Architecture using integrated backup control and protection hardware

This disclosure claims priority to U.S. Provisional Application No. 61/250,113 which was filed on Oct. 9, 2009.

This disclosure relates to controls, and more particularly to an electronic control architecture using integrated protection and backup control hardware.

Existing electronic controls utilize a primary control, a protection control, and an external backup control to control a device, also known as a “plant.” Under normal fault-free conditions the primary control controls the plant, and the protection control may assume control if the primary control malfunctions in a “non-gross” manner (i.e., the primary control is still operating but is experiencing an undetected error and requires assistance from the protection control to compensate for the error). The protection control is sometimes referred to as a “nanny”, because the protection control prevents unacceptable behavior by the primary control. The external backup control may assume control if the primary control experiences some threshold degree of damage or error from which the primary control cannot recover (e.g., a “gross error” which occurs if the primary control is unable to operate due to a channel-wide failure such as a primary control processor failure or a power supply failure).

An example electronic control configuration includes at least one secondary microprocessor operable to control a device. The at least one secondary microprocessor assumes protection control of the device responsive to a first type of failure by transmitting a protection control signal to a first effector. The at least one secondary microprocessor assumes backup control of the device responsive to a second type of failure by transmitting a backup control signal to a second effector. The backup control functionality of the at least one secondary microprocessor can be selectively disabled.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

FIG. 1 a schematically illustrates an electronic control configuration utilizing a combined protection and backup control unit, in which Channel A has an enabled backup and Channel B has a disabled backup control.

FIG. 1 b schematically illustrates another electronic control configuration utilizing a combined protection and backup control unit, in which both Channel A and B have an enabled backup control.

FIG. 2 a schematically illustrates de-energized dual-coil solenoid windings.

FIG. 2 b schematically illustrates energized dual-coil solenoid windings.

FIG. 3 schematically illustrates switching logic for a first channel of the control configuration of FIG. 1 a.

FIG. 4 schematically illustrates switching logic for a second channel of the control configuration of FIG. 1 a.

FIG. 1 a schematically illustrates a multi-channel electronic control configuration 10 a for a controllable device 12 , also known as a “plant.” The device 12 is controllable by a first, protection effector 18 along a shaft 19 and a second, primary/backup effector 16 along a shaft 17 . Using the example of an aircraft, the device 12 could collectively refer to controllable mechanical components of the aircraft, such as a turbine engine, a gearbox, a mechanical fuel control valve, or another mechanically controllable device. In other examples, the device 12 could correspond to a controllable automobile, a power plant, or a building that includes anti-vibration actuators.

The effector 16 may be controlled via one of two windings 20 , 22 , and the protection effector 18 may be controlled via one of two windings 26 , 28 . In one example the windings 20 , 22 are dual stepper motor windings and the windings 26 , 28 are dual solenoid windings (see FIGS. 2 a - b ). Of course, other configurations are also possible, and the windings may correspond to other devices, such as dual torque motor windings.

FIG. 2 a schematically illustrates the windings 26 , 28 as de-energized dual-coil solenoid windings, such that the effector 18 is in a first position and a bias member 29 (e.g., a spring) is in an expanded position. FIG. 2 b schematically illustrates the windings 26 , 28 as energized dual-coil solenoid windings, such that the effector 18 is moved to a second position and the bias member 29 is in a compressed position.

Referring again to FIG. 1 a , a first primary control 30 a for a first channel (“channel A”), a second primary control 30 b for a second channel (“channel B”), a first protection/backup control 32 a for the first channel (“channel A”), and a second protection/backup control 32 b for the second channel (“channel B”) are in communication with each other via a serial data bus 36 , and are in communication with the device 12 to receive sensor signals via connections 38 (e.g., speed measurement and/or a temperature measurement). The protection/backup controls 32 a - b are secondary controls as compared to the primary controls 30 a - b . The dual-channel configuration offers redundancy and fault tolerance. In one example, the controls 30 a - b , 32 a - b include microprocessors. The primary controls 30 a - b are operable to control the device 12 via effector 16 . The protection/backup controls 32 a - b are capable of performing a protection function by controlling device 12 via protection effector 18 if the primary controls 30 a - b experience a first type of failure. The protection/backup controls 32 a - b are capable of performing a backup control function by controlling device 12 via primary/backup effector 16 if both the primary controls 30 a - b experience a second type of failure. This operation will now be described in greater detail.

