This is a copy/paste of what I posted at Seti. No reason to change it.
Here's another drone video, my first shot on a sunny day. I went out along BNSF's Aurora Sub and parked west of Hinckley at the east end of Mored siding. I arrived too late to set up for the first train that came along, but my computer showed two more coming that would meet here.
Calibrating the drone's compass requires spinning it around the vertical axis, then turning it to point down and spinning it around the vertical again. This is most easily done by just spinning myself, but this time I kept spinning a couple more times before I could stop myself!
I got up in the air just as the westbound stack train approached and followed it west to where I thought the head of the eastbound oil train would pull up to. I didn't expect it to stop short of the farmer's driveway until it had a signal to proceed out of the siding. I followed it back east and was going to record the whole train going by, but the SD card got full. From now on, there will be a 64GB card in it.
Unfortunately, when it returned to me, it wasn't very accurate and I tried to override it. First, it kept going in different directions than I wanted. Then it landed much harder than it ever has before. This still would have been okay, but I was also slewing it sideways rather quickly and it flipped over, breaking a blade. This would not be a major problem, but I can't find the extra set of props and the removal tool that came with it. I tried flying it again, but it immediately flipped over due to lack of lift on one corner. I'll have to run over to Microcenter and buy another set.
Addendum: it's just as well it wouldn't take off when I tested it. I may have been within 5 miles of an airport, where flying a drone requires permission from the airport office AND the tower.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
Calibrating the drone's compass requires spinning it around the vertical axis, then turning it to point down and spinning it around the vertical again. This is most easily done by just spinning myself, but this time I kept spinning a couple more times before I could stop myself!
That confirms that they are likely doing ( digital ) inertial integration of angle increments, and thus need a rate calibration ( angle per second ) on differential accelerometer outputs.
Quote:
Unfortunately, when it returned to me, it wasn't very accurate and I tried to override it. First, it kept going in different directions than I wanted. Then it landed much harder than it ever has before. This still would have been okay, but I was also slewing it sideways rather quickly and it flipped over, breaking a blade. This would not be a major problem, but I can't find the extra set of props and the removal tool that came with it. I tried flying it again, but it immediately flipped over due to lack of lift on one corner. I'll have to run over to Microcenter and buy another set.
That means that prior to the first ( blade-breaking ) crash the rotational aspect of the inertial platform wasn't properly rate adjusted with respect to that all-too-important local gravity field. The error accumulated to the threshold when it became a grossly incorrect input to the ( homeostatic ) control loop ie. gravity never sleeps and always points to actual down. Your description indicates this was an issue on several axes.
At a guess it is possible/probable that the craft has the bare/minimal set of accelerometers. This rotation rate business can be solved by having more on board but suitably placed & analysed.
{ There is a related issue with 'spinning top' type gyros where there is a just sufficient number of gimbal axes ( if you go to four then it doesn't 'lock' and drift effects may be suppressed ). There is a ( semi- ) humorous story* upon gimbal lock with Apollo 11 to the effect that it is difficult to have a fourth one delivered when in space. }
The essential plan is to first solve for very accurately for 'down' ( a vector ) by over-specified inputs ( more accelerometers ), then use that down vector in a further lot of spin manoeuvres ( not about the vertical axis ) to count full rotations against/versus the rate output from the accelerometers. To be purer you can group accelerometers in pairs and use a 'difference of differences' to get higher order corrections if you like. But I have no doubt just doubled/tripled/quadrupled the cost of the device .... and, to my knowledge, you are intending future use as a strike platform ! :-)))))
Quote:
Addendum: it's just as well it wouldn't take off when I tested it. I may have been within 5 miles of an airport, where flying a drone requires permission from the airport office AND the tower.
Who would probably say no anyway ..... not because of you personally or your particular plans, but simply that if they say yes to you that might set a precedent. I would admit to some sympathy with that view having been a light plane pilot. It would likely be a danger to the human carrying craft but not so for the obvious reason of actual collision, but unwise responses from distracted pilots. For me I would let the drone 'eat propeller' as it were. However that's a bit cavalier and it is very expensive to have one replaced and/or re-machined. Bird strikes - even squashier biological matter - have been famously known to bring down a relative Goliath. Now I'm not at all saying you are intending to be a nuisance etc, but you could well be viewed as one regardless. Aviators are very propriety towards 'their' airspace ! :-0
Cheers. Mike.
