1. An aircraft control system comprising:
a first feedback assembly movable relative to a mechanical ground;
a first stick movable relative to the mechanical ground and the first feedback assembly, wherein:
a) a first stick position is the position of the first stick relative to the mechanical ground;
b) a first feedback position is the position of the first feedback assembly relative to the mechanical ground; and
c) a first relative error is the first stick position minus the first feedback position; and
a second feedback assembly movable relative to the mechanical ground;
a second stick movable relative to the mechanical ground and the second feedback assembly, wherein:
a) a second stick position is the position of the second stick relative to the mechanical ground;
b) a second feedback position is the position of the second feedback assembly relative to the mechanical ground; and
c) a second relative error is the second stick position minus the second feedback position; and
a control arrangement including a cross-coupled mode in which the control arrangement provides first and second feedback position commands to position the first and second feedback assemblies wherein the first feedback position command is equal to the second relative error and the second feedback position command is equal to the first relative error.
2. The aircraft control system of claim 1, wherein the first feedback assembly provides passive tactile feedback to the first stick when the first stick is transitioned from a first feedback neutral position of the first feedback assembly; and
wherein the second feedback assembly provides passive tactile feedback to the second stick when the second stick is transitioned from a second feedback neutral position of the second feedback assembly.
3. An aircraft control system comprising:
a first feedback assembly movable relative to a mechanical ground;
a first stick movable relative to the mechanical ground and the first feedback assembly, wherein:
a) a first stick position is the position of the first stick relative to the mechanical ground;
b) a first feedback position is the position of the first feedback assembly relative to the mechanical ground; and
c) a first relative error is the first stick position minus the first feedback position; and
a second feedback assembly movable relative to the mechanical ground;
a second stick movable relative to the mechanical ground and the second feedback assembly, wherein:
a) a second stick position is the position of the second stick relative to the mechanical ground;
b) a second feedback position is the position of the second feedback assembly relative to the mechanical ground;
c) a second relative error is the second stick position minus the second feedback position; and
a control arrangement including a cross-coupled mode in which the control arrangement provides first and second feedback position commands to position the first and second feedback assemblies wherein the first feedback position command is equal to the second relative error and the second feedback position command is equal to the first relative error;
wherein the first feedback assembly provides passive tactile feedback to the first stick when the first stick is transitioned from a first feedback neutral position of the first feedback assembly;
wherein the second feedback assembly provides passive tactile feedback to the second stick when the second stick is transitioned from a second feedback neutral position of the second feedback assembly; and
wherein the first feedback assembly includes a first cam surface defining the first feedback neutral position and a first resistance arrangement, the first stick includes a first cam follower, wherein the first resistance arrangement increasingly resists movement of the first cam follower from the first feedback neutral position to provide the passive tactile feedback; and
wherein the second feedback assembly includes a second cam surface defining the second feedback neutral position and a second resistance arrangement, the second stick includes a second cam follower, wherein the second resistance arrangement increasingly resists movement of the second cam follower from the second feedback neutral position to provide the passive tactile feedback.
4. The aircraft control system of claim 3, wherein the first and second feedback resistance arrangements are provided by spring and damper arrangements; and
the first and second cam surfaces are generally V-shaped with the first cam follower positioned within the V-shape of the first cam surface and the second cam follower is positioned within the V-shape of the second cam surface, wherein the first and second feedback neutral positions are when the first and second cam followers contact both sides of the V-shaped surfaces.
5. The aircraft control system of claim 2, wherein the first feedback assembly includes a first gimbal arrangement that provides the passive tactile feedback to the first stick and that defines the first feedback neutral position, the first feedback assembly further including a first actuator for adjusting the position of the first feedback neutral position relative to the mechanical ground; and
wherein the second feedback assembly includes a second gimbal arrangement that provides the passive tactile feedback to the second stick and that defines the second feedback neutral position, the second feedback assembly further including a second actuator for adjusting the position of the second feedback neutral position relative to the mechanical ground.
6. The aircraft control system of claim 5, wherein the first gimbal arrangement and the first stick are pivotally affixed to the mechanical ground for pivotal movement about a first common axis, wherein the second gimbal arrangement and the second stick are pivotally affixed to the mechanical ground for pivotal movement about a second common axis.
7. The aircraft control system of claim 5, wherein the first feedback assembly is configured such that failure of the first actuator does not prevent movement of the first stick relative to the mechanical ground and the first feedback assembly and wherein the second feedback assembly is configured such that failure of the second actuator does not prevent movement of the second stick relative to the mechanical ground and the second feedback assembly.
