Document
NASA Technical Memorandum 86688 USAAVSCOM Technical Memorandum 85-A-1
NASA- TM-86688
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Effects of Side - Stick Controllers
on Rotorcraft Handling Qualities
for Terrain Flight
Edwin W. Aiken
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United States Army 9.·
National Aeronautics and Aviation Systems ~ Space Administration Command
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NF01054 NASA Technical Memorandum 86688 USAAVSCOM Technical Memorandum 85-A-1
Effects of Side - Stick Controllers
on Rotorcraft Handling Qualities
for Terrain Flight
Edwin W. Aiken, Aeromechanics Laboratory, U. S. Army Research & Technology Laboratories-AVSCOM, Ames Research Center, Moffett Field, California April 1985
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National Aeronautics and United States Army Space Administration Aviation Systems Command Ames Research Center St. Louis, Missouri 63120 Moffett Field, California 94035 EFFECTS OF SIDE-STICK CONTROLLERS ON ROTOR CRAFT HANDLING QUALITIES FOR TERRAIN FLIGHT Edwin W. Aiken Aeromechanics Laboratory, U.S. Army Research and Technology Laboratories - AVSCOM NASA Ames Research Center Moffett Field, California 94035 U.S.A.
Abstract improvements in reliab1lity; pilot safety and comfort may also be enhanced by the resultant Pertinent fixed- and rotary-wing feasibility improvements in vis1bility, ingress/egress, crash- studies and handling-qualities research programs worthiness, and by the elimination or the poor are reviewed and the effects of certain controller posture caused by conventional controller loca- characteristics on handling qualities for specific tion. However, until recently, the effects of rotorcraft flight tasks are summarized. In par- this advanced controller concept on the ease and ticular, the effects of the controller for<:e- preCision with which a pilot is able to perform deflection relationship and the number of con- terrain flight tasks were largely unknown.
trolled axes that are integrated in a single controller are examined. Simulation stUdies con- Much of the background information presented ducted as part of the Army's Advanced Digital/ in this paper is based upon investigations of the Optical Control System (ADOCS) program and flight effects of controller characteristics on aIrcraft research program3 performed by the National Aero- handling qualItIes: "those qualIties or charac- nautical Establi3hment of Canada provide a signif- teristics of an aircraft that govern the eas'~ and icant part of the available handling qualities precIsion with which a pilot is able to perform data. These stu,l1es demonstrate the feasibility the tasks required in support of an aircraft of using a single, properly designed, limited- role."1 Hand11ng qualities are, therefore, 1nflu- displacement, multi-axis controller for certain enced not only by aircraft stability and control relatively routi1e fl~ght tasks in a two-crew characteristics but also by factors such as the rotorcraft with nominal levels of stability and design of the cockpit interface--the controllers control augmentation. However, for the more and displays provided for the required tasks. All demanding terrain flight tasks, unless high levels of these handling qualities studies have assumed a of stability and control augmentation with a high two-crew situation; no d'lties such as navigation, degree of reliability are incorporated, separated communication, and battle-captain functions, which three- or two-axis controller configurations are would be performed by th~ pilot of a Single-crew required for acceptable handling qualities.
combat rotorcraft, were Issigned to the pilots.
Therefore, extrapolation of these results to the Single-crew situation mUlt be based upon sound Introduction engineering and piloting judgment. The controller tradeoffs addressed In this paper are: 1) conven- Advanced flight control systems which employ tional versus side-stick controllers, 2) d1splace- fly-by-wire or fiberoptic technology provide the ment versus force controllers, and 3) separated control system designer with the flexibility to versus i~tegrated controllers.
synthesize the system based upon pilot-oriented design criteria. In addition to multimode control laws which vary as a function of mission task and Conventional versus Side-Stick Controllers flight condition, these systems will include advanced pilots' controllers with designs that are Cockpit Design Implications no longer constrained by the characteristics of a mechanical flight control system. One particu- The replacement of the conventional set of larly appealing design concept is the replacement primary controllers by a single side-stick con- of the conventional set of primary controllers by troller can yIeld sIgnifIcant benefits. An a single side-stick controller. This appro~ch to increase In available cockpit volume provides controller design provIdes sIgnIfIcant benerits to valuable room for the addItional avionics requIred the cockp1t designer by increasing the available to perform the advanced scout/attack mission. In cockpit space, by a savings in weight, and by a comparison or conventional cockpIt controllers with a configuration consistIng of a two-axIs side-stick and small-displacement collectIve and Presented at the International Conrerence on pedals, Rer. 2 reports a 30J weight savings with Rotorcraft Basic Research, Research Triangle Park, the side-stick configuration. This same study North Carolina, February 19-21, 1985.
claims significant improvements in both flIght safety and mission reliability using the advanced lems between the longitudinal and vertical axes, a controllers.
three-axis controller was eventually implemented with vertical control effected through a standard Certain human factors and man-machine inte- collective lever. Pilots were also critical of gration benefits can also be derived from a cock- the longitudinal control implementation; the large pit design which employs a side-stick controller.
displacement (4.5 in.) and viscous damping created Potential benefits include improvements in: a controller which felt massive and heavy. Both 1) visibility caused by the removal of the pedals the lateral axis (a base-pivot design) and the and cyclic stick; 2) ingress and egress, espe- directional axis (a twist-grip) were considered cially if the side-stick can be mounted on a acceptable. The use of multi-axis controllers was movable armrest as in Ref. 3; 3) crashworthiness, rejected for the Heavy Lift Helicopter (HLH) pri- caused by the removal of potentially lethal mary flight control system ; however, a four-axis objects from the cockpit; and 4) pilot comfort, by finger-ball displacement controller was imple- eli~lnating the need for the traditional helicop- mented at the load-controlling crewman's station ter pilot slouch over the controls, and by allow- in that vehicle for precision cargo handling tasks ing feet-on-the-floor flight. However, "any bene- requiring a high level of stability and control fits gai~ed in a substantial deviation from this augmentation.
(conventional) arrangement must be weighed against the costs of retraining the pilot's spontaneous In a three-degree-of-frecdom moving-base control command patterns, particularly in high simulation of the unaugmented Lynx helicopter at workload and emergency situations."4 the Royal Aircraft Establishment (RAE) Bedford, a two-axis displacement side-stick was compared with Feasibility Studies the conventional C~CliC controller for 11 differ- ent flight tasks. When a suitable control sen- Simulator and flight investigations have sitivity was selected, the side-stick compared demonstr!ted the feasibility of the use of a side- favorably wi th the conventional controll.?r and, in stick co,troller in both fixed- and rotary-wing fact, was preferred for some of the tasks which aircraft for certain tasks. All of the fixed-wing required only small control movements. Manual studies involved side-sticks with two axes of trimming was considered to be difficult because of control: pitch and roll. In a 1951 NACA- the trim-button location and the force required to sponsored program, a Navy F9F was equipped with a . operate it; inadvertent control inputs were the side-stick controller to investigate the control result. A simple armrest drew no adverse com- implications of such a device. All of the pilots ments, but a wrist support was recommended. In a were able to execute precision flying tasks with piloted simulation of an Advanced Scout Helicopter no performance degradation. Pilot effort was felt (ASH), an A-1IF-16 two-axis side-stick was found to be reduced because of the lighter control to be feasible for an ASH mission when employed forces and the comfort provided by the controller with suitable levels of stability and control armrest. In 1910, the Air Force Test Pilot School augmentation.
flew an F-104 equipped with a side-stick con- troller.~ The side-stick was unanimously pre- A feasibility study of a four-axis isomet~ic ferr~d to the conventional center stick and pro- (rigid) side-stick controller was conducted far' a vide1 superior trajectory control with drastically 11 wide range of flight tasks in the Canadian reduced pilot workload. Over 60 pilots flew with National Aeronautical Establishment (NAE) the side-stick and accumulated 810 hr of flight Airborne Simulator, a variable stability Bell time with no controller failures. A direct com- Hodel205A-1. Two primary side-stick configura- parison of pilot performance with a center-stick tions, a four-axis controller and a three-axis and a side-stick was performed at Wright-Patterson controller with normal pedal control, were evalu- AFB in 1910. 1 The study concluded that a side- ated together with variations in the level of stick was feasible for use in high-speed, hlgh- stability and control augmentation. A conclusion altitude maneuvering tasks; it resulted in of this study was: "It is clear from these exper- improved performance for landings and other preCi- iments that a helicopter can be flown thro'lgh a sion maneuvers, but it yielded degraded perfor- wide range of visual and instrument flight tasks mance for large-amplitude maneuvers at low using either a three-axis or four-axis iso'1etric altitudes.
side-arm controller--without requiring exc,~ptional pilot skill or concentration and within the bounds Feasibility studies of the use of side-stick of normal helicopter work load demands." In a controllers in helicopters began in 1968 with the follow-on flight investigation,12 a comparison of Tactical Aircraft Guidance System (TAGS) program.
conventional controllers with the same two isomet- That system was implemented in a CH-4"B aircraft riC side-stick configurations was conducted by and initially included a four-axis di~placement flying the Airborne Simulator with augmented controller; because of anatomical coupling prob- pitch, roll, and yaw-rate damping through a low-altitude course involving both maneuvering and Displacement versus Force Controllers precision flight. For this experiment, "the pilots generally considered isometric (side-stick) Input Bandwidth control to be more difficult and less precise, in With a conventional set of controllers, the this type of closely bounded task, than conven- position of each controller with respect to some tional control."
reference point is the pilot's input to the con- trol system; the relationship between the applied Handling Qualities Studies force and the resultant displacement may be Han,lltng qualities studies--those which expressed as a second-order response with charac- elici t both Cooper-Harper pilot ratings and pilot teristics determined by the force-feel system of commentar'y--which include a comparison or conven- the aircraft. The use of a force controller elim- tional controllers with side-stick controllers are inates this second-order "filter" on the control rare. The Rer. 11 flight data, as interpreted in input, thus allowing closer control or the flight- Ref. 12, revealed that, when appropriate gains, path of the aircraft since the applied rorce is shaping, and prefiltering were applied to the itself the input quantity. As a result, the pilot's rorce input in each controlled axis, pilot inputs as seen by the control system could have a ratings comparable to those that were obtained much higher rrequency content, or bandwidth, than with conventional controls were achieved by both when displacement controllers are employed. This primary side-stick conrigurations. In two moving- characteristic provides the potential for 'a more
base simulations or helicopter visual terrain
precise control of the flight path but also makes flight,13 it was determined that the employment of the control system, and hence the aircraft a properly designed two-axis displacement side- response, more sensitive to sharp control inputs, stick controller could, in fact, improve handling to inertial forces such as those experienced in qualities over those provided by conventional high-g maneuvers, and to aircraft vibrations that controlle~s (Fig. 1) but that increased levels of are fed through the controller grip. It was for stability augmentation were required to achieve these reasons that the original rorce-sensing comparabl~ pilot ratings ir a three- or four-axis stick of the F/A-18 was replaced by a displacement isometric controller was employed (Fig. 2). controller during full-scale development test- ing. In that program, forward-path prerilters Summary (:onventional versus Side-Stick) were employed in the digital flight control system to smooth the pilot's inputs from the force stick, The IJse of a single side-stick controller to but those filters also yielded degraded con- replace the conventional set of helicopter con- trollabilIty. Extra weight was required to mass- trollers offers significant advantages to the balance the stick against the forces caused by cockpit designer and has the potential for enhanc- catapult launch. Notch filters in the flight ing pilot safety and comfort. However, based upon control software were required to prevent struc-
the results or the feasibility and handling quali-
tural interaction through the inertia of the grIp ti~s studies cited in this section, a single, and the pilot's arm at structural resonance fre- multi-axi,l side-stick controller has never been quencIes; these filters also caused addItional demonstra';ed to improve handling qualities for any time delays which further degraded handling quali- helicopte~ flight tasks; in fact, there is a ties and caused pilot-Induced oscillations.
strong indication that lncreased levels or stabil-
ity and control augmentation are required to Advantages and Disadvantges achieve e'len comparable handling quali ties for visual terrain flight tasks similar to those The advantages of a force controller lie in requi red or advanced cOlnbat rotorcraft. Only a its inherent Simplicity, relIabIlIty, and low properly designed two-axis side-stick has been parts count. In addition, no force-feel system shown to offer the potential for improved handling is requIred to provIde the control force charac- qualities when it is compared to a conventional terIstics that are dIctated by handlIng qualIties cyclic stick; it is very possible, however, that requirements. However, the lack of explicIt con- improved conventional cyclic stick force charac- trol position information from a force controller teristics would negate, or reduce the significance can be a sIgnIfIcant disadvantage. Although the of. this advantage. human pIlot Is not a partIcularly accurate sensor of controller displacement, the lack of any dis- placement cues can degrade the ability to make smooth and precIse control Inputs. An operational problem that Is caused by this lack of control position InformatIon was highlIghted In the Refs. 11 and 12 flight experIments. Because of the use of the force controller, the analogIes b€tween conventional cyclic-stick position and a very adequate performance was only possible for main rotor tip-path plane orientation and between As the restricted range of control sensitivities.
pedal displacement and the remaining yaw-control the amount of controller compliance increased, authority were eliminated. The former relation- also region of acceptable control sensitivities ship is particularly important for slope takeoffs increased to some maximum value.
whereas the latter provides important information With further increases in controller deflec- when operating with large yaw rates or in the tion-per-unit-applied-force, degraded handling presence of large sideslip angles. A visual pres- qualities occurred with comments about excessive entation of this information was added to the stick motion requirements and overshoots in air- instrument panel to compensate for the loss of craft response. the results of these flight control position cues. Problems caused by the experiments were incorporated in a design guide lack of absolute collective pitch-angle informa- for two-axis side-stick controllers used in tion were rEvealed in simulations conducted to fighter aircraft. Aircraft design experience support the JVX development. The conventional also substantiates the limited-displacement collective stick position, as an analog for col- requirement. The original side-stick design for lective pitch angle, provides important informa- the F-16 prototype incorporated a virtually zero- tion to the pilot during takeoffs, autorotations, or maneuvere at high power. As a result, the displacement force controller (±O.030 in. at the grip); subsequent refinement for the production original force controller used for vertical con- F-16 showed that a ±O.2 in. displacement was trol inputs was replaced by a small displacement desired for longitudinal control and a ±O.10 in.
controller.
displacement was desired for lateral control.
Oecaus€ of the lack of motion of a pure force A total of seven different four-axis side- controller, both trimming and control transfer stick controllers, exhibiting a wide range of become more difficult to implement. With a force-deflection characteristics, was evaluated sophisticated flight control system the need for for use in helicopter terrain flight during the manual trim inputs may be eliminated by incor- ADOCS Advanced Cockpit Controls/Advanced Flight porating automatic trim logiC in the control laws.
Control S,stem (ACC/AFCS) simulator investiga- Similar logic may be incorporated to assist in tions. - 9 Three of these controllers are illus- control trarsfer to minimize aircraft transient trated in Fig. 3. Early in that program, it was response. rowever, in situations with a degraded flight control system, trimming and control-trans- found that, as in the fixed-wing investigations, the introduction of a limited amount of deflection fer may have to be performed unaided. Low-force in the pitch and roll axes yielded improved task trim switches are required to eliminate the possi- performance and handling qualities (Fig. 4).
bility of inadvertent control inputs while trim- Comments on sluggish control response and less ming; in addition, the rate of removal of steady precise attitude control resulted when there was trim forces must be carefully selected to minimize too much deflection. Later in the program, har- any transients.
mony among the four control axes was also found to In a related area of concern, any secondary be an important consideration; a controller with control functions or selectors that are mounted on two limited-deflection control axes (pitch and the grip of a force controller must be implemented roll) and two rir,id control axes (vertical and so as to minimize any hand motion or application directional) was judged to be only marginally of force which might cause inadvertent primary acceptable (Fig. 5). All pilots felt that deflec- control inputs. Low-force switches or buttons are tion in all control axes improved the ability to a requirement when using a force controller.
modulate single-axis forces, prod\Jced less ten- dency for overcontrol and anatomi1al coupling, and Results of Force/Deflection Studies enhanced control precision for hi ,;h-gain piloting tasks such as precision hover.
Results of both fixed- and rotary-wing han- dling qualities research in the investigation of To compensate for the potent:al of an the relative benefits of force and displacement increased control input bandwidth with a force- side-stick controllers indicate significant advan- sensing controller, both the ADOC:; and NAE side- tag~s for limited-displacement controllers. In stick implementations included SO:1e preprocessing 'l()V( ral fixed-wing flight investigations typified of the control force input before it was used to by f~ef. 15, an "optimum" region for force- drive the control systems. A nonlinear shaping deflection relationships was defined for two-axis function, consisting of a dead zone (or breakout) side-stick controllers. Typically, isometric and quadratic (NAE) or piecewise-linear (ADOCS) force controllers yielded performance which was control sensitivity function, was employed to very sens i t1 ve to the control sensi ti vi ty provided provide acceptable levels of control sensitivity (aircraft response per-unit-of-applied-force); around zero force with minimum coupling of control inputs while permitting large, short-duration 3) compensation for human pilot characteristics in inputs to be made without the use of excessive both hardware and software.
c~ntrol force. In addition, to guard against the response of the aircraft to sharp pilot inputs A number of two- and three-axis hand control- such as the rapid release of large control forces, lers have been investigated for fighters, space- both systems incorporated techniques to smooth craft, and helicopters. These controllers have the control input. The NAE system employed a used a variety of reference systems for the con- 16 rad/sec first-order filter in each control trol inputs. The roll-control axis has been axis whereas the ADOCS control laws included a parallel to the forearm and beneath the hand in "derivative rate limiter" designed to limit peak almost every controller tested. ·,Hth this roll accelerations for large control inputs without axis, the most intuitively correct pitch-control affecting control precision for small force axis is horizontal and is perpendicular to, and inputs.
intersects, the roll axis. This axis system, used for the conventional center stick and for the F-16 Summary (Displacement versus Force) Side-stick, requires some forearm motion for pitch inputs to a displacement controller, which is a A summary of the advantages and disadvantages possible disadvantage in a h1gh-g or v1bratory of a force-sensing controller is presented in environment. As a result, other pitch pivots Table 1. Small-displacement force controllers which allow operation without arm movement, such have been shown to provide significant handling as wrist- or palm-pivots, have been investigated.
qualities advantages over rigid controllers.
Both the ADOCS and the NAE research programs However, the control system software employed with employed a more conventional base-pivot set for this type of controller must provide: 1) the pitch and roll to minimize the risk that is inher- means to compensate for sharp pilot inputs and ent in a transition to a side-stick controller.
vibratory forces; 2) the capability for both auto- The yaw axis of control in a hand controller has matic and manual trimming; and 3) control transfer been implemented in several ways; the most preva- in a two-crew situation. Low-force buttons and lent has been the grip twist about the vertical switches are required for any grip-mounted secon- axis of the hand grip itself. Alternatives, such dary controllers or selectors. The lack of as a thumb lever to avoid the input cross-coupling explicit control position information may pose a problems that are inherent in the grip twist problem under operational conditions such as slope approach, result in hand-fit problems and pilot take~ffs or in flight with large sideslip angles, fatigue. To maintain control input-aircraft and in emergency conditions such as engine and response compatibility, vertical control was flight-control system failures.
effected through the application of pure up and down forces in both the ADOCS and NAE programs. A configuration that was evaluated by the NAE using Separated versus Integrated Controllers grip twist as the ve~tical input was confusing and unacceptable.
For the purposes of this discussion, fully "integrated" controllers are those which combine Much more stringent reqUirements for grip all ~rimary control functions on a single device.
design exist for integrated controllers than for "Sepdrated" controllers are produced when one or separated, conventional controllers. The grip more of these functions is removed from the inte- must be shaped so as to assist the pilot in iden- grat.,d controller. Levels of integration evalu- tifying the controlled axes by providing a con- ated in both the ADOCS and NAE investigations stant hand position with respect to the grip. It rang~ from a fully integrated four-axis device to must be designed to .lllow the pilot to make clean a s'3,)arated-controller configuration consisting of control inputs into .~ach axis with a minimum of 3 two-axis side-stick and conventional collective inadvertent inputs into other axes. The original and pedals (Fig. 6). Two primary issues are dis- hand grip that was supplied with the isometriC CUSS'3d in this s€,ction: 1) human factors require- controller and evaluated by the NAE was found to ment.! for controller integration; and 2} handling cause vertical-to-pitch and roll-to-yaw input qualities effects of the level of integration.
cross-coupling; a re.1esigned grip was found to be more acceptable. This new grip formed the basis 'luman Factors Requirements for the design of th'l integrated controller grip which is implemented in the ADOCS demonstrator Three "humar. factors" requi rements di rectly helicopter.
related to the integration of multiple control axes on a single controller are discussed: 1} the Other deSign fa.~tors, while important for selection of an appropriate controlled axis refer- separated controllers, become critical for inte- ence system; 2) grip design requirements; and grated controllers. The controller location, orientation, and arml'est/wrist support design are ~r~~ial factors in determining the pilot's ability results were substantiated by the flight evalua- to make smooth, uncoupled control inputs with a tion. Pilot comments indicate that the integrated ~inimum of effort and maximum comfort. The ADOCS four-axis Side-stick created high workload and program has supplied a significant number of les- degraded flightpath performance, especially during sons learned in this regard (Fig. 7). Finally, to the multi-axis maneuvering tasks. The three-axis compensate for relative arm/armrest/controller controller which incorporated pitch, roll, and yaw geometry effects, it may be necessary to provide control on the side-stick was the preferred con- asymmetric control sensitivities in certain con- troller configuration because of the decoupllng of trol axes. For example, the NAE program revealed vertical control inputs and improved directional that it was significantly easier for the pilot to control. With all stability and control augmenta- produce an upward vertical force than a downward tion removed, a fully separated controller config- force using the four-axis controller configura- uration was required to perform a decelerating tion; a larger value of control sensitivity in the approaCh to hover and landing; the four-aXis con- downward direction was provided as a result.
figuration resulted in an uncontrollable aircraft Additionally the ADOCS program provided a higher for this task. Pilots indicated that they would control sensitivity in the yaw axis for a clock- have preferred conventional displacement control- wise directional input than it did for a counter- lers for landing the aircraft in this condition.
clockwise torque to compensate for a similar human asymmetry. From the handling qualities investigations conducted in flight by the NAE, it is apparent Handling Qualities Effects of Controller that integrated controllers are certainly feaSible Integration and do not degrade aircraft handling qualities when compared to conventional controllers for A significant handling qualities data base nonprecision tasks such as cruise flight and has been created to substantiate an interactive maneuvering at altitude. However, for precision effect which must be assessed during the advanced flight tasks and high workload situations such as rotorcraft cockpit design process: the interac- encountered in NOE flight, the ADJCS simulation tion between controller integration and the level studies and limited flight validation results of stability and control augmentation. In gen- indicate that, unless high levels of stability and eral, for a given piloting task, increasing levels control augmentation are employed, integrated of controller integration must be accompanied controllers can cause significantly degraded han- by increasing levels of stability and control dling qualities when compared to ,eparated con- augmentation to ensure that performance and han- troller configurations.
dling qualities are not degraded. In the ADOCS ACC/AFCS simulations, it was found that controller A Single, integrated controller may be a configurations which included a separated vertical requirement for a Single-crew combat rotorcraft in controller--with either a three- or two-axis side- order to allow the pilot to perform the other stick--exhibited handling qualities which were supervisory and control functions required during generally improved when compared to the integrated the mission. Accordingly, an experiment was con- four-axis controller configurations for the lower ducted to investigate the use of multi-axis side- levels of stability and control augmentation that stick controllers for fllghtpath control together were investigated (Fig. 8). Separation of the with a keyboard entry task using the free hand.
vertical controller eliminated any inadvertent The results show that keyboard entry tasks inter- coupling of control inputs from the vertical axis fere with the performance of fllghtpath tracking to the pitch or roll axes, and reduced pilot work- and, conversely, that fllghtpath tracking inter- load for multi-axis tasks such as NOE maneuvering. feres with keyboard entry. If a degradation in For the higher levels of stability and control performance occurs, the use of a multi-axis con- augmentation that were investigated, handling troller to free a hand for mission management qualities were less affected by the level of con- tasks may not be appropriate.
troller integration. There was a general prefer- ence for Side-stick rather than pedal control of Summary (Separated versus Integrated) the yaw axis, despite a tendency to couple yaw Flight and simulation studies have shown the inputs into the roll axis, because of the precise feasibility of using properly designed limited- directional control which could be achieved with a displacement, integrated controllers for certain hand controller.
relatively routine flight tasks in two-crew rotor- In a four flight-hour "validation" of the craft with nominal levels Of stability and control ADOCS simulation results for the lower levels of augmentation. However, for the more demanding stability and control augmentation that was con- flight tasks typical of an advanced combat rotor- ducted in the NAE Airborne Simulator, Boeing craft mission, unless high levels of stability and Vertol pilots found that many of the Simulation control augmentation with a high degree of reliability are incorporated, separated controller 4Sinclair, S. R. H., "Flight Experiments with configurations are required for acceptable han- Integrated Side-Arm Controllers in a Variable dling Qualities.
Stability Helicopter," AGARD Flight Hechanics Panel SympOSium on Criteria for Handling Qualities of Hilitary Aircraft, Ft. Worth, Texas, Apr. 1982.
Concluding Remarks 5SjOberg, S. A., Russell, W. R., and Alford, This paper has highlighted several signifi- W. L., "Flight Investigation of a Small Side- cant advantages .)f employing a limi ted- Located Control Stick Used with Electronic Control displacement, integrated side-stick controller in Systems in a Fighter Airplane," NACA RH L56L28A,.
certain areas, including human factors and man- 1957.
machine integration issues such as improved visi- bility, ingress/egress, crashworthiness, and pilot 6Staten, K. E. and Theurer, B., "F-104D Side comfort. However, in order to provide acceptable Stick Control system," 14th Annual SETP Symposium, handlinG qualities with an integrated controller, Beverly Hills, Calif., Sept. 1970.
high levels of stability and control augmentation 7Kemmerling, P., Cronbury, J. G., and with a high degree of reliability are required: Thorburn, D. E., "A Comparison of Pilot Perfor- flight control or propulsion system failures may mance Using a Center Stick vs. Sidearm Control cause this acceptable aircraft to become uncon- Configuration," ASD-TR-70-39, Nov. 1970.
trollable.
8Deardorff, J. C., Freisner, A. L., and Design criteria which include pilot-oriented Albion, N., "Flight Test Development of the Tacti- requirements are crucial in the development of an cal Aircraft Guidance System," AHS Preprint acceptable integrated-controller configuration.
No. 761, Hay 1973.
Details such as controller location and orienta- tion, armrest and wrist support design, and grip 9Hutto, A. J., "Flight Test Report on the design including buttons and switches that are Heavy-Lift Helicopter Flight Control system," AHS important for conventional controllers, are criti- Preprint No. 961, Hay 1975.
cal for integrated, limited-displacement, force- sensing controllers. An equally important set of 10padfield, G. D., Tomlinson, B. N., and design criteria involves the flight-control system Wells, P. H., "Simulation Studies of Helicopter software which is used with the controller: the Agility and Other TopiCS," RAE Technical Hemoran- characteristics of the control input preprocessing dum, July 1978.
and the type of stability and control augmentation system have a dominant effect on the suitability 11Sinclair, H. and Horgan, H., "An Investiga- of a particular controller. As with many other tion of Hulti-Axis Isometric Side-Arm Controllers aspects of advanced rotor craft cockpit design in a Variable Stilbllity Helicopter," NRC, trade-offs, an effective analysis of controller NAE LR-606, Aug. 1981.
issues must be based upon an integrated applica- 12Morgan, J. M., "Some Piloting Experience tion of principles and guidelines employed by with Hultifunction Isometric Side-Arm Controllers several communities including pilots, avionics in a Hellcopter," Helicopter Handling Qualities, engineers, engineering psychologists, control NASA CP-2219, Apr. 1982.
engineers, and human factors specialists.
13 A1ken , E. W., "Simulator Investigati·,ns of Various Side-Stick Controller/Stability and Con- References trol Augmentation Systems for Hellcopter Terrain Fllght," AlAA Paper 82-1522, San Diego, Calif., 1Cooper, G. E. and Harper, Jr., R. P., "The Aug. 1982.
Use of Pilot Rating in the Evaluation of Aircraft Handling Qualities," NASA TN D-5153, Apr. 1969.
14society of Experimental Telt Pilots 1982 Report to the Aerospace Professio~, 26th Annual 2McManus, B. L. and Landis, K. H., "Advanced Proceedings, "Development of the F/A-18 Handling Scout Helicopter (ASH) Fly-by-Wire Flight Control Qualities Using Digital Flight COltrol Technol- System Preliminary Design," ogy," Sept. 1980.
USAAVRADCOM-TR-81-D-9A, Mar. 1981.
15 , G. W. and Smith, R •. :., "FligM Ha11 30iamond, E. D. and Haciolek, J. R., "The Investigation of Fighter Side-Stick Force- Impact on Helicopter Cockpits of Integrated Deflection Characteristics," AFFDL-TR-75-39, May Advanced Flight Controls, AVionics and Optics," 1975.
Proceedings of the 37th Annual AHS Forum, New Orleans, La., May 1981, pp. 252-262.
16Black, G. T. and Hoorhouse, D. J., "Fly1ng 19Aiken, E. W., Hilbert, K. B., Land1s, Qualities Design Requirements ror Sidestick Con- K. H., and Glusman, S. I., "An Investigation Of trollers," AFFDL-TR-79-3126, Oct. 1979. Side-Stick Controller/Stability and Control Aug- mentation System Requirements ror Hel1copter Ter- 17Landis, K. and Aiken, E., "An Assessment or rain Flight Under Reduced Visibility Conditions," Various Side-Stiek Controller/StabiUty and Con- AIAA Paper 84-0235, Jan. 1984.
trol Augmentation Systems for Night Nap-or-the- Earth Fl1 ght ," HflU copter Handll ng QuaU t1 es, NASA 20Horgan, J. H., "A P110ted Experiment in the
CP-2219, Apr. 1982. Use or Hult1-Function Side-Arm Controllers in a
Variable Stability Helicopter," Paper No. 63, 9th 18Landis, K. H., Dunrord, P. J., Aiken, European Rotorcrart Forum, Stresa, Italy, Sept.
E. W., and Hilbert, K. B., "A Piloted Simulator 1983.
Investigation or Side-Stick Controller/Stability and Control Augmentation System Requirements for 21 HcGee , J., "An Experimental Investigation Helicopter Visual Flight Tasks," 39th AHS Forum, or the Interface Between a Right Hand Side Arm Paper A-83-39-59-4000, Hay 1983. Controller Tracking Task and a Lert Hand Switch Operation Task," Sikorsky Engineering Report 510128, Jan. 1982.
Table 1 Force-sensing controller attributes Advantages Disadvantages 2 2-AXIS (LIGHT GRAD. I SATISFACTORY High control input Susceptible to sharp pilot 3 '\~ rA.
bandwidth inputs, inertial rorces, CJ Sim;:>l1ci ty vibratory inputs z
CONVENTlO~~AL :-
ReLabll1ty Lack of control position ~ c( ADEQUATE information Low parts count t-
"
No force-reel system Hanual trimming and control 2-AXIS (HEAVY GRAD.I O -' 8 required transfer more dirricult i: Low-rorce buttons and switches required to 7 prevent inadvertent INADEQUATE inputs 8 RATECMD.
RATE ATT.
DAMPING CMD. ATT. HOLD SCAS CONFIGURATION Fig. 1 Conventional versus two-axis side-stick controllers (Ref. 13).
SATISFACTORY C!)4 ADEQUATE z
~5
0:
b6
-I 0:: (3 + 1) COLLECTIVE INADEQUATE STIFF STICK SMALL·DEFLECTION SMALL.DEFLECTION (PITCH/ROLL) ALL AXES Fig. 3 ADOCS four-axis side-stick controllers (Ref. 18).
RATE RATECMD.
(a) DAMPING ATT.HOLD SCAS CONFIGURATION CMDSYSTEM TASK ATT RATE SATISFACTORY 0 NOE TRAVELING
•
30 - knot SLALOM T 'i1 III ACCEL/DECEL C!) 4 ~ONAL z SATISFACTORY (3+1)CO~ADEQUATE ~ 5 0: :: .
b 6
-I
-- -- -.,-~ -- ------ ----
4-AXIS C!)
z INADEQUATE i= 5 <{ a: ADEQUATE
b 6
-I INADEQUATE RATE RATE CMD.