* Nothing actually 'locks'. A series of manouevres can lead to a chance alignment of two or more gimbal axes, in which case from then on you lose a degree of freedom ie. a 3D gyro functions as a 2D one. You have to reset the device and then take some physical bearings etc to realign to the real universe. A fourth gimbal is actively tracked and monitored, keeping it away from chance alignment with the other three. If any two of the inner gimbals align, then the fourth can recover their non-degenerate alignment without reset etc. While quite unlikely : if the three inner ring axes coincide simultaneously then you're stuffed without reset. I think the idea here is that other sequelae from whatever generated such a scenario indicate platform loss being the least of your problems ie. way out of control spinning.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Addendum: it's just as well it wouldn't take off when I tested it. I may have been within 5 miles of an airport, where flying a drone requires permission from the airport office AND the tower.
Naughty boy, looks like you were about 1 mile from the airport!
That confirms that they are likely doing ( digital ) inertial integration of angle increments, and thus need a rate calibration ( angle per second ) on differential accelerometer outputs.
Well of course we all knew that didn't we folks? And written in Basic Engly Twenty Fido, oh yes, with deep joy.
Waiting for Godot & salvation :-)
Why do doctors have to practice?
You'd think they'd have got it right by now
... written in Basic Engly Twenty Fido, oh yes, with deep joy ...
ROFL! I'd never heard of Stanley Unwin, but I just looked him up eg. guide to buying a car ! I must strive much more for his perfect standard of 'Clear And Comprehensive' presentations. :-)
I must apologise, I have just re-read :
Quote:
.... the rotational aspect of the inertial platform wasn't properly rate adjusted with respect to that all-too-important local gravity field. The error accumulated to the threshold when it became a grossly incorrect input to the ( homeostatic ) control loop ie. gravity never sleeps and always points to actual down ....
which has the same Unwinese cadence. I maintain the statement makes great sense, but to paraphrase the consummate* Mandy Rice Davies : I would say that, wouldn't I ? :-)
Cheers, Mike.
* Double entendre definitely intended here.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Believe I have completed the coding logic for the Pi2 tank/crawler. Trying to combine forward/reverse/left/right into one joystick on a PS3 game controller did not work due to stick sensitivity, i.e., it is hard to move the stick forward without deflecting the stick left or right causing unwanted turning motion. I decided that the left stick would be forward/backward and the right stick left/right turn and the buttons on the front to control the pan/tilt logic on the camera mount. Seems to have worked out well. At least I do not need 10 opposable fingers to reach this button configuration unlike my first attempt. Here is a video I put together using Linux's kdenlive video editing package (I need to spend more time with this package). I attempted a split screen mode where two videos were cobined in sync with each other, i.e., the onboard camera and a 2nd camera. There is no sound because the motors are distracting. The drive motors have metallic gear transmissions built in and the servos also feature metal gears. The servos are a bit "too much" for the weight of the camera, but I used what I had. The video can be seen here - a short tour of two crunchers.
Now when the printer arrives I will be able to print a suitable body for the crawler.
Before I try to make sense of all that, let me add a few details and see if you care to revise your theories.
First, when you do the compass calibration, you can't be too close to a major ferrous mass. In this case, on my first attempt, I was too close to my car and had to move farther away. This may have contributed to my dizziness. I was also pretty close to power lines, which you may have noticed it suddenly rising to avoid not too long into the video.
