Delta RMC151 - Manual (Page 200)

RMC70/150 and RMCTools User Manual
a. Define a control axis with the feedback type required (position, velocity, pressure,
force, or acceleration). For the feedback source, choose Custom.
b. Create a reference axis for the feedback input to be used.
c. Configure the feedback parameters for the reference axis and verify that the
transducer gives valid readings.
d. Set the Scale and Offset so that the reference axis provides correct values
throughout the entire range.
4. Use the Curve in the Custom Feedback User Program
a. Create a single-step user program with a Jump Link Type and a Repeat Jump To
location.
b. Add an Expression (113) command.
c. In the expression, use the CRV_INTERP_Y function to get the curve's interpolated
desired true value from the transducer's measurement.
d. Set the CustomErrorBits.NoTrans bit according to the state of the active feedback. This
can be done by using the Feedback OK status bits of the reference axes.
5. Make Sure the User Program Always Runs
As described in more detail in the Custom Feedback topic, do the following:
a. Set the RMC to start in RUN mode.
b. Use a _FirstScan condition in the Program Triggers to start the user program when the
RMC enters RUN mode.
c. Make sure the Task does not stop when an axis halts.
6. Tune the Axis
Tune the axis manually (auto-tuning does not work in RUN mode).
3.10.4. Feedback Linearization Using a Mathematical
Formula
This topic describes how to implement single-axis feedback linearization if you have a
mathematical formula that describes the relationship between the transducer and the real
measurement you need. For example, a transducer may be mounted in a cylinder that drives
a swing arm, but you actually need the position of the end of the arm. Given the machine
geometry, a mathematical formula can be used to convert the transducer measurement to the
position of the swing arm.
Another method of feedback linearization is via curves, as described in Feedback Linearization
using Curves. In fact, even if you have a mathematical formula, you can create a curve from
the formula and use that method.
Tip: The Examples section of Delta's online forum includes a Feedback Linearization Using
Mathematical Formula example. You can use that example to help you get started.
Setting Up Feedback Linearization Using a Mathematical Formula
Read the Custom Feedback topic before completing this procedure.
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