Hi folks,
I need to drive 4 (3-10 amp) dc motors and run a PWM signal for two other channels (1 is a 2 amp load & the other a 4 amps load).
I know there are 2 on-board motor drivers on the Orangutan2 board.
Can I do this with the Orangutan2?
If so, could someone point me in the correct direction?
Thanks in advance.
Hello.
Can you tell me a little bit more about your project? Do you need bidirectional control of your four motors? What are you planning on running off of the two PWM channels?
The Orangutan X2 is capable of driving two bidirectional DC motors (~12 A continuous per channel, 30 A peak). You could use the X2 with a second dual VNH2SP30 motor driver board (or a higher-level qik 2s12v10 dual motor controller) to get two additional motor channels.
- Ben
Hi Ben and thanks for the speedy reply.
The application is a small Remote Operated Vehicle for use in fresh or seawater down to 100m.
The 4 motors will be thrusters (L,R, vertical and horizontal-much like a bow thruster).
The two PWM signals will be used to control two sets of lights- one set of LEDs for normal navigation and a pair of halogens.
There will also be three TV cameras after the unit is full developed as well as a couple of interchangable tool modules.
Control will be (hopefully) over duplex fiber. The learning curve on implementing fiber at a reasonable cost has proven to be fairly steep.
Thanks for any ideas/insight.
Bill Black
Roseland, FL
Bill,
I’m not all that familiar with ROVs, so I’m still not entirely clear on what you need. For example, would you ever use the L and R thrusters simultaneously? Are they bidirectional or unidirectional?
- Ben
Hi Ben,
I am sorry I was not more clear.
An ROV is set up to drive much like a water-borne tracked tank. Each thruster must be capable of bi-directional operation at any time at any available power level.
L & R full forward: straight and fast
L full Forward-R full Reverse: spin L
etc.
The vertical thruster is responsible for up/down movement in the water column. Small “inspection class” or “flying eyeball” ROVs are usually set up to be very slightly positively buoyant, so in case of some critical failure such as loss of power or having the tether cut, the machine will float to the surface for recovery. Therefore the vertical thruster is on a good bit of the time.
The transverse thruster provides lateral movement. This will be the first time I have used one, but I want to be able to maintain a parallel course at a specific distance from, for instance, the hull of a ship or a breakwater wall.
Water currents can present some very complex challenges to 3D navigation, even more so when peering at a screen.
I hope this clarifies what I am attempting.
Thanks again for your help.
Bill Black
Roseland, FL
I have a few suggestions for you:
-
Use two TReX motor controllers controlled by the same serial line (they can be daisy-chained together). These motor controllers have the same motor drivers as the Orangutan X2, and each one can control two bidirectional motors and a single unidirectional motor. You could use the unidirectional motor port on each TReX to directly power your lights directly, but you should note that this unidirectional port uses a relative low-frequency PWM (38 Hz), so your lights might visibly flicker. I know of someone who used three daisy-chained TReXs in his underwater ROV.
-
Use an Orangutan X2 to drive two of your motors and:
a) Use a qik 2s12v10 to drive your other two motors. The qik gives you a high-level serial interface to the same motor drivers that the X2 users, making it easy to control additional motors. You can use PWM outputs from the Orangutan X2’s I/O lines to control MOSFETs that deliver power to your lights, or you could get a second qik 2s12v10 and use the motor channels to power your lights.
b) Use a Dual VNH2SP30 motor driver carrier to drive your other two motors. Board is the same as the one used as the X2’s motor driver board, but it will require more work to interface with. You will need to use the X2 to supply it with PWMs if you want to achieve variable motor speeds. The X2 is certainly capable of this, but I’m not sure what kind of experience you have with embedded programming. You could use a second board to power your lights, or you could use PWM-gated MOSFETs.
Do these suggestions make sense? Do you have any questions?
- Ben