[Ovmsdev] Locations and scripts
Mark Webb-Johnson
mark at webb-johnson.net
Thu May 30 09:17:47 HKT 2019
Steve,
Great work. Thanks for tracking this down.
The intent of the ‘flatbed’ feature was to alert the user of the car moving while parked. I don’t think we’re ever going to be able to alert early enough for the owner to be able to rush out and stop the theft (even if that was a wise things to try to do); so perhaps the solution is to simply increase the threshold. The difference between 500 metres and 2,000 metres, for example, would not impact the use case much. I suggest that we simply increase the theft alert radius to 2,000 metres, to workaround this issue.
As to the GPS data itself, perhaps we can smooth out readings to reduce spikes and invalid values? 200kph is 55 metres in one second. We get readings from the roadster every 10ms, and it is not reasonable to see a difference of 640m or 753m between neighbouring readings. From your data, it seems that the invalid readings last for some time (several consecutive readings), so it is not trivial. Perhaps a kalman filter?
https://en.wikipedia.org/wiki/Kalman_filter <https://en.wikipedia.org/wiki/Kalman_filter>
http://www.cs.unc.edu/~welch/kalman/Levy1997/index.html <http://www.cs.unc.edu/~welch/kalman/Levy1997/index.html>
http://kalman.sourceforge.net/index.php <http://kalman.sourceforge.net/index.php>
https://github.com/lacker/ikalman <https://github.com/lacker/ikalman>
Some people talking about the issue here:
https://stackoverflow.com/questions/1134579/smooth-gps-data <https://stackoverflow.com/questions/1134579/smooth-gps-data>
I suspect that when the Roadster is in motion, the GPS uses velocity to smooth out its location. But when the car is parked, it doesn’t have that capability.
Regards, Mark.
> On 30 May 2019, at 8:08 AM, Stephen Casner <casner at acm.org> wrote:
>
> I caught one! (An instance of a "vehicle on flatbed" alert while
> recording a CAN log of the GPS data.)
>
> What I see is a sharp deviation in the GPS position at the time of the
> alert. So it may just be that I should set the alert threshold to a
> larger value, or perhaps that the default value should be increased.
> We might also make the trigger more robust by considering the rate of
> change to be consistent with moving the car rather than a shift in GPS
> position calculation.
>
> The deviation that triggered the alarm was followed by a deviation of
> larger magnitude about an hour later, but repeat alarms are disabled
> until the car is turned on and then parked again. The duration of my
> recording was approximately one day; I should probably gather more
> data to see if I get any deviations that are even larger.
>
> I've attached the data and my analysis for others to view. It is a
> zip file containing four files:
>
> location.crtd is the recording of CAN bus 1 with a filter for ID
> 0x100 and a hack to keep only records with data.u8[0] = 83, 84 or
> 85.
>
> location.graf is the output of an awk script I wrote to graph the
> deviations in the GPS latitude, longitude and altitude values.
> These are output as a sequence of three X,Y timeseries with the X
> values being GMT timestamps and the Y values being the difference
> in the GPS coordinate values relative to the first sample in the
> recording. The latitude and longitude values are in degrees; the
> altitude values are in megameters to make them similar in scale to
> the lat/lon. A fourth timeseries shows the calculated distance
> relative to the first sample, again in megameters. A fifth
> timeseries shows artificial values to mark GPS lock transitions;
> there was no transition near the time of the alert. I translated
> the CRTD timestamps to absolute time by equating the last log
> timestamp with the log file write time, so there may be some
> inaccuracy. The notification I received on my phone was at 21:30
> GMT and in the data the spike begins at 1559079188.763 = 21:33:08.
>
> wander.png is a large screenshot of the graph presented by a
> little graphing tool named graf that runs under X on *nix and is
> good for data exploration. If you are interested you can find the
> source at https://github.com/kernelsid/graf
>
> zoomed.png is a screenshot of the same graf session zoomed in on
> the spike that triggered the warning.
>
> The distance that triggered the warning was 640 meters, greater than
> the 500 meter default threshold. The larger distance that occurred
> about an hour later was 753 meters.
>
> -- Steve
>
> On Thu, 23 May 2019, Stephen Casner wrote:
>
>> Finally, after some travel and other delays, getting back to this
>> question of the false flatbed alarms. I've started logging with:
>>
>> OVMS# can log crtd /sd/location.crtd 1:100
>>
>> Plus I've hacked the filter function in canlog to save only those
>> frames with data.u8[0] = 83, 84 or 85, so the total is about 5MB per
>> day. I can leave that running for a while.
>>
>> -- Steve
>>
>> On Tue, 2 Apr 2019, Mark Webb-Johnson wrote:
>>
>>> The 'can log crtd ...' would be fine. That logs directly to disk, and would be the easiest for a replay (to try to recreate the problem).
>>>
>>> I don't think there is any easy way to pre-filter for B1, so the whole of ID 0x100 would be fine.
>>>
>>> If we can get a full crtd trace around the time of the problem, then get told 'I got a text notification of vehicle on flatbed at 7:50pm on 4th', we can narrow it down and replay just that part.
>>>
>>> Regards, Mark.
