STAUBLI RX60 PROJECT
The RX60 is a very fast industrial robot. Mine was made back in 2001 so it's a little old now. The original controller is no longer functioning, but the arm is ok.
This is the story of how I intend to bring it back to life, the long painstaking process of finding out about how it works, and a chance to share the information with others who may be want to do the same.
Thank you to RoboDK for helping me with this software control for this project. Their offline programming tools are fantastic for simulation and program exports. Have a look here: www.robodk.com
Click the links below for specific sections.
THE ARM AND MOTORS
The arm is beautifully made. It's cast aluminum with a tough paint finish. Mine is the 'Clean Room' version so it's white and has a smooth finish. Having removed the access covers, it becomes apparent that there are three motors made by Baldor and three by Maximmotor. All are geared via custom-designed gearing in the arm, and the first three joints have breaks incorporated to stop the arm collapsing when unpowered.
The original controller service manual states that the motor-bus voltage should be between 190V and 210V DC. This tallies with the 'specification plate' on the first two joint motors. My other robot (an early Puma 560) used 48V DC motors which were a little safer to deal with than these. Playing around with 200V DC isn't something to be taken lightly. And the motors being AC rather than DC has its own complications when it comes down to finding a suitable driver.
Staubli decided to use Resolvers to close the servo loop on all six motors. This was presumably the case as they’re particularly suited to harsh environments and high vibration. The bad news is they're more difficult to work with for an ammeter like me. You either have to interpret the signals they produce directly, or convert the signals to something easier to deal with, like an incremental digital signal for example. Resolvers are new to me so lots of digging around trying to understand how they work was required. Something I didn't realise initially is that they're 'absolute' devices which makes sense when you know how they work. That could be useful later down the line to aid calibration if the arm, I think. There's more info on them here: WIKI
THE CONNECTING CABLE
At the base of the arm are two connectors; one to connect it to the controller, and the other for 'user connections'. The latter is basically a multi-pin setup that repeats pin-for-pin to a corresponding socket near the end of the arm. There's also three pneumatic hoses that go up there but it’s unlikely I’ll be using those.
The connector for the controller is a little more scary! It's a heavy-duty HAN108 type which looks a little overkill for a robot of this size. I then had the problem of working out what all the connections were which initially seemed a little daunting.
Following yet more trawling of the web for information, I cam across the London Hackspace. It turns out they have an RX60L there and have documented their setup pretty well, so I had a good starting point when it came to the pinouts. Actually, it's a little different to their one, but it certainly helped. Luckily I have the original cable too which has saved a lot of time and confusion. I've decided to break out the cable to individual sections, each one relating to each joint. You can see how that works here: XCELL SHEET
WHERE DO WE GO FROM HERE?
So, I have a robot, I've worked out what the connections to each motor are, I know they have Resolvers on, I know roughly how Staubli did it in the original controller, but now it's my turn to have a go.
I have a number of issues to overcome:
I need to work with high-voltage motors. Maybe they run at a lower voltage ok? I need something to test them with.
I have very limited information on each motor, next to nothing in fact.
I need to work with AC motors, not DC.
I need to utilise the Resolvers or somehow convert their signals to something easier to deal with.
I need to control six motors at once (eventually) in a coordinated fashion.
I have very limited software knowledge so need something that I can use 'out of the box', or with very little setup.
I have a limited budget as this is a personal project.
Again, after huge amounts of time trawling the internet for suitable (or at least what I think would be suitable) drives, I stumbled across two systems that I think will work. They both have their pros and cons. The two drives are the STMBL and the Argon. There’s more detail regarding these on the ’Servo Drives’ page.