Question Hydraulic 6DOF Stewart Platform Control Hardware?

Hi everyone!

I have recently acquired a large 6DOF Stewart motion platform on eBay (For a total of $500AU!). It apparently originally came from an arcade where it was paired with a cinema screen with a total of 9 seats on top. Unfortunately, through the changing of hands, the computer that ran the software is no longer with it, and it only has the control board. It looks to have 6 solenoids to control the hydraulic rams, and some chinese board that runs the solenoids. The board looks to have a 4 pin input that is labelled COM, so I am assuming it communicates via some form of UART to send control signals, but I have no idea what the protocol is. I have tried reaching out to the original manufacturer of the sim as well as the control board and they no longer have anyone working there who is familiar with the system.

Is anyone familiar with this sim/control board, and if not, what are my options for replacing the control board with another controller that will work with the hydraulics?

Photos are attached below of the sim.

Cheers,
Khaotic

Not sure if this helps you - https://www.alibaba.com/product-det...pm=a2700.7724838.2017121.5.13343ddfzzVYRs&s=p

They might be able to sell you the missing pieces, but ultimately if you can get it working with Simtools, it opens your 9 seater up to video ride player and NoLimits2, etc.

Thanks guys. Shame that forum thread ended in him selling it before he got it working! I've been looking at the AMC1280USB controller and trying to figure out whether I will be able to get it to control the hydraulic solenoids. Not sure the exact signals required to control them and whether I'll need to use an Arduino to sit in the middle. Have you guys used that controller before?

Maybe the creator of the AMC1280 can answer you? @Thanos

So I've spent a bit more time looking over the existing control board and I have a pretty good idea of how it is working and how I could add the AMC1280USB. I have annotated the board below:



Firstly, the red chip is some sort of microprocessor with unknown firmware on it. The 4 pin yellow input is the COM input, where I assume the serial connection to the controlling computer comes in and is processed by the microprocessor. The cyan wires connect to the 6 variable resistor sensors attached to the hydraulic rams to give position information. The big magenta block contains 12 24V MOSFETs that drive the 6 pairs of solenoids on the hydraulic manifold, which go out via the two magenta connectors. The orange block of MOSFETs connect to 3 valves that let air through to little rubber pipes that whip the user's feet.

What I am thinking is, I could be able to desolder the microcontroller off the board and replace it with the AMC1280USB, running its 5V outputs directly to the pins under where the micro was to directly the control the solenoids. My only concern is I don't think the AMC currently supports 12 outputs, so I may need to put a NOT gate on each of the outputs to the corresponding paired solenoid. If @Thanos is around, I'd love to hear if he thinks that would work!

The AMC1280USB, has 12 digital outputs for direction, so you could connect the solenoids there. The position sensors are also connected in the 6 inputs on the AMC1280USB. The only thing missing is the speed. I don't think this platform supports speed control. It will require to setup the AMC1280USB with low "step" setting to simulate the missing speed control, so it will switch its direction pins on and off proportional to the feedback sensors to approximate the position.

I believe it can be done if you use the AMC1280USB 5V signals to bypass that control chip.

Thanks
Thanos

Awesome, thanks @Thanos! When do you think you'll be getting another batch of AMC1280USBs made? I've jumped on the wait list, I'm just a bit impatient!

I'm restocking parts currently, some parts are getting hard to get and take longer to ship and arrive to USA

Right now the waitlist on Tindie is 5 people and growing each day...

Looking forward to getting my hands on one of the controllers @Thanos! Thanks for the work you're doing on them!

Hi @Thanos. I recently received my AMC1280USB and I have started connecting it up to my motion simulator and I have a few questions for you. I have removed the old micro off the board and mapped out the pins on the footprint to each of the solenoids. The control signals for the solenoids appear to be triggered when the input pins are pulled down from 5v to gnd. I have found a CMOS inverter that I should be able to use if the digital outputs on the AMC are at 5V when trying to trigger the solenoid (TI CD74HC04E). How do I set the AMC up to use 2 channels for each ram, one for up and one for down? And how do I set the low "step" setting to simulate the missing speed control?

Cheers,
Khaotic

First, you need to setup the board in the menu, the Input for Analog with 10bit, 180.
Then setup the Output for Analog 8bit, and bi-directional.

Second, did you connect the analog position sensors to the analog inputs of the AMC?
(A1, A2, A3, A4, A5 and A6), I assume the position feedback sensors on your platform are linear potentiometers, right? Can you show them here?

Based on the feedback on the sensors, the AMC will enable each of the two digital direction outputs, so each should be connected to the solenoid for up and down. When the position sensor is on target, both digital outputs are disabled (0v). The gap for these two outputs to be off, is small, but you can increase it if you increase the Min Speed parameter (i think it goes up to 14).

Also decrease the PID settings down to:
P= 10, I=0, D=0, for all motors.

Then, to create virtual steps for controlling the speed, try to decrease the STEP parameter, that is located under the 6DOF home position menu item. Set the step down to 10.

Give it a try, if the actuators move all the way to one direction, you may need to reverse the connection for the two digital direction pairs for the actuator to get the correct direction.

Thanks
Thanos

Awesome, that's super useful info. Will give it a try soonish and let you know how we go! The sensors are these linear potentiometers, which already operate from 0-5V from my testing, so they should just work out of the box.



Fingers crossed we get it working and don't kill someone in the process!

Connect one linear potentiometer and one set of solenoid first to try one actuator... dont try all together!!

Yeah that's the plan. I have removed one of the linear pots from the side of the rams so I can manually adjust it, and the hydraulics run on a separate circuit from the solenoids, so I can operate the solenoids without the 3 phase hydraulic pump turned on.

I wish I would have seen this thread years ago. I would loved to have the chance to get that thing going.