Second, while it does not necessarily use it for flying stability, it definitely uses GPS for navigation. Actually, there are three flying modes. The easiest to understand for a novice like me uses GPS to know where "home" is. When you first start the propellers, it sets its current position as home. You can also reset home at any time, even in mid-flight, by command on the phone or tablet you are using to monitor the flight. You can command it to land right where it is or return to home and land (which is what I do). There is a command to lift off and hover at abut 4', and then you can set home there. If you then tell it to return to home, it will return to that position and hover. It will also return to home when the battery gets low or when it loses contact with the remote. And if your phone's GPS is working, you can tell the drone to return to where the phone is, or to follow it at whatever altitude and angle you set.
Anyway, public GPS resolution being what it is, the accuracy of the return point is measured in feet, not inches, which is why I always have to correct its final approach. I think in this case it got the home altitude wrong as well as the position, thus landing too hard.
In this flying mode, the right joystick is horizontal movement (both are sprung to center) and the left is up/down and spin. As I have mentioned before, there is a separate knob to tilt the camera up and down. Panning is accomplished by just spinning the whole UAS (FAA-speak meaning unmanned aircraft system).
I took it out again yesterday, first stopping to buy two pairs of props and replacing the broken one. However, when I got where I was going and found the train I was looking for (a single Amtrak train detouring on a different railroad for the first part of its trip), I decided not to fly because A: besides the 1500VDC wires over the tracks it was on, there were also major transmission lines nearby (not too far from a power plant), and B: I have not reached a level of confidence where I can leave it alone, even just hovering still, while I also take pictures with my DSLR, which I thought was more important. Plus, I didn't know what the timing of the train's movement would be and the battery life is limited. After that, I could have stayed there and reconsidered the safety of the wires, or gone somewhere else, but the sun was already getting low in the sky and the gas was getting low in my tank (when I eventually filled it, it took 20.666 gallons), and I had a long drive home to get some sleep (which I didn't) to go to work in the morning. I'll probably return to that area in the summer.
I checked a map and discovered that I was farther from the airport than I thought the other day. I was right on the edge of the 5 mile radius. I'd have to make a more detailed analysis to know whether I was safe.
Now, does that cover everything I wanted to say?...
[edit]
No, one more thing. I don't know about Apollo 11, but there was a well-known incident on 13 where they came very close to a gimbal lock. This was not only in the movie, but also in Lovell's book on which the movie was based, and, I presume, supported by the TV archives of the actual event. (According to the book, his use of the word "frapping" was shocking for the era, especially with the whole world listening. He later had to keep telling Opie's screenwriters to cut out the swearing because he never used that kind of language. I think they had him say "damn" in that scene.)
[edit2]
And with that, I'm overdue for bed, having never visited Seti all day.
[edit3]
You may have also noticed at certain points of the video that it was seeing the blades. I think what's going on there is that when it flies forward, it tilts its body that way, and the camera gimbal tilts up to keep it level. I should have tilted the camera down a little anyway. I'll have to remember that in the future.
Another thing: while flying in GPS mode, you can set waypoints and then tell it to repeat same flight path. I haven't yet found a use for this, but I might. Also, besides following the phone, it can also follow a moving point of interest. I'm thinking that sometime this summer, I'll have it follow a streetcar around the loop at the museum. Not while I'm running the car, though.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
I checked a map and discovered that I was farther from the airport than I thought the other day. I was right on the edge of the 5 mile radius. I'd have to make a more detailed analysis to know whether I was safe.
David, don't take this as criticism of you. I'm simply trying to point out to anyone who wants to fly a drone there are a few more things to check before you fly. As they told us in ground school the pilot must check all available information before flight.
Not sure which airport you are thinking about, but Hinkley Airport's active runway is in your shot, about 2x farther than the farmer's house driveway, on the other side of the highway. It is a grass strip used for sailplane operations. There are several other private airports in the vicinity as well, I expect you were within 5 miles of some of them as well. There are a lot of airports in some areas.
You may wish to consult http://vfrmap.com/?type=vfrc&lat=41.771&lon=-88.703&zoom=10 to map out areas where it is legal to fly along the tracks, which are prominently shown on the Sectional chart. Paper Sectional charts will be available at any flight school at an airport. As a drone operator, you don't need the current one, after all airports don't move that often, so if you explain that you want it to sure you are staying 5 miles from airports, etc., they might give you an outdated one if they have one.
