Improved bang-bang controlled velocity command generator

Claim 2

Apparatus for indicating a desired velocity for a moveable element according to a predefined distance velocity relationship responsive to an existing distance between a desired terminal position and a current position, comprising comparing means for comparing the existing distance between the desired terminal position and the current position with at least one predefined distance and generating at least one indication when the existing distance exceeds the predefined distance or distances, first means for producing velocity values in response to distances with a preselected range of distances; second means for producing at least one signal of predefined level in response to the indication or indications generated by said comparing means; and means for summing a velocity value produced by said first means and the signal or at least one of the signals of predefined level.

Claim 3

Apparatus for indicating a desired velocity for a moveable element according to a predefined distance velocity relationship responsive to an existing distance between a desired terminal position and a current position, comprising comparing means for comparing the existing distance between the desired terminal position and the current position with at least one predefined distance and generating at least one indication when the existing distance exceed the predefined distance or distances, first means for producing velocity values in response to distances within a preselected range of distances, second means for producing at least one signal having a predefined level, and third means for selecting the indication of the desired velocity from the velocity values produced by said first means and the signal or signals produced by said second means in response to the indication or indications produced by said comparing means.

Claim 4

Apparatus for indicating a desired velocity for a moveable element according to a predefined distance velocity relationship responsive to an existing distance between a desired terminal position and a current position, comprising comparing means for comparing the existing distance between the desired terminal position and the current position with at least one predefined distance and generating at least one indication when the existing distance exceed the predefined distance or distances, first means for producing velocity values in response to distances within a preselected range of distances, second means for producing at least one signal having a predefined level, and third means for selecting the indication of the desired velocity from the velocity values produced by said first means and the signal or signals produced by said second means in response to the indication or indications produced by said comparing means.

Claim 5

Apparatus according to claim 2 for producing a signal to control the position of a moveable element from a current position to a desired terminal position according to a predefined distance velocity relationship responsive to a desired terminal position indication, a signal representative of the velocity of the moveable element, and a position signal of the moveable element, comprising first means for determining the distance of the moveable element from the current position to the desired terminal position responsive to the desired terminal position indication and the position signal, comparing means for comparing the distance of the moveable element from the current position to the desired terminal position with at least one predefined distance and generating an indication or indications when the existing distance exceeds the predefined distance or distances, second means for producing velocity values in response to distances within a predefined range of distances, third means for producing at least one signal having a predefined level, fourth means responsive to an indication produced by said comparing means for producing a desired velocity responsive to the velocity values produced by said second means and at least one signal produced by said third means, and fifth means responsive to the difference between the desired velocity-and the signal representative of the velocity of the moveable element for producing the signal to control the position of the moveable element.

Claim 6

Apparatus according to claim 2 and arranged for producing a signal to control the position of the moveable element according to the predefined distance velocity relationship, further comprising means responsive to the difference between the selected indication of desired velocity and a'signal representing the velocity of the moveable element means for producing the signal to control the position of the moveable element.

Claim 11

A method according to claim 6 wherein for producing a signal to control the position of the moveable element according to the predefined distance velocity relationship a signal representative of the velocity of the moveable element is subtracted from the selected indication of desired velocity.

Claim 12

A method according to claim 6 or claim 7 further comprising determining the distance of the moveable element from the current position to the desired terminal position responsive to the desired terminal position indication and the position signal.

Claim 13

A control system in which a moveable. element is driven from an initial position to a terminal position in accordance with a predetermined relationship between velocity of the element and the distance of it from the terminal position, wherein for a final portion of the travel of the element to the terminal position the energisation of an actuator for the element is continuously controlled in accordance with the said profile and wherein while the distance of the element from the terminal position within a range terminating at the said final portion the said distance is compared with several predetermined distances from the terminal point and as the said distance of the member from the terminal position decreases below each of the predetermined distances the actuator is provided with a constant energisation to produce substantially constant acceleration or deceleration of the member until the velocity of the member exceeds a velocity value automatically selected in accordance with the comparison, whereupon the energisation of the actuator is switched to a value which effectively provides no acceleration or deceleration of the member until the distance of the member from the terminal position matches the next smaller of the predetermined distances.

Claim 14

A control system in which a moveable. element is driven from an initial position to a terminal position in accordance with a predetermined relationship between velocity of the element and the distance of it from the terminal position, wherein for a final portion of the travel of the element to the terminal position the energisation of an actuator for the element is continuously controlled in accordance with the said profile and wherein while the distance of the element from the terminal position within a range terminating at the said final portion the said distance is compared with several predetermined distances from the terminal point and as the said distance of the member from the terminal position decreases below each of the predetermined distances the actuator is provided with a constant energisation to produce substantially constant acceleration or deceleration of the member until the velocity of the member exceeds a velocity value automatically selected in accordance with the comparison, whereupon the energisation of the actuator is switched to a value which effectively provides no acceleration or deceleration of the member until the distance of the member from the terminal position matches the next smaller of the predetermined distances.

Claim 15

A control system according to claim 9 wherein the moveable element is a transducer which is movable across a multiplicity of parallel or concentric recorded tracks and the distances defined in terms of integral numbers of tracks.