The present invention generally relates to devices that are spring biased to a null position and, more particularly, to a cantilever spring return to null assembly that provides controllable dual spring rates.
Human-machine interfaces that are used to translate human movements to machine movements are used in myriad industries. For example, some aircraft flight control systems include a human-machine interface in the form of one or more hand or foot user interfaces. The user interfaces are typically configured to be disposed in a null position and the flight control system, in response to input forces supplied to the user interface from the pilot that move the user interface from its null position, controls the movements of various aircraft flight control surfaces. No matter the particular end-use system, the human-machine interface preferably includes some type of haptic feedback mechanism back through the interface to the interface operator. These haptic feedback mechanisms may be implemented using active devices, passive devices, or both.
Passive devices are generally implemented using one or more springs that not only supply haptic feedback, but also supply forces that urge the user interface, when moved from the null position, back toward the null position. Moreover, in some implementations, it may be desired to supply different force magnitudes to the user interface depending on the direction in which the user interface is being moved. For example, it may be desirable to supply a greater force magnitude when the user interface is being moved in one direction than when it is being moved in another direction. In the context of the above-mentioned aircraft user interfaces, it may be desirable to supply a greater force magnitude when the user interface is being moved in an inboard direction than when it is being moved in an outboard direction.
In some instances, one or more cantilever springs may be used to implement passive, return-to-null devices. In such instances, the cantilever spring may be coupled at one end to a rotating shaft. One drawback with using this type of spring is that cantilever springs, when rotated from a shaft with a fixed pivot point, are inherently non-linear. This is due, at least in part, to the spring length varying as the angular displacement of the shaft varies from its null position. More specifically, the spring rate of the cantilever springs decreases as the angular displacement from the null position increases. Another drawback with this type of spring is that plural cantilever springs may be needed to exhibit the desired variations in force magnitudes for different user interface movement directions.
Hence, there is a need for a passive return-to-null device, such as a cantilever spring, that exhibits little, if any, spring rate non-linearity its fixed pivot point is rotated from a null position, and/or that may be configured to exhibit variations in force magnitudes for different user interface movement directions. The present invention addresses at least these needs.
In one embodiment, and by way of example only, a return-to-null assembly includes a shaft, a cantilever spring, and a pivot assembly. The shaft is configured to rotate from a null position to a plurality of control positions. The cantilever spring includes a fixed end, a free end, and opposing first and second sides. The cantilever spring fixed end is coupled to the shaft and is configured to supply a torque to the shaft, at least when the shaft is rotated from the null position, that urges the shaft toward the null position. The pivot assembly engages the cantilever spring at a location that is closer to the cantilever spring free end than the cantilever spring fixed end, and includes a first contact, a second contact, a first load spring, and a second load spring. The first contact engages the cantilever spring first side, the second contact engages the cantilever spring second side, the first load spring supplies a first force to the first contact that urges the first contact into engagement with the cantilever spring first side, and the second load spring supplies a second force to the second contact that urges the second contact into engagement with the cantilever spring second side.
In another exemplary embodiment, a spring-return-to-null assembly includes a cantilever spring and a pivot assembly. The cantilever spring includes a fixed end, a free end, and opposing first and second sides. The cantilever spring fixed end is adapted to be coupled to a shaft and is configured to supply a torque to the shaft at least when a torque is supplied to the cantilever spring fixed end. The pivot assembly engages the cantilever spring at a location that is closer to the cantilever spring free end than the cantilever spring fixed end, and includes a first contact, a second contact, a first load spring, and a second load spring. The first contact engages the cantilever spring first side, the second contact engages the cantilever spring second side, the first load spring supplies a force to the first contact that urges the first contact into engagement with the cantilever spring first side, and the second load spring supplies a force to the second contact that urges the second contact into engagement with the cantilever spring second side.
In yet another exemplary embodiment, a spring pivot assembly includes a frame and a pair of spring-loaded roller assemblies. The pair of spring-loaded roller assemblies are movably disposed within the frame, and each includes a bracket, a roller shaft, a roller, a plurality of bearings, and a load spring. The bracket is movably disposed within the frame, the roller shaft is coupled to the bracket, and the roller surrounds at least a portion of the roller shaft. Each bearing includes an inner race and an outer race, and each of the inner races is mounted on the roller shaft, and the roller is mounted on each of the outer races. The load spring is disposed between the frame and the bracket.
In still exemplary embodiment, a hand controller assembly includes a user interface and a cantilever spring. The user interface is configured to rotate from a null position to a plurality of control positions. The cantilever spring assembly is coupled to the user interface and is configured to supply a force to the user interface, at least when the user interface is rotated from the null position, that urges the user interface toward the null position. The cantilever spring assembly comprises a plurality of individual cantilever springs stacked in parallel. Each individual cantilever spring is in sliding contact with at least one other individual cantilever spring. Each individual cantilever spring includes a fixed end and a free end, and the fixed end of each individual cantilever spring is coupled to the user interface.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
An exemplary embodiment of a portion of a human-machine interface assembly 100 is depicted in
The gimbal assembly 104 is mounted within a housing assembly 110 and is configured to allow the user interface 102 to be moved from a null position 109, which is the position depicted in
No matter its specific end use, the gimbal assembly 104 includes, among various other components, a first shaft (or shafts) 122 and a second shaft 124 that are each rotationally mounted in the housing assembly 110. The first shaft(s) 122 is (are) rotationally mounted along the first rotational axis 111, and the second shaft 124 is rotationally mounted along the second rotational axis 113. The gimbal assembly 104, via the first and second shafts 122, 124, and its various other components, allows the user interface 102 to be movable about the first rotational axis 111 in a port direction 112 and a starboard direction 114, and about the second axis 113 in a forward direction 116 and an aft direction 118. It will additionally be appreciated that the gimbal assembly 104 is configured to allow the user interface 102 to be simultaneously rotated about the first and second rotational axes 111, 113 to move the user interface 102 in a combined forward-port direction, a combined forward-starboard direction, a combined aft-port direction, or a combined aft-starboard direction, and back to or through the null position 109. A detailed description of the gimbal assembly 104 is not needed to fully enable or describe the invention, and will thus not be provided.
