I have explored the issue of using arduino or similar platform as an autopilot head for a boat. I have built the drive that interfaces with the boats steering.
I am thinking of using ardurover as the autopilot head. Can someone provide help with interfacing with my steering drive. The drive has a clutch, ground and 2 power leads for right and left steering all 12v. The motor is rated at 60 watts or 5 amps. I assume some kind of h bridge would work but not clear how to interface with the ardurover.
@victorbreen,
Yes, you can use the ArduRover2 code and an APM to provide steering and throttle control for your boat.
You did not indicate the voltage and current requirements for your steering unit so I cannot advise you on what to use to drive it. However guessing that it runs off of 12vdc and maybe could take between 10 - 20 amps, you might try to find a single channel servo motor controller, that accepts PWM input, that would meet those requirements. You would have to provide a servo feedback signal ( a pot connected to the rudder shaft) to the servo motor controller to complete the servo loop. You would use the APM steering output to drive the rudder servo motor controller.
For your propulsion motor of 60 watts and 5 amps, you could use a brushed motor car speed controller as long as it could handle the current of 5 amps or more and the running voltage of, I assume, 12vdc. Hobby Kind Intl sells 30 amp brushed car speed controllers for around $12 USD. You would use the APM throttle channel output to command the speed controller.
Regards,
TCIII Developer
As Thomas has indicated above, this probably will basically work even in a full sized boat.
But the rate of response may be way too fast for a full sized boat and it is not easily reset to a satisfactory range by a user.
Also, the APM / Pixhawk is intended for hobby and UAV use and is not evaluated at all for use in human containing vehicles.
Essentially this is fly by wire for a 32 foot boat you are talking about and there are definite potential safety issues.
T-boning somebodies sailboat at 20 knots would probably not be a good thing and using this for underwater obstacle avoidance or to maneuver in fog would also exceed it’s safe operational expectations.
On commercial units there are extensive alarms to warn of internal problems and failures (like with GPS fix)
Whereas the ones we have are not suited to that use.
Just a caution you should NOT depend on an APM to keep you safe, if you go below decks while an APM is operating your boat, you have made a serious mistake.
Sure you can play with it for this use, but if you really want to use it like a commercial autopilot, get a commercial autopilot.
@gary,
Good words! Yes, I would not recommend this for open ocean or any congested water way due, as you have pointed out, to the potential for unexpected glitches that could cause an unintended accident.
Regards,
TCIII Developer
Uhm, guys, I would say that a 32ft boat is pretty much fullsize and hence I would guess, that the 12v 5A motor is, in fact, the steering motor and not the main drive… We have a 30ft boat in inland water rescue and that boat’s drive is 2x750hp… (=1119kilowatts)
The propulsion of the boat is a gas 190 hp motor but doesnt need to be controlled. On boats of this size once the throttle is set it tends to stay the same for long periods of time.
I understand the safety concerns. The reason for the autopilot is to decrease the workload of long trips up and down the Columbia river. Driving the boat requires continuous monitoring whether on autopilot or not.
Now re the feedback loop. The steering is driven by a chain and rod system. The rods turn and connect in the stern to a crankcase that pushes the rudder back and forth. What kind of device would sense that?
I am also concerned about thr response time issue raised. The boat runs at 7 knots and is slow to respond to steering inputs. I would have thought the software of ardurover would have a variable time day. Yes?
I am looking for some help on which autopilot to buy to work with ardurover for my project. The two choices appear to be the apm 2.6 and Pixhawk. I understand the first is a mature platform and the 2nd newer and more robust. I would buy the latter if I thought it would be reliable.
@victorbreen,
If you want to future proof your autonomous navigation system, go with the Pixhawk. The APM is just about out of room for any further firmware functionality updates except for the rover code. Once the move to the Pixhawk begins, the APM updates will being to fall by the wayside as the developers begin to turn their attention to the Pixhawk and other more powerful mcu like the BeagleBone Black.
Regards,
TCIII Developer
