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USB powered hubs to control 4 devices


#1

Hello, I hope people are having a good day.
Im looking at buying 4 x 21v3 JRKS, but would need to control them via a central 4 port USB hub. So one USB going to the PC.
Does anyone know if this would work? and would a decent PC be needed . Ive an old dual core centrino laptop that I currently use for 2 x 12v12 JRKS but each has a USB port. Theres 4 ports total on the PC, but only 3 work
I appreciate any advice.
Kindest Regards, David Lane.


#2

You can actually daisy-chain these devices via their tx/rx lines. I have chained 2 together - any more apparently requires some additional logic on the return tx line, but should still be possible.
You could easily do 2x2 with your two usb ports.
Depending on how much latency you care about, it might actually be easier to program with 1 usb connected to 4 devices.


#3

Hello and thanks, probably 1 usb and program in windows 4 comports might be better. It would be 20ms latency.
Cheers. David.


#4

I should explain more .
Im planning to build a GS4 seat that has panels in it that press against you to replicate motion, of course, seat belts would be needed.
I have built a heap of 2 DOF seat movers and full 2 DOF frames over the years, but my latest project needs a GS4 style seat. They are expensive to buy, over $3000 if you can find one. As they have 4 panels per seat, thats 4 motors and potentially 4 drivers from an arduino or 4 JRKS. I could put something together for a shade under $1000. Im code hopeless and would struggle with finding an ard code, however as Im experienced with JRKS, it would be a piece of cake to set up, be it costly.
But Id have to use 4 USB ports of which I really dont have…I was hoping to run this off a dual core laptop that will easily run a 2 DOF motion sim , using individual USB ports.
But Id like to try to use a hub to run 4 JRKS and obviously one usb to the pc.
Heres a video of someones elses build from a while back, so you can see what I mean


Cheers.


#5

double edit, I take it I could hook up rc servos to JRKS?


#6

Hello, David.

Using a powered USB hub to control 4 jrks through a single USB port should be fine, and as hughsando mentioned, daisy-chaining is also an option.

As far as RC servos, the jrk does not output standard hobby RC signals. It can control a brushed DC motor with analog feedback (e.g. feedback from a potentiometer) and essentially turn it into a servo. For example, the Torxis servo uses a jrk as the control electronics, accepting a hobby RC signal as an input and controlling the brushed DC motor inside of the servo. If you are looking for a USB device that outputs hobby RC signals for controlling RC servos, you might consider the Maestro servo controllers.

Brandon


#7

Morning Brandon.
Ok, thanks for info on using 4 port usb powered hub to run 4 controllers to one usb port on a PC. That helps heaps.
Ive used the JRK 12v12 a lot and I usually build a DC motor / feedback setup on them so that I know.
As Im not familiar with RC servos, I will look further, but I thought they were basically a DC motor with a feedback built in?
Maybe the feedback could be used on a JRK?
Is it not just a pot or encoder on them?

The servo you suggested is WAAAAAAY too expensive for what im planning, but thanks anyway.


#8

the maestro controllers are not much good to me as Im not able to connect them to the motion software I use.


#9

EDIT, I see serial commands. I can use serial commands in older simtools motion software to hook up 12v12. Id have to ask if maestro can be done as well,
I will read a bit more into its utility program in windows.


#10

Servos have their own electronics built-in, and typically use a potentiometer and DC motor inside as you mentioned. However, standard servos do not give the user access to the potentiometer feedback or direct access to the motor leads. Instead, they accept a hobby RC signal and manage the control system internally. You can find more information about servos in our “Engage Your Brain” blog series, starting with this “Introduction to servos” post. Depending on your servo, it might be possible to open up a servo, remove the control electronics, and essentially replace them with the jrk; however, please note that this is an advanced modification that could potentially damage your servo.

I am not very familiar with the SimTools software, but the Maestro does accept TTL serial commands like the jrk. You might try posting on the XSimulator forums to see if anyone there has experience using the two together.

By the way, I was not suggesting to use the Torxis servo for your application (although it might work); I was just using it as an example of how the jrk can be used to create a servo.

Brandon