Directed Perception PTU-D46 Series - 4.4 Speed Control Commands and Queries

PTU-D46 User’s Manual (v2.14.0) COMMAND REFERENCE
page 13
4.3.10 Monitor (Autoscan) Command
Description
Command defines and initiates repetitive monitoring (scanning) of the pan-
tilt. Autoscanning is immediately terminated upon receipt of a character from
the host computer, and the pan-tilt is sent to its home position.
Syntax
Initiate monitor (autoscan) in pan axis only:
M<pan pos 1>,<pan pos 2><delim>
Initiate monitor (autoscan) in both pan and tilt axes:
M<pan pos 1>,<pan pos 2>,<tilt pos 1>,<tilt pos 2><delim>
Initiate last defined monitor (autoscan) command (the default at power up is
pan axis only autoscan between the pan limit positions):
M<delim>
Enable monitor (autoscan) at power up: ME<delim>
Disable monitor (autoscan) at power up: MD<delim>
Query monitor status at power up: MQ<delim>
Example
When executed at power up,
M *
the pan-tilt begins scanning between the minimum and maximum pan limit
positions.
<delim>
terminates the scanning and homes the pan-tilt. Other monitoring command
forms:
M-2500,100 *
M-2500,100,-800,600 *
M0,0,-300,300 *
Related Topics
• Limit Position Queries (see Section 4.3.4)
4.4 Speed Control Commands & Queries
4.4.1 Speed Control & Relevant Terms
The Pan-Tilt Unit provides for precise control of axis speed and acceleration. This subsection
briefly describes how speed control is performed and it introduces relevant terms.
As shown in Figure 4, upper and lower speed limits determine the bounds on nonstationary
pan-tilt velocities. The base (start-up) speed specifies the velocity at which the pan-tilt axis can be
started from a full stop without losing synchrony (as described in Section 3.5), and it is more a
function of the motors rather than load characteristics. Due to base speed requirements and the
property that motors lose torque as speed increases, acceleration is required to achieve axis speeds
above the base rate. The pan-tilt controller uses trapezoidal acceleration and deceleration for
speeds above the base rate and less than the maximum allowed speed. Figure 4 shows two
acceleration cases. In the first, an axis accelerates up to a desired constant speed (slew rate), then
decelerates. The second case shows the case when the unit does not have sufficient time to
accelerate up to the desired slew speed before the need to decelerate to the desired position.
The pan-tilt controller provides for on-the-fly position and speed changes. If the direction is
changed on-the-fly, the controller manages all deceleration, direction reversal, and acceleration to
achieve the most recently specified target pan-tilt speed and acceleration rates.