Patent Description:
In some embodiments, vibration and noise control systems utilize force generators (FGs) to actively eliminate or reduce the effect and impact of unwanted vibratory disturbances on a system. Vibration disturbances can wreak havoc on systems by reducing the life expectancy of the systems, structurally damaging the systems, and/or reducing the overall system performance. These impacts create potentially unsafe conditions when the systems are used.

Implementing active vibration and noise control (e.g., via FGs) is increasing and often preferred over implementing passive vibration control (e.g., via passive dampers or absorbers), in some aspects, to reduce the overall system weight. Some active vibration control systems (AVCS) are also an increased safety risk for some systems, as some AVCS are safety-critical systems. Safety-critical systems are those systems whose failure could result in loss of life, property, and/or damage to the environment. AVCS become safety-critical, for example, when the vibrations being cancelled have the ability to critically impact operations or by putting life or property at risk should a failure of the AVCS, or portions thereof, occur.

One non-limiting example of an AVCS that is a safety-critical system is in the aviation field, where active vibration control is used to mitigate vibrations having damaging effects on different systems (e.g., rotor(s), propeller(s), stator(s), engine(s), gearbox(es), etc.) and/or avionics. Other negative impacts from vibration in the aviation field include damage inflicted to human occupants and/or cargo. Other exemplary systems that may be negatively impacted by exposure to vibration forces include industrial equipment and manufacturing structures, buildings, vehicles (e.g., automobiles, avionics, aerospace), transportation, maritime structures, and/or any other structure or system subjected to an unwanted or potentially damaging vibratory input. The negative impacts can vary per situation.

One problem with current AVCSs is the inability to adequately detect system problems (e.g., failures or faults) and actively and/or autonomously adjust appropriately to handle failure modes for safety-critical systems. For example, one safety-critical system in the aerospace field impacts aerospace certification due to loss of function and/or an erroneous function. In this example, loss of function refers to an AVCS failure where it stops providing vibration control. In this same example, erroneous function refers to failure modes where the force output of the FGs is not a desired output or the FG erroneously induces vibration that is not wanted. Other examples include hydroelectric turbines, fast spinning industrial equipment, propulsion systems, and/or any other system or structure where the failure of a vibration control system has a damaging or catastrophic effect. Further problems with current AVCS include a lack of redundancy while minimizing weight and space penalties on the systems being controlled.

<CIT> discloses a method and system is disclosed for controlling problematic vibrations in an aircraft.

The method and system have the ability to cancel problematic rotary wing helicopter vibrations using independent active force generator power and with distributed communications therebetween.

German Patent Publication No. <CIT> discloses an arrangement having a control device connectable with a body of an aircraft i.e. helicopter. The interface is arranged in a connecting path system from the control device to actuators (<NUM>) and has a set of interface connecting unit. A rotor blade (<NUM>) is provided with two groups of actuators (31a-31c, 32a-32c). The control device is connected with the groups of actuators by the interface connecting units, respectively. The control device and the interface are designed to supply the groups of actuators with energy via the interface and via two control units. Independent claims are also included for the following: (<NUM>) a method for controlling a set of actuators arranged at a rotor blade (<NUM>) a computer program comprising a set of instructions for performing a method for controlling a set of actuators arranged at a rotor blade (<NUM>) a computer-readable medium comprising a set of instructions for performing a method for controlling a set of actuators arranged at a rotor blade.

<CIT> discloses a rotary wing aircraft including a vehicle vibration control system. The vehicle vibration control system includes a rotary wing aircraft member sensor for outputting rotary wing aircraft member data correlating to the relative rotation of the rotating rotary wing hub member rotating relative to the nonrotating body. The system includes at least a first nonrotating body vibration sensor. The at least first nonrotating body vibration sensor outputting at least first nonrotating body vibration sensor data correlating to vibrations. The system includes at least a circular force generator, the at least circular force generator is fixedly coupled with the nonrotating body. The system also includes a distributed force generation data communications network link.

