WO2015175065A2

WO2015175065A2 - Non-contact control rod monitor (ncm)

Info

Publication number: WO2015175065A2
Application number: PCT/US2015/016486
Authority: WO
Inventors: Joe MAY; Christopher Murdoch; Matthew Mcconnell
Original assignee: Eit Llc.
Priority date: 2014-02-21
Filing date: 2015-02-19
Publication date: 2015-11-19
Also published as: WO2015175065A3

Abstract

A non-contact control rod monitor (NCM) includes non-contact sensors for monitoring the positions of the four control rods of a rotary wing aircraft. In an exemplary embodiment, target indicia are arranged on the control rods to assist in detection of their positions with optical sensors. The detected positions are transmitted to a processor which converts the data to position information for the collective, cyclic, and anti-torque pedal controls of the aircraft.

Description

NON-CONTACT CONTROL ROD MONITOR (NCM)

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to an electronic system which monitors and records data associated with flight and operation of rotary wing aircraft and, more particularly, to obtaining and recording data concerning the positions of the collective, cyclic, and anti-torque controls of the rotary wing aircraft.

Background Description

Small helicopters have a main rotor that typically has four blades, although helicopters generally may have as few as two or up to five blades. The helicopters furthermore have a tail rotor which provides a thrust counter to the counter rotation torque induced by the main rotor in order to maintain stable flight. The control of the main rotor by the pilot is achieved by a series of control rods that tilt and/or raise and lower a rotor swash plate which controls the angle of attack of the rotor blades. Similarly, the control of the tail rotor by the pilot is achieved by control rods that vary the pitch of the tail rotor blades. A helicopter has three basic separate control inputs and, in addition, a throttle control. The main controls are the collective lever, the cyclic stick, and the anti-torque pedals. The collective and cyclic controls are mechanically interlinked so that push rods, in combination, provide both collective and cyclic control of the main rotor.

As shown in Figure 1, the collective control 10, or collective lever, is normally located adjacent (e.g., on the left side of) the pilot's seat 1 1. The collective control 10 is raised (arrow 12) and lowered (arrow 13) to change the collective pitch angle of all the main rotor blades at the same time independent of their position about the rotor swash plate. This results in increases or decreases in total lift. In level flight, this would cause an ascent (i.e., climb) or descent. With the helicopter pitched forward, an increase in total lift would produce an acceleration together with a given amount of ascent. As shown in Figure 2, the cyclic control 20 is ordinarily located between the pilot's legs and may be moved forward or aft (arrow 21), to control forward or backward flight, and moved left or right (arrow 22), to control flight to the left and to the right. The cyclic control is also commonly called the cyclic stick. It is called the cyclic control because it changes the pitch of the main rotor blades depending on their position as they rotate around the hub. The change in the cyclic pitch has the effect of changing the angle of attack and thus the lift generated by each individual blade as it moves around the rotor swash plate. This in turn causes the blades to change angle of attack up or down in sequence, depending on the tilt of the rotor swash plate. If the rotor swash plate tilts forward, a thrust vector is produced in the forward direction. If the pilot pushes the cyclic stick to the right, the rotor swash plate tilts to the right and produces thrust in that direction, causing the helicopter to move sideways in a hover or to roll into a right turn during forward flight, much as in a fixed wing aircraft. Similarly, direction of flight to the rear and to the left is controlled by moving the cyclic stick aft or to the left, respectively.

As shown in Figure 3, the anti-torque pedals 30 and 32 are on the floor of the cabin and operated by the pilot's feet to control the yaw (i.e., heading) of the helicopter. The anti-torque pedals are located in the same position as the rudder pedals in a fixed wing aircraft and serve the same purpose. Pressing the left anti-torque pedal 30 forward or aft (arrow 31) causes the right pedal 32 to move in the opposite direction (i.e., aft or forward, along arrow 33), and vice versa. This changes the pitch of the tail rotor blades, increasing or reducing the thrust produced by the tail rotor causing the nose of the helicopter to yaw in the direction of the applied pedal.

