Height limitation flying over water

[Zbip57]

Cant the optical handle that like in the Mini2? {...] Could it be alignment of the optical sensors 2 patterns similar to how some of the first range finders in WW2 worked?

There is only one optical sensor, and two infrared sensors. The optical sensor is used for horizontal position holding. The infrared sensors measure height.

I thought it switched to VPS at 98ft because the infrared was more accurate than the Barometer.

I'm not questioning whether the VPS is capable of that sort of range, or whether the infrared sensor heights are accurately being recorded into the flight log. The question is, what possible function is accomplished by this?

The drone's height is always controlled by the barometric altimeter, except when within ~2ft of any surface below its underside.

Unless you move the throttle stick to climb or descend, the drone will hold a constant height regardless of whether it's hovering in place, or moving forward/backward, or left/right. And it will hold that constant height regardless of whether the actual height over ground is changing due to sloping surfaces or obstacles like bushes and trees. The infrared sensor measurement never produces any visible effect at all on the drone's height, unless it registers something closer than ~2ft below it.

Let's say the drone is travelling at a constant height of 50' and it passes over a 25' tall tree. The barometer won't know the tree exists, so the drone remains at that same constant 50' height the whole time, clearing the top of the tree by 25'. The infrared sensors however can "see" the tree, and the flight log will record the VPS height changing from 50' above ground to suddenly only 25' above the top of the tree as the drone passes over, then back to 50' above ground once the drone clears the tree.

If, as you say, the VPS is somehow used to more accurately control the drone's height, wouldn't the drone suddenly jump 25' higher to maintain a constant 50' height above the ground, and 50' above any obstacles (trees) it encounters along the way? It doesn't do that because the drone's height is instead always controlled by the barometer, which never sees the tree.

The only time the infrared height sensors of the VPS system ever trigger any sort of noticeable reaction from the drone is if it encounters something closer than ~2ft underneath the drone.

Try flying slowly at low height over a picnic table. If the drone clears the table by at least 2ft, it's height never changes as it passes over the table because the height is controlled only by the barometric altimeter. But if you fly the drone lower than 2ft across the picnic table, the infrared sensors of the VPS system will detect the table top and the drone will automatically jump up in height to clear the table by at least 2ft, then continuing on at that new higher altitude.

If you fly too fast though, the drone reacts too slowly and may not jump up until after clearing the table top.

 

[Meta4]

The only time the infrared height sensors of the VPS system ever trigger any sort of noticeable reaction from the drone is if it encounters something closer than ~2ft underneath the drone.

The only thing I can add is that the infrared sensors will begin to slow a fast descent from about 10 ft above a surface or object when the drone descends fast.
The distance may vary with different models.

 

[Ranman1022]

Then what are the 2 holes on either side of the light?

There is only one optical sensor, and two infrared sensors. The optical sensor is used for horizontal position holding. The infrared sensors measure height.
View attachment 155511


I'm not questioning whether the VPS is capable of that sort of range, or whether the infrared sensor heights are accurately being recorded into the flight log. The question is, what possible function is accomplished by this?

The drone's height is always controlled by the barometric altimeter, except when within ~2ft of any surface below its underside.

Unless you move the throttle stick to climb or descend, the drone will hold a constant height regardless of whether it's hovering in place, or moving forward/backward, or left/right. And it will hold that constant height regardless of whether the actual height over ground is changing due to sloping surfaces or obstacles like bushes and trees. The infrared sensor measurement never produces any visible effect at all on the drone's height, unless it registers something closer than ~2ft below it.

Let's say the drone is travelling at a constant height of 50' and it passes over a 25' tall tree. The barometer won't know the tree exists, so the drone remains at that same constant 50' height the whole time, clearing the top of the tree by 25'. The infrared sensors however can "see" the tree, and the flight log will record the VPS height changing from 50' above ground to suddenly only 25' above the top of the tree as the drone passes over, then back to 50' above ground once the drone clears the tree.

If, as you say, the VPS is somehow used to more accurately control the drone's height, wouldn't the drone suddenly jump 25' higher to maintain a constant 50' height above the ground, and 50' above any obstacles (trees) it encounters along the way? It doesn't do that because the drone's height is instead always controlled by the barometer, which never sees the tree.

The only time the infrared height sensors of the VPS system ever trigger any sort of noticeable reaction from the drone is if it encounters something closer than ~2ft underneath the drone.

