Fixes a problem observed in a flight log where rapid temperature change caused the accel bias to change faster than the EKF could keep up.
This allows the bias to be learned faster but with acceptable level of noise in the estimate
IMU data was being corrected before being used by the co-variance prediction, whereas the delta angles and velocities in the derivation were supposed to be uncorrected.
This patch creates separate variable for the corrected data
Volatile will provide protection to sequence re-ordering and guarantee
the variable is fetched from memory, but it won't provide the memory
barrier needed to ensure that no re-ordering (by either the compiler or
the CPU) will happen among other threads of execution
accessing the same variables.
For more info about this effect can be found on articles about
std::memory_order.
When using reserved(), the reserved memory cannot be read before it's
written, therefore we cannot update 'tail' until the caller of
reserved() is done writing.
To solve that, a method called 'commit()' was added so the caller can
inform that is done with the memory usage and is safe to update 'tail'.
The caller also has to inform the length that was actually written.
This solution was developed to work considering the usage context of
this class: 1 reader and 1 writer **only**.
Adds a method called `reserve()`, that will take a ByteBuffer::IoVec
array of at least two elements, and return the number of elements
filled out. 0 will be returned if `len` is over the total space of
the buffer; 1 will be returned if there's enough contiguous bytes in
the buffer; 2 will be returned if there are two non-contiguous blocks
of memory.
This method is suitable to be used with POSIX system calls such as
readv(), and is an optimization to not require temporary memory copies
while reading from a file descriptor.
Also modify the write() method to use reserve(), so that similar checks
are performed only in one place.
Modify ByteBuffer class to have a `peekiovec()` method, that takes in a
`struct IoVec` array (similar to `struct iovec` from POSIX), and a
number of bytes, and returns the number of elements from this array
that have been filled out. It is either 0 (buffer is empty), 1
(there's enough contiguous bytes to read that amount) or 2 (ring buffer
is wrapping around).
This enables using scatter-gather I/O (i.e. writev()), removing calls
to memcpy(). That's one call when no wrap-around is happening, and
two calls if it is.
Also, rewrite `ByteBuffer::peekbytes()` to use `peekiovec()`, so that
some of the checks performed by the former are not replicated in the
latter.
- Correctly sort includes and add missing AP_Math.h
- Use anonymous struct for trim_registers in _load_trim_values,
renaming its members so they don't start with underscore
- Don't change _dig* values when we failed to read from sensor
- Add some blank lines
- Make _dig_* members be inside a _dig struct
- Use constrain_int32 instead of if/else chain
- s/time_us/time_usec/
- Construct raw_field with a single constructor in _update()
- Add missing copyright notice
- Group methods together in declaration
this gives more control over throttle for petrol
helis. H_RSC_POWER_NEGC allows for a asymmetric V-curve, which allows
for less power being put into the head when landing or when sitting on
the ground. That can lead to significantly less vibration and chance
of ground oscillation. A heli not being flown with aerobatics does not
need to use high throttle at negative collective pitch.
The H_RSC_SLEWRATE allows for a maximum throttle slew rate to be
set. Some petrol motors can cut if the throttle is moved too
quickly. We had this happen at a height of 6m when switching from
ALT_HOLD to STABILIZE mode. It also lowers the chance of the blades
skewing in their holders with the sudden change of power when the heli
is disarmed. In general it is a bad idea to do instantaneous large
movements of a IC engine throttle.
