What is Pan & Tilt Pointing?

For larger pan & tilt systems such as those used with film and television cameras, radar pointing systems, and fire control mechanisms three-phase Brushless DC motors are the norm. These motors are driven using position servo control loops which allow sophisticated feedforward compensation techniques to be applied. This technique is especially important for systems which slew very rapidly such as fire control systems and high speed camera applications used in sports and nature filming.

For such ultra-high performance servo-based systems a full understanding of the resonance characteristics of the load is vital. The best control solutions not only use resonance dampening filters in the control loop such as provided by biquad filters, they also seek to avoid stimulating resonance in the load by using smooth s-curve profiles or special trajectory profiles tuned to avoid injecting resonance into the load.

Finally, depending on the end application, the motion system may need to provide coordinate transformation. For example if a laser mounted on a pan & tilt mechanism is used to ‘paint’ on a flat surface a transformation of the target reference frame (the flat surface) to the pin & tilt frame must occur. This type of coordinate re-mapping falls under the general heading of kinematic transformation and is common in other motion applications such as SCARA arm control where the actuator mechanical arrangement is not orthogonal.