Method of varying response fineness in a control system

• US 4,589,061 A
• Filed: 04/18/1984
• Issued: 05/13/1986
• Est. Priority Date: 04/18/1983
• Status: Expired due to Term

• Current Assignee: Saab-Scania Aktiebolag
• Original Assignee: Saab-Scania Aktiebolag
• Inventors: Nordstrom, Lennart
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/601,644
• Time in Patent Office: 755 Days
• Field of Search: 364/154, 364/157, 364/160, 318/592, 318/594, 318/561, 244/195
• US Class Current: 700/37
• CPC Class Codes: B64C 13/50 using electrical energy
• CPC Class Codes: G05D 1/0061 for transition from automatic pilot to manual pilot and vice versa

Abstract

In a system for controlling a servo actuated controlled device, an input signifying the position of displacement of an aircraft stick or similar manipulatable unit is processed to provide a variable gain to the controlled device. In a predetermined range of positions of the stick in which it is spaced to one side of neutral (or in such a range at each side of neutral) the system operates with low gain during displacement of the stick through a predetermined distance in either direction from a turning point to which the stick had been brought by displacement in the opposite direction. For all other displacements in that range the system operates with high gain. The method thus provides for fast, positive response to coarse stick movements but fine response to small trimming movements.

Claims

1. A method of controlling response fineness in a control system comprising a manipulated unit that is displaceable from and toward a null position, in increase and decrease directions respectively, and a controlled device that is actuated respectively from and toward a neutral position in response to displacements in said directions of said unit, wherein input signals are generated at substantially regular intervals, each designating, by a magnitude thereof, the existing position of displacement of said unit, and an output signal is produced for each input signal, each output signal having a magnitude which signifies a position that the controlled device is to have and which is a function of the magnitude of its input signal and of a gradient relationship between respective displacements of said unit and said device, said method being characterized by:

A. defining a first sequence of output signal magnitudes

(1) related to respective input signals that designate positions of said unit between said null position and a first position spaced therefrom in said increase direction,

(2) said magnitudes in said first sequence having a first gradient of increase in said increase direction relative to their related input signal magnitudes;

B. defining a second sequence of output signal magnitudes

(1) related to respective input signals that designate positions of said unit between said first position and a second position spaced therefrom in said increase direction,

(2) said magnitudes in said second sequence having a second gradient which is substantially higher than said first gradient;

C. defining a third sequence of output signal magnitudes,

(1) related to respective input signals that designate positions of said unit between a third position, intermediate said first and second positions, and a fourth position spaced in said increase direction from the second position, and

(2) having a gradient on the order of said second gradient and such that for a given input signal the related magnitude in said third sequence signifies a smaller displacement of said device from its neutral position than the related magnitude in the second sequence;

D. defining a set of "trim" sequences of output signal magnitudes

(1) related to respective input signals that designate positions of said unit between said first and fourth positions,

(2) all of said "trim" sequences having like gradients on the order of said first gradient,

(3) there being a "trim" sequence in said set for each output signal magnitude in each of said second and third sequences, and

(4) each "trim" sequence including a magnitude that is in said second sequence and a different magnitude that is in said third sequence, each of which magnitudes has a unique relationship to its related input signal whereby the "trim" sequence is identifiable;

E. for each generated input signal that designates a position of said unit between said null position and said first position, producing an output signal having the magnitude in the first sequence that is related to that generated input signal;

F. for each produced output signal, storing information related to

(1) its magnitude and

(2) the input signal for which it was produced whereby a "trim" sequence is identifiable;

G. for each generated input signal that designates a position of said unit between said first and said fourth positions,

(1) assigning as a presumptive output signal magnitude its related magnitude in the "trim" sequence identified by stored information for the last previously produced output signal,

(2) comparing said presumptive output signal magnitude with the respective magnitudes in said second sequence and in said third sequence that are related to the generated input signal, and

(a) if the presumptive magnitude is equal to or larger than the compared magnitude in said second sequence, producing an output signal having that compared magnitude,

(b) if the presumptive magnitude is equal to or smaller than the compared magnitude in said third sequence, producing an output signal having that compared magnitude, and

(c) if the presumptive magnitude is larger that the compared magnitude in the third sequence and smaller than the compared magnitude in the second sequence, producing an output signal having said presumptive magnitude as its magnitude.

2. A method of controlling response fineness in a control system comprising a manipulated unit that is displaceable from and toward a null position, in increase and decrease directions respectively, and a controlled device that is actuated respectively from and toward a neutral position in response to displacements in said directions of said unit, wherein input signals are generated at substantially regular intervals, each designating, by a magnitude thereof, the existing position of displacement of said unit, and an output signal is produced for each input signal, each output signal having a magnitude which signifies a position that the controlled device is to have and which is a function of the magnitude of its input signal and of a gradient relationship between respective displacements of said unit and said device, said method being characterized by:

A. defining a pair of sequences of output signal magnitudes

(1) the output signal magnitudes of one of said sequences being related to respective input signals that designate positions of said unit between a first position and a second position spaced from said first position in said increase direction,

(2) the output signal magnitudes of the other of said sequences being related to respective input signals that designate positions of said unit between a third position, intermediate said first and second positions, and a fourth position spaced in said increase direction from the second position, and

(3) said output signal magnitudes in each of said sequences having a first substantially steep gradient of increase in said increase direction relative to their related input signals, so that for a given input signal the related magnitude in said one sequence signifies a larger displacement of said device from its neutral position than the related magnitude in said other sequence;

