Double-drive automatic sliding door operator

A sliding door operator, comprising:

• a slidable door panel having a top and a bottom;
• a first endless flexible member connected to the top of said door panel;
• first rotary means including a bidirectional electric motor for causing said flexible member to translate longitudinally in either one of two horizontal directions, one direction causing said door panel to move one way thereby opening said door, and the other direction causing said door panel to move another way thereby closing said door;
• characterized by the improvement comprising:
• a second endless flexible member connected to the bottom of said door panel;
• second rotary means including a bidirectional electric motor for causing said second flexible member to translate longitudinally in either one of said two directions;
• a first encoder interconnected with said first flexible member for providing first signals indicative of the translation thereof;
• a second encoder interconnected with said second flexible member for providing second signals indicative of the translation of said second rotary means;
• and
• control means for providing speed signals indicative of desired speed as a function of position in a preestablished motion profile and responsive to said first and second signals for providing separate command signals to each of said motors in accordance with said motion profile.