Try flying slowly at low height over a picnic table. If the drone clears the table by at least 2ft, it's height never changes as it passes over the table because the height is controlled only by the barometric altimeter. But if you fly the drone lower than 2ft across the picnic table, the infrared sensors of the VPS system will detect the table top and the drone will automatically jump up in height to clear the table by at least 2ft, then continuing on at that new higher altitude.

If you fly too fast though, the drone reacts too slowly and may not jump up until after clearing the table top.

 

[Zbip57]

Then what are the 2 holes on either side of the light?

Which 2 holes, which light, where?

 

[Ranman1022]

Which 2 holes, which light, where?

Are you not familiar with the Air2S? It has a light on bottom. On either side looks like a optical sensor.

 

[Zbip57]

Are you not familiar with the Air2S? It has a light on bottom. On either side looks like a optical sensor.

Ah, no. I thought you were talking about the Mini2, when you said:

Cant the optical handle that like in the Mini2?

 

[Ranman1022]

Ah, no. I thought you were talking about the Mini2, when you said:

The topic is still the Air2S. His topic, I just referenced the Mini2. Plus YOU mentioned the infrared sensors. So the topic was still the Air2S.

But the Mini2 has two optical sensors. In the pic you showed its two. One pair = one sensor?

I believe it basically mirrors the two images to maintain position.

 

[Zbip57]

The topic is still the Air2S. His topic, I just referenced the Mini2. Plus YOU mentioned the infrared sensors. So the topic was still the Air2S.

I don't have an Air2S, but I do know that optical sensors are used for horizontal position hold in the absence of GPS signal or during precision landing (does the Air2s have that?), and infrared sensors are used to measure distance (height in this case), and even then only during the last phase of the landing process as the barometric altimeter otherwise is the primary sensor for height control.

But the Mini2 has two optical sensors. In the pic you showed it's two. One pair = one sensor?
I believe it basically mirrors the two images to maintain position.

I also do not have a Mini2. I do have a Mini1. I also have a Phantom3Pro which has a similar arrangement with a single optical sensor, and two ultrasonic sensors rather than two infrared sensors.

However, the pic I posted above is directly from the Mini2 User Manual, which clearly states that the Mini2 does not have two optical sensors. The Mini2 only has one optical sensor and two infrared, as shown in the User Manual.

 

[karlblessing]

I don't have an Air2S, but I do know that optical sensors are used for horizontal position hold in the absence of GPS signal or during precision landing (does the Air2s have that?), and infrared sensors are used to measure distance (height in this case), and even then only during the last phase of the landing process as the barometric altimeter otherwise is the primary sensor for height control.

In the case of the Air 2S you have 3 things below. There are two sensors that are for the downward obstacle avoidance. In the middle of those two is the auxiliary LED light (it kicks on when it detects ground and needs more light), and then at the very rear the blue-ish mirror thing with a thing line breaking it into two is the infrared sensor, they seem to go a step further and block out all other light with the filter on it.



Far as flying over water, it gets confused a lot of times. Based on my experience shooting infrared photography for the last decade or so, water doesn't reflect it very well and depending on the wavelength it's reading, it can seem opaque black. So despite seeing a reflection of the bridge in light visible to the human eye, the sensor if strictly infrared would just see solid black on an extremely calm water surface, with maybe a glint or shimmer every so often if sunlight managed to bounce off just right in small areas that did create waves.

In windier conditions or conditions that create more ripple or waves, that's where the sunlight (primary source of infrared light during the day, if there isn't an infrared light source built in) will bounce off at parts, but because it's constantly moving and changing, it can't get an accurate reading between the two sensors.

 

[wisefish]

Good info from everybody and thanks for educating me about all this stuff. I fly almost exclusively over water (mainly small rivers/creeks). I routinely notice my Air2S slowly descends or ascends on its own when stationary over water. For this reason I never hover closer than about 10 feet above the water in order to avoid an accidental dunking. I also keep the Air2S within a couple hundred feet if I am low to the water. If I'm 50 ft.+ above the water surface I'll fly the max VLOS possible.

 

[karlblessing]

Good info from everybody and thanks for educating me about all this stuff. I fly almost exclusively over water (mainly small rivers/creeks). I routinely notice my Air2S slowly descends or ascends on its own when stationary over water. For this reason I never hover closer than about 10 feet above the water in order to avoid an accidental dunking. I also keep the Air2S within a couple hundred feet if I am low to the water. If I'm 50 ft.+ above the water surface I'll fly the max VLOS possible.

Sound like a good candidate for some of @Phantomrain stuff if you want to get that close, can land and take off from water.