Synch 12-axis for force control

I’m working with my customer on setting up a 12-axis force control system. Each axis will be setup one at a time with a specified preload for each axis. This will be done manually with a jog sequence for each axis. Right now we do not know if the preload will be the same for each axis (say 50 lbs) or a percentage of the axis max force in which case each preload will be different. Each axis will have a different max force requirement. Once all 12 axis are setup and ready for operation the user (from an HMI) will give a signal to the RMC150E’s to step the force up 1% of the max force for each axis. All 12 axis should start the move at the same time and once the target force has been reached hold that force until given a new input signal. Each input signal from the user will be to move a percentage of max force, currently that is 1% but that could change to a higher value. Thus for each axis the new target force will be different. Some suggestions on how to best accomplish this up would be most helpful. Our customer’s HMI will be a computer using Labview to communicate with the RMC150’s via Ethernet.

This has been done with 60 axes but the controls were done over Ethernet from a Control Logix PLC which has very fast Ethernet. If the HMI has fast Ethernet so that it can send commands to all three RMC150s are the same time then there is no problem. I would download the preload and max force for each axis in the variable table and then when operating download only the percentage. A user program in the RMC150 will multiply the percentage times the force range and add the preload to compute the current force set point.

The NI Labview 's Ethernet should be fast enough to download the percentage set points to all three RMC150s within a few milliseconds. If tighter synchronization is required then a digital output from the PC can be used to start all three RMC150 at the same time. So far this has never been necessary because the Ethernet was fast enough.