A number of flight/operation parameters may be monitored in helicopters using appropriate and existing transducers. For example, rotor RPM uses a rotating permanent magnet and a Hall Effect device to detect revolutions of the rotor. Engine RPM uses a switch closure with each rotation of the engine cam. Outside air temperature (OAT) uses a conventional thermistor temperature probe. However, measuring collective, cyclic, and anti-torque pedal positions present a difficult problem. In the past, these positions have been measured by systems physically connected to the controls. These included string pots (spring motor driven

potentiometers), linear variable differential transformers (LVDTs), and other devices that require physical connections along the mechanical paths leading from the controls/sticks to the rotors. These devices are bulky, subject to failure, and can cause jamming failures of the control rods. SUMMARY

It is therefore an object of the present invention to provide an improvement in obtaining and recording flight/operations data which allows positions of flight controls to be accurately determined and recorded without resorting to physical attachments to the mechanical linkages that connect the flight controls and the aircraft's rotor(s).

By accurate measurement and recording of data concerning the positions of the flight controls, exemplary embodiments also provide collection of data representative of the pitch of the main rotor blades, the total lift produced by the collective changes in pitch angle of all the main rotor blades, and the pitch of the tail rotor blades.

According to the invention, there is provided a non-contact system which allows the above-mentioned data to be ascertained and/or collected via accurate measurement of the positions of the control rods. In an exemplary embodiment, unique target indicia (e.g., bar codes or other markings) are applied to each of the control rods. One or more small cameras, e.g., microchip cameras, are arranged in proximity to the control rods, for instance one for each control rod, and with a field of view of the target indicia. The cameras detect the corresponding target indicia and their vertical movement and send resulting data to a processor and

subsequently a storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects, and advantages will be better understood from the following detailed description of an exemplary embodiment of the invention with reference to the drawings, in which:

Figure 1 is an illustration of the collective control in the cabin of a helicopter;

Figure 2 is an illustration of the cyclic control in the cabin of a helicopter;

Figure 3 is an illustration of the anti-torque pedals in the cockpit of a helicopter;

Figures 4A and 4B are illustrations of the control rods passing through the cabin to the swash plate; and

Figure 5 is a schematic diagram of the control rods and a non-contact control rod monitor

(NCM) according to the invention. DETAILED DESCRIPTION

Referring once again to the drawings, Figures 4A and 4B are views into a helicopter showing the several control rods, labeled control rods A, B, C, and D, which link the collective control, the cyclic control, and the anti-toque pedals to the mechanisms that control the pitches of the main rotor and the tail rotor, respectively. In Figure 4B, lower portions of the control rods extending downward within the helicopter are obscured from view by other mechanical components. All three controls 10, 20, and 30/32 (see Figures 1-3) are connected via various complex mechanical linkages (not shown) to one or more of the four control rods A, B, C, and D. Rods B, C, and D are connected to the stationary swash plate 41 on the rotor mast and, ultimately, their vertical motion controls main rotor blade pitch. The rotating swash plate is indicated by reference numeral 42. The mechanical motions of each of the rods A, B, C, and D are independent of one another. As may be appreciated from the illustrations of Figures 4A and 4B, their vertical motions are not in a single plane but, rather, have motions in three dimensions throughout their travels during helicopter operation. While the movement is predominantly vertical, the out of plane motion of each of the control rods makes accurate detection of their positions at any point in time difficult.

A solution according to the invention is a unique, non-contacting measurement system or non-contact control rod monitor (NCM) 50, which is schematically illustrated in Figure 5. An NCM 50 measures only the linear motions, and in particular vertical movements 1 , 52, 53, and 54, of control rods A, B, C, and D, respectively, and translates these motions into corresponding control (cyclic, collective, and anti-torque pedal) positions and movements. As shown in Figure 5, unique bar codes 55a, 55b, 55c, and 55d are applied to each of the control rods A, B, C, and D, respectively. The bar codes are target indicia which, once placed, serve as small points/objects the movements of which are representative of the movements of the entire control rods, which are much larger. Other target indicia besides bar codes may also be used, as will be apparent to one of ordinary skill in the art. In an exemplary embodiment, non-contact sensors 56a, 56b, 56c, and 56d are optical sensors such as microchip cameras, one for each control rod in the illustrated embodiment, are located in proximity to the control rods A, B, C, and D and have a field of view of the bar codes 55a, 55b, 55c, and 55d. It is only necessary that that each optical sensor has a field of view of the bar code of one control rod (e.g., optical sensor 56a has a field of view of bar code 55a). It is preferable that each bar code 55a, 55b, 55c, and 55d is distinguished from the others such that in the case more than one bar code is visible to any one optical sensor, the one bar code for the control rod for which that one camera has been provided is readily and properly identified.

