Position control system

Claim 2

In a position control system having temporary storage means for storing a command position to which a machine member is to be moved, a first counter, the contents of said first counter indicating the present position of said member, and motor means for moving said member, the improvement comprising: a reversible counter, means for loading said reversible counter with a number equal to the algebraic difference between the contents of said temporary storage means and the contents of said first counter, said number representing the distance and directiOn said member must be moved to reach said command position, control means for controlling operation of said motor means in response to the contents of said reversible counter, said means for loading comprising a comparator for determining whether the contents of said first counter is more than, less than, or equal to the contents of said temporary storage means, means for decrementing or incrementing said first counter if the contents thereof are, respectively, more than or less than the contents of said temporary storage means, said decrementing or incrementing terminating when the contents of said first counter and said temporary storage means become equal, means for simultaneously incrementing said reversible counter by a like amount, means for changing the sign of said reversible counter to indicate whether said first counter is incremented or decremented. means for decrementing said reversible counter as said motor means moves said member toward said command position, and means for terminating said motion when said member reaches said command position, the residual contents of said reversible counter when said member stops representing any positioning error.

Claim 3

A position control system according to claim 1 further comprising means for decrementing said reversible counter to zero subsequent to said termination of motion and for accordingly changing the contents of said first counter to represent the actual position at which said member stopped.

Claim 4

In a position control system having temporary storage means for storing a command position to which a machine member is to be moved, a first counter, the initial contents of said first counter indicating the present position of said member and motor means for moving said member, the improvement comprising: a reversible counter, a comparator for determining whether the contents of said first counter is more than, less than, or equal to the contents of said temporary storage means, means responsive to said comparator for providing count pulses to both said first counter and said reversible counter when the contents of said first counter is unequal to the contents of said temporary storage means, said count pulses decrementing or incrementing said first counter if the contents of said first counter are, respectively, more than or less than the contents of said temporary storage means, said count pulses also incrementing said reversible counter from zero, said count pulses terminating when the contents of said first counter and said temporary storage means become equal, whereby the resultant contents of said reversible counter equal the difference between the contents of said temporary storage means and the initial contents of said first counter, said resultant contents representing the distance said member must be moved to reach said command position, control means for controlling operation of said motor means in response to the contents of said reversible counter, and means for causing said count pulses to decrement said reversible counter in response to error current derived from relative displacement of a first member associated with the movable

Claim 5

In a position control system having temporary storage means for storing a command position to which a machine member is to be moved, a first counter, the initial contents of said first counter indicating the present position of said member and motor means for moving said member, the improvement comprising: a reversible counter, a comparator for determining whether the contents of said first counter is more than, less than, or equal to the contents of said temporary storage means, means responsive to said comparator for providing count pulses to both said first counter and said reversible counter when the contents of said first counter is unequal to the contents of said temporary storage means, said count pulses decrementing or incrementing said first counter if the contents of said first counter are, respectively, more than or less than the contents of said temporary storage means, said count pulses also incrementing said reversible counter from zero, said count pulses terminating when the contents of said first counter and said temporary storage means become equal, whereby the resultant contents of said reversible counter equal the difference between the contents of said temporary storage means and the initial contents of said first counter, said resultant contents representing the distance said member must be moved to reach said command position, control means for controlling operation of said motor means in response to the contents of said reversible counter, and means for causing said count pulses to decrement said reversible counter in response to error current derived from relative displacement of a first member associated with the movable

Claim 6

In a position control system having temporary storage means for storing a command position to which a machine member is to be moved, a first counter, the initial contents of said first counter indicating the present position of said member, and motor means for moving said member, the improvement comprising: a reversible counter, a comparator for determining whether the contents of said first counter is more than, less than, or equal to the contents of said temporary storage means, means responsive to said comparator for providing count pulses to both said first counter and said reversible counter when the contents of said first counter is unequal to the contents of said temporary storage means, said count pulses decrementing or incrementing said first counter if the contents of said first counter arE, respectively, more than or less than the contents of said temporary storage means, said count pulses also incrementing said reversible counter from zero, said count pulses terminating when the contents of said first counter and said temporary storage means become equal, whereby the resultant contents of said reversible counter equal the difference between the contents of said temporary storage means and the initial contents of said first counter, said resultant contents representing the distance said member must be moved to reach said command position. control means for controlling operation of said motor means in response to the contents of said reversible counter. means for storing a sign indicative of whether said first counter has been decremented or incremented, and wherein said control means causes said motor means to move in a direction determined by said sign, said motor movement causing said member to advance toward said command position, means for decrementing said reversible counter toward zero as said member moves toward said command position, said means for decrementing comprising means for generating counter toggle pulses in response to motion of said machine member, each of said counter toggle pulses representing movement by said member of an incremental distance, and means for causing said count pulses to decrement said reversible counter, said control means causing said motor to operate at a speed determined by the magnitude of the contents of said reversible counter, logic means cooperating with said reversible counter for producing speed control signals responsive to the magnitude of the contents of said reversible counter, said control means being responsive to said speed control signals, said motor control means causing said motor to run at progressively slower speeds at decreasing values of the magnitude of the contents of said reversible counter, occurrence of the final speed control signal causing deenergization of motor means, said final speed control signal being selected so that said member coasts to said command position subsequent to deenergization of said motor means, and means for causing said count pulses to decrement said reversible counter in response to error current derived from relative displacement of a first member associated with the movable machine member and movable relative to a second member of a position measuring transformer having cyclically spaced zero positions.

