Context
In an electric cylinder, whatever the machine pushes against ends up as axial force on the ballscrew and its bearings. In press-fit, tightening and pressing work that force is the process: it decides whether the part is good. It is also where wear and a failing lubricant show themselves first.
Fitting a load cell to a production machine is another matter. Cost and the space it takes rule it out of most designs, so a quantity a test rig measures directly stays invisible on the equipment actually running. Motor current is the usual stand-in. But current tracks torque, and between torque and axial force sit the inertia and the compliance of the mechanism; the two are not related by a constant.
What we tested
We built a model that estimates axial force from the signals a drive already holds: the individual phase currents, the active current, and the speed. Nothing was added to the machine. The model is built on the family of lightweight machine-learning techniques we work with across our projects (reservoir computing).
Validation used a public dataset in which electric cylinders were run continuously to failure with every sensor recorded throughout. We applied the same procedure to three cylinders of the same type. Each model saw only the early-life interval of its own cylinder, with no data pooled across units, and accuracy was measured on a later interval used neither for training nor for tuning.
What it shows
The force waveform could be reproduced on the held-out interval, and at the same level on all three cylinders: the quantity is available without a load cell in the machine.
The model this takes is under a kilobyte and runs on the existing controller as it is. No GPU, no cloud connection.
This may apply to your equipment
If the pushing force decides your part quality or your service intervals and a load cell is impractical to fit, the same idea may be worth exploring: electric cylinders, electric presses, press-fit and tightening stations, transfer and positioning axes. The signals it needs are ones your drive already reports. A short conversation is normally enough to tell whether your case fits.
The inverse approach, pulling out the force a motion command does not account for, is described on the servo axis torque page.