EPC
SERVO AMPLIFIER MODULE
Part Number L723888-3xx
ELECTRONIC
Telephone: (231) 929-1660
Oilgear
Fax:
(231) 929-7879
1424 International Dr
Issued May 31, 2018
Web Site:
www.oilgear.com
Traverse City, MI USA 4 9 6 8 6
Bulletin 836260F
51
The Potential Step can be computed from the Step setting:
Example 1
: A Rate of 255 and a Step of 1 is used for a 1600 Hz module. The Ramp Rate in
Volts/second is
Ramp Rate = 1600 x 0.004884 x (1 / 255) = 0.03064 Volts/second
so a 10 Volt step would ramp over a period of 326 seconds (5 minutes:26 seconds).
The setting of Rate = 255 and Step = 1 results in the slowest ramping rate.
Example 2
: A Rate of 1 and a Step of 255 is used for a 1600 Hz module. The Ramp Rate in
Volts/second is
Ramp Rate = 1600 x 0.004884 x (255 / 1) = 1993 Volts/second so
a 10 Volt step would ramp in only 5 milliseconds.
The setting of Rate = 1 and Step = 255 results in the quickest ramping rate.
A user should select a ramp rate that is close to a desired value, while not producing an
undesirable step. Generally, the lower the values for rate and step, the smaller the step.
Example 3
: Which of the following are the optimal settings for a 0.5 Volt/second ramp?
(a) Rate = 15, Step = 1
(b) Rate = 31, Step = 2
(c) Rate = 47, Step = 3
(d) Rate = 125, Step = 8
Assuming a 1600 Hz closed loop response, the settings for (a) result in:
Ramp Rate = 1600 x 0.004884 x (1 / 15) = 0.5210 Volts/second or
a 1 x 0.004884 = 5mV step every 15/1600 = 9 milliseconds.
Similarly, the settings for (b), (c), and (d) result in
(b) Ramp Rate = 0.5042 Volts/second (10mV step every 19 milliseconds)
(c) Ramp Rate = 0.4988 Volts/second (15mV step every 29 milliseconds)
(d) Ramp Rate = 0.5001 Volts/second (39mV step every 78 milliseconds)
The optimal setting depends on the ramp requirements and system dynamics. If time is not critical,
the settings for (a) which have the smallest step size would be optimal. If time is critical and the
system dynamics allow for a larger step size, the settings in (d) should be used since the ramping is
closer to the desired value (0.5001 V/s rather than 0.5210 V/s).
Deductive reasoning can be used to find the rate and step values for a desired ramp.