First, when you do the compass calibration, you can't be too close to a major ferrous mass. In this case, on my first attempt, I was too close to my car and had to move farther away. This may have contributed to my dizziness. I was also pretty close to power lines, which you may have noticed it suddenly rising to avoid not too long into the video.
At a minimum you need two reference directions, preferably close to orthogonal eg. down, plus one in the horizontal plane ( magnetic north here ). You still need some rate knowledge/calibration ( something per angle ) to get intermediate vectors.
Quote:
Second, while it does not necessarily use it for flying stability, it definitely uses GPS for navigation. Actually, there are three flying modes. The easiest to understand for a novice like me uses GPS to know where "home" is. When you first start the propellers, it sets its current position as home. You can also reset home at any time, even in mid-flight, by command on the phone or tablet you are using to monitor the flight. You can command it to land right where it is or return to home and land (which is what I do). There is a command to lift off and hover at abut 4', and then you can set home there. If you then tell it to return to home, it will return to that position and hover. It will also return to home when the battery gets low or when it loses contact with the remote. And if your phone's GPS is working, you can tell the drone to return to where the phone is, or to follow it at whatever altitude and angle you set.
Cool.
Quote:
Anyway, public GPS resolution being what it is, the accuracy of the return point is measured in feet, not inches, which is why I always have to correct its final approach. I think in this case it got the home altitude wrong as well as the position, thus landing too hard.
Yep. Civilian GPS gives you rough ( enough ? ) location but really no orientation information. You could hover for half an hour to improve the fix but why would you ?
Quote:
In this flying mode, the right joystick is horizontal movement (both are sprung to center) and the left is up/down and spin. As I have mentioned before, there is a separate knob to tilt the camera up and down. Panning is accomplished by just spinning the whole UAS (FAA-speak meaning unmanned aircraft system).
The Gemini/Apollo craft joysticks had several modes. The question is whether that control input selects either position or orientation, or the rate change of those. All had spring return to neutral position plus detente ( meaning lock/inactivate ). Do you know what the first two executed commands were upon landing the Eagle on the Moon ? Shutting off the descent engine and controller to detente. Having succeeded they didn't want to inadvertently (a) jump up off the surface nor (b) flip the lander over because they left the attitude adjustment active.
Quote:
I took it out again yesterday, first stopping to buy two pairs of props and replacing the broken one. However, when I got where I was going and found the train I was looking for (a single Amtrak train detouring on a different railroad for the first part of its trip), I decided not to fly because A: besides the 1500VDC wires over the tracks it was on, there were also major transmission lines nearby (not too far from a power plant), and B: I have not reached a level of confidence where I can leave it alone, even just hovering still, while I also take pictures with my DSLR, which I thought was more important. Plus, I didn't know what the timing of the train's movement would be and the battery life is limited. After that, I could have stayed there and reconsidered the safety of the wires, or gone somewhere else, but the sun was already getting low in the sky and the gas was getting low in my tank (when I eventually filled it, it took 20.666 gallons), and I had a long drive home to get some sleep (which I didn't) to go to work in the morning. I'll probably return to that area in the summer.
I was looking at those lines ( aplenty ! ) and those would be an expensive encounter. Even flying between two phase wires without touching could result in circuit completion, by the presentation of a lower resistance pathway. :-)
Quote:
I checked a map and discovered that I was farther from the airport than I thought the other day. I was right on the edge of the 5 mile radius. I'd have to make a more detailed analysis to know whether I was safe.
It would almost certainly be the standard airspace definition for such a facility ie. cylindrical shape with ground datum as the lower boundary within the 5 mile radius. Large airports may have an inverted cone definition ie. the lower boundary increases linearly with distance from the ( ground level ) cone tip/centre. But there are variants/combo galore and typically many special local rulings. Beware*.
