| 摘要 |
This system provides a wide range of smooth and precisely controlled low and high speeds for pan-tilt-zoom surveillance cameras, in which a brushless motor is controlled by a microcontroller in a low speed mode by sinusoidal synchronous commutation, in a high speed mode by block commutation, and in in a transition phase from the low speed mode to the hig h speed mode by modulating integrated pulse-width modulation (PWM) square waves with sine waves. PID and lookup table registers are used by a microcontroller for a smooth transition from high speed mode to low speed mode, and from low speed mode to high speed mode, phase locking a sine position during transitions, in order to give a surveillance camera an abili ty to quickly move from one target to another at up to 100 degrees per second yet track objects that are moving very slowly. |
