shoot pictures a foot off the ground there are better ways to do that not using a drone. Perhaps an RC car with a camera would be better? If building a flight plan there's no reason to input an altitude error. We have plenty of time to check and double check altitudes before an aircraft leaves the ground If establishing points for a CCC route while in flight I'd be real nervous if I was setting one up real close to the ground. No hurry, no worries, right? Give your aircraft some room. They are not precision instruments.

 

[Skeets]

Thanks for the replies, guys!

If building a flight plan there's no reason to input an altitude error. We have plenty of time to check and double check altitudes before an aircraft leaves the ground .

You are exactly right. I ALWAYS check and double check all altitudes, obstacles and whatever might come into play before uploading the mission and taking off. My example of inputting 1 foot instead of 100 was just an example as to what would happen "IF" someone would do that. Would the H's air pressure sensor or bottom sensors be smart enough to keep it from going that low? I realize that Obs Avoidance is not available during CCC missions, so the bottom sensors are inactive anyway, but I am keeping them in my question simply for discussion purposes

 

[PatR]

Just got a video from a friend using CCC to perform a high to low pass to a runway. He said that if it missed the ground by 2" he'd be surprised. Based on his experiment the H will hit the ground.

 

[Sam77]

Yup. I'm that guy. I wanted to do a CCC shot of our model airplane runway from a landing approach, rollout down the runway, and then climb out. I set starting waypoint about 50 feet up, cruised down and set my "low" waypoints down the runway at 5 to 6 feet (ol' eyeball guesstimation), then back up and out at the end of the runway. I flew the H back to near the starting point and kicked things off.

Mind, you, this was my first go at using CCC, so I wanted to keep things simple - not thinking about how GPS uncertainty would mess with my proposed CCC route. It was neat watching it start, and then slowly move forward / descend, until it got to the second waypoint over the end of the runway. I remember thinking to myself that the ground sensors would kick in at any time. Then more dread thinking "come on, kick in anytime now". I was able to cancel CCC and pull up and out just in the nick of time, but if there was more than 2 inches of daylight between the bottom of my CGO3+ and the runway, I'd be shocked.

Now, for your viewing pleasure, "How not to use CCC Mode on a Typhoon H":

 

[Dr Delta]

Yup. I'm that guy. I wanted to do a CCC shot of our model airplane runway from a landing approach, rollout down the runway, and then climb out. I set starting waypoint about 50 feet up, cruised down and set my "low" waypoints down the runway at 5 to 6 feet (ol' eyeball guesstimation), then back up and out at the end of the runway. I flew the H back to near the starting point and kicked things off.

Mind, you, this was my first go at using CCC, so I wanted to keep things simple - not thinking about how GPS uncertainty would mess with my proposed CCC route. It was neat watching it start, and then slowly move forward / descend, until it got to the second waypoint over the end of the runway. I remember thinking to myself that the ground sensors would kick in at any time. Then more dread thinking "come on, kick in anytime now". I was able to cancel CCC and pull up and out just in the nick of time, but if there was more than 2 inches of daylight between the bottom of my CGO3+ and the runway, I'd be shocked.

Now, for your viewing pleasure, "How not to use CCC Mode on a Typhoon H":

WOW.......!
As we call it in NL.....: BOFBIPS!

 

[PatR]

Sam,

Thanks for the description. That's what I wanted to ask you when I called.