{ Tullamarine or Melbourne Airport has an airspace which is the union of a central cylinder and inverted cone, both having a common vertical axis of symmetry. But the tip of the cone is underground. It's a gradual cone eg. some 25km away you still have to stay under 2000ft, going to 8000ft in another 20km. But that 8000ft is then a lower bound for the regional airspace ie. large body commercial IFR flights only. Since those extents covered one side of my training area to the other then it was drilled into my brain. Alas the transponder tells all, where the central radar facility 'tweets' my plane once per sweep and it responds by saying Who I Am. Darn. The flight school never got a 'please explain' letter on my account, in any event excuses are neither tolerated nor are useful ! In theory you could pop up and duck down a few metres into the cone between sweeps and remain not in breach but I think that would be labelled as a sporting move. :-)) }
Quote:
No, one more thing. I don't know about Apollo 11, but there was a well-known incident on 13 where they came very close to a gimbal lock. This was not only in the movie, but also in Lovell's book on which the movie was based, and, I presume, supported by the TV archives of the actual event. (According to the book, his use of the word "frapping" was shocking for the era, especially with the whole world listening. He later had to keep telling Opie's screenwriters to cut out the swearing because he never used that kind of language. I think they had him say "damn" in that scene.)
It was Michael Collins in 11 that politely brought the topic up.
Not having a four gimbal gyro was a definite design decision made. Adding a fourth one in certainly greatly increases the complexity ( read : usability and reliability ). That added outer ring has to be independently driven to keep it away from co-linearity with the axes of any of the inner three ( while tracking & recording said adjustments ). It's not actually used moment to moment for orientation, but available to avoid full reset and calibration to external markers ie. a lock state on the inner three.
Cheers, Mike.
* As Gary points out this is the pilot's ( your ) responsibility, ignorance is no defence etc. From the right source eg. the local pilot's shop there will be maps to define in detail the height vs position information that you need. I don't know what happens in the USA but DownUnda there is a potential penalty of $10K applicable ( plus loss of licensing etc ). The official sensitivity to incursions upon controlled airspace has gone exponential in recent years, for obvious reasons. The benefit of any doubt is no longer on offer. We don't yet have an F-18, or three, on CAP.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
This is a copy/paste of what
This is a copy/paste of what I posted at Seti. No reason to change it.
Here's another drone video, my first shot on a sunny day. I went out along BNSF's Aurora Sub and parked west of Hinckley at the east end of Mored siding. I arrived too late to set up for the first train that came along, but my computer showed two more coming that would meet here.
Calibrating the drone's compass requires spinning it around the vertical axis, then turning it to point down and spinning it around the vertical again. This is most easily done by just spinning myself, but this time I kept spinning a couple more times before I could stop myself!
I got up in the air just as the westbound stack train approached and followed it west to where I thought the head of the eastbound oil train would pull up to. I didn't expect it to stop short of the farmer's driveway until it had a signal to proceed out of the siding. I followed it back east and was going to record the whole train going by, but the SD card got full. From now on, there will be a 64GB card in it.
Unfortunately, when it returned to me, it wasn't very accurate and I tried to override it. First, it kept going in different directions than I wanted. Then it landed much harder than it ever has before. This still would have been okay, but I was also slewing it sideways rather quickly and it flipped over, breaking a blade. This would not be a major problem, but I can't find the extra set of props and the removal tool that came with it. I tried flying it again, but it immediately flipped over due to lack of lift on one corner. I'll have to run over to Microcenter and buy another set.
Addendum: it's just as well it wouldn't take off when I tested it. I may have been within 5 miles of an airport, where flying a drone requires permission from the airport office AND the tower.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
RE: Calibrating the drone's
That confirms that they are likely doing ( digital ) inertial integration of angle increments, and thus need a rate calibration ( angle per second ) on differential accelerometer outputs.
That means that prior to the first ( blade-breaking ) crash the rotational aspect of the inertial platform wasn't properly rate adjusted with respect to that all-too-important local gravity field. The error accumulated to the threshold when it became a grossly incorrect input to the ( homeostatic ) control loop ie. gravity never sleeps and always points to actual down. Your description indicates this was an issue on several axes.
At a guess it is possible/probable that the craft has the bare/minimal set of accelerometers. This rotation rate business can be solved by having more on board but suitably placed & analysed.