<CIT> discloses a multiple redundant computer system includes three primary processor modules (PPM) and three redundant processor modules (RPM) operating synchronously. Each primary and redundant processor module receives input data from associated primary and redundant input modules respectively, executes control program and transfers output data to an output module. The output module produces a system output as the result of <NUM>-out-of-<NUM> voting among output data generated by PPMs. In response to PPMs hard failures, the output module still produces the system output as the result of <NUM>-out-of-<NUM> voting among output data generated by any combination of the PPM and the RPM. The output module also compares output data that it has received from each pair of the associated PPM and RPM for detecting a disparity between said output data due to the occurrence of transient faults.

<CIT> discloses a real-time multi-tasking digital control system with rapid recovery capability. The control system includes a plurality of computing units comprising a plurality of redundant processing units, with each of the processing units configured to generate one or more redundant control commands and communicate those commands to an actuator. The processing units are externally positioned from the actuators. The control system also includes a plurality of actuator control units each in operative communication with the computing units and externally positioned from the actuators. The actuator control units are configured to initiate a rapid recovery if data errors are detected in one or more of the processing units.

Accordingly, there is a need for lighter weight AVCS and methods that are redundant, safety-critical, and configured to implement autonomous vibration control.

According to the present invention, there is provided an active vibration control system, AVCS, in accordance with claim <NUM>.

Figures (also "<FIG> illustrate various views and/or features associated with AVCS and related methods for controlling vibration of and/or operability to reduce noise and vibration within various structures, vehicles, aircraft, helicopters, machinery, equipment, buildings, bridges, etc., which experience vibration during operation. In some aspects, safety-critical AVCS or "SCAVCS" and methods are provided herein, for implementing redundant, autonomous vibration control.

As used herein, the terms "microprocessor" and "controller" each refer to physical devices including hardware in combination with software and/or firmware. A controller includes at least one hardware processor, at least one memory element, at least one input interface, and at least one output interface for sending and receiving signals (e.g., from sensors or inputs) between components of a system, such as sensors and rotary actuators (e.g., force generators (FGs), such as circular force generators (CFGs)). A microprocessor is configured to execute instructions stored within a memory element thereof for implementing vibration control by instructing one or more FGs (e.g., via force commands or force command control signals).

Referring now to <FIG>, a first embodiment of an Active Vibration Control System (AVCS), generally designated <NUM>, is illustrated. System <NUM> is configured to actively detect vibrations occurring on, within, and/or to a structure and implement vibration control, in part, upon generation of vibration cancelling forces via one or more rotary actuators or FGs. Various structures and/or systems are subjected to vibrating forces, and may therefore benefit from use or incorporation of system <NUM>, for example, structures and/or systems include, and are not limited to, industrial equipment structures and/or systems; industrial machinery structures and/or systems; building structures and/or systems; fuselage structure(s); engine structures and/or systems; jet engine aircraft structures and/or systems; turboprop aircraft structures and/or systems; tiltrotor aircraft structures and/or systems; helicopter structures and/or systems; ship structures and/or systems; hovercraft structures and/or systems; semi-truck structures and/or systems; train structures and/or systems; and/or any other vehicle structures and/or systems.

System <NUM> includes a plurality of FGs, designated FG<NUM>, FG<NUM>, FGn (where "n" is a whole number integer > <NUM>) digitally linked between a plurality of communication lines. FG<NUM> to FGn are each configured to generate and/or impart vibration(s) to a structure, or portions thereof, for countering and/or cancelling the vibration force(s) that negatively affect the structure. System <NUM> includes a plurality of digital communications lines for communicating information to, from, and/or between FGs (e.g., FG<NUM> to FGn), for example, at least a first digital bus line <NUM> and a second digital bus line <NUM>. In one embodiment, first and second bus lines <NUM> and <NUM>, respectively, are digitally linked to each other and configured to communicate via a digital communication line or digital data link <NUM> through their respective microprocessor. In an alternate embodiment, first and second bus lines <NUM> and <NUM>, respectively, are not configured to digitally communicate through their respective microprocessor 110B as in FGn. That is, microprocessors 110B of FGn are not linked and/or digitally connected to each other. First and second bus lines <NUM> and <NUM>, respectively, are also digitally linked to each FG<NUM> to FGn, for example, via microprocessors 110A disposed within each FG<NUM> to FGn.

