Pixhawk Details #4: Audio adds Safety

This video illustrates a bit better why we believe the safety switch, buzzer and multicolor led help to greatly improve ground and air safety. The video just showcases a few new key safety features and is not a complete reference / mapping, as blink patterns might differ depending on the flight stack running and/or user settings.  Some details:

  • The safety pushbutton indicates safety on with a slow blink pulse and becomes solid when armed
  • The main led shows the breathe pattern if disarmed and becomes solid when armed
  • Arming is only possible after the safety has been disengaged. This is to prevent accidental arming via RC
  • On arming, the buzzer first emits the arming tune, and then the props are slowly spun up to (a configurable) idle speed after a short delay. User tests show that users can disarm fast enough if having accidentally armed.
  • There are two distinct low battery patterns for low and critically low battery. Since the buzzer is driven with 32V, it can be easily heard from a distance, so even when not looking at the GCS and battery voltage, there is now an intuitive warning, in time to land safely.

We believe that this will greatly help to improve situational awareness of the pilot and prevent a range of potential ground and air accidents.

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  • (Ie. makes Lost quad/plane easier to find!). Would need auto disarm for same state too.
  • A constant SOS audio alarm would be good if the FCC detects that Roll angle = 180' for more than 10 seconds + altitude = 0 AGL...:-)
  • The fact of the matter is the Pixhawk is almost certainly destined to become our premier if not our only flight controller within the next 3 months or so and it has a few more facilities for squeaking and squawking and blinking and breathing than the APM currently does.

    So what is probably most important is what facilities the Pixhawk provides.

    Of course it would be good to have as much commonality between them as possible.

    Euans considerations for current "normal" common meanings of colors is an important consideration.

    Easily associated functions like blinking single color = specific alarm message, Solid color = various fly ready and fly mode or condition messages and breathing = various not yet ready to fly messages mean that the type of led state immediately informs you of the category of expected message.

    And Audible messages really need to be kept simple and few in number, because they quickly get out of hand.

    SOS in Morse code for the fact that the SD card isn't inserted, while cute is stretching it a bit.

    And the bottom line is, provide a good basic subset of potential alarm messages, but then give users the easy (parameter) ability to enable or disable the ones they want to use for their own application.

    I don't want 20 different potential messages I want 5 or 6 and I want them to be the ones I want.

    Any more than that and they will contribute more to confusion than problem solution.

    KISS (Keep It Simple Stupid)

  • Developer

    Just need to point out that this is related to the px4 flight controller software and not arducopter/arduplane.  It's a bit confusing but basically the ETH guys have their own flight controller software that also runs on the px4/pixhawk but we also share the operating system (ROS/Nuttyx) and drivers.

    We generally try to reuse stuff so for example the arming tone and low battery tone is the same but many of the LED warnings are different.

  • yeah fair comment. would be pretty cool though

  • Nicholas, that would require much more system resources to generate a voice.  Plus, then you need to carry around a speaker on your aircraft.  And you'd only ever hear it properly if the motors were off.  I don't think it would be a popular option.  

  • @Chris: You mean for telemetry, the ground station uses voice? But what about using a voice instead of the beeps on the flight controller. That way there could be no mistake on what the FC is doing. I think that this is the most simple and user friendly solution.

  • I think Gary is on the right track IMO, with the only addition being the use of "human stereotypes" for colour. eg: Green = ok, amber = warning, red = critical. And blue for GPS issues.


    Breathing - ready for flight

    Green for all systems and failsafes passed, blue for "waiting for GPS lock". Amber for "low battery" (flight possible, but not advised), Red for "invalid mode for take off" or "battery <3.3v" (ie: flight impossible).

    Constant - in flight, all ok.

    Green for all systems ok, amber for less than optimal conditions (vibes exceeded for longer than x seconds? magfield/compass accuracy too low? RSSI? Telemetry lost? FC volts too high/low?), red for error that will affect flight performance critically (auto flight plan cannot be executed without failure - eg: route has terrain conflict, geofence conflict, desired climb/descent rates not possible between waypoints etc)

    Blinking/audio - alarm (while in flight)

    Red: battery volts <3.3V

    Amber: Battery volts <3.5V

    Blue: GPS lock lost


    Arming: only possible from breathing green or amber - gives a 3 second constant red with audio tone, then change to solid green (or flashing amber/red if take off was done with low battery).

    Disarming - gives a 3 second constant red with disarm audio tone, then change to breathing green


    As Gary says...KISS.



  • 3D Robotics

    Nicholas: If you're connected to a ground station (laptop or tablet/phone) it does use voice. 

  • Is this is the same multi-colour external LED from here with integreted switch, or is the switch seperate? If it's seperate from the LED, does it come as standard with the Pixhawk?

    And when will we have the mount dimensions (hole diameter, hole spacing etc) for all these "externals"?

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