Drive controlling apparatus

• US 4,965,502 A
• Filed: 05/26/1989
• Issued: 10/23/1990
• Est. Priority Date: 05/31/1988
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Ogasawara, Akira
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/357,726
• Time in Patent Office: 515 Days
• Field of Search: 318/264, 318/265, 318/266, 318/275, 318/277, 318/282, 318/286, 318/466, 318/467, 318/468, 318/469, 318/603, 318/626, 318/628
• US Class Current: 318/628
• CPC Class Codes: G05B 19/23 for point-to-point control
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
• CPC Class Codes: G05B 2219/34489 Watchdog with adaptive timeout as function of speed of motor
• CPC Class Codes: G05B 2219/37622 Detect collision, blocking, stall by change, lag in position
• CPC Class Codes: G05B 2219/42288 Limit, stop drive current if axis obstructed, blocked, force against stop
• CPC Class Codes: G05B 2219/45184 Filming, photography, camera

Abstract

A drive controlling apparatus for controlling movement of a movable member having a mechanically limited range of movement, comprises a drive device for driving the movable member, a feedback pulse generator for detecting the movement of the movable member and for outputting a number of pulse signals corresponding to an amount of the movement of the movable member, a main timer for measuring the period of the pulse signals, and for outputting a signal when a measured time period coincides with one of a plurality of comparison values, a sub timer for measuring one or more time periods from the start of the drive device to the steady state of the drive device and for changing the plurality of comparison values successively, and a control circuit for stopping the drive device in response to the signal outputted from the main timer.

Claims

1. A driver controlling apparatus for controlling movement of a movable member having a mechanically limited range of movement, comprising:

drive means for supplying power to a motor to move said movable member;

feedback pulse generating means for detecting the movement of said movable member and for serially outputting a number of pulse signals corresponding to an amount of the movment of said movable member;

main timer means responsive to said pulse signals for successively measuring time periods between successive pulse signals, comparing the measured time period with a comparison level and outputting a signal when said measured time period has a predetermined relationship with said comparison level;

sub time means for measuring a time period from the start of said drive means, and for changing the value of said comparison level when the time period measured by said sub timer means is equal to a predetermined time period; and

control means for causing said drive means to stop supplying power to said motor in response to said signal from said main time means.

2. A drive controlling apparatus according to claim 1, wherein said main timer means includes counter means for starting a clear operation each time when it receives the pulse signal from said feedback pulse generating means and an output signal from said sub time means, and a comparison means for outputting a signal to said control means when a counted value in said counter means coincides with said comparison value.

3. A drive controlling apparatus according to claim 1, wherein said sub timer means has register means for successively registering a plurality of comparison values previously set in accordance with the start characteristic of said drive means to correspond to respective time periods which become shorter, in steps, successively from the start of said drive means to the steady state of said drive means, and reads out said comparison values to said main timer means in the order from the largest one to the smallest one, thereby to provide different comparison levels for comparison with respective time periods measured by said main timer means.

4. A drive controlling apparatus according to claim 1, further including counter means for receiving said pulse signals outputted from said feedback pulse generating means and for outputting a signal corresponding to the amount of movement of said movable member, moving command setting means for setting an objective value of movement of said movable member, and comparison means for outputting a signal for clearing said counter means and a signal for stopping said drive means when said signal outputted from said counter means coincides with said movement objective value set by said moving command setting means.

5. A drive controlling apparatus according to claim 1, further including calculating means for calculating said comparison level in the steady state of said drive means by multiplying the time period of said pulse signals measured by said main timer means by an appropriate factor of safety, each time when said pulse signal is output in the steady state.

6. A drive controlling apparatus according to claim 1, further including calculating means for storing a plurality of time periods measured by said main timer means, for calculating said comparison level in the steady state by multiplying an average value of said stored time periods, and of a new time period measured by said main timer means, by an appropriate factor of safety, and for replacing the oldest stored time period with the new time period.