First and second digital bus lines <NUM> and <NUM>, respectively, include digital communication lines, channels, and/or links for providing two-way communications between components of system <NUM> via a communications protocol such as CAN A, CAN B, and/or ARINC429. Digital bus lines <NUM> and <NUM> are configured to communicate the same (i.e., identical and/or redundant) information to each FG (e.g., FG<NUM> to FGn), thereby allowing for flexible data sharing and safety-critical, autonomous vibration control.

Each FG (e.g., FG<NUM> to FGn) may include a rotary actuator, not limited to a CFG. CFGs are configured to generate circular forces upon co-rotation of imbalance masses (not shown) disposed therein. In an exemplary embodiment, FG<NUM> to FGn may each include a CFG configured to generate vibratory forces at one or more frequencies, as needed, to cancel the vibration associated with, for example, a main rotor of a rotary wing aircraft. System <NUM> may be implemented within any vibrating structure or system, not limited to the field of aircraft or avionics.

Each FG includes one or more mechanical and electrical components disposed within a housing or enclosure thereof. For example, FG<NUM> to FGn may each include at least one accelerometer <NUM>, a plurality of microprocessors 110A, at least one motor <NUM>, and at least one pulse width modulator (PWM) <NUM> circuit or component. In some embodiments, FG<NUM> to FGn can each receive electrical power via at least one power (PWR) input module <NUM>. Electrical power may be transmitted to FG<NUM> to FGn via PWR module <NUM> or across the digital bus lines <NUM> and <NUM>. Only one, or in some aspects, multiple PWR modules <NUM> (e.g., <FIG>) are contemplated.

In some embodiments, electronic components of FG<NUM> to FGn are configured to receive information from sensors, for example, regarding vibration information, and then execute instructions stored within microprocessors 110A causing motor <NUM> to implement a speed, frequency, and phase position control needed to generate an appropriate force output via rotation of imbalance masses (not shown).

In some embodiments, system <NUM> includes a SCAVCS, as microprocessors 110A receive and process redundant information, such that in case a failure should occur at one FG, the information is not lost and/or can be easily shared or communicated to one or more of the other FGs. Thus, vibration control can be implemented or shared and/or offloaded to one or more of the remaining, active FGs to compensate for a failed FG. In addition to this, system <NUM> includes a flexible architecture in which a defective FG can be bypassed (e.g., via multiple bus lines <NUM>, <NUM>) and/or shut-down (e.g., via disabling power to that FG) where the force output generated by the defective FG is not a desired output, or where the FG erroneously induces unwanted vibration.

In some embodiments, FG<NUM> to FGn each include one or more accelerometers <NUM> (e.g., bi-axial or uniaxial) for measuring or detecting vibration, and supplying redundant vibration signals to each of the plurality of microprocessors 110A. Providing multiple microprocessors 110A at each FG reduces the risk of failure at the FG, as each microprocessor 110A is configured to individually generate and execute force commands (i.e., force command control signals) as needed, and act as a back-up should one microprocessor 110A fail. In some embodiments, at least one microprocessor 110A (e.g., a master microprocessor) is configured to instruct motor <NUM> to co-rotate masses at a determined speed, frequency, and/or phase for generating a vibration cancelling force according to a detected vibration. Should one microprocessor 110A fail, at least one other microprocessor 110A is digitally linked thereto and present within system <NUM> for implementing vibration control. In some embodiments, FG<NUM> to FGn each produce oscillatory forces for cancelling vibration.

In some embodiments, each microprocessor 110A operates and/or functions as a controller for the respective FG (e.g., FG<NUM> to FGn), thereby obviating the need for a separate, centralized controller. In some embodiments, each microprocessor 110A operates independently of the other microprocessors 110A and each independent microprocessor 110A is electronic communication with each of the other microprocessors within the respective FG for improved robustness, autonomy, and redundancy.