{ There is a related issue with 'spinning top' type gyros where there is a just sufficient number of gimbal axes ( if you go to four then it doesn't 'lock' and drift effects may be suppressed ). There is a ( semi- ) humorous story* upon gimbal lock with Apollo 11 to the effect that it is difficult to have a fourth one delivered when in space. }
The essential plan is to first solve for very accurately for 'down' ( a vector ) by over-specified inputs ( more accelerometers ), then use that down vector in a further lot of spin manoeuvres ( not about the vertical axis ) to count full rotations against/versus the rate output from the accelerometers. To be purer you can group accelerometers in pairs and use a 'difference of differences' to get higher order corrections if you like. But I have no doubt just doubled/tripled/quadrupled the cost of the device .... and, to my knowledge, you are intending future use as a strike platform ! :-)))))
Who would probably say no anyway ..... not because of you personally or your particular plans, but simply that if they say yes to you that might set a precedent. I would admit to some sympathy with that view having been a light plane pilot. It would likely be a danger to the human carrying craft but not so for the obvious reason of actual collision, but unwise responses from distracted pilots. For me I would let the drone 'eat propeller' as it were. However that's a bit cavalier and it is very expensive to have one replaced and/or re-machined. Bird strikes - even squashier biological matter - have been famously known to bring down a relative Goliath. Now I'm not at all saying you are intending to be a nuisance etc, but you could well be viewed as one regardless. Aviators are very propriety towards 'their' airspace ! :-0
Cheers. Mike.
* Nothing actually 'locks'. A series of manouevres can lead to a chance alignment of two or more gimbal axes, in which case from then on you lose a degree of freedom ie. a 3D gyro functions as a 2D one. You have to reset the device and then take some physical bearings etc to realign to the real universe. A fourth gimbal is actively tracked and monitored, keeping it away from chance alignment with the other three. If any two of the inner gimbals align, then the fourth can recover their non-degenerate alignment without reset etc. While quite unlikely : if the three inner ring axes coincide simultaneously then you're stuffed without reset. I think the idea here is that other sequelae from whatever generated such a scenario indicate platform loss being the least of your problems ie. way out of control spinning.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
RE: Addendum: it's just as
Naughty boy, looks like you were about 1 mile from the airport!
RE: That confirms that they
Well of course we all knew that didn't we folks? And written in Basic Engly Twenty Fido, oh yes, with deep joy.
Waiting for Godot & salvation :-)
Why do doctors have to practice?
You'd think they'd have got it right by now
RE: ... written in Basic
ROFL! I'd never heard of Stanley Unwin, but I just looked him up eg. guide to buying a car ! I must strive much more for his perfect standard of 'Clear And Comprehensive' presentations. :-)
I must apologise, I have just re-read :
which has the same Unwinese cadence. I maintain the statement makes great sense, but to paraphrase the consummate* Mandy Rice Davies : I would say that, wouldn't I ? :-)
Cheers, Mike.
* Double entendre definitely intended here.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Believe I have completed the
Believe I have completed the coding logic for the Pi2 tank/crawler. Trying to combine forward/reverse/left/right into one joystick on a PS3 game controller did not work due to stick sensitivity, i.e., it is hard to move the stick forward without deflecting the stick left or right causing unwanted turning motion. I decided that the left stick would be forward/backward and the right stick left/right turn and the buttons on the front to control the pan/tilt logic on the camera mount. Seems to have worked out well. At least I do not need 10 opposable fingers to reach this button configuration unlike my first attempt. Here is a video I put together using Linux's kdenlive video editing package (I need to spend more time with this package). I attempted a split screen mode where two videos were cobined in sync with each other, i.e., the onboard camera and a 2nd camera. There is no sound because the motors are distracting. The drive motors have metallic gear transmissions built in and the servos also feature metal gears. The servos are a bit "too much" for the weight of the camera, but I used what I had. The video can be seen here - a short tour of two crunchers.
Now when the printer arrives I will be able to print a suitable body for the crawler.
