Commit Graph

70 Commits

Author SHA1 Message Date
Andrew Tridgell f2316747f5 APM_Control: re-work to allow for rate based control 2013-07-11 09:10:41 +10:00
Paul Riseborough 2204b30e66 Plane: Added APM_Control integrator limits to table used to covert old PID values 2013-06-22 21:59:47 +10:00
Paul Riseborough 147856e73c APM_Control: Added integrator limiting adjustable by an advanced user parameter
this is compatible with the old IMAX settings
2013-06-22 21:55:27 +10:00
Paul Riseborough 3ad35363be Plane : APM_Control : Removed scaler incorrectly applied to the integrator path 2013-06-04 18:09:06 +10:00
Andrew Tridgell 05889391e5 APM_Control: cope with zero integrator or tconst
if the user zeros the integrator tuning factor, we need to zero the
integrator
2013-06-01 22:29:38 +10:00
Andrew Tridgell 14c8c1bdfc APM_Control: tweak code layout and param descriptions 2013-05-31 17:24:55 +10:00
Andrew Tridgell f4efa92d3b APM_Control: fixed parameter names 2013-05-31 15:31:25 +10:00
Andrew Tridgell 3e8af05d15 APM_Control: match parameter names with old PID controllers
this will make upgrading easier
2013-05-31 14:06:56 +10:00
Andrew Tridgell 53d3ce7d2c APM_Control: fixed some documentation (old parameter names) 2013-05-31 07:58:29 +10:00
Paul Riseborough 716c124f73 APM_control: Modified gain definitions for roll and pitch controllers so PID gains behave like previous servo PIDS
Gain definitions in roll and pitch controllers were updated previously
so that the old PID tuning values could be transferred across.
Updated tuning guide for revised gain definition.
2013-05-31 07:58:20 +10:00
Andrew Tridgell 6c5718a63b APM_Control: fixed indent-tabs-mode 2013-05-30 09:53:02 +10:00
Andrew Tridgell 604bfd0700 APM_Control: adjust recommended ranges 2013-05-05 21:51:09 +10:00
Andrew Tridgell 7af3c667a5 APM_Control: added roll controller parameter docs 2013-05-05 21:51:09 +10:00
Andrew Tridgell 23d9c31b0a APM_Control: fixed build and merge errors 2013-05-05 21:51:08 +10:00
Paul Riseborough 10ecffce01 APM_Control: ROLL and PITCH controllers
These changes reduce height variation in turns and improve
robustness. the specific changes are:

1) Linked roll and pitch integrator protection to the final output
value so that if final output is on upper limit, the integrator is
prevented from increasing and vice-versa. This improves wind-up
protection.

2) Modified rate feedback in roll and pitch controllers to use body
rates rather than Euler or earth rates.

3) Changed the roll to pitch compensation to use measured roll angle
and estimated airspeed to calculate the component of turn rate
(assuming a level coordinated turn) around the pitch axis. This a
mathematically correct calculation and will work over a range of bank
angles and aircraft with minimal (if any) tuning required.

4) The integrator in the roll and pitch loop is clamped when the
estimated speed is below the minimum FBW speed

5) The noise filter in the pitch and roll loop has been changed to use
a FOH discretisation. This gives improved noise rejection and less
phase loss when compared to the previous filter that used a ZOH or
equivalent discretisation.

This has been flown on the rascal in the SITL and on a X-8 with
limited flight testing. Initial results have been encouraging with
reduced height variation in turns.  Compare to standard PIDS, the
revised pitch and roll controllers allow the use of rate feedback
(effectively the same as the old D term) without beating the servos to
death.  The bank angle compensation in the pitch loop works
effectively over a much larger range of bank angles and requires
minimal tuning compared to the old calculation.

YAW CONTROLLER

Currently testing the a 3-loop acceleration autopilot topology for the
yaw loop with feed forward yaw rate for turn compensation. This 3-loop
topology is commonly used in tactical skid to to turn missiles and is
easy to tune. The following block diagram shows the general signal
flow

Note that the acceleration measurement has to pass through an
integrator before it gets to the actuator. This is a important feature
as it eliminates problems of high frequency noise and potential
coupling with structural modes associated with direct feedback of
measured acceleration to actuator.

The high pass filter has been inserted to compensate for airspeed and
bank angle measurement errors which will cause steady state errors in
the calculation of the turn yaw rate.

The yaw controller flies SITL well, but hasn't been flight tested
yet. It can be configured either as a simple yaw damper, or the
acceleration and integral term can be turned on to allow feedback
control of lateral acceleration/sideslip.

TO DO:

Need to reduce number of tuning parameters and provide consistent
naming Need to provide guidance on tuning these loops with definitions
for all the gain terms.  Need to check signs and units into and out of
lateral loops.

DESIGN DECISIONS PENDING:

1) Can we remove the noise filters? Provided the mpu6k noise filter is
running they are of limited benefit given the 25Hz Nyquist frequency

2) If we do remove them and rely on the mpu6k noise filter, what is
the apprporiate default cutoff frequency for plane use. 20Hz is
probably OK for most setups, but some noisy/high vibration setups
would require as low as 10Hz

3) The inverted flight logic looks like a crash waiting to
happen. It's problematic to test and even if implemented correctly
would still crash a plane with poor inverted flight capability. We
should either implement it properly and fully tested or delete it.
2013-05-05 21:51:08 +10:00
priseborough 99f0fb6bd2 APM_Control : Removed 20Hz low-pass filters on rate gyro inputs.
These are not required due to MPU 6000 filtering.
2013-05-05 21:51:08 +10:00
James Bielman 4fa7bb1486 Add AVR compatibility header for missing math.h definitions.
- Define float versions of math functions to the double versions
  on AVR (eg. #define sinf sin).
- These macros appear to be missing in older versions of avr-libs.
- Include AP_Math.h rather than math.h to get these definitions.
2013-01-16 13:52:17 +11:00
James Bielman 5631f865b2 Update floating point calculations to use floats instead of doubles.
- Allows use of hardware floating point on the Cortex-M4.
- Added "f" suffix to floating point literals.
- Call floating point versions of stdlib math functions.
2013-01-16 13:52:01 +11:00
Pat Hickey 95a13bdbd2 APM_Control: ported to AP_HAL
Unable to test since there are no unit tests.
2012-12-20 14:51:26 +11:00
Jonathan Challinger 59875f8d53 APM_Control: added new APM controllers library
See
http://www.challinger.us/2012/07/16/tuning-arduplane-roll-and-pitch-controllers/
for details
2012-08-22 12:39:07 +10:00