Electricity: motive power systems – Positional servo systems – Time-sharing or multiplexing systems
Reexamination Certificate
2002-03-05
2004-08-24
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
Time-sharing or multiplexing systems
C318S684000, C307S044000, C340S315000
Reexamination Certificate
active
06781336
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to servomechanisms and more particularly to servomechanisms having an actuator configured to convert electrical energy into mechanical energy, hereinafter referred to as “electric servomechanisms”.
Typical electric servomechanisms include an actuator configured to convert electrical energy into mechanical energy, also called an electric actuator. Electric Servomechanisms also typically include an amplifier, a controller, an actuator power cable, a feedback data cable and one or more transducers mounted on or within the actuator. The amplifier is electrically connected to the controller and receives electrical current from an external electrical power source. The amplifier is further electrically connected to the actuator via the actuator power cable and electrically connected to the transducer via the feedback data cable. In operation, the controller sends actuator command signals to the amplifier. The amplifier appropriately amplifies these electrical signals and transmits them to the actuator, thereby activating the actuator. The transducers measure actuator data, such as actuator temperature, velocity and position. This data, called feedback data, is transmitted through the feedback data cable to the amplifier and thereafter delivered to the controller. The controller compares this feedback data with desired input values. Based on this comparison, the controller determines the instructions necessary to bring the actuator data to the desired values and transmits these instructions to the amplifier.
Servomechanisms require separate cables to transmit electrical current to the actuator and feedback data to the amplifier. The cost of installing and maintaining such servomechanisms thus includes the cost of installing and maintaining both a power cable and a data cable. To reduce cost and maintenance, some electric servomechanisms include the amplifier electronics within the actuator. However, having the amplifier electronics within the actuator causes the actuator to run hotter and results in an increase in size to make room for amplifier electronics. Further, the amplifier still requires electrical current from an external electrical power source and an electrical connection to the controller for reception of actuator command signals.
BRIEF SUMMARY OF THE INVENTION
In one aspect, a servomechanism is provided that includes an actuator configured to convert electrical energy into mechanical energy and a controller configured for electrical connection to a power source. A power cable electrically connects the actuator and the controller. The power cable is configured to transmit electrical current from the controller to the actuator. At least one transducer is coupled to the actuator. The transducer is electrically connected to the power cable and is configured to transmit data over the power cable.
In another aspect, a servo motor assembly is provided that includes a motor and at least one transducer coupled thereto. A power cable configured for electrical connection to a power source is electrically connected to the motor and the transducer. The transducer is configured to transmit data over the power cable.
In yet another aspect, a method is provided for controlling a servomechanism including an actuator configured to convert electrical energy into mechanical energy. The servomechanism also includes a controller, a power cable electrically connected to the controller and the actuator, and a transducer coupled to the actuator. The power cable is configured to transmit electrical current from the controller to the actuator. The method includes electrically connecting the transducer to the power cable and transmitting data from the transducer over the power cable.
In a further aspect, a method is provided for installing an actuator configured to convert electrical energy into mechanical energy into a servomechanism. The servomechanism includes a controller, a power cable electrically connected to the controller, and at least one transducer configured to receive data from the actuator. The method includes electrically connecting the power cable to the actuator such that the power cable is configured to transmit electrical current from the controller to the actuator. The method further includes electrically connecting the transducer to the power cable and configuring the transducer to transmit data over the power cable.
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Armstrong Teasdale LLP
GE FANUC Automation North America, Inc.
Ro Bentsu
Vick, Esq. Karl A.
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