RE: gravity never sleeps
Only in the Northern Hemisphere. It points upwards down under, or sideways in China :-)
* Ah yes Randy Mice Davies, died aged 70 in 2014. Keeler is still alive aged 73. Profumo died 2006 aged 91.
Waiting for Godot & salvation :-)
Why do doctors have to practice?
You'd think they'd have got it right by now
Before I try to make sense of
Before I try to make sense of all that, let me add a few details and see if you care to revise your theories.
First, when you do the compass calibration, you can't be too close to a major ferrous mass. In this case, on my first attempt, I was too close to my car and had to move farther away. This may have contributed to my dizziness. I was also pretty close to power lines, which you may have noticed it suddenly rising to avoid not too long into the video.
Second, while it does not necessarily use it for flying stability, it definitely uses GPS for navigation. Actually, there are three flying modes. The easiest to understand for a novice like me uses GPS to know where "home" is. When you first start the propellers, it sets its current position as home. You can also reset home at any time, even in mid-flight, by command on the phone or tablet you are using to monitor the flight. You can command it to land right where it is or return to home and land (which is what I do). There is a command to lift off and hover at abut 4', and then you can set home there. If you then tell it to return to home, it will return to that position and hover. It will also return to home when the battery gets low or when it loses contact with the remote. And if your phone's GPS is working, you can tell the drone to return to where the phone is, or to follow it at whatever altitude and angle you set.
Anyway, public GPS resolution being what it is, the accuracy of the return point is measured in feet, not inches, which is why I always have to correct its final approach. I think in this case it got the home altitude wrong as well as the position, thus landing too hard.
In this flying mode, the right joystick is horizontal movement (both are sprung to center) and the left is up/down and spin. As I have mentioned before, there is a separate knob to tilt the camera up and down. Panning is accomplished by just spinning the whole UAS (FAA-speak meaning unmanned aircraft system).
I took it out again yesterday, first stopping to buy two pairs of props and replacing the broken one. However, when I got where I was going and found the train I was looking for (a single Amtrak train detouring on a different railroad for the first part of its trip), I decided not to fly because A: besides the 1500VDC wires over the tracks it was on, there were also major transmission lines nearby (not too far from a power plant), and B: I have not reached a level of confidence where I can leave it alone, even just hovering still, while I also take pictures with my DSLR, which I thought was more important. Plus, I didn't know what the timing of the train's movement would be and the battery life is limited. After that, I could have stayed there and reconsidered the safety of the wires, or gone somewhere else, but the sun was already getting low in the sky and the gas was getting low in my tank (when I eventually filled it, it took 20.666 gallons), and I had a long drive home to get some sleep (which I didn't) to go to work in the morning. I'll probably return to that area in the summer.
I checked a map and discovered that I was farther from the airport than I thought the other day. I was right on the edge of the 5 mile radius. I'd have to make a more detailed analysis to know whether I was safe.
Now, does that cover everything I wanted to say?...
[edit]
No, one more thing. I don't know about Apollo 11, but there was a well-known incident on 13 where they came very close to a gimbal lock. This was not only in the movie, but also in Lovell's book on which the movie was based, and, I presume, supported by the TV archives of the actual event. (According to the book, his use of the word "frapping" was shocking for the era, especially with the whole world listening. He later had to keep telling Opie's screenwriters to cut out the swearing because he never used that kind of language. I think they had him say "damn" in that scene.)
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And with that, I'm overdue for bed, having never visited Seti all day.
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You may have also noticed at certain points of the video that it was seeing the blades. I think what's going on there is that when it flies forward, it tilts its body that way, and the camera gimbal tilts up to keep it level. I should have tilted the camera down a little anyway. I'll have to remember that in the future.
Another thing: while flying in GPS mode, you can set waypoints and then tell it to repeat same flight path. I haven't yet found a use for this, but I might. Also, besides following the phone, it can also follow a moving point of interest. I'm thinking that sometime this summer, I'll have it follow a streetcar around the loop at the museum. Not while I'm running the car, though.