In an exemplary embodiment, the non-contact sensors 56a, 56b, 56c, and 56d are microchip cameras having sensitivity to the visible portion of the electromagnetic spectrum. One exemplary commercially available camera for use as non-contact sensors 56a, 56b, 56c, and 56d is OVM7690-RYAA by Omnivision Technologies, Inc. Alternative embodiments may have non- contact sensors which are optical sensors which are able to detect electromagnetic radiation in one or more of the RF, UV, infrared, and visible spectra. It is expected that sufficient light (i.e., electromagnetic radiation, generally but not necessarily the visible spectrum of the

electromagnetic spectrum) will be incident upon the bar codes to permit their detection by the optical sensors. However, if needed, one or more light emitting devices (e.g., light emitting diodes, LEDs, not shown) may be included in a NCM to provide sufficient illumination of the bar codes for their detection by the optical sensors. In Figure 5, the non-contact sensors 56a, 56b, 56c, and 56d are arranged to the side of the control rods (e.g, in a radial direction from the rods). In an alternative embodiment, one or more of the non-contact sensors (e.g., all of the sensors) may be arranged at ends of control rods and detect displacements of the rod ends. For example, in some embodiments, the non-contact sensors may be LIDAR sensors which include or are paired with a light emitting portion (i.e., a laser) and a light receiving portion for capturing the reflected light. In still a further variation, in some embodiments one or more of the non-contact sensors (e.g., all of the sensors) may be sonic sensors which include or are paired with sonic transmitters, such as ultrasonic ranging devices.

Furthermore, some embodiments may monitor the controls rods where they pass through an underbelly of the aircraft. In this case, the lateral motion (instead of the vertical motion) of the control rods is monitored by the NCM. Generally, the motion of a control rod which is monitored is that motion which is substantially parallel with the primary axis of the rod. This motion is referred to herein as "linear motion" of a control rod, and may be, for example, vertical motion (if the control rods are monitored where they are vertical as in Figures 4A and 4B), or lateral motion (if the control rods are monitored where they pass through an underbelly of the aircraft). The signal outputs of the non-contact sensors 56a, 56b, 56c, and 56d are transmitted to a processor 57. These signal outputs contain information concerning the detected positions of the bar codes 55a, 55b, 55c, and 55d of the respective control rods A, B, C, and D over time. In other words, the non-contact sensors detect the vertical motion(s) of the control rods per detection of the bar code positions over time. One exemplary commercially available processor is

PIC32MX534F064H-I/PT from Microchip Technology, Inc.

Because the control rods do not all move in a simple, single axis linear movement (that is, the control rods have three dimensional (3D) movement) the processor 57 is configured to include a corrective procedure to eliminate detected non-vertical motion (i.e., isolate the vertical component of rod movement). The corrective procedure will vary among different aircraft but requires only a single configuration at the time of installing a NCM system.

In an alternative embodiment, a single optical sensor may be provided which has a field of view of the bar codes of all four control rods A, B, C, and D. In this case, the processor 57 is configured to perform an object-recognition procedure and identity each of the respective positions and vertical displacements over time of the four bar codes 55a, 55b, 55c, and 55d and thus the positions and vertical displacements over time of control rods A, B, C, and D.

It is desirable to consider the full range of motion for each control 10, 20, and 30/32 (Figures 1 -3). For the collective control position, the limits are full down and full up. For the cyclic control position, the limits are full left to full right and full fore to full aft. For the anti- torque pedal position, the limits are full left to full right.

Anti-torque pedal position is relatively easily derived from the vertical position of control rod A. Full left pedal corresponds to full down position of control rod A, and full right pedal corresponds to full up position of control rod A. This motion is single dimension. Neutral pedal position corresponds to the midrange position of control rod A. Cyclic and collective positions are determined from control rods B, C, and D and are more difficult to derive because control rods B, C, and D have independent vertical movements which are partially three dimensional. As previously discussed, elimination of the non-vertical motion of the three control rods B, C, and D is performed by the processor 57.

Once the linear motions of the control rods B, C, and D are resolved, the equations below are used to calculate each individual control rod position for collective and cyclic controls. ( B + D

Cyclic_{Fi A} = k C

Cyclic _L, _R = k₂ {B - D)

Collective = k₃ k₄C + k₅

2

where kj-ks are empirically derived constants which depend on a given helicopter's particular system mechanics, B is the linear displacement of control rod B in inches, C is the linear displacement of control rod C in inches, and D is the linear displacement of control rod D in inches. Alternative units of measurement (e.g., centimeters) are of course also usable. Cyclic "F/A" refers to "forward-aft" and cyclic "L/R" refers to "left-right". Calculation of the positions of the controls 10, 20, and 30/32 are repeatedly determined at regular time intervals, thereby providing data on their movement with respect to time.