Claim 7

In a position control system having temporary storage means for storing a command position to which a machine member is to be moved, a first counter, the initial contents of said first counter indicating the present position of said member, and motor means for moving said member, the improvement comprising: a reversible counter, a comparator for determining whether the contents of said first counter is more than, less than, or equal to the contents of said temporary storage means, means responsive to said comparator for providing count pulses to both said first counter and said reversible counter when the contents of said first counter is unequal to the contents of said temporary storage means, said count pulses decrementing or incrementing said first counter if the contents of said first counter arE, respectively, more than or less than the contents of said temporary storage means, said count pulses also incrementing said reversible counter from zero, said count pulses terminating when the contents of said first counter and said temporary storage means become equal, whereby the resultant contents of said reversible counter equal the difference between the contents of said temporary storage means and the initial contents of said first counter, said resultant contents representing the distance said member must be moved to reach said command position. control means for controlling operation of said motor means in response to the contents of said reversible counter. means for storing a sign indicative of whether said first counter has been decremented or incremented, and wherein said control means causes said motor means to move in a direction determined by said sign, said motor movement causing said member to advance toward said command position, means for decrementing said reversible counter toward zero as said member moves toward said command position, said means for decrementing comprising means for generating counter toggle pulses in response to motion of said machine member, each of said counter toggle pulses representing movement by said member of an incremental distance, and means for causing said count pulses to decrement said reversible counter, said control means causing said motor to operate at a speed determined by the magnitude of the contents of said reversible counter, logic means cooperating with said reversible counter for producing speed control signals responsive to the magnitude of the contents of said reversible counter, said control means being responsive to said speed control signals, said motor control means causing said motor to run at progressively slower speeds at decreasing values of the magnitude of the contents of said reversible counter, occurrence of the final speed control signal causing deenergization of motor means, said final speed control signal being selected so that said member coasts to said command position subsequent to deenergization of said motor means, and means for causing said count pulses to decrement said reversible counter in response to error current derived from relative displacement of a first member associated with the movable machine member and movable relative to a second member of a position measuring transformer having cyclically spaced zero positions.

Claim 8

A position control system according to claim 4 wherein the residual contents of said reversible counter represent the magnitude of any positioning error when said member coasts to a halt.

Claim 9

A position control system according to claim 5 further comprising means for changing said stored sign if said member coasts beyond said command position, said changed sign indicating an overshoot.

Claim 10

A position control system according to claim 6 further comprising means for decrementing said reversible counter to zero and for simultaneously accordingly incrementing or decrementing said first counter, depending on said stored sign, whereby the contents of said first counter represent the actual position at which said member halted.

Claim 11

A position control apparatus including a system for measuring and controlling the position of a first member movable relative to a second member employing a position-measuring device having cyclically spaced zero positions, a motor for driving said first member, and means providing an error signal depending on relative displacement of said members, said system comprising: an internal counter controlled by said position-measuring device, the contents of said counter indicating the relative position of said first member between two adjacent-spaced zero positions, means for storing a part-start position representing the distance of said first member from a reference not necessarily corresponding with one of said spaced zero positions, an external counter having a grEater number of digits than said internal counter, a control logic for presetting said external counter to said part-start position during a setup mode and for slaving said preset external counter to said internal counter during a readout mode, whereby during said readout mode said external counter operates starting from said preset part-start position as said internal counter operates starting from said relative position, switching means for selecting either a readout mode or a positioning mode, said readout mode including means for slaving said external counter to said internal counter, said error signal being operative to supply digital pulses to said internal counter and to said external counter, each of said pulses corresponding to motion of an incremental distance, to increment or decrement both of said counters depending upon the direction of motion of said movable machine member, said movable machine member being movable to a new position where said pulses will increment both of said counters, whereby the contents of the internal counter represent the new position with respect to an adjacent sine zero and the contents of said external counter represent the actual distance of the new position from a reference zero, a delta counter controlling said motor, means for deriving other pulses from said digital pulses for loading said delta counter depending on a comparison of present and new positions of said first member, and means employing said digital pulses for unloading said delta counter.

