A positioning servomechanism, which is liable to damage, or positions other equipment which is liable to damage if extremeties in its positioning locus are encountered at speed, is protected against uncontrolled and catastrophic acceleration towards these extremeties by the provision of apparatus which shuts off power to the servomechanism in the event of its drive output exceeding a predetermined limit, indicative of saturation, for more than a predetermined time period, power being restored by the application of an external signal.
A magnetic head driving unit according to the present invention includes a microprocessor. The microprocessor determines whether a first seek operation for positioning the head on an initial position of a cylinder is completed. If the first seek is not completed, analog switch is triggered ON by a control signal from the microprocessor. Upon the ON operation of the analog switch, the limiter restrains a driving current for a motor in a predetermined value, thereby preventing overrun of the motor.
a An apparatus for preventing damage to components of a hard disk drive having a microprocessor when the microprocessor fails. The hard disk drive further includes at least one read/write head and a data storage disk having a designated parking zone. The apparatus includes a microprocessor monitoring circuit configured to be coupled to the microprocessor. The microprocessor monitoring circuit is configured for detecting a microprocessor failure condition in the microprocessor. The apparatus further includes a head park circuit coupled to the microprocessor monitoring circuit. The head park circuit is configured to receive a park command from the microprocessor monitoring circuit when the microprocessor failure condition is detected by the microprocessor monitoring circuit. The head park circuit, upon a receipt of the park command, parks the at least one read/write head of the hard disk drive over the designated parking zone, whereby the microprocessor monitoring circuit issues the park command to cause the parking of the at least one read/write head without intervention from the microprocessor when the microprocessor failure condition is detected by the microprocessor monitoring circuit.
The output response of a pilot valve controlled servo 10 is monitored by a computer 20 using a transducer 16 on the main control valve 12 and a transducer 11 on the servo output 10a. The response is compared by determining the predicted output response and response time from a mathematical model for the servo, and if the response or response time is incorrect, a warning indication is provided.
Each of some automatic machines, such as an industrial robot of the type having a servo-amplifier (4) controlled by a central processing unit (1) through a servo-control (3), has a plurality of control modes for moving a movable part (50), for example, teaching and playback modes. In the specified control mode, for example, the teaching mode, the velocity or driving force of the movable part (50) is restrained directly via a man-machine interface (7) by controlling either or both of the servo-amplifier (4) and a power source (5) to regulate driving energy supplied by a servo-motor (8) to the movable part (50) so as to mitigate danger to a person who is near the movable part.
Damaging head crashes are prevented in a disk drive system by providing a specially chosen RC network between the head position control servo and the head actuator. The values of the RC network are chosen in conjunction with the servo output voltage so that, without detracting from head access time, the maximum head velocity will be limited to a value which will prevent damaging head crashes even when a fault occurs in the system.