Before proceeding further, it is noted that the human-machine interface assembly 100 may be implemented as either an active system or a passive system. If implemented as an active system, the assembly 100 may further include one or more non-illustrated motors to actively supply force feedback to the user interface 102. If implemented as a passive system, it will be appreciated that the assembly 100 would not include any motors. In either instance, however, the assembly 100 would preferably include the spring return-to-null assemblies 106. In the case of the active system, the motors would be the primary means of supplying feedback force to the user interfaces 102, with the spring return-to-null assemblies 106 being the back-up feedback force source. It will nonetheless be appreciated that in the remainder of the description, the assembly 100 is described as if it were implemented as a fully passive system.
The spring return-to-null assemblies 106, which in the depicted embodiment each include a first spring return-to-null assembly 106-1 and a second spring return-to-null assembly 106-2, are mounted on the housing assembly 110 and are used to supply force feedback to the user interface 102 when the user interface 102 is moved from the null position 109. The first spring return-to-null assembly 106-1 is configured to supply force feedback to the user interface 102 in opposition to user interface displacements having a vector component in either the forward or backward direction 116, 118. The second spring return-to-null assembly 106-2 is configured to supply force feedback to the user interface 102 in opposition to user interface displacements having a vector component in either the port or starboard direction 112, 114. The spring return-to-null assemblies 106 are also configured such that the force feedback each supplies is adjustable, depending on the direction in which the user interface 102 is moved. That is, the spring return-to-null assemblies 106 may be adjusted such that the feedback force it supplies to the user interface 102 differs, depending on the direction in which the user interface is moved. For example, when the user interface 102 is moved in the port direction 112, the first spring return to null assembly 106-1 may supply feedback force magnitudes that are unequal to the feedback force magnitudes it supplies (for a given displacement magnitude) when the user interface 102 is moved in the starboard direction 114. Similarly, when the user interface 102 is moved in the forward direction 116, the second spring return to null assembly 106-1 may supply feedback force magnitudes that are unequal to the feedback force magnitudes it supplies (for a given displacement magnitude) when the user interface 102 is moved in the aft direction 118. A particular preferred embodiment of one the spring return-to-null assemblies 106 is depicted in
The spring return-to-null assemblies 106 each include a spring 202, a clamp 204, and a pivot assembly 206. The spring 202 is implemented as a cantilever spring, and thus includes a fixed end 208 and a free end 210, and additionally includes a first side 212 and an opposing second side 214. The cantilever spring fixed end 208 is coupled to the shaft 122 (124) via the clamp 204 and thus rotates whenever the shaft 122 (124) is rotated. The cantilever spring free end 210 is disposed between first and second contacts 216, 218 in the pivot assembly 206, which is described in greater detail further below. As will also be described in greater detail below, the first and second contacts 216, 218 are configured such that the cantilever spring 202 is free to move axially between the first and second contacts 216, 218 whenever the cantilever spring free end 208 is rotated. It will thus be appreciated that the cantilever spring 202, via the free end 210, supplies a torque to the shaft 122 (124), whenever the user interface 102, and thus the shaft 122 (124), is rotated out of the null position 109, that urges the shaft 122 (124) toward the null position.
Briefly returning to
The cantilever spring 202 may be variously implemented; however, and with reference now to
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The pivot assembly first and second contacts 216, 218, in addition to being spring loaded toward the cantilever spring 202, are also configured to rotate relative to the cantilever spring 202. The first and second load springs 220, 222 preferably supply equivalent (or at least substantially equivalent) force magnitudes to the respective contacts 216, 218. Moreover, the first and second forces are preferably of magnitudes sufficient to allow the cantilever spring 202 to move freely, while maintaining contact with the first and second contacts 216, 218 throughout the range of operation. The pivot assembly 206 may be disposed such that the cantilever spring 202 exhibits equal (or at least substantially equal) spring rates no matter the direction (e.g., clockwise or counterclockwise) in which the shaft 122 (124) is rotated, or it may be mounted such that the cantilever spring 202 exhibits dual spring rates, depending on the direction in which the shaft 122 (124) is rotated. It will be appreciated that the pivot assembly 206 may be variously configured and implemented. However, a particular preferred implementation of the pivot assembly 206 is depicted in
Referring first to
With continued reference to
The roller shafts 528 are each coupled to one of the brackets 526, via suitable openings in the bracket guides 536, and the rollers 532 are each rotationally mounted on one of the roller shafts 528 via the plurality of bearings 534. In particular, as is shown most clearly in
Returning once again to
Referring now to
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With reference now to
Operation of the spring return-to-null assembly 106 when the pivot assembly 206 is mounted as depicted in
The spring return-to-null assembly 106, in addition to being configurable to exhibit either equal or dual spring rates, also maintains smooth motion, by virtue of the continuous engagement between the first and second contacts 216, 218 and the cantilever spring 202, throughout the full rotational range(s) of the shaft(s) 122 (124). As a result, a crossover “click” is not exhibited when the shaft 122 (124) is rotated through the null position. The spring return-to-null assembly 106 also does not exhibit the non-linear effect that is typically associated with cantilever springs with a fixed pivot point. Moreover, when strain gages are included on the compression spring(s) 202, position and health monitoring functions can be implemented.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.