Claim 12

A position control apparatus including a system for measuring and controlling the position of a first member movable relative to a second member employing a position-measuring device having cyclically spaced zero positions, a motor for driving said first member, and means providing an error signal depending on relative displacement of said members, said system comprising: an internal counter controlled by said position-measuring device, the contents of said counter indicating the relative position of said first member between two adjacent-spaced zero positions, means for storing a part-start position representing the distance of said first member from a reference not necessarily corresponding with one of said spaced zero positions, an external counter having a grEater number of digits than said internal counter, a control logic for presetting said external counter to said part-start position during a setup mode and for slaving said preset external counter to said internal counter during a readout mode, whereby during said readout mode said external counter operates starting from said preset part-start position as said internal counter operates starting from said relative position, switching means for selecting either a readout mode or a positioning mode, said readout mode including means for slaving said external counter to said internal counter, said error signal being operative to supply digital pulses to said internal counter and to said external counter, each of said pulses corresponding to motion of an incremental distance, to increment or decrement both of said counters depending upon the direction of motion of said movable machine member, said movable machine member being movable to a new position where said pulses will increment both of said counters, whereby the contents of the internal counter represent the new position with respect to an adjacent sine zero and the contents of said external counter represent the actual distance of the new position from a reference zero, a delta counter controlling said motor, means for deriving other pulses from said digital pulses for loading said delta counter depending on a comparison of present and new positions of said first member, and means employing said digital pulses for unloading said delta counter.

Claim 13

Apparatus according to claim 8, said positioning mode including a slowdown and stop-positioning mode wherein said external counter initially contains a prior dimension with respect to a part zero and the contents of said delta counter being zero, means for supplying command data of a new position, a temporary storage for data of said new position, a comparator for comparing the contents of said temporary storage with the contents of said external counter, means responsive to the output of said comparator for supplying said other pulses to said delta counter and to said external counter thereby causing the contents of said external counter to approach the value of the contents of said temporary storage and simultaneously increment said delta counter, means for inhibiting generation of said other pulses when said comparator indicates that the contents of said temporary storage and said external counter are equal at which time the contents of said external counter represent the new command position and the contents of said delta counter represent how far said machine member must be moved to reach the new command position, and means for initiating actual positioning of said first member upon said inhibition of the generation of said other pulses.

Claim 14

Apparatus according to claim 9, said slow down and stop-positioning mode operation continuing until said movable member reaches a position in the proximity of the new position whereupon pulses are provided for (a) counting said delta counter to zero; (b) incrementing said internal counter to have new contents representing the command position within one of said cycles as measured with respect to an adjacent sine zero; (c) changing the contents of said external counter to represent the command position with respect to a reference zero; and means for putting said motor under control of the error signal derived from said position-measuring device.

Claim 15

Apparatus according to claim 9, comprising means for storing the sign of the number in said delta counter, and means for displaying said last-mentioned sign and certain least significant digits of said delta counter.

Claim 16

Apparatus according to claim 8 wherein after positioning in a slow down and stop mode said external counter contains a count representing the actual position said first member reaches in coming to rest at the desired command position including undershoot or overshoot.

Claim 17

Apparatus according to claim 12 including means for displaying the amount and sign of saiD undershoot or overshoot.

Claim 18

Machine tool control apparatus comprising means for comparing the count in temporary storage with the count in a first counter, means operative when said comparison indicated inequality to (a) load a second reversible counter with certain pulses and (b) direct said certain pulses to correspondingly change the contents of said first counter, means for deriving said certain pulses from other pulses derived from the error current of a position measuring device having a movable element fixed to a movable machine member driven by a variable speed motor, a control device responsive to the count in said second reversible counter to control the operation of said motor, means for decrementing both of said counters in response to said other pulses, and means changing the frequency of said other pulses in response to the magnitude of said error current.

Claim 19

Machine tool control apparatus comprising means for comparing the count in temporary storage with the count in a first counter, means operative when said comparison indicated inequality to (a) load a second reversible counter with certain pulses and (b) direct said certain pulses to correspondingly change the contents of said first counter, means for deriving said certain pulses from other pulses derived from the error current of a position measuring device having a movable element fixed to a movable machine member driven by a variable speed motor, a control device responsive to the count in said second reversible counter to control the operation of said motor, means for decrementing both of said counters in response to said other pulses, and means changing the frequency of said other pulses in response to the magnitude of said error current.