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
RE: I checked a map and
David, don't take this as criticism of you. I'm simply trying to point out to anyone who wants to fly a drone there are a few more things to check before you fly. As they told us in ground school the pilot must check all available information before flight.
I'm sure I have your launch location https://goo.gl/maps/1L5mxm5EbGG2
Not sure which airport you are thinking about, but Hinkley Airport's active runway is in your shot, about 2x farther than the farmer's house driveway, on the other side of the highway. It is a grass strip used for sailplane operations. There are several other private airports in the vicinity as well, I expect you were within 5 miles of some of them as well. There are a lot of airports in some areas.
You may wish to consult http://vfrmap.com/?type=vfrc&lat=41.771&lon=-88.703&zoom=10 to map out areas where it is legal to fly along the tracks, which are prominently shown on the Sectional chart. Paper Sectional charts will be available at any flight school at an airport. As a drone operator, you don't need the current one, after all airports don't move that often, so if you explain that you want it to sure you are staying 5 miles from airports, etc., they might give you an outdated one if they have one.
RE: First, when you do the
At a minimum you need two reference directions, preferably close to orthogonal eg. down, plus one in the horizontal plane ( magnetic north here ). You still need some rate knowledge/calibration ( something per angle ) to get intermediate vectors.
Cool.
Yep. Civilian GPS gives you rough ( enough ? ) location but really no orientation information. You could hover for half an hour to improve the fix but why would you ?
The Gemini/Apollo craft joysticks had several modes. The question is whether that control input selects either position or orientation, or the rate change of those. All had spring return to neutral position plus detente ( meaning lock/inactivate ). Do you know what the first two executed commands were upon landing the Eagle on the Moon ? Shutting off the descent engine and controller to detente. Having succeeded they didn't want to inadvertently (a) jump up off the surface nor (b) flip the lander over because they left the attitude adjustment active.
I was looking at those lines ( aplenty ! ) and those would be an expensive encounter. Even flying between two phase wires without touching could result in circuit completion, by the presentation of a lower resistance pathway. :-)
It would almost certainly be the standard airspace definition for such a facility ie. cylindrical shape with ground datum as the lower boundary within the 5 mile radius. Large airports may have an inverted cone definition ie. the lower boundary increases linearly with distance from the ( ground level ) cone tip/centre. But there are variants/combo galore and typically many special local rulings. Beware*.
{ Tullamarine or Melbourne Airport has an airspace which is the union of a central cylinder and inverted cone, both having a common vertical axis of symmetry. But the tip of the cone is underground. It's a gradual cone eg. some 25km away you still have to stay under 2000ft, going to 8000ft in another 20km. But that 8000ft is then a lower bound for the regional airspace ie. large body commercial IFR flights only. Since those extents covered one side of my training area to the other then it was drilled into my brain. Alas the transponder tells all, where the central radar facility 'tweets' my plane once per sweep and it responds by saying Who I Am. Darn. The flight school never got a 'please explain' letter on my account, in any event excuses are neither tolerated nor are useful ! In theory you could pop up and duck down a few metres into the cone between sweeps and remain not in breach but I think that would be labelled as a sporting move. :-)) }
It was Michael Collins in 11 that politely brought the topic up.
Not having a four gimbal gyro was a definite design decision made. Adding a fourth one in certainly greatly increases the complexity ( read : usability and reliability ). That added outer ring has to be independently driven to keep it away from co-linearity with the axes of any of the inner three ( while tracking & recording said adjustments ). It's not actually used moment to moment for orientation, but available to avoid full reset and calibration to external markers ie. a lock state on the inner three.
Cheers, Mike.
* As Gary points out this is the pilot's ( your ) responsibility, ignorance is no defence etc. From the right source eg. the local pilot's shop there will be maps to define in detail the height vs position information that you need. I don't know what happens in the USA but DownUnda there is a potential penalty of $10K applicable ( plus loss of licensing etc ). The official sensitivity to incursions upon controlled airspace has gone exponential in recent years, for obvious reasons. The benefit of any doubt is no longer on offer. We don't yet have an F-18, or three, on CAP.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal