US3415466A - Time response matching process and product - Google Patents

Description

Dec. 10, 1968 H. A. POOLE, JR 3,415,466

TIME RESPONSE MATCHING PROCESS AND PRODUCT Filed May 16, 1966 3 sheets-Sheet 1 FIG. I

INVENTOR. HARMON A. POOLE, JR.

BYPQW LU MM ATTORNEY Dec. 10, 1968 H. A. POOLE, JR 3,415,466

TIME RESPONSE MATCHING PROCESS AND PRODUCT Filed May 16. 1966 3 Sheets-Sheet 2 FIG. 4

FIG. 3

INVENTOR. HARMON A. POOLE, JR.

' P Law ATTORNEY Dec. 10, 1968 H. A. POOLE, JR 3,415,466

I TIME RESPONSE MATCHING PROCESS AND PRODUCT Filed May 16, 1966 3 Sheets-Sheet 5 U o I g RETRACT P 50 g m 53 25 9,3

F o. O l 2 3 4 5 RESPONSE TIME- MILLISECONDS FROM COMMAND SIGNAL FIG. 6

I II a" I I I i I 2 I H l g I I 3 x x x x x x x I e i ii if 38 Y 48 q I, I I

| I! II I III l I f l I III F 0 I 'l 37 i I 4 t I I8 I! m 45 54 I 5 i' 56 53 4s 0 O o O 0 O 0 O INVENTOR.

HARMON A. POOLE-JR. FIG. 5

ATTORNEY United States Patent 3,415,466 TIME RESPONSE MATCHING PROCESS AND PRODUCT Harmon A. Poole, Jr., Simsbury, Conn., assignor to Chandler Evans Inc., West Hartford, Conn., a corporation of Delaware Filed May 16, 1966, Ser. No. 550,331 3 Claims. (Cl. 244-3.21)

ABSTRACT OF THE DISCLOSURE A bang-bang missile control system alters angle of attack by subjecting the missile to pure pitch or yaw moment influences produced by paired control surfaces disposed on opposite sides of a missile and separately actuated in time-mismatched limited concert, such that roll moments cancel out despite actuator hysteresis and one control surface is driven by a first actuator in an extend mode while the control surface paired therewith is driven by a second actuator in a retract mode.

This invention relates to missile flight control systems and has particular reference to a process and structure whereby the response mismatch among a plurality of aerodynamic fins is limited to a narrow absolute time response tolerance band regardless of fin position. Application No. 550,459 for Circular Manifold, filed by Alexander M. Wright in May 1966, now US. Patent No. 3,347,494, discloses and claims the manifold structure which serves the actuator assemblies disclosed and claimed in this application.

An object of this invention is to provide a process and product whereby a plurality of bang-bang type actuator assemblies and supporting structure will co-act to exhibit within narrow limits similar response times associated with similar load positions irrespective of the limit position from which the load position is approached.

A further object is to provide synchronized equal total effective operation of separate control members having driving means operating out of phase with each other.

Further objects and advantages of this invention will become evident upon examination of the drawings and specifications.

FIGURE 1 is a cutaway side elevation of a portion of a missile incorporating the invention.

FIGURE 2 is a fragmentary view, partly in section, taken along lines 2-2 of FIGURE 3.

FIGURES 3 and 4 are respectively plan and sectional views of the manifold.

FIGURE 5 is a schematic representation of a section taken along line 55 of FIGURE 3.

FIGURE 6 is a plot of Stroke versus Time in the Extend and Retract modes of actuator stroke.

FIGURE 1 shows two of the four fins 10 which protrude from the missile aft section 12. Solenoids 14 operate ball valves 16 which control fluid flow to fin actuator pistons 18 which drive links 20 connected to fins 10. Dither motions of fins 10 through an arc I are initiated by electronic control signal inputs from the missile computer (not shown) to solenoids 14. The links 20 are longitudinally disposed in the annular space 22 between the missile skin 24 and the rocket thruster tube 26. Manifold structure 28 is concentrically mounted in annular space 22 and attached to the missile skin 24 by screws 30, thereby enveloping a longitudinal portion of rocket thruster tube 26.

Pressure source 44 (see FIG. 2) is threaded into valve housing 32 and a manually controlled puncturing device 45 is threaded into valve housing 32 to effect the release of fluid from pressure source 44. Solenoid valve-actuator assemblies 46 (see FIG. 3) are substantially equally spaced around valve housing 32. Pins 50 fix sleeve 36 in housing 32.

Manifold structure 28 (see FIG. 4) comprises an annular valve housing 32 having a central bore 34, a sleeve 36 fixed concentrically within said housing 32, a toroidal passageway 38 formed between said sleeve 36 and said housing 32, packing means 40 disposed outwardly of said passageway 38 to seal any annular clearance 42 between said sleeve 36 and said housing 32, a pressure source 44 carried by said housing 32, a plurality of solenoid valveactuator assemblies 46 substantially equally spaced around said annular housing 32, conduit means 48 connecting said toroidal passageway 38 to pressure chamber 54, and to each of said plurality of assemblies 46. Said pressure source 44 (see FIG. 5) supplies fluid to pressure regulating valve 53 via passageway 56 (see FIG. 5), the regulated fluid thence flowing into chamber 54, thence into connecting conduit means 48, thence into toroidal passageway 38, and finally to a plurality of ball valves 16 and actuating pistons 18 via conduit means 48. Pulse-width modulated signals from the missile computer (not shown) energize valve operating means such as solenoids 14 to control valve means 16 which control the position of each fin. Since the missile operates at a high velocity and the total time of flight is very short, the actuator must be fast and the unbalanced moments produced by any control action must be minimized to provide accurate stable flight. Unbalanced moments of any single pair will produce unwanted roll. The response time of each actuator unit can be matched to the response time of all of the other actuator units such that a very narrow band of response time mismatch between individual units is established by the process of summing individual elemental time response such that for a large number of assembled actuator units the over-all response time of each individual assembled actuator unit will be matched to all the other assembled units to within a narrow absolute time response tolerance band such as one millisecond. Conduit means 48 direct regulated pressure directly to the rod side of the actuator pistons 18 which are constantly pressurized while the system is in operation, and also to valve assemblies 16.

If the solenoid is in a tie-energized condition, the flow will be stopped by the ball valve itself, which is then seated by spring 3 onto the lower seat. In this position the valve permits venting of the upper actuator cavity. As each individual solenoid is fully energized, the corresponding ball valve will be seated on the upper seat and regulated pressure is introduced to the large area side of the corresponding piston.

If the solenoid is de-energized, the piston 18 will sna'p under the influence of fluid force on the rod side of the piston 18 to the retract position. If the solenoid is energized, the piston 18 will snap under the influence 'of fluid force on the opposite side of the piston 18 to the extend position. The particular organization utilized for the instant actuator assembly is such that one actuator will extend while the diametrically opposite actuator will simultaneously retract. However, the mechanical linkage between the actuators and the aerodynamic fins is such that the fin connected to one actuator will move in response to a retract signal in the same direction as the fin connected to the diametrically opposite actuator moves in response to an extend signal. Thus paired aerodynamic fins move in the same direction in response to an opposed actuator movement within their paired actuator assemblies. A similar operational characteristic exists between the remaining paired actuators and their respective aerodynamic fins. This operational arrangement is important in understand ing the extend and retract absolute time response mismatch curve shown in FIGURE 6. The dead time and extend and retract rates depicted in FIGURE 6 can be adjusted by individually selecting electrical means such as diodes 1 or resistors 2 to be placed in the solenoid lead wires or by mechanical means such as adjusting the spring 3 to vary the load acting on the solenoid plunger.

When the computer control signal to a solenoid is a balanced square wave, the fin will snap from the extend stop to the retract stop without producing any appreciable net control moment. Yaw or pitch control moments are produced by actuators respectively acting in pairs with the dwell time at one stop position longer than at the other stop position. The corrective moment produced by this unbalanced dwell time is related to the integral of the pair of actuator position-time traces. The significance of mismatch is indicated by the example shown in FIG- URE 6. This shows response matching as a time function, not just an end condition. For this reason, the response time of the matched actuator units must be capable of achieving almost matched time response over a Wide range of missile operating and fin loading conditions.

