Torque/Force Foldback Input
There are several applications that require the torque/force to be limited at a certain time in a machine cycle (and perhaps only in a certain direction). These applications include endpoint clamping, insertion of parts into sockets, spring emulation, etc. SSt servo drives allow you to limit the torque/force delivered in your application to a pre-set level in either or both directions by simply asserting the Mode input on an SSt servo drive. This digital input can be toggled by your CPU, or actuated by a sensor as shown below, for an endpoint clamping application. This easy-to-use feature opens up numerous possibilities, enhancing your design flexibility.
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- Figure 1: Using a switch at the end of axis travel to limit torque for clamping
Note that the torque can, if desired, be limited in only the clamping direction to allow fast retraction of the axis.
Because the SSt servo drive can be set up to limit torque in one direction only, clamping can be done with a gentle approach yet still allow a rapid retraction using full torque. This can be accomplished without any software overhead or CPU output lines, minimizing your software development effort.
The Torque/Force Foldback Input feature (together with the RAS, Hard Stop Homing, Limit Switch Homing and flexible input resolution) helps enable the use of low cost controls that lack encoder feedback inputs, even in machines that require state-of-the-art performance.