DAMPING ATT. HOLD (b) 8 SCAS CONFIGURATION Fig. 2 Conventional versus multi-axis side-stick DEFLECTION I A~ __________ \ controllers (Ref. 13). a) NOE traveling; b) hover/bob-up.
STIFF SMALL MEDIUM LARGE
o .2 .4 .6 .8 1.0 1.2 1.4 1.6
LONGITUDINAL AND LATERAL DEFLECTION/FORCE GRADIENT, deg/lb Fig. 4 Effect of side-stick controller deflection/force gradient on pilot ratings (Ref. 17).
: COLLECTIVE - 1_.
COLLECTIVE t <"i'; YAW I PITCH ~ PITCH "1 "--,\ ROLL yAW..... .,--\-ROLL SMALL DEFLECTION SATISFACTORY (ALL AXES)
3 "''o "?_~'
~.
"" _~ ,I, (!)
~
_.Q ~
.@
2: 4 i= 4·AXIS (3 + 1) PEDALS ~ 5
l3 6
..J 0:: 7 SMALL DEFLECTION STIFF (PITCH/ROLL) (ALL AXES) INADEQUATE ACCCMD RATECMD ATTCMD ATTCMD RATE HOLD ATT HOLD ATT HOLD VEL HOLD 2+1+1 (3 -t: 1) COLLECTIVE PITCH/ROLL AFCS CONFIGURATION Fig. 6 Levels of controller integration.
Fig. 5 Effects of control harmony (NOE traveling) .
SATISFACTORY RIGHT HAND CONTROLLER MOUNTING Cl 2: i= <I: a: l- S ..J
-- ------
0: INADEQUATE 4-AXIS II ARMREST (3 + 1) PEDALS V (3 + 1) COLLECTIVE .oi\l 0.5° INBOARD LATERAL TILT 2 + 1 + 1
AND 3° INBOARD TWIST ABOUT ct
• 10
LI ______ ~ ______ ~ _______ J ACCEL FlATE ATT ATT CMD CMD CMD CMD LEFT HAND CONTROLLER MOUNTING RATE ATT ATT VEL HOLD HOLD HOLD HOLD PITCH/ROL.L SCAS CONFIGUFIATION Fig. 8 Effects of controller integration on han- dling qualities (30-knot slalom).
PARALLEL TO FLOOR
-~y
/' SO INBOARD LATERAI_ TILT
AND 4° INBOARD TWIST ABOUT ct
Fig. 7 Side-stick controller orientation (Ref. 19).
1. Report No. NASA TM-86688 2. Government Accession No. 3. Recipient's Catalog No.
USAAVSCOMTM 85-A-1 4. Title and Subtitle 5. Report Date EFFECTS OF SIDE-STICK CONTROLLERS ON ROTORCRAFT April 1985 6. Performing Organization Code HANDLING QUALITIES FOR TERRAIN FLIGHT 7. Author(s) B. Performing Organization Report No.
85141 Edwin W. Aiken 10. Work Unit No.
9. Performing Organization Name and Address Ames Research Center and Aeromechanics Laboratory, 11. Contract or Grant No.
U. S. Army Research and Technology Laboratories (AVSCOM), Ames Research Center. Moffett Field. CA 13. Type of Report and Period Covered 94035 12. Sponsoring Agency Name and Address Technical Memorandum National Aeronautics and Space Administration, 14. Sponsoring Agency Code Washington, D. C. 20546 and U. S. Army Aviation Systems Command, 63120 St. Louis. MO 15. Su p!?lementarl Notes Edwin W. Aiken, Ames Research Center, MS 211-2, P01nt 0 Contact: Moffett Field, CA 94035 (415)694-5362 or FTS 464-5362 16. Abstract rotary-wing feasibility studies and handling- Pertinent fixed- and qualities research programs are reviewed and the effects of certain controller characteristics on handling qualities for specific rotorcraft flight tasks are summarized. In particular, the effects of the controller force-deflection relationship and the number of controlled axes that are integrated in a single controller are examined. Simulation studies conducted as part of the Army's Advanced Digital/Optical Control Systems (ADOCS) program and flight research programs performed by the National Aeronautical Establishment of Canada provide a significant part of the available handling qualities data. These studies demonstrate the feasibility of using a single, properly designed, limited-displacement, multi-axis controller for certain relatively routine flight tasks in a two-crew rotor- craft with nominal levels of stability and control augmentation with a high degree of reliability are incorporated, separated three- or two-axis controller configurations are required for acceptable handling qualities.
17. Key Words (Suggested by Author(s)) lB. Distribution Statement Flying qualities Unlimited Flight control systems Side-stick controllers Subject Category 08 Helicopter 19. Security Oassif. (of this report) 20. Security Classi!. (of this page) 21. No. of Pages 22.
1 Price"
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