In one example, the first type of failure is a failure in which one of the primary controls 30 a - b is able to control the device 12 but requires assistance from its corresponding protection/backup control 32 a - b to avoid damaging the device. The first type of failure includes non-gross failures that the failing primary control 30 is not able to detect. For example, the first type of failure may include a temporary failure of memory of the controls 30 a - b (e.g., due to cosmic radiation), or may include one of the primary controls 30 a - b erroneously measuring an operating speed of the device 12 (e.g., a primary control 30 determines that the device 12 is operating at 60% speed but the device 12 is actually operating at 120% speed). In the example of the overspeed condition due to erroneous speed detection, the protection/backup control 32 may assume protection control by reducing fuel flow to the device 12 such that the primary control 30 is still controlling the device but the corresponding protection/backup control 32 assists to prevent the primary control 30 from damaging the device 12 , acting in a so-called “nanny” role.

In one example, the second type of failure is a failure in which one of the primary controls 30 a - b is unable to control the device 12 and relinquishes control of the device 12 to either the other of the primary controls 30 a - b or to one of the protection/backup controls 32 a - b (i.e., a detected gross failure or detected non-gross failure). For example, the second type of failure may include a processor failure of the primary control 30 a or 30 b . When one of the primary controls 30 a - b detects its own failure, the failing primary control 30 a - b will annunciate its failure to the other primary control channel 30 a or 30 b or to its corresponding backup controller 32 a (in the example of FIG. 1 a the corresponding backup controller for both primary controls 30 a - b is the protection/backup control 32 ).

During normal fault-free operating conditions, the first primary control 30 a controls effector 16 via winding 20 by transmitting control signals to the winding 20 . Per FIG. 1 a , in the event of the first type of failure, both protection/backup controls 32 a and 32 b assume protection control of the protection effector 18 via winding 26 by transmitting a protection control signal to the windings 26 , 28 .

If the first primary control 30 a experiences the second type of failure and the first primary control 30 a cannot return to normal operation without being serviced or replaced, the first primary control 30 a relinquishes control of the device 12 and the second primary control 30 b assumes control of the effector 16 via winding 22 . In the event of the first type of failure of the second primary control 30 b , both of the protection/backup controllers 32 a - b assume protection control of the backup effector 18 via the windings 26 , 28 .

In the configuration 10 a (see FIG. 1 a ), if both the primary controls 30 a - b experience the second type of failure, the protection/backup control 32 a assumes backup control of the device 12 at the effector 16 via winding 20 . In one example the protection/backup control 32 a is only able to assume backup control if both of the primary controls 30 a - b experience the second type of error, are able to detect that they are experiencing the error, and relinquish control of the device 12 . In the example of the electronic control configuration 10 a , although the protection/backup control 32 b also has backup control capabilities, the backup control functionality of control 32 b is disabled such that the control 32 b only acts as a protection control. This simplifies the configuration 10 a , because protection/backup controls 32 a - b may be manufactured in large quantities, and then backup control functionality may be selectively disabled. Note, that in the configuration 10 a , no external dedicated backup control unit is needed.

In the configuration 10 b (see FIG. 1 b ) the backup control functionality of the protection/backup control 32 b is enabled such that either of the protection/backup controls 32 a - b is operable to assume backup control from either of the primary controls 30 a - b . In one example, the protection/backup control 32 that ultimately assumes protection control belongs to the channel of the primary control 30 that last had control (e.g., if primary control 30 a last had control of the device 12 then protection/backup control 32 a would be able to ultimately assume backup control, and if primary control 30 b last had control of the device 12 then protection/backup control 32 b would be able to ultimately assume backup control). In one example, the protection/backup control 32 a is only able to assume backup control if both of the primary controls 30 a - b experience the second type of error, are able to detect that they are experiencing the error, and relinquish control of the device 12 . Note, that in the configuration 10 b , as in the configuration 10 a , no external dedicated backup control unit is needed.