Still referring to <FIG> and in some embodiments, each microprocessor 110A is configured to receive and/or monitor electronic communications or signals from at least one set of sensors <NUM>, system devices transmitting system parameters <NUM> and/or additional inputs <NUM>. First and second bus lines <NUM> and <NUM> are configured to transmit the same (i.e., redundant) information regarding sensors <NUM>, system parameters <NUM>, and/or inputs <NUM> so that information is recoverable should one communication line fail or become disabled during operation.

Microprocessors 110A and therefore, FGs (e.g., FG<NUM> to FGn) are configured to share information using one or both bus lines <NUM> and <NUM> in the event of a failure. Each microprocessor 110A is configured to receive the same information, which may be communicated from different communication lines. That is, one microprocessor 110A receives information regarding sensors <NUM>, parameters <NUM>, and inputs <NUM> from first bus line <NUM>, while the at least one other microprocessor 110A at each FG receives the same information from sensors <NUM>, parameters <NUM>, and inputs <NUM> from second bus <NUM>. Information regarding sensors <NUM>, parameters <NUM>, and inputs are indicative of active conditions at or on the vibrating structure or system, and used to control vibration.

For example, a plurality of sensors may be provided to send vibration information to FGs. In some embodiments, "n" number of sensors (where "n" is a whole number integer > <NUM>) are provided per system <NUM>. First and second bus lines <NUM> and <NUM>, respectively, also convey a plurality (i.e., n) of system parameters <NUM> and a plurality (i.e., "n") of additional inputs <NUM>. Sensors <NUM> may include any component suitable for detecting noise and/or vibration of a structure, or any portion thereof, and including and not limited to accelerometers, microphones, strain gauges, inertial motion systems, temperature sensors, force sensors, motion detectors, and any other device capable of measuring a physical condition associated with a vibrating structure or system. One or more types of sensors <NUM> may be used.

System parameters <NUM> represent any number of inputs that may also be communicated to or between components of system <NUM>. For example and using an aircraft or helicopter platform as the non-limiting example, system parameters may include flight data (e.g., true airspeed, altitude), angle of attack, engine speed (tachometer or tach), rotor azimuth, rotor speed, weather conditions, landing conditions, or any other electronically available data from the aircraft or helicopter. One or more types of system parameters may be simultaneously provided to a plurality of different bus lines <NUM>, <NUM> for intra-system <NUM> redundancy as well as to a plurality of different microprocessors 110A within FGs for intra-FG (e.g., FG<NUM> to FGn) redundancy. System <NUM> includes multiple levels of redundancy, so that system <NUM> may re-configure as needed to maintain vibration control in the event of any component (e.g., bus lines, FG, etc.) failure.

Additional inputs <NUM> represent any number of inputs that may impact the performance of the vibrating system. Continuing with the non-limiting example of an aircraft or helicopter platform, additional inputs <NUM> may include the type of cargo, center of gravity loaded and unloaded, type of responsiveness of the platform (e.g., to unwanted vibration), or any other electronic information that may impact performance of system <NUM>.

System <NUM> may implement active vibration control using computer hardware or software, and may also provide a safety architecture having redundancy in the data communication lines (e.g., conveying identical information simultaneously) as well as having redundancy within the actuators themselves (e.g., within FG<NUM> to FGn). Where weight allows, a plurality of motors <NUM> may also be provided for further redundancy. Motors <NUM> are co-located at FGs (e.g., FG<NUM> to FGn, for reducing the risk of excessive electromagnetic emissions and simplifying system wiring. This architecture also allows for some of the power electronics to be separated from the FGs (e.g., FG<NUM> to FGn) for reducing weight. System <NUM> is configured to detect faults within the system, and/or components (e.g., FG<NUM> to FGn) thereof, and either correct the problem or shutdown the defective component, as needed, to avoid a system shutdown. System <NUM> utilizes flexible data sharing to reconfigure communications, as needed, in case of faults, errors, failures, and/or data losses within a communication line. In some embodiments, FG<NUM> to FGn may be shut down by severing of power thereto, for example, using a shutdown switch or communication carried via data bus lines <NUM> or <NUM>.

