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msg ROS2 compatibility, microdds_client improvements (timesync, reduced code size, added topics, etc), fastrtps purge
- update all msgs to be directly compatible with ROS2 - microdds_client improvements - timesync - reduced code size - add to most default builds if we can afford it - lots of other little changes - purge fastrtps (I tried to save this multiple times, but kept hitting roadblocks)
This commit is contained in:
Daniel Agar
@@ -100,6 +100,7 @@ px4_add_module(
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sensor_calibration
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geo
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mavlink_c
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timesync
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tunes
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version
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UNITY_BUILD
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@@ -72,82 +72,7 @@ MavlinkTimesync::handle_message(const mavlink_message_t *msg)
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} else if (tsync.tc1 > 0) { // Message originating from this system, compute time offset from it
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// Calculate time offset between this system and the remote system, assuming RTT for
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// the timesync packet is roughly equal both ways.
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int64_t offset_us = (int64_t)((tsync.ts1 / 1000ULL) + now - (tsync.tc1 / 1000ULL) * 2) / 2 ;
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// Calculate the round trip time (RTT) it took the timesync packet to bounce back to us from remote system
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uint64_t rtt_us = now - (tsync.ts1 / 1000ULL);
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// Calculate the difference of this sample from the current estimate
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uint64_t deviation = llabs((int64_t)_time_offset - offset_us);
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if (rtt_us < MAX_RTT_SAMPLE) { // Only use samples with low RTT
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if (sync_converged() && (deviation > MAX_DEVIATION_SAMPLE)) {
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// Increment the counter if we have a good estimate and are getting samples far from the estimate
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_high_deviation_count++;
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// We reset the filter if we received 5 consecutive samples which violate our present estimate.
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// This is most likely due to a time jump on the offboard system.
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if (_high_deviation_count > MAX_CONSECUTIVE_HIGH_DEVIATION) {
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PX4_ERR("[timesync] Time jump detected. Resetting time synchroniser.");
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// Reset the filter
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reset_filter();
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}
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} else {
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// Filter gain scheduling
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if (!sync_converged()) {
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// Interpolate with a sigmoid function
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double progress = (double)_sequence / (double)CONVERGENCE_WINDOW;
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double p = 1.0 - exp(0.5 * (1.0 - 1.0 / (1.0 - progress)));
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_filter_alpha = p * ALPHA_GAIN_FINAL + (1.0 - p) * ALPHA_GAIN_INITIAL;
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_filter_beta = p * BETA_GAIN_FINAL + (1.0 - p) * BETA_GAIN_INITIAL;
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} else {
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_filter_alpha = ALPHA_GAIN_FINAL;
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_filter_beta = BETA_GAIN_FINAL;
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}
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// Perform filter update
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add_sample(offset_us);
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// Increment sequence counter after filter update
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_sequence++;
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// Reset high deviation count after filter update
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_high_deviation_count = 0;
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// Reset high RTT count after filter update
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_high_rtt_count = 0;
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}
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} else {
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// Increment counter if round trip time is too high for accurate timesync
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_high_rtt_count++;
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if (_high_rtt_count > MAX_CONSECUTIVE_HIGH_RTT) {
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PX4_WARN("[timesync] RTT too high for timesync: %llu ms (sender: %i)", rtt_us / 1000ULL, msg->compid);
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// Reset counter to rate-limit warnings
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_high_rtt_count = 0;
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}
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}
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// Publish status message
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timesync_status_s tsync_status{};
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tsync_status.timestamp = hrt_absolute_time();
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tsync_status.source_protocol = timesync_status_s::SOURCE_PROTOCOL_MAVLINK;
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tsync_status.remote_timestamp = tsync.tc1 / 1000ULL;
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tsync_status.observed_offset = offset_us;
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tsync_status.estimated_offset = (int64_t)_time_offset;
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tsync_status.round_trip_time = rtt_us;
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_timesync_status_pub.publish(tsync_status);
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_timesync.update(now, tsync.tc1, tsync.ts1);
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}
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break;
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@@ -181,58 +106,3 @@ MavlinkTimesync::handle_message(const mavlink_message_t *msg)
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break;
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}
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}
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uint64_t
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MavlinkTimesync::sync_stamp(uint64_t usec)
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{
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// Only return synchronised stamp if we have converged to a good value
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if (sync_converged()) {
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return usec + (int64_t)_time_offset;
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} else {
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return hrt_absolute_time();
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}
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}
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bool
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MavlinkTimesync::sync_converged()
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{
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return _sequence >= CONVERGENCE_WINDOW;
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}
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void
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MavlinkTimesync::add_sample(int64_t offset_us)
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{
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/* Online exponential smoothing filter. The derivative of the estimate is also
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* estimated in order to produce an estimate without steady state lag:
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* https://en.wikipedia.org/wiki/Exponential_smoothing#Double_exponential_smoothing
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*/
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double time_offset_prev = _time_offset;
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if (_sequence == 0) { // First offset sample
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_time_offset = offset_us;
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} else {
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// Update the clock offset estimate
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_time_offset = _filter_alpha * offset_us + (1.0 - _filter_alpha) * (_time_offset + _time_skew);
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// Update the clock skew estimate
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_time_skew = _filter_beta * (_time_offset - time_offset_prev) + (1.0 - _filter_beta) * _time_skew;
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}
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}
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void
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MavlinkTimesync::reset_filter()
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{
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// Do a full reset of all statistics and parameters
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_sequence = 0;
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_time_offset = 0.0;
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_time_skew = 0.0;
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_filter_alpha = ALPHA_GAIN_INITIAL;
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_filter_beta = BETA_GAIN_INITIAL;
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_high_deviation_count = 0;
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_high_rtt_count = 0;
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}
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@@ -42,55 +42,7 @@
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#include "mavlink_bridge_header.h"
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#include <uORB/PublicationMulti.hpp>
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#include <uORB/topics/timesync_status.h>
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#include <drivers/drv_hrt.h>
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#include <math.h>
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#include <float.h>
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using namespace time_literals;
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static constexpr time_t PX4_EPOCH_SECS = 1234567890ULL;
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// Filter gains
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//
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// Alpha : Used to smooth the overall clock offset estimate. Smaller values will lead
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// to a smoother estimate, but track time drift more slowly, introducing a bias
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// in the estimate. Larger values will cause low-amplitude oscillations.
