Door operator for controlling a door and method of same

1. A door operator for controlling operation of a door, the door operator having a motor to open the door against a spring force, said door operator further comprising:

a door position sensor for transmitting a signal indicative of door position; and

a controller for:

controlling a motor current to generate a predetermined motor force to open the door to a predetermined angle;

receiving the signal from the door position sensor and determining a door position and a door speed based on the signal;

measuring the time for the door to reach the predetermined angle from a closed position;

measuring the current to hold the door at the predetermined angle;

converting the measured current to an equivalent force of the motor acting on the spring, which represents the spring force;

determining a first torque value acting on the door based on the spring force;

determining a second torque value acting on the door based on the predetermined motor force to open the door to the predetermined angle;

subtracting the first torque value from the second torque value to determine a net torque acting on the door; and

calculating a door moment of inertia based on the net torque and the time for the door to reach the predetermined angle from the closed position.

2. A door operator for controlling operation of a door, the door operator having a motor to open the door against a spring force, said door operator further comprising:

a door position sensor for transmitting a signal indicative of door position; and

a controller for:

opening the door to a first position at a predetermined angle;

measuring the current to hold the door at the predetermined angle;

converting the measured current to an equivalent force of the motor acting on the spring, which represents the spring force;

determining a torque value acting on the door based on the spring force;

releasing the door to a second position at a predetermined angle

measuring the time for the door to reach the second position at a predetermined angle

calculating a door moment of inertia based on the torque applied and the time for the door to reach the second position at a predetermined angle.

3. A door operator for controlling operation of a door, the door operator configured to operate in a manual mode wherein a user provides opening power or in a powered mode using a motor for converting electrical energy stored in a chargeable battery to open the door and to act as a braking load to control door closing speed when charging the chargeable battery in a generator mode during door closing, said operator further comprising:

a nonvolatile door position sensor for transmitting a signal indicative of door position; and

a controller for:

receiving the signal from the nonvolatile door position sensor;

determining the door position and a door speed;

comparing the door speed to a desired door speed based on a door speed-position profile and generating a door speed error signal;

minimizing the door speed error signal by adjusting the braking load resulting from charging the chargeable battery using the motor as a generator.

4. The door operator as claimed in claim 3 , comprising a clutch to disengage the motor during manual door opening and engage the motor on door closing when the motor can act as a generator.

5. The door operator as claimed in claim 3 , wherein the nonvolatile door position sensor is a potentiometer.

6. The door operator as claimed in claim 3 , wherein the door speed-position profile is based on door weight and size.

7. The door operator as claimed in claim 3 , wherein the door speed-position profile is based on door weight, size and predetermined time intervals during an opening of the door and a closing of the door.

8. The door operator as claimed in claim 3 , wherein the door operator is independent of external power if the door is manually opened no more than five (5) times for each battery powered opening.

9. The door operator as claimed in claim 4 , wherein the clutch is adapted to engage the motor on door opening after receiving an engagement signal.

10. The door operator as claimed in claim 4 , wherein the door speed-position profile is dependent upon a computation of door inertia, said computation being based on data from a dynamic test of an installed door.