The total or integrated time response of the actuator unit is composed of the sum of the individual time responses of the following elements:

(1) Solenoid rise time (partly the function of the solenoid triggering circuit).

(2) Ball travel transient time.

(3) Pneumatic response time (pressurized fluid flow time through passages and orifices between ball and actuator piston inlet).

(4) Piston travel time (including time consumed to pneumatically fill piston chamber).

It is to be noted the above total time response relates to the extend position of the actuator piston rod. The total retract position response time is composed of the sum of times 2, 3 and 4, as set forth above, plus the solenoid dropout time, which again is partly a function of the solenoid triggering circuit.

It is important to note that the total or integrated extend response time will not necessarily be the same as the total or integrated retract response time. FIGURE 6 shows a rapid extend rate combined with a relatively long dead time used for solenoid energization and valve travel, and a relatively slow retract rate combined with a relatively short dead time used for solenoid decay and valve travel.

Realistic response time limits can be established for each of the elements that contribute to each of the individual time response set forth in items 1-4 above such that a cumulative maximum response time tolerance mismatch A (see FIG. 6) of no more than one millisecond between units can be established.

By selecting and assigning a response time tolerance band to each of the elements that compose the complete actuators assembly an absolute mismatch time band of one millisecond can be established among a plurality of solenoid valve-differential actuator assemblies by the technique of matching and summing incremental time response characteristics.

While certain details have been described herein, it will be understood that other modifications and changes may be made without departing from the spirit and scope of the appended claims.

I claim:

1. A control method for missile flight steering comprising simultaneously independently moving a pair of coacting separate control members on the missile in the same direction in a continuous movement from one matched terminal position where they have one control effect to an opposite matched terminal position where they have an opposite control effect, one member having a longer travel time than the other, any mismatch of position causing an undesirable control effect, initiating starting movement of the member having the longer travel time before initiating starting movement of the other member, thus causing a first temporary mismatch in one direction, bringing the members to a simultaneous position match intermediate the control movement and then moving the members to a mismatch in the opposite direction in the remainder of the control movement to thereby cancel the effect of the first mismatch.

2. A missile control for a movable body comprising a pair of bidirectional movable control fins disposed on diametrically opposite sides of said body and having a path of bidirectional movement between opposed limiting stop positions in which positions the fins have matched cumulative control effects, unequal dwell times at the opposed stop positions causing a net control result, an individual actuator. connected to each respective fin, each actuator having a slower operating rate in one direction than in the other, means connecting each fin and its respective actuator so as to move one fin at the slower rate and the other at a faster rate when moving both fins in the same direction, similar means controlling said actuators and having different operating rates in opposite directions, each of said controlling means being connected to a respective actuator so that the controlling means operation in the faster operation direction is effective to actuate said actuator in said slower actuator operating rate direction, and means for operating said controlling means, said means being so timed that the adverse control effect of a fin position mismatch in one direction in the first part of the fin movement is cancelled by an equal mismatch in the opposite direction in the later part of the fin movement.

3. Means for simultaneously independently operating a pair of control members on a missile in the same direction and over the same distance comprising, a differential piston operatively connected to each respective member for moving the respective control member bidirectionally, means continuously supplying pressure fluid to the smaller side of the piston, valve means controlling the flow of pressure fluid to and from the larger side of the piston, a solenoid controlling each valve, and having a longer energizing time than decay time, each of said pistons having a longer retract time than extend time, said solenoids being so connected that energizing a solenoid will cause extension of its respective piston, one piston operating one control member by extending and the other piston simultaneously operating the other control member in the same direction by retracting.

References Cited UNITED STATES PATENTS 2,557,829 6/ 1951 Lavelle 244 2,584,127 2/1952 Harcum et al 2443.21 3,245,352 4/ 1966 Summers 2443.21

BENJAMIN A. BORCHELT, Primary Examiner.

VERLIN R. PENDEGRASS, Assistant Examiner.

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