>>>
>>>> On 2 Apr 2019, at 2:53 PM, Stephen Casner <casner at acm.org> wrote:
>>>>
>>>> I think Mark is requesting "can log trace" rather than "can log
>>>> crtd". For the former you have already implemented rotation of
>>>> the log files based on max size as configurable in the web UI, right?
>>>>
>>>> -- Steve
>>>>
>>>> On Tue, 2 Apr 2019, Michael Balzer wrote:
>>>>
>>>>> I've used the trace command to log high volume CAN traffic, that's no problem (at least with a recent module having the SD speed fix).
>>>>>
>>>>> The tracing just lacks a file rotation, but that shouldn't be hard to add.
>>>>>
>>>>> Regards,
>>>>> Michael
>>>>>
>>>>>
>>>>> Am 02.04.19 um 04:58 schrieb Mark Webb-Johnson:
>>>>>> I am not sure if the SD is fast enough to store can log files. It would not be too hard to start/stop logging in javascript (without code changes).
>>>>>>
>>>>>> Regards, Mark.
>>>>>>
>>>>>>> On 2 Apr 2019, at 10:28 AM, Stephen Casner <casner at acm.org> wrote:
>>>>>>>
>>>>>>> Well, for my car this event has occurred twice in a few months, so the
>>>>>>> idea of running a CAN bus dump in a wifi session all the time is not
>>>>>>> practical. What we would need would be a CAN bus dump to rotating
>>>>>>> files, like the error message logging can do.
>>>>>>>
>>>>>>> -- Steve
>>>>>>>
>>>>>>> On Tue, 2 Apr 2019, Mark Webb-Johnson wrote:
>>>>>>>
>>>>>>>> Steve,
>>>>>>>>
>>>>>>>>> What should I look for when this false alarm occurs? Is it likely
>>>>>>>>> that the alarm is issued when stable GPS operation is restored, so
>>>>>>>>> what I really would need to see is a log of conditions before the
>>>>>>>>> alarm?
>>>>>>>> What we would ideally need would be at the time of the issue:
>>>>>>>>
>>>>>>>> metric list v.p
>>>>>>>> CAN bus dump (can1) ID #100, B1=0x83,0x84,0x85
>>>>>>>>
>>>>>>>> I appreciate that is hard. Perhaps just leave a CAN bus dump running
>>>>>>>> over wifi throughout the event? You could leave that running for
>>>>>>>> hours. We could then replay that back through a box to recreate the
>>>>>>>> issue.
>>>>>>>>
>>>>>>>>> And now that I have issued some messages in the app, how do I switch
>>>>>>>>> back to other functions? Is there a way to make the keyboard drop and
>>>>>>>>> then find the buttons at the bottom of the screen? (I realize that
>>>>>>>>> restarting the app would be a solution.)
>>>>>>>> Just click on the screen, away from the keyboard.
>>>>>>>>
>>>>>>>> Regards, Mark.
>>>>>>>>
>>>>>>>>> On 2 Apr 2019, at 5:47 AM, Stephen Casner <casner at acm.org> wrote:
>>>>>>>>>
>>>>>>>>> Mark,
>>>>>>>>>
>>>>>>>>> The false alarm occured again a few minutes ago. I wanted to use the
>>>>>>>>> web shell UI to check some status, but using the new messages feature
>>>>>>>>> of the iPhone app I found the wifi was wedged again. After I turned
>>>>>>>>> wifi off and then back to client mode I would log in from the web
>>>>>>>>> again. I issued a location status command that indicated good lock.
>>>>>>>>>
>>>>>>>>> What should I look for when this false alarm occurs? Is it likely
>>>>>>>>> that the alarm is issued when stable GPS operation is restored, so
>>>>>>>>> what I really would need to see is a log of conditions before the
>>>>>>>>> alarm?
>>>>>>>>>
>>>>>>>>> And now that I have issued some messages in the app, how do I switch
>>>>>>>>> back to other functions? Is there a way to make the keyboard drop and
>>>>>>>>> then find the buttons at the bottom of the screen? (I realize that
>>>>>>>>> restarting the app would be a solution.)
>>>>>>>>>
>>>>>>>>> -- Steve
>>>>>>>>>
>>>>>>>>> On Mon, 1 Apr 2019, Mark Webb-Johnson wrote:
>>>>>>>>>
>>>>>>>>>> I don't see this on the Model S vehicle.
>>>>>>>>>>
>>>>>>>>>> I suspect the issue is not handling GPS lock indicator correctly
>>>>>>>>>> in the vehicle modules. For the roadster, we use ID#100, B1=0x85
>>>>>>>>>> (GPS direction and altitude), B2==1 to control this, but that was
>>>>>>>>>> always a 'best guess' without much data to back it up.
>>>>>>>>>>
>>>>>>>>>> Regards, Mark.
>>>>>>>>>>
>>>>>>>>>>> On 31 Mar 2019, at 11:12 PM, Stephen Casner <casner at acm.org> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Mark,
>>>>>>>>>>>
>>>>>>>>>>> This message reminds me to mention that both Timothy Rodgers and I
>>>>>>>>>>> have received false alarm car-theft notifications from OVMS. Have
>>>>>>>>>>> you? I presume these are caused by temporary inaccuracy in the GPS
>>>>>>>>>>> signal.
>>>>>>>>>>>
>>>>>>>>>>> -- Steve
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