Hello everyone - the last hardware needed for my boat build arrived today, and I am planning on doing extensive testing in a lake on this coming Tuesday. Our platform is a 45" long RC speed boat, that has had its very basic control system, brushed DC motors, and psuedo servo removed, and replaced with the ardupilot, a 9 channel receiver, 2x 50A ESCs (liquid cooled), 2x brushless motors (liquid cooled), and a strong servo. This weekend I'll be finishing the motor and servo mounts, and securing everything in the hull. The system will be powered by two 2S 5000mAh batteries for now, with the option to add a 3S 5000 mAh battery in the future. I am using a 3DR radio for telemetry.
I do have a couple of questions for the group:
First - I am running two drive units, so I was planning on having only one of the batteries BEC connect the the ardupilot (apm2.5) to power it - the other ESC will connect only it's ground wire (to establish a common ground) to the ardupilot. The 5V line from this second ESC will not connect to anything, and I believe that if I want the same throttle level sent to both motor controllers, the white signal wire needs to be spliced so that both ESCs receive the same signal. Is this correct?
Second - does anyone have any experience with the PID settings in relation to a boat? I assume that the ArduRover code is configured for a land rover, and will experiment with settings, but if someone has some data as a starting point, that would be great.
Third (and final) - While speeding around at high speed is fun, it will definitely run down the batteries quickly. I'd like to test for awhile, and so would like to set a throttle or speed limit - where is the best place to do this? In the Mission Planner software, or at some point in the ArduRover code?
Thanks very much to whoever reads all that - and especially if you have any advice to offer. I'd like to mention that I have access to two 3D printers - one is my own personal, and another at work - so if anyone ever needs a part (in ABS plastic) please don't hesitate to communicate with me, and we can either print your .stl file or I can assist in designing whatever part you might need. My motor and servo mounts are 3D printed, as well as the APM mount and 3DR mount - it makes the whole building experience quite painless and enjoyable! I plan to develop a larger propeller design and print those for use on the boat, as well as larger scoops for the intakes of my water cooling system.
tl;dr - Starting to test an ArduRover boat - have a few questions on wiring, PID, and speed governor. Also am willing to trade 3D printed parts for advice, or just for the fun of helping out on cool projects.
-Tony
Replies
HI,
My boat runs with PID settings
P = 0.9
D = 0.07
I = 0.01
but it is controlled by one motor and one rudder so probably settings will be different. Also my goal speed is around 2 knots, if you plan to go fast reduce P value to prevent flips !
here the last run....
http://youtu.be/ZWIY-hDTsu0
Good luck !
Flavio
@Anthony,
First: Yes, both white (signal) wires and both black (gnd) wires should be tied in parallel so that the APM throttle command will drive both ESCs. However, you should only have one of the ESC's red wire providing power to the APM.
Second: Sorry, but I have no experience with the ArduRover PIDs in relation to a boat. I have not changes the PID settings with my rovers.
Third: You can use the MP to set the cruise/maximum throttle settings. The boat throttle settings should be just like an airplane with 1.0ms being 0% throttle and 2.0ms being 100% throttle. You might want to start somewhere between 30 - 50% throttle to see how it performs.
Hope this helps.
Regards,
TCIII