122-28176 Parallax Inc, 122-28176 Datasheet - Page 279

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Chapter 8: Proportional-Integral-Derivative Control · Page 269
Figure 8-10 Derivative Evaluation Using Light
Set 4
With a decrease in time between evaluation sampling, roughly the same curves increased
the output. With closer sampling, the maximum change of the signal is better evaluated.
Note the negative output spike at 60 seconds. When the controller was reset, the value of
the last error was reset to zero. When a reading was performed, it was calculated as a
sudden change in error.
Set 5
With the shorter time and higher rates of error change, the output was significantly
higher.
Note the measured readings: With a current error of 458, and a last error of 390, this
produced a change in error (∆E) of 68. With a change in time (∆t) of 0.5 seconds, this
resulted in an output (∆E/∆t) of 68/0.5 or 136.