Window operator control

In a window operator having an electrically controlled drive for moving a window between open and closed positions in response to a command, the improvement comprising:

• means for commanding movement of the drive to move the window to a select desired position between the open and closed positions;
• position sensing means for sensing actual position of the window between the open and closed positions, comprising a timer means for storing a value representing actual position, the value being selectively incremented or decremented at a select rate in response to duration of operation of the drive to move the window between the open and closed positions;
• supply sensing means for sensing electrical power supplied to the drive;
• adjustment means operatively associated with said position sensing means and said supply sensing means for adjusting the select rate of said timer means in response to electrical power deviating from a select desired power level;
• and
• a control coupled to said commanding means and said position sensing means including comparing means for comparing said desired position to said actual position and output means coupled to said drive for developing an electrical signal to control said drive responsive to a difference between said select and actual positions to minimize said difference.