FIG. 3 schematically illustrates a control circuit 50 a for the protection/backup control 32 a of the configurations 10 a - b that enables the backup functionality of the protection/backup control 32 a via a switch 52 a having a first position in which backup control functionality is enabled (see FIG. 3 ), and a second position in which backup control functionality is disabled (see FIG. 4 ). The switch 52 a may be a solid state switch (e.g., MOSFET, IGBT, etc.), for example, or other type of switch (e.g., a relay). Notably, FIGS. 3 and 4 illustrate only the functional enabling/disabling of the backup control.

The switch 52 a is controllable by an AND gate 58 a . When the AND gate 58 a output is high (“1”), the switch 52 a is ON and the backup control functionality is enabled. When the AND gate 58 a output is low (“0”), the switch 52 a is OFF and the backup control functionality is disabled. The AND gate 58 a only outputs an ON signal if each of its four inputs has an ON signal (“1”).

The inputs of the AND gate 58 a include primary control 30 a channel fail signal 60 , primary control 30 b channel fail signal 62 , a first backup enable signal 64 a , and a second backup enable signal 66 a . The signals 60 , 62 , 64 a , 66 a are each connected to a pull-up voltage 68 . The signal 64 a is connected to an inverter 74 a . A buffer 70 a is responsive to the fail signal 60 in that the buffer 70 a only outputs a high output (“1”) if the channel fail signal 60 is not asserted low (“0”) to ground. Similarly, a buffer 72 a is responsive to the fail signal 62 in that the buffer 72 a only outputs a high output (“1”) if the fail signal 62 a is not asserted low (“0”) to ground. For channel A of the two backup controllers ( 32 a ), the first backup signal 64 a is always asserted to ground, and so inverter 74 a always outputs a high output (“1”). For channel A of the two backup controllers ( 32 a ), the signal 66 a is connected to a buffer 76 a , not an inverter, and because the buffer 76 a is connected to pull-up voltage 68 , the buffer 76 a always outputs a high output (“1”). Thus, the backup signals 64 a , 66 a always provide high inputs to the AND gate 58 a , and whether the switch 52 a is ON or OFF depends only upon whether or not the primary controls 30 a - b indicate failure.

FIG. 4 schematically illustrates a control circuit 50 b for the protection/backup control 32 b of the configuration 10 a that disables the backup functionality of the protection/backup control 32 b via switch 52 b having a first position in which backup control functionality is enabled (see FIG. 3 ), and a second position in which backup control functionality is disabled (see FIG. 4 ). The switch could be a solid state switch (e.g., MOSFET, IGBT, etc.), for example, or could be any other type of switch (e.g., a relay).

The switch 52 b is controllable by an AND gate 58 b . When the AND gate 58 b output is high (“1”), the switch 52 b is ON and the backup control functionality is enabled. When the AND gate 58 b output is low (“0”), the switch 52 b is OFF and the backup control functionality is disabled. The AND gate 58 b is responsive to its four inputs in that the AND gate 58 b only outputs an ON signal if each of its four inputs has an “ON” signal. However, the circuit 50 b of FIG. 4 guarantees that the AND gate 58 b only outputs an OFF signal, because inverter 74 b will always have a low output (“0”) (as signal 64 b is always open for channel B in the configuration of FIG. 1 a ), and buffer 76 b will always have a low output (“0”) (as signal 66 b is tied to ground for channel B in the configuration of FIG. 1 a ). Thus, with two inputs always being low, the AND gate 58 b will always have an OFF output such that switch 52 b disables the backup control functionality. However, in the configuration of FIG. 1 b , the control circuit 50 a of FIG. 3 would apply to both Channels A and B because the backup functionality of both of the protection/backup controls 32 is enabled.

Although only the protection/backup controls 32 a - b have been described as having protection control functionality, it is also possible that the primary controls 30 a - b could have built-in protection control functionality such that if primary control 30 a experienced the first type of failure then primary control 30 b could provide protection control, and if primary control 30 b experienced the first type of failure then primary control 30 a could provide protection control.

Also, although only two channel configurations 10 a - b have been discussed, it is understood that the configurations 10 a - b are only examples, and that other quantities of channels could be used.

Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.