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//
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// Beta : Used to smooth the clock skew estimate. Smaller values will lead to a
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// tighter estimation of the skew (derivative), but will negatively affect how fast the
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// filter reacts to clock skewing (e.g cause by temperature changes to the oscillator).
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// Larger values will cause large-amplitude oscillations.
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static constexpr double ALPHA_GAIN_INITIAL = 0.05;
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static constexpr double BETA_GAIN_INITIAL = 0.05;
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static constexpr double ALPHA_GAIN_FINAL = 0.003;
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static constexpr double BETA_GAIN_FINAL = 0.003;
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// Filter gain scheduling
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//
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// The filter interpolates between the INITIAL and FINAL gains while the number of
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// exhanged timesync packets is less than CONVERGENCE_WINDOW. A lower value will
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// allow the timesync to converge faster, but with potentially less accurate initial
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// offset and skew estimates.
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static constexpr uint32_t CONVERGENCE_WINDOW = 500;
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// Outlier rejection and filter reset
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//
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// Samples with round-trip time higher than MAX_RTT_SAMPLE are not used to update the filter.
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// More than MAX_CONSECUTIVE_HIGH_RTT number of such events in a row will throw a warning
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// but not reset the filter.
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// Samples whose calculated clock offset is more than MAX_DEVIATION_SAMPLE off from the current
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// estimate are not used to update the filter. More than MAX_CONSECUTIVE_HIGH_DEVIATION number
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// of such events in a row will reset the filter. This usually happens only due to a time jump
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// on the remote system.
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// TODO : automatically determine these using ping statistics?
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static constexpr uint64_t MAX_RTT_SAMPLE = 10_ms;
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static constexpr uint64_t MAX_DEVIATION_SAMPLE = 100_ms;
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static constexpr uint32_t MAX_CONSECUTIVE_HIGH_RTT = 5;
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static constexpr uint32_t MAX_CONSECUTIVE_HIGH_DEVIATION = 5;
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#include <lib/timesync/Timesync.hpp>
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class Mavlink;
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@@ -106,47 +58,9 @@ public:
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* Convert remote timestamp to local hrt time (usec)
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* Use synchronised time if available, monotonic boot time otherwise
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*/
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uint64_t sync_stamp(uint64_t usec);
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uint64_t sync_stamp(uint64_t usec) { return _timesync.sync_stamp(usec); }
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private:
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/* do not allow top copying this class */
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MavlinkTimesync(MavlinkTimesync &);
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MavlinkTimesync &operator = (const MavlinkTimesync &);
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protected:
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/**
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* Online exponential filter to smooth time offset
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*/
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void add_sample(int64_t offset_us);
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/**
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* Return true if the timesync algorithm converged to a good estimate,
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* return false otherwise
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*/
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bool sync_converged();
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/**
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* Reset the exponential filter and its states
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*/
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void reset_filter();
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uORB::PublicationMulti<timesync_status_s> _timesync_status_pub{ORB_ID(timesync_status)};
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uint32_t _sequence{0};
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// Timesync statistics
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double _time_offset{0};
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double _time_skew{0};
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// Filter parameters
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double _filter_alpha{ALPHA_GAIN_INITIAL};
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double _filter_beta{BETA_GAIN_INITIAL};
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// Outlier rejection and filter reset
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uint32_t _high_deviation_count{0};
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uint32_t _high_rtt_count{0};
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Mavlink *const _mavlink;
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Timesync _timesync{};
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};
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