Sorry for such a newbie post, but I’m at my wits end. I’m almost to the point of hiring a Pakistanian software engineer on fiverr to help out.
I’m a high school English teacher who has been volun-told to teach Robotics. We’re trying to build an autonomous boat. We can’t figure out how to get the pixhawk and mission planner to move a servo. I know it’s something simple but we just can’t figure it out. We’ve been doing research and watching youtube for three weeks now and still can’t make it work. Please help.
Here’s what we have:
pixhawk 2.4.8 with GPS module, xt60 power module, and telemetry radio
Taranis X9D plus 2019
X8R receiver
Windows 7 laptop with current MP software
ASMC-04B heavy duty servo for rudder control
futaba s3003 servo for testing
Generic ESC from amazon
Here’s what we have done:
Installed MP on laptop
Installed latest Rover firmware on Pixhawk
run initial calibration on pixhawk
bound the x8r to the taranis
updated taranis with open tx
we can see the transmitter working when calibrating the radio in MP
Kids have figured out how to make waypoint missions in MP
We can’t figure out how to make a servo actually move. Which of the outputs on the pixhawk to use, how to map the transmitter signal through the pixhawk/mission planner to an output on the pixhawk.
We need to set up a button on the taranis to toggle between manual and waypoint mission control.
We need to figure out how to bind the ESC to pixhawk.
I’ve been the robotics coach for a few years now but we’ve been using the VEX EDR stuff which is just plug and play. I’ve got a handle on all the mechanical engineering stuff but this software simply eludes me. I can’t get my head around it. What I really need is a three hour sitdown with an expert, but we live in rural Arkansas and I don’t know of anyone around that can help. I’m willing to travel to Dallas, Oklahoma City, Shreveport, or other similar locations to get help. Or Zoom or just here via chat. Willing to provide compensation for time spent.
Sorry for the long post but I’m pulling my hair out trying to get this to work. My kids have already destroyed one laptop and almost bricked the pixhawk trying stupid stuff.
The output bus on the flight controller isn’t powered. You need to feed it 5v, typically from the ESC/BEC to power the servos.
ESC calibration can be a pain, but there’s a couple of tricks to get it done. One way is to connect the system to a battery and USB. With the RC connected arm the flight controller in manual mode through mission planner (you’ll probably need to force arm it). Disconnect the battery, but leave the controller plugged in by USB. Move the RC throttle to max, and plug in the battery again. wait for the beeping to stop. Move the throttle back to min and again wait for the beeping to end. Power cycle everything and you should be good.
Don’t be afraid to post your questions here. Many of us are teachers, from primary to post-secondary, so you’ll find a ton of people willing help.
If that is ESC calibration, you need to know that:
ESC’s regulate speed depending in most simple cases on a PPM signal (really PDM) which consists in positive pulses moreless 1 to 2ms repeated at 50Hz.
Those pulses are part of a train of pulses in a predefined order for the low channels. Throttle (ESC’s) is CH3.
The universal convention is 1ms<>low speed and 2ms<>high speed.
To acomodate ESC’s to transmitter generated pulses (moreless 1-2ms (transmitter with default parameters)) ESC’s alone can be calibrated. Universally if when being switched on they see a very long pulse they will enter into calibration (they must learn how long is the long pulse ( ~2ms) and how short is the short pulse ( ~1ms)). Consult the ESC manual, but you will see that calibration starts with transmitter on at full throttle, and then powering the ESC (with a motor connected that won’t move), tones at the motor, throttle at minimum, etc.
To assure that for example a quadrotor takes off vertically, all four ESC’s must have learnt the same values for the low and high pulse durations.
That learning can be done by Ardupilot, but you can also connect the receiver throttle signal to the four ESC’s to five sets of pins soldered in parallel on a piece of uniprint PCB (three pins for one ESC supplying the receiver (if it can) and the receiver, and two pins (signal, GND) for the other three ESC’s (don’t connect the ESC’s 5V supplies in parallel (and don’t worry to much if you have done it))), and calibrate the four ESC’s at the time. The four ESC’s must have a common battery supply (connected with transmitter on) and you can have motors connected to hear the tones (which shouldn’t move).
