Fig 1.
Block diagram of the system hardware design.
Fig 2.
One-phase drive circuit schematic for the unipolar stepper motor.
Fig 3.
RS-422 transceiver circuit schematic.
Fig 4.
Constant voltage drive circuit of the stepper motor.
Fig 5.
RS-422 transceiver circuit.
Fig 6.
Common drive modes of the stepper motor.
(a) Single triple beat. (b) Double triple beat. (c) Single and double six-beat.
Fig 7.
Flowchart of the focusing software.
Fig 8.
Experimental setup: (a) ground test equipment, (b) position monitoring and control system hardware, (c) focusing mechanism.
Table 1.
Main electronic components.
Table 2.
Main parameters of the stepper motor.
Fig 9.
Drain potential waveform of the power MOSFET in each phase drive circuit and the current waveform of phase A, where the yellow line represents phase A, the green line represents phase B, the blue line represents phase C, and the red line represents the phase A current.
Fig 10.
Waveform of .
Fig 11.
Collector potential waveform of the transistor in phase A drive circuit.
Fig 12.
Motor output torque at different speeds.
Fig 13.
Reducer output torque at different speeds.
Fig 14.
Graph of closed-loop focusing results.
Fig 15.
Graph of absolute value of closed-loop focusing error.
Table 3.
Experimental results of closed-loop focusing.
Fig 16.
Graph of open-loop focusing results: (a) forward direction, (b) reverse direction.
Fig 17.
Graph of absolute value of open-loop focusing error: (a) forward direction, (b) reverse direction.
Table 4.
Experimental results of open-loop focusing.