In some embodiments, each microprocessor 110A is configured to monitor at least one of the other microprocessors 110A, and in some embodiments each of the other microprocessors 110A, in addition to performing its intended function (e.g., generating/transmitting force commands to control FGs). In the event of a failure of one microprocessor <NUM> or FG (e.g., FG<NUM> to FGn), the other active microprocessors 110A are able to compensate for the failure autonomously. This also provides safety-critical redundancy. In further embodiments, at least microprocessor 110A functions as a controller and the other(s) microprocessors 110A function as a monitor to monitor the health and effectiveness of vibration control provided by system <NUM>. In this embodiment, if there is a failure in the controller microprocessor 110A, then the other monitoring microprocessor(s) <NUM> can act as a backup and take command of the FG having the failed microprocessor 110A for keeping it operable within system <NUM>.

Utilizing microprocessor(s) 110A to monitor other microprocessors 110A can also include monitoring sensor information <NUM> and/or system parameters <NUM> for protecting the vibrating structure from receiving an erroneous force. Where system <NUM> is creating too much vibratory acceleration, force, strain, noise, temperature, etc., then the monitoring microprocessor 110A is configured to detect it and either shut down the defective FGs (e.g., via severing power) or adjusting the force to compensate for the defective FG. The monitoring microprocessor <NUM> can also detect internal faults within one or more FGs. Internal faults can include erroneous outputs including force magnitude(s), speed(s), or phase(s), or internal temperature of key components such as bearings, motors, and electronics. Internal faults can also include faults associated with CFG components (e.g., FG<NUM> to FGn), power supplies, microprocessors, motor drive electronics, motor sensors, etc..

In some embodiments and as noted above, FG<NUM> to FGn may each also include multiple motors <NUM> for further mitigating the risk of failure, if weight constraints are met and/or can be maintained. Each microprocessor 110A is configured to receive information from one or more speed sensors disposed at each motor <NUM> for monitoring the speed of the motor and co-rotation of masses. PWM <NUM> includes a modulator device or circuit for controlling the width of the pulse and/or pulse duration provided to motor <NUM>. PWM <NUM> a control for controlling power supplied to electrical devices, such as motor <NUM>, for providing accurate active vibration control.

Referring now to <FIG>, a schematic block diagram of a further embodiment of an AVCS, generally designated <NUM> is illustrated. System <NUM> includes a safety-critical, autonomous, and/or redundant system as it provides redundant and autonomous vibration control to a vibrating structure, system, or platform (e.g., aircraft, vehicles, structures, buildings, industrial machinery, etc.).

System <NUM> includes a plurality of digital communications lines for communicating information to, from, and/or between a plurality of FGs (e.g., FG<NUM> to FGn), between for example, at least a first digital bus line <NUM> and a second digital bus line <NUM>. First and second bus lines <NUM> and <NUM>, respectively, are digitally linked to each other and configured to communicate via a digital communication line or digital data link <NUM>.

As <FIG> illustrates, system <NUM> is similar in form and function to system <NUM>, however, the microprocessors at each FG do not function as controllers. Instead, a plurality of separate controllers <NUM> and <NUM> are provided. Each controller <NUM> and <NUM> is associated a respective bus line <NUM> and/or <NUM>, which provides redundant digital or electronic input to each FG (i.e., FG<NUM> to FGn). A plurality of inputs <NUM> provides identical (i.e., redundant) information simultaneously to controllers <NUM> and <NUM>. Inputs <NUM> include information from a plurality of sensors, various system parameters, and additional inputs (e.g., <NUM> through n, where "n" is a whole number integer greater than or equal to <NUM>). Inputs <NUM> may include electrically communicated signals sent to and/or received by the separate controllers <NUM> and <NUM> directly through a wired or wireless connection, or indirectly across one or more digital bus lines <NUM> and <NUM>.