In an exemplary embodiment, control position values are continuously stored in nonvolatile memory 58 for future retrieval and display. If desired, the control rod position information may be transmitted directly to a display device 59 so as to be available to the pilot of the helicopter. The resolution of the measurements is generally limited by the resolution of the optical sensors. For the example discussed above using OVM7690-RYAA camera chips, the theoretical resolution is approximately 0.005 inches and could be made even higher. However, other considerations, such as geometry, vibration, and cost, reduce the resolution to between 1% to 5%.

An NCM has several major advantages over traditional methods. First, there is no physical contact or moving parts which eliminates the possibility of jamming, increases system reliability because there are no components subject to physical wear, and does not impose any mechanical load on the controls. Second, the NCM requires much less physical space as compared to prior art systems. Third, the NCM requires very low power and has the further advantage of low cost of manufacture. Advantageously, a NCM 50 may be installed in new helicopters at the time of manufacture or retrofitted to helicopters already in use.

While the invention has been described mostly in terms of a single exemplary embodiment, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims.

Claims

CLAIMS Having thus described our invention, what we claim as new and desire to secure by Letters Patent is as follows:

1. A non-contact control rod monitor system for a rotary wing aircraft, comprising:

one or more non-contact sensors configured to detect linear motion of one or more control rods of the rotary wing aircraft, the one or more non-contact sensors having no physical contact with any of the one or more control rods,; and

a processor configured to determine positions of a collective control, cyclic control, and anti-torque pedal control of the rotary wing aircraft based on data received from the one or more non-contact sensors.

2. The non-contact control rod monitor system of claim 1, further comprising a non-volatile memory in which the processor stores data concerning the positions of the collective control, cyclic control, and anti-torque pedal control over time.

3. The non-contact control rod monitor system of claim 1 , further comprising a display device for displaying, as a function of time, the positions of the collective control, cyclic control, and anti-torque pedal control determined by the processor.

4. The non-contact control rod monitor system of claim 1 , wherein the one or more non-contact sensors include a separate sensor for each respective rod of the one or more control rods.

5. The non-contact control rod monitor system of claim 1 , wherein the one or more non-contact sensors include four sensors, one each for the one or more control rods which include a first rod for the anti-torque pedal control and second, third, and fourth rods for the cyclic and collective controls together.

6. The non-contact control rod monitor system of claim 1, wherein the one or more non-contact sensors are optical sensors that detect electromagnetic radiation in one or more of the RF, UV, infrared, and visible spectra.

7. The non-contact control rod monitor system of claim 6, wherein the one or more optical sensors detect electromagnetic radiation in the visible spectrum.

8. The non-contact control rod monitor system of claim 6, wherein the one or more control rods each have a target indicium, the one or more non-contact sensors being configured to monitor the target indicium to detect the linear motion of a respective control rod of the one or more control rods.

9. A method for monitoring control rods in a rotary wing aircraft, comprising steps of:

detecting with one or more non-contact sensors the linear motion of one or more control rods of the rotary wing aircraft, the one or more non-contact sensors having no physical contact with any of the one or more control rods; and

determining with a processor positions of a collective control, cyclic control, and anti- torque control of the rotary wing aircraft based on data received from the one or more non- contact sensors of the detecting step.

10. The method of claim 9, further comprising a step of storing in a non-volatile memory data concerning the positions of the collective control, cyclic control, and anti-torque pedal control over time as determined by the processor.

1 1. The method of claim 9, further comprising a step of displaying with a display device the positions of the collective control, cyclic control, and anti-torque pedal control, as a function of time, determined by the processor.

12. The method of claim 9, wherein the one or more non-contact sensors include a separate sensor for detecting motion of each respective rod of the one or more control rods in the detecting step.

13. The method of claim 9, wherein the one or more non-contact sensors include four sensors, one each for the one or more control rods which include a first rod for the anti-torque pedal control and second, third, and fourth rods for the cyclic and collective controls together.

14. The method of claim 9, wherein the one or more non-contact sensors are optical sensors that detect electromagnetic radiation in one or more of the RF, UV, infrared, and visible spectra in the detecting step.

15. The method of claim 14, wherein the one or more optical sensors detect electromagnetic radiation in the visible spectrum in the detecting step.

16. The method of claim 14, wherein the one or more control rods each have a target indicium, the detecting step including monitoring the target indicium to detect the linear motion of a respective control rod of the one or more control rods.