Abstract: A power generating system for the generation of energy from the wave motions of the sea is buoyantly supported by the sea. The system comprises spine elements defining a spine on which ducks are rockably mounted, the system further including tension cable means pressing the spine elements towards each other thereby to define a spine, and energy conversion means for converting the rocking motion into electrical power.

Abstract: A cargo loading and unloading shutoff system is used to control transfer of loads between a cargo aircraft and a loading dock. Control logic means compares commands entered on a control console and the existing conditions in the aircraft and on the dock during a loading or unloading operation. On loading, the logic means shuts off the dock conveyor drive immediately when all loads are transferred to selected aircraft positions and then shuts off the aircraft conveyor drive a predetermined period later. On unloading, the logic means shuts off both the aircraft and dock conveyor drives simultaneously when all loads are transferred to selected dock positions. The logic means also prevents energization of the aircraft and dock conveyor drives when the number of load positions selected in the aircraft is different from the number of load positions selected on the dock.

Abstract: Beds, such as hospital beds, in which at least some portion of the bed is movably actuated by an electric motor (or motors) are provided with a control circuit to determine proper energization of the motor from an AC power source. Since the AC signal from the power source could be harmful to the person selecting a desired direction of travel of the movable portion of the bed, the selecting portion of the control circuit is isolated by appropriate transformers from the power portion that supplies the motor. Bidirectional switching devices, such as triacs, are utilized to convey the power to the motor. Other bidirectional switching devices, such as triacs, are used to gate the power handling triacs through appropriate gating transformers. A phase shifting arrangement is utilized in connection with the gating transformers to provide proper commutation of the power handling triacs.

Abstract: A motor is electrically coupled to a power source through a motor starter. The motor starter is selectively operated by a relay to connect and disconnect the power source to the motor. A counter is set whenever a select motor temperature condition exceeds a predetermined level to provide an indication of the number of motor starts. The relay is operated to cause the motor starter to disconnect the power source from the motor whenever the motor fails to run continuously during a given time period following a predetermined number of starts.

Abstract: An ac induction motor is supplied with variable frequency and amplitude excitation voltage by a power converter. Precise regulation of torque independent of motor parameter changes is achieved by feedback control loops for maintaining at command values constant airgap flux and also the real component of stator current with respect to airgap voltage as measured by a voltage sensor. The real stator current error controls the slip frequency which adjusts to maintain constant airgap power.

Abstract: A method and control system for minimizing peak current levels in a direct current traction motor drive system in which the traction motor is powered by periodic current pulses metered from a direct current source by a controllable switch. The control system includes apparatus for comparing actual motor current to commanded motor current and for controlling the duty factor of the controllable switch in a manner tending to minimize any difference between actual and commanded currents. The control system further includes apparatus for changing the repetition rate of the current pulses in response to the magnitude of current in the motor, without effecting the commanded duty factor of the controllable switch, so that the ripple currents which are inversely related to repetition rate are reduced as average motor current is increased to thereby maintain total peak current levels within predetermined limits.

Abstract: Apparatus is disclosed for controlling the speed of an electric motor by selectively connecting a field weakening resistor across the field winding of an electric motor. A first means is provided for comparing the field voltage to a fixed reference voltage and for generating a first signal in response to the field voltage falling below a first predetermined value and a second signal in response to the field voltage rising above a second predetermined value. A second means responsive to the first and second signals is provided for selectively connecting a field weakening resistor across the field winding of the motor in response to the field voltage falling below the first predetermined value. The second means responsive also disconnects the field weakening resistor in response to the field voltage rising above the second predetermined value.

Abstract: A numerical control system having a digitized phase loop comprising a motor for moving an object being controlled, a servo amplifier for driving the motor, feedback means coupled to the motor for generating a first signal indicative of the actual position of the object, and means for converting the first signal to a digital signal indicative of a change in the actual position of the object. Further provided is means for comparing a command digital signal indicative of the desired change in position of the object with the digital signal indicative of the actual change in position of the object to generate an error digital signal and for converting the error signal to an analog signal for driving the servo amplifier.