stud_wallz

Rest assured its a category 4 safety system that monitoring all safety aspects... plenty of redundant safeties both mechanically as well as electronically... I didn't mention it because it was irrelevant to the controlling issue... I have dual string pots along with the encoder for position verification, in addition to 4 limit limit switches along travel... and a sliding counterweight box that moves as the load shifts to balance the load... its a pretty intelligent system...

This looks great for creating an S-Curve, thank you... but how can I get this curve to relate to position, so that time is a variable based on current position and desired position... in other words take a snapshot of the current position (0VDC), then take a snapshot of commanded position (10VDC) then calculate the time window based on maximum time (15 seconds) to achieve the move... to create the S-Curve... then if I were do the same thing where we would again take a snapshot of the current position (5VDC), then take a snapshot of commanded position (7VDC) then calculate the time window based on maximum time roughly say a percentage of maximum time (for arguments sake 7 seconds) to achieve the move... to create the S-Curve... but the maximum speed should never be achieved because the distance between the current position (5VDC), and the commanded position (7VDC) is too short to get up to full speed of the motor... is this right or am I missing something?

I've got a project I'm working on and I just can't seem to wrap my head around the best approach to it. I'm hoping someone can lend me some insight. Here is the problem: I'm using a ControlLogix 1756-L61 controller with the ENET adapter talking to a PowerFlex 755 VFD drive, controlling a 25hp AC motor. I've got an encoder and brake on the back of the motor which gives me safe control over the motor. Externally I've got a "string pot" or potentiometer that gives me 0-10vdc feedback as to position. All that being said, this is what I want to do. I'm trying to control a lift (14,000 lbs) and move from the current position to its commanded new position, using the "string pot" to determine position I want to make that move in a smooth S-Curve, ramping the motor VFD reference frequency out of its current position up to full speed, then ramping down as it nears the commanded position. (kinda of like a crane or elevator movement and control) I can sure use help in writing the ladder logic to do that...