Hello,
I'm looking for input on a current project. I'm retrofitting the controls on a older sausage stuffer. The stuffer has a fixed displacement feed rotor driven by a hydraulic motor, which is controlled by a hydraulic proportional valve. The rotor has an incremental encoder for position feedback.
The basic process is that the hydraulic motor needs to be ramped up to a set speed, and ramped back down again to stop at a predetermined encoder position. The positioning needs to be very accurate, because obviously the machine needs to dispense a specific volume of product based on what the operator has entered. Also, the whole operation happens relatively quickly, depending on the size of the portion being dispensed. Ideally we want a motion profile something like this: 150 milliseconds to accelerate, 200 milliseconds at full speed, and 150 milliseconds to decelerate to a stop. The customer is OK with slowing down a bit if necessary to get the accuracy we need, but for now I'm aiming at a total time of 500 milliseconds for dispensing one portion.
I'm hoping to control this with a BRX, using a 4-20 mA signal to a proportional valve driver, and the encoder feedback for closed loop operation. I'm thinking that the way to go about this will be to use a virtual axis and the motion control commands, with the axis CurrentVelocity scaled to the analog output, but I'm not certain on the details of how to make this work, especially to get it to ramp down to a precise stop. I've done some other motion control projects of varying complexity, but never with hydraulics.
I'll try to get a video on here tomorrow for a visual of the process.
Anybody have suggestions on how to go about the control?
Topic: Hydraulic position control application (Read 6249 times)