Digital servo system for moving body by a distance equal to an integral multiple of a predetermined pitch

Claim 1

A digital servo system for moving a body by a distance equal to an integral multiple of a predetermined pitch, the digital servo system having a predetermined sampling rate and corresponding sample time, comprising: acceleration/deceleration means for moving the body at a constant acceleration/deceleration level; coast means for causing the body to move at a constant velocity; and control means, operatively coupled to said acceleration/deceleration means and coast means, for controlling the movement of said body so that said movement includes an acceleration mode, a first coast mode, a second coast mode, and a deceleration mode; wherein said constant acceleration/deceleration level is equal to a rational multiple of the pitch divided by the square of the sample time; and wherein said control means comprises; normalization means for expressing the distance to be moved as a normalized first digital number M' representing the distance in terms of integral pitches to be moved; half-way approximating means for generating a second digital number D H which is approximately one half the value of the first digital number M'; look-up table means for storing a first set of distance values D 11 , D 12 , . . . D 1n and a corresponding set of maximum velocity values V max1 , V max2 , . . . V maxn which may be reached during a duration of N 1 sample times for an acceleration equal to said predetermined acceleration/deceleration level; table search means for finding in the look-up table means the largest distance value D 1 in the set D 11 , D 12 , . . . D 1n which is less than or equal to the second digital number D H and the corresponding maximum velocity value V max of that largest distance value D 1 from the set V max1 , V max2 , . . . , V maxn ; first duration computing means for computing the number N 1 of sample times required for traveling the distance represented by the distance value D 1 ; remaining distance computing means for computing the difference between the first digital number M' and twice the distance value D 1 found in the look up table means; and mode duration setting means for setting the duration of each of the acceleration and deceleration modes equal to the number N 1 of sample times computed by the first duration computing means and for setting the combined duration of the first and second coast modes such that the difference distance computed by the remaining distance computing means will be traveled in the first and second coast modes.

Claim 7

A method for moving a body by a total distance equal to an integral multiple of a predetermined pitch distance, comprising: sampling the position of the body at periodic sample times t n =nΔt; calculating a square distance D 1 =(V max ) 2 /2A c that is equal to or less than half the total distance where A c is an acceleration level equal to rational multiple of the pitch divided by the square of the sample time Δt; calculating the number N 1 of sample times required for accelerating the body at said acceleration level A c to reach the maximum velocity V max ; and accelerating the body at said acceleration level over one or more periods of time whose total duration equals N 1 sample times.

Claim 8

A method for moving a body by a total distance equal to an integral multiple of a predetermined pitch distance, comprising: sampling the position of the body at periodic sample times t n =nΔt; calculating a square distance D 1 =(V max ) 2 /2A c that is equal to or less than half the total distance where A c is an acceleration level equal to rational multiple of the pitch divided by the square of the sample time Δt; calculating the number N 1 of sample times required for accelerating the body at said acceleration level A c to reach the maximum velocity V max ; and accelerating the body at said acceleration level over one or more periods of time whose total duration equals N 1 sample times.

Claim 11

A method for moving a body by a total distance equal to an integral multiple of a predetermined pitch distance, comprising: sampling the position of the body at periodic sample times; calculating a distance that is equal to or less than half the total distance, where the distance is inversely proportional to an acceleration level equal to rational multiple of the pitch divided by the square of the sample time and the distance is proportional to the square of the maximum velocity of the body; calculating the number of sample times required for accelerating the body at said acceleration level to reach the maximum velocity; and accelerating the body at said acceleration level over one or more periods of time whose total duration equals the number of sample times.

Claim 12

A method for moving a body by a total distance equal to an integral multiple of a predetermined pitch distance, comprising: sampling the position of the body at periodic sample times; calculating a distance that is equal to or less than half the total distance, where the distance is inversely proportional to an acceleration level equal to rational multiple of the pitch divided by the square of the sample time and the distance is proportional to the square of the maximum velocity of the body; calculating the number of sample times required for accelerating the body at said acceleration level to reach the maximum velocity; and accelerating the body at said acceleration level over one or more periods of time whose total duration equals the number of sample times.