Additional inputs <NUM> may receive electrical power from controllers <NUM> or <NUM>, or directly from portions of the vibrating structure/system (e.g., aircraft, helicopter, system, platform, etc.). In some embodiments, individual power connections may be used in lieu of power from controllers and/or in addition to the power from controller <NUM>, <NUM>. This power architecture may also be applicable to <FIG>.

Each controller <NUM>, <NUM> may include a hardware processor and memory for executing instructions, algorithms, and/or processing data or information. Controllers <NUM>, <NUM> also include a plurality of input and output communication interfaces for receiving input signals from a plurality of sensors and/or signals regarding parameters or additional inputs <NUM>. Each controller <NUM>, <NUM> may also determine vibration and noise levels, generate force cancelling control signals or commands, and output the force control signals or commands to vibration control devices, such as FG<NUM> to FGn. FG<NUM> to FGn may receive and execute the control commands thereby actively and dynamically cancelling vibration and mitigating noise within a system, structure, or platform.

In some embodiments, bus lines <NUM> and <NUM> communicate redundant information including force control command signals from controllers <NUM>, <NUM> to each FG, so that each FG may process the commands (e.g., via microprocessor <NUM>) and generate a vibration cancelling force for cancelling unwanted vibration. System <NUM> utilizes a plurality of digital bus lines for communicating identical (i.e., redundant) information simultaneously thereby providing redundant, safety-critical active vibration control. FG<NUM> to FGn are configured to generate vibration cancelling forces until a desired level of vibration and/or noise is achieved.

Controllers <NUM> and <NUM> are lightweight, dimensionally compact, and include a low power design configured to receive and use approximately <NUM> volts-DC (VDC) from a power supply or power source. Each FG is also configured to receive approximately <NUM> VDC of power either from a power source directly or through controllers <NUM>, <NUM>. Each controller <NUM>, <NUM> can receive up to fourteen (<NUM>) accelerometer <NUM> inputs and operate up to twelve (<NUM>) FGs (i.e., FG<NUM> to FGn) or CFGs.

In some embodiments, separate electronics residing at each of FG<NUM> to FGn receive and distribute electrical power and communication information. Feedback accelerometers or sensors measure the vibration error at specific locations within the vibrating system (e.g., vehicle, aircraft, equipment, etc.) and communicate the information to controllers <NUM>, <NUM>. Electrical power may come from different aircraft busses and/or any number or power sources to further increase safety of system <NUM>.

In some aspects, FG<NUM> to FGn are each configured to co-rotate a plurality of masses (not shown) driven by the at least one motor <NUM>. Motors <NUM> can execute force commands generated at controllers <NUM>, <NUM> and passed through microprocessors <NUM> at a speed and frequency specified the least one accelerometer <NUM> and plurality of speed sensors. For example, speed sensors monitor the speed of motor <NUM> and the one or more accelerometers <NUM> monitor the co-rotating masses with both providing input to microprocessors <NUM>. In addition to the foregoing, FG<NUM> to FGn may each include PWM <NUM>. In some embodiments, FG<NUM> to FGn each include CFGs configured to generate and/or induce vibration cancelling forces to the vibrating structure or system.

In some embodiments, each microprocessor <NUM> operates \independently of each of the other microprocessors, and is configured to control one or more FGs (e.g., FG<NUM> to FGn), as needed. Each microprocessor receives all electronic communications from at least one set of sensors, accelerometers, and identical, simultaneous control commands from controllers <NUM> and <NUM>. Each microprocessor <NUM> can monitor system inputs <NUM>, parameters, sensors, controllers <NUM>, <NUM>, and/or FGs (i.e., FG<NUM> to FGn) for ensuring adequate vibration control, and for reducing the effects of component/data communication failures. Microprocessors <NUM> can detect faults, errors, and/or failures in system <NUM> and/or components thereof.

In some embodiments, microprocessors <NUM> function or act as local controllers for the respective FG while receiving input commands from controllers <NUM> or <NUM>. In some embodiments, FG<NUM> to FGn each include at least a first microprocessor <NUM> that receives input and/or force commands from one (e.g., a first) controller <NUM> and at least a second microprocessor <NUM> that receives input and/or force commands from the other controller <NUM>. Any number of microprocessors <NUM> and/or controllers <NUM>, <NUM> may be provided per system <NUM>. Microprocessors <NUM> are also configured to monitor other microprocessor <NUM> and/or FGs, and provide redundant information to the controllers <NUM>, <NUM> either together or individually. In some embodiments, microprocessors <NUM> are in electronic communication with digital bus lines <NUM>, <NUM> and with controllers <NUM>, <NUM> via data links <NUM>.

In all embodiments, and as illustrated in <FIG>, redundancy is provided. In one embodiment the redundancy is provided via microprocessors <NUM> within each FG (i.e., FG<NUM> to FGn) where each microprocessor <NUM> is capable of functioning individually or in concert with other microprocessors <NUM> as a local FG controller, a networked controller interacting with all other microprocessors or controllers, a monitor of the FG, and/or as a monitor of inputs (e.g., sensors, system parameters, and/or additional inputs). In some embodiments, microprocessors <NUM> are configured to provide one of these redundancy elements or a combination of two or more of the redundancy elements. Additionally, each microprocessor <NUM> is capable of being subordinated to one or more external controllers <NUM>, <NUM> in electronic communication with digital buses <NUM>, <NUM>. In some embodiments, system <NUM> redundancy allows one microprocessor <NUM> to assume control if another one fails, or if a controller <NUM>, <NUM> should fail.

A plurality of rectifiers or rectifier electronics <NUM> is provided within system <NUM>. Separated rectifier electronics are provided when the design envelope and the force requirement coupled with the need for a low weight system is present. Such a configuration improves electromagnetic emissions and simplifies system wiring. Rectifier electronics <NUM> converts <NUM>-phase <NUM> VAC to <NUM> VAC for use by FG<NUM> to FGn. In some embodiments, each rectifier electronic <NUM> can deliver power to at least four FGs, or more or less than four FGs, where desired.

Referring collectively to systems <NUM> and <NUM>, multiple levels of redundancy are provided. For example, multiple microprocessors <NUM> provide redundancy by receiving and processing identical information/data, and can be used to provide control of system <NUM> should one or more of the controllers fail. In addition to this, redundancy is provided by the at least two digital bus lines <NUM>, <NUM> and at least two controllers <NUM>, <NUM>. Controllers <NUM>, <NUM> are configured to monitor overall system <NUM> performance and instruct FGs to produce vibration cancelling forces via microprocessors <NUM>. System <NUM> includes a system architecture that is autonomous and reconfigurable for allowing the recovery of lost data, bypassing and/or shutting down of defective equipment (e.g., FGs), and allowing autonomous control using any of the multiple controllers <NUM>, <NUM> and/or microprocessors <NUM>. If one digital bus line <NUM>, <NUM> fails, then the other is able to continue operations with little to no degradation in system <NUM> performance. Each digital bus line <NUM>, <NUM> is in electronic communication with each controller <NUM>, <NUM>, FG (i.e., FG<NUM> to FGn), and at least one microprocessor <NUM> residing at and/or within each FG.

In some embodiments, redundant active vibration control systems are safety-critical as redundancy ensures that the FGs (i.e., FG<NUM> to FGn) responsible for cancelling or controlling vibration are operable approximately <NUM>% of the time. By providing a plurality of autonomously controlled FGs and redundant communications thereto, safety is advantageously enhanced. For example, each of systems <NUM> and <NUM> ensure that if one FG fails, the controllers and/or microprocessors are able to command the remaining FGs to pick up, manage, and/or share the load previously carried by the now failed or defective (e.g., and/or bypassed) FG, and the impact of the single failure is minimized.

Returning to the earlier non-limiting example of an aircraft or helicopter, typical failure rates for aviation systems are captured in Table <NUM> below. These rates indicate the type of failure and the allowable failures per incident. For most aviation related situations the FAA identified allowable failure rate for a Class IV airplane for flight critical systems is found in FAA AC <NUM>-1E, dated November <NUM>. Table <NUM> represents the most stringent case for airplanes. The failures are defined by the FAA Table <NUM>.

