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AX2500/2850 Motor Controller User’s Manual 37
Selecting the Motor Control Modes
Closed Loop Speed Control
In this mode, illustrated in Figure 15, an analog tachometer or an optical encoder (AX2850
only) is used to measure the actual motor speed. If the speed changes because of changes
in load, the controller automatically compensates the power output. This mode is preferred
in precision motor control and autonomous robotic applications. Details on how to wire the
tachometer can be found in “Connecting Tachometer to Analog Inputs” on page 58.
Closed Loop Speed control operation is described in “Closed Loop Speed Mode” on
page 123.
Close Loop Position Control
In this mode, illustrated in Figure 15, the axle of a geared down motor is coupled to a
potentiometer that is used to compare the angular position of the axle versus a desired
position. This AX2500/2850 feature makes it possible to build ultra-high torque “jumbo ser-
vos” that can be used to drive steering columns, robotic arms, life-size models and other
heavy loads. Details on how to wire the position sensing potentiometers and operating in
this mode can be found in “Closed Loop Position Mode” on page 115.
Controller
FIGURE 13. Effect of commands to motors examples in
mixed mode
Tachometer or
Optical Encoder (AX2850 & AX3500 only)
Speed Feedback
FIGURE 14. Motor with tachometer or Encoder for Closed Loop Speed operation