Can anyone suggest a compatible speed that would have an output of 0-5 volts. The set of thrusters I am using have a +/- 5 volt control system.
Hi Kevin,
Can you explain this a little more? You are using thrusters that require a 0-5v control signal? Do they already have some sort of speed controller?
-Rusty
We are using thrusters from an old Sub Alantic Navajo. The thrusters run
off of 300vdc for drive power and use a (-5) 0 5 volt reference for speed
-5 volt being full reverse 0 being stop and 5 volt full ahead.
The old system uses a bunch of analog cards and copper teather to control
the machine and was EOL’d about 5 years ago.
The plan is to pull all the guts out of the bottle except for the 300v
isolation transformer 12v power supply and 5v power supply, then reinstall
an advanced electronics package. The teather we have already has multi mode
fiber, the plan would be to use fiber modems for Ethernet coms and a mux
for the rs485 sonar.
We also have an INS, USBL and DVL that can be integrated as a separate
package for station keeping.
This is really an experiment to see if we can more life out of these
machines or are they scrap.
Any input would be apreacated
Kevin
Kevin,
Awesome! That sounds like a fun project.
You’ll definitely need some sort of PWM to analog 0-5vdc converter. I don’t think I’ve ever seen anything like that. Do you know what the motor controllers are? Perhaps they have an alternate input method besides analog that could be used.
Are the motor controllers built into the thrusters?
-Rusty
Attached is the link for the spec, we have 6 of the SPE-75’s with the 5 VDC
control system. Yes the controllers are built in to the thrusters, so we
are stuck with them. We all like the Blue ROV design just need more HP to
drive some larger sensor packages.
http://www.f-e-t.com/images/uploads/data-sheets/Brushless_DC_Thrusters.pdf
You’ll definitely need some external circuitry. The autopilot is capable of outputting motor control as a 0-100% duty cycle at 16kHz (this is different than the more common RC PWM signals). Look for something that will convert a duty cycle to a voltage. Here is a simple example to convert to an analog signal, but this might not be a good enough solution due to the ripple and lag.
I can find a lot of options to go from PWM to 0-5 Vdc its getting the
reversing side figured out. full speed forward is +5vdc and full speed
reverse is (-)5 vdc reversing the outputs is the issue
You can do this sort of conversion with op-amps. Here is an example.