8. The aircraft control system of claim 1, wherein the control arrangement also includes a priority mode in which a selected one of the first or second sticks has its feedback assembly maintained in a fixed position relative to mechanical ground and the control arrangement is configured to adjust the position of the feedback assembly of the non-selected one of the first and second sticks based on a difference between the first and second stick positions.
9. The aircraft control system of claim 8, wherein when the first stick is the selected one of the sticks, the control arrangement controls the second feedback position such that the second feedback position is equal to the second feedback position plus the first stick position minus the second stick position and when the second stick is the selected one of the sticks, the control arrangement controls the first feedback position such that the first feedback position is equal to the first feedback position plus the second stick position minus the first stick position.
10. The aircraft control system of claim 1, wherein the first feedback assembly and the first stick are pivotally affixed to the mechanical ground for pivotal movement about a first common axis, wherein the second feedback assembly and the second stick are pivotally affixed to the mechanical ground for pivotal movement about a second common axis; and wherein the first stick position and first feedback position are measured in degrees about the first common axis, wherein the second stick position and second feedback position are measured in degrees about the second common axis.
11. An aircraft control system comprising:
a first stick, and
a first feedback arrangement providing a passive first feedback profile for the first stick relative to mechanical ground, at least a portion of the first feedback arrangement being movable relative to the mechanical ground and the first stick for adjusting the first feedback profile; and
a first actuator coupled to the first passive feedback arrangement for adjusting the position of the first passive feedback arrangement relative to the mechanical ground for adjusting the first feedback profile;
a second feedback arrangement providing a passive second feedback profile for the second stick relative to mechanical ground, at least a portion of the second feedback arrangement being movable relative to the mechanical ground and the second stick for adjusting the second feedback profile;
a second actuator for adjusting the position of the second passive feedback arrangement relative to the mechanical ground for adjusting the second feedback profile; and
a feedback controller arrangement configured to control the first actuator for adjusting the position of the first passive feedback arrangement relative to the mechanical ground, the feedback controller arrangement is configured to control the second actuator for adjusting the position of the second passive feedback arrangement relative to the mechanical ground.
12. The air craft control system of claim 11, wherein the second feedback arrangement defines a feedback neutral position and wherein the feedback controller arrangement is configured to adjust the position of the first feedback arrangement to a position equal to the position of the second stick relative to the second feedback neutral position.
13. The air craft control system of claim 11, wherein the feedback controller arrangement is configured to control the second actuator to adjust the position of the second feedback arrangement to provide a biasing force biasing the second stick toward a same absolute position relative to the mechanical ground as the absolute position of the first stick relative to the mechanical ground.
14. The air craft control system of claim 11, wherein the first stick has a first stick position relative to the mechanical ground and the first feedback arrangement has a first feedback position relative to the mechanical ground;
wherein the second stick has a second stick position relative to the mechanical ground, and
wherein the feedback controller arrangement is configured to control the first actuator for adjusting the position of the first passive feedback arrangement such that a current first feedback position of the first feedback assembly is equal to a prior feedback position of the first feedback assembly plus a difference between the first stick position and the second stick position.
15. The air craft control system of claim 11, wherein the second stick has a second stick position relative to the mechanical ground, and
wherein the first stick has a first stick position which is the position of the first stick relative to the mechanical ground and the feedback controller arrangement is configured to control the first actuator to oscillate back and forth the first feedback arrangement when the second stick position is not equal to the first stick position.
16. A method of providing feedback to a control stick of an aircraft comprising the steps of:
sensing a first stick position which is the position of a first stick relative to a mechanical ground;
sensing a first feedback position which is the position of a first feedback assembly relative to the mechanical ground;
determining a first relative error which is the first stick position minus the first feedback position; and
adjusting, using a control arrangement, a second feedback position, which is the position of a second feedback assembly of a second stick relative to the mechanical ground, such that the second feedback position is equal to the first relative error; and
further comprising the steps of:
sensing a second stick position which is the position of the second stick relative to the mechanical ground;
sensing the second feedback position;
determining a second relative error which is the second stick position minus the second feedback position; and
adjusting, using the control arrangement, the first feedback position such that the first feedback position is equal to the second relative error.
17. The method of claim 16, wherein the steps of adjusting the first and second feedback positions occurs substantially continuously such that when one of the first and second sticks is