Has anyone investigated using water jets in an ROV instead of a multi-thruster system? I am imagining a single flow source like a pump with a diffuser inlet attached to a multi-outlet valve manifold. The manifold would use one actuator with position control (like a servo) and would duct the flow to ports around the ROV that would give it motion. I feel this system makes sense because it would only use one motor and one actuator, simplifying the control system and likely reducing the power needs?
I want to hear people's input, and I will work on drawing up a simple schematic of what I am talking about.
Jets With Valve Control
Re: Jets With Valve Control
Whether you pump water to a jet or you move water with a thruster, you are still gonna pull power.
You can 'simplify' the thruster controls by using a Pixhawk running Ardusub, with Q-Ground-Control on a PC at the surface. This will act as an autopilot, allowing you to move a joystick on the surface, letting the Pixhawk on the ROV decide which thruster to run in what direction. You can configure the system to move the ROV with as little as 3 thrusters.
You can 'simplify' the thruster controls by using a Pixhawk running Ardusub, with Q-Ground-Control on a PC at the surface. This will act as an autopilot, allowing you to move a joystick on the surface, letting the Pixhawk on the ROV decide which thruster to run in what direction. You can configure the system to move the ROV with as little as 3 thrusters.
Re: Jets With Valve Control
interesting idea there ARES.
unfortunately water jet propulsion is notoriously inefficient at low speed, at least in boats it is, so I suspect you would increase power needs rather than reducing them.
Having driven a twin jet drive diesel RIB and had to refuel it far more frequently than a similar sized twin 90hp petrol outboard driven RIB at similar speeds I can agree with this. thankfully I wasn't paying the fuel bill.
The control algorithm for the actuator would be a good challenge though. I like that you're thinking outside convention.
The jet RIB has "buckets" that you drop over the steerable output nozzles to direct the flow for reverse whereas I think you are talking about having maybe four fixed nozzles for horizontal and one or two for vertical movement.
having a nozzle pointing down will certainly stir up sediment if you want to hover close to the seabed.
If it was me I wouldn't go that route but nothing was ever gained by not trying, so if you're up for experimenting then by all means give it a try and let us know how it goes.
unfortunately water jet propulsion is notoriously inefficient at low speed, at least in boats it is, so I suspect you would increase power needs rather than reducing them.
Having driven a twin jet drive diesel RIB and had to refuel it far more frequently than a similar sized twin 90hp petrol outboard driven RIB at similar speeds I can agree with this. thankfully I wasn't paying the fuel bill.
The control algorithm for the actuator would be a good challenge though. I like that you're thinking outside convention.
The jet RIB has "buckets" that you drop over the steerable output nozzles to direct the flow for reverse whereas I think you are talking about having maybe four fixed nozzles for horizontal and one or two for vertical movement.
having a nozzle pointing down will certainly stir up sediment if you want to hover close to the seabed.
If it was me I wouldn't go that route but nothing was ever gained by not trying, so if you're up for experimenting then by all means give it a try and let us know how it goes.