May 06, 2015

Programming the Taranis for a better Motor_stop

After posting my last Blog about motor_stop or not, I posted the blog to the QLD FPV gurus on facebook to get their take on the plus and minuses of setting motor_stop.

As initially though this topic has a lot of controversy - with people on both camps. What I did like though was something that came a bit from left field.

Most people around the mini quad circuit have heard of the infamous and famous FinalGlideAus whose amazing antics can be found on his youtube channel https://www.youtube.com/channel/UCuibbKUX0wT5yie0_EM0Smw The interesting setup that he uses is along the lines of a two switch setup, that allows the quad to be armed when they are in a certain positions and disarms when either of them is switched back (this means the motors stop immediately when disarmed - no delay after stick hold necessary) which was my main concern of not setting motor_stop on cleanflight. He also discussed ramping up the throttle on arm to have it spin slowly allowing the gyros to always be active even on a zero stick throttle spin.

So with all credit to him, I decided to do something along this concept using the Taranis.

I will start by saying there might be a more efficient method of doing this, as I just threw the logic together and if you have a better way to achieve the same goal please post it below.

I will use the simulator to show you the setup as this is the easiest way to show this on the blog

So lets start by showing what switches will control arming. So looking at the below we will use the two way switch SF on the left back of the TX and the momentary trainer switch SH on the back right.

My ideas is the SF switch is like the ignition switch. It must first be switched on (forward) before the starter switch SH is held forward for 1 second to arm the quad. On arming the motors will spin up and moving either switch will disarm the quad.

As an additional safety feature the throttle stick must be at the bottom to arm.

 

So the process is

To ARM

1. Move throttle stick all way down

2. Switch SF forward = ignition on

3. Hold switch SH forward for 1 sec - quad is armed - motors will spin

To DISARM

1. Move either Switch SF or SH

As a safety precaution the SF switch (ignition) must be moved backward to reset before arming again.

 

So how does this magic work I hear you ask. Well here is my logical switch setup. You can either do this in OpenTX and transfer it across to the TX or the TX directly

So lets break this down. I am using logical switches to do the logic...makes sense hey.

Might be best to work backward - L6 is used to trigger the arming via Special function 1 (on channel 8 on my quad - aux4). So if switch L5 is set it will arm and if switch L7 is set it will disarm

So lets look at what L5 is looking for - it wants switches L4 and L2 to be set before it becomes active. So L4 will be on if L3 is active and off if the SF switch is moved back. This is the reset of the ignition switch for safety. L2 does a similar thing and check if L8 is on (the throttle position safety and starter L1 check) and the ignition SF is forward)

So if L6 (arm) is on push channel 8 up to 100%  (otherwise -100%). Just need to set up the arm function on Cleanflight to aux 4 and make the it arm when it is high.

I also added a couple of things to the mixes function on CH3 (throttle).

For safety if the quad isnt armed the throttle will always send zero throttle to the quad regardless of stick position. This can be seen on the IfKilled setting.

I have set the arming to increase the throttle by a weight of 20 to spin the motors slightly (Boost). You need the delay in here so it can arm before it does this. This parameter could be left out if you still want to use the traditional motor spin on arm.

So i have tested this in the simulator and with my quad without props on and all looks ok. So it should be fine but need some test flights to make sure.

Let me know your feedback.

2016/08/29

Rigo said:

Nice, this was very useful info and I learned a few things about the “edge” logic switch.

Thanks for sharing this!

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