PX4 Tech Dev Call: November 21, 2018

rroche · November 21, 2018, 7:51am

Wednesday 5PM CET, 11AM EST, 8AM PST (subscribe to calendar)

Join the call: https://zoom.us/j/625711763
Meeting ID: 625 711 763
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thomasgubler · November 21, 2018, 3:59pm

github.com

korigod/mavlink-rfcs/blob/pr-mav-frames-revision/text/0002-local-frames-revision.md

* Start date: 2018-03-21
* Contributors: Andrei Korigodski <akorigod@gmail.com>, Oleg Kalachev <okalachev@gmail.com>, Hamish Willee <hamishwillee@gmail.com>
* RFC PR: [mavlink/rfcs#2](https://github.com/mavlink/rfcs/pull/2)
* Related issues: [mavlink/mavlink#861](https://github.com/mavlink/mavlink/issues/861)

# Summary

Revise MAVLink local frames of reference to create a clear and comprehensive frames system. Agree on the frames naming convention, add some useful frames and correct the descriptions.

# Motivation

## Importance of an appropriate frames system

Rich enough but clear set of coordinate frames is essential for effective drone control.

For example, let's consider a setup in which a companion computer with a camera is used for navigation by recognizing fiducial markers with known coordinates. The location of the drone is calculated and `VISION_POSITION_ESTIMATE` messages are transmitted.

Different frames of reference are necessary in different cases:

* the camera can be installed externally (e.g. motion capture system) — in this case coordinates are naturally in fixed w.r.t. the Earth NED-oriented frame;

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rroche · November 21, 2018, 4:14pm

rroche · November 21, 2018, 7:33pm

QGC and Firmware flashing

The conversation started from qgroundcontrol/Issue#2797

Proposal: Very light schema and transaction protocol for firmware negotiation with an HTTP endpoint.

HTTP rest server for firmware payloads
Firmware parameter metadata (no metadata if you flash from QGC right now)

Direct motor control access

Pedro-Roque: We need a direct interface to the motors. Currently, you can’t send a motor PWM of 2000, and we needed something that was easy enough to use

Action: Dev team has some feedback on implementation.

github.com

PX4/Firmware/blob/master/src/modules/mavlink/mavlink_receiver.cpp#L1463


		    mavlink_system.compid)) {	// This is a returned ping message from this system. Calculate latency from it.


		const hrt_abstime now = hrt_absolute_time();


		// Calculate round trip time
		float rtt_ms = (now - ping.time_usec) / 1000.0f;


		// Update ping statistics
		struct Mavlink::ping_statistics_s &pstats = _mavlink->get_ping_statistics();


		pstats.last_ping_time = now;


		if (pstats.last_ping_seq == 0 && ping.seq > 0) {
			// This is the first reply we are receiving from an offboard system.
			// We may have been broadcasting pings for some time before it came online,
			// and these do not count as dropped packets.


			// Reset last_ping_seq counter for correct packet drop detection
			pstats.last_ping_seq = ping.seq - 1;
		}

VTOL rate control improvements

Rebased and ready for testing, the test team will fly again.

UAVCAN support

Test team needs help setting up their test units; we don’t have proper documentation for setup on dev.px4.io

ESCs
MotorId should start at index 0 and be unique

Motor 1: 0
Motor 2: 1
Motor 3: 2
Motor 4: 3

Nodeid can be random numbers as long as they are unique

Motor 1: 11
Motor 2: 12
Motor 3: 13
Motor 4: 14

Make sure to set the voltage to at least 20 on VOLT_PARAM

Action: Flight testing of UAVCAN vehicles should happen at least once a week

Action: Get UAVCAN hardware for CI and Developers

Localization

Lorenz will propose next week on PX4 dev call, there’s a massive push for localization and there are messages in the firmware that need localization

rroche · November 21, 2018, 7:33pm

Audio recording (click jpg)