B. defining a set of "trim" sequences of output signal magnitudes

(1) related to respective input signals that designate positions of said unit between said first and fourth positions,

(2) all of said "trim" sequences having like gradients substantially less steep than said first gradient,

(3) there being a "trim" sequence in said set for each output signal magnitude in each of said one and said other sequences, and

(4) each "trim" sequence including a magnitude that is in said one sequence and a different magnitude that is in said other sequence, each of which magnitudes has a unique relationship to its related input signal whereby the "trim" sequence is identifiable;

C. for each produced output signal, storing information related to

(1) its magnitude and

(2) the input signal for which it was produced whereby a "trim" sequence is identifiable;

D. for each generated input signal that designates a position of said control unit between said first and said fourth positions,

(1) assigning as a presumptive output signal magnitude its related magnitude in the "trim" sequence identified by stored information for the last previously produced output signal,

(2) comparing said presumptive output signal magnitude with the respective magnitudes in said one sequence and in said other sequence that are related to the generated input signal, and

(a) if the presumptive magnitude is equal to or larger than the compared magnitude in said one sequence, producing an output signal having that compared magnitude,

(b) if the presumptive magnitude is equal to or smaller than the compared magnitude in said other sequence, producing an output signal having that compared magnitude, and

(c) if the presumptive magnitude is larger than the compared magnitude in said other sequence and smaller than the compared magnitude in said one sequence, producing an output signal having said presumptive magnitude as its magnitude.

3. A method of controlling response fineness in a control system comprising a manipulated unit that is displaceable from and toward a null position in increase and decrease directions respectively, and a controlled device that is actuated respectively from and toward a neutral position in response to displacements of said unit, wherein an input is generated that has a magnitude which at each instant designates the existing position of displacement of said unit from its null position and an output is produced that has a magnitude which at each instant signifies the position that the controlled device is to have and which is related to the existing magnitude of the input, said method being characterized by:

A. when said unit is in a predetermined range of its positions of displacement, and during every displacement of said unit through no more than a predetermined distance in each said direction that next follows a displacement of said unit in the opposite direction, varying said magnitude of the output in accordance with a first gain relationship between input and output magnitudes;

B. when said unit is in said range of positions, and during every displacement of said unit in the increase direction other than as aforesaid, increasing said magnitude of the output in accordance with a second gain relationship between input and output magnitudes having a substantially higher gradient than said first gain relationship; and

C. when said unit is in said range of positions, and during every displacement of said unit in the decrease direction other than as aforesaid, decreasing said magnitude of the output in according with a third gain relationship

(1) which has a gradient on the order of that of said second gain relationship but

(2) wherein the output magnitude related to each position of displacement of said unit signifies a greater displacement of the controlled device from its neutral position than the output magnitude of the second gain relationship that is related to the same position of said unit.

4. The method of claim 3 wherein said control unit is displaceable to opposite sides of its said null position and at each said side thereof is displaceable in increase and decrease directions that are respectively from and toward said null position, and wherein said predetermined range of positions is substantially duplicated, there being one such range at each said side of the null position.

5. The method of claim 3, further characterized by:

when said unit is between its said null position and said range, and during every displacement of said unit in each said direction, varying said magnitude of the output in accordance with a gain relationship between input and output magnitudes that is on the order of said first gain relationship.

6. The method of claim 3 wherein said input comprises input signals generated at substantially regular intervals, each having a magnitude signifying the existing position of displacement of said control unit, and said output comprises an output signal for each input signal, further characterized by:

D. defining a pair of sequences of output signal magnitudes,

(1) the output signal magnitudes of one of said sequences

(a) being related to respective input signals that designate positions of said control unit between a first position, at the end of said range that is proximal to said null position, and a second position in said range that is spaced in said increase direction from said first position and

(b) having said third gain relationship to their related input signal magnitudes, and

(2) the output signal magnitudes of the other of said sequences

(a) being related to respective input signals that designate positions of said control unit between a third position in said range, intermediate said first and second positions, and a fourth position that is at the end of said range remote from the null position, and

(b) having said second gain relationship to their related input signal magnitudes;

E. defining a set of "trim" sequences of output signal magnitudes

(1) related to respective input signals that designate positions of said unit between said first and fourth positions,

(2) the output signal magnitudes in each of said "trim" sequences having said first gain relationship to their related input signals,

(3) there being a "trim" sequence in said set for each output signal magnitude in each of said one and said other sequences, and

(4) each "trim" sequence including a magnitude that is in said one sequence and a different magnitude that is in said other sequence, each of which magnitudes has a unique relationship to its related input signal whereby the "trim" sequence is identifiable;

F. for each produced output signal, storing information related to

(1) its magnitude and

(2) the input signal for which it was produced whereby a "trim" sequence is identifiable;

G. for each generated input signal that designates a position of said unit between said first and said fourth positions,

(1) assigning as a presumptive output signal magnitude its related magnitude in the "trim" sequence identified by stored information for the last previously produced output signal,

(2) comparing said presumptive output signal magnitude with the respective magnitudes in said one sequence and in said other sequence that are related to the generated input signal, and

(a) if the presumptive magnitude is equal to or larger than the compared magnitude in said one sequence, producing an output signal having that compared magnitude,

(b) if the presumptive magnitude is equal to or smaller than the compared magnitude in said other sequence, producing an output signal having that compared magnitude, and

(c) if the presumptive magnitude is larger that the compared magnitude in said other sequence and smaller than the compared magnitude in said one sequence, producing an output signal having said presumptive magnitude as its magnitude.