To further increase the safety/reliability of systems <NUM> and <NUM> from "Minor" to a higher criticality level, additional redundancy may be added to each FG (i.e., FG<NUM> to FGn). This could consist of and/or include redundant bearings, motors, motor controllers, and/or power supplies.

Systems <NUM> and <NUM> described herein can weigh approximately six (<NUM>) to <NUM> pounds, dependent upon the number of FGs, and the size (e.g., <NUM>" diameter, etc.) of FGs provided per system.

<FIG> is a block diagram illustrating a method, generally designated <NUM> of providing a redundant AVCS. At block <NUM>, the method includes providing a plurality of digital bus communication lines (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <FIG> and <FIG>). In some aspects, the digital bus communication lines are lined together and include digital channels or links for providing two-way communications between components of a system via a communications protocol such as CAN A, CAN B, and/or ARINC429.

At block <NUM>, at least one CFG is electrically connected to each of the digital bus communication lines for facilitating electrical communication therewith. At block <NUM>, redundant information is electrically communicating simultaneously to the CFG, using the plurality of digital bus communication lines. In some embodiments, the redundant information is communicated to two or more microprocessors disposed in the CFG. The CFG can then process the redundant information and generate a force that substantially cancels an unwanted vibration force.

<FIG> illustrates an embodiment of a redundant FG, generally designated <NUM>, for use in a redundant AVCS (e.g., <NUM> or <NUM>) as described herein. That is, systems <NUM> and <NUM> may be configured to incorporate FG <NUM> as an alternative to FG<NUM> to FGn (<FIG> and <FIG>). FG <NUM> is similar in form and function to FG<NUM> to FGn (<FIG> and <FIG>) however; FG <NUM> includes an additional level of redundancy. FG <NUM> is connected to first and second bus lines <NUM> and <NUM> via data links <NUM> as previously described. In addition to this, FG <NUM> includes at least a first set <NUM> and a second set (e.g., a redundant set) <NUM> of components. Each of first and second sets <NUM> and <NUM> may include an accelerometer <NUM>, a microprocessor <NUM>, a motor <NUM>, and a PWM <NUM>. Thus, if any component within first set <NUM> should fail, the remaining redundantly configured component in second set <NUM> may take over, and vice versa, for preventing failure of the overall FG <NUM> and/or respective AVCS (e.g., <NUM>, <NUM>) in which it is provided.

In some embodiments, FG <NUM> includes multiple microprocessors <NUM> configured to drive a respective motor <NUM> for rotating a single imbalance mass to create a force. If the respective accelerometer <NUM>, speed sensor, PWM <NUM> and/or motor <NUM> should fails on one microprocessor <NUM>, then the remaining microprocessor <NUM> may take over. In some embodiments, FG <NUM> utilizes a motor <NUM> having redundant windings. The same microprocessor <NUM> may communicate with one or more motors <NUM> as illustrated in <FIG>.

Redundancy is provided within each CFG via the plurality of microprocessors (and optionally redundant motors and PWM e.g., <FIG>) and redundancy is also provided in the overall system via the plurality of digital bus communication lines and optional controllers, where microprocessors do not function as controllers.

Claim 1:
An active vibration control system (AVCS) (<NUM>, <NUM>) comprising:
a plurality of digital bus communication lines (<NUM>, <NUM>, <NUM>, <NUM>);
at least one circular force generator (CFG) in electrical communication with each of the plurality of digital bus communication lines (<NUM>, <NUM>, <NUM>, <NUM>);
wherein each of the plurality of digital bus communication lines (<NUM>, <NUM>, <NUM>, <NUM>) is configured to electrically communicate redundant information simultaneously to the at least one CFG;
wherein the CFG is configured to process the redundant information and produce a force that substantially cancels an unwanted vibration force; and
wherein the at least one CFG is configured to process the redundant information via a plurality of microprocessors (<NUM>, 110A, <NUM>).