| 摘要 |
A method and apparatus for detecting an aberrant velocity of a motor used to drive an element in a plastics processing machine, such as an injection molding machine, for example. The velocity of the motor is detected by a first sensor and a machine parameter associated with the machine operation is provided. A velocity limit is determined based upon the machine parameter and an error signal is generated when the motor velocity exceeds the velocity limit by more than a predetermined tolerance value. Preferably, the machine parameter comprises the position of the element driven by the motor, which is sensed by a sensor, such as a linear displacement transducer. The velocity limit can be based upon this measured element position as well as data entered for the particular machine, such as a minimum element position, a maximum element position, and a maximum motor velocity, such that a desired motor operating envelope is defined. Also, the motor velocity command is preferably set equal to the velocity limit when it exceeds the limit. In another embodiment, the machine parameter comprises a motor velocity command for controlling the velocity of the motor. The velocity command is compared to the previous velocity command and the velocity limit is set equal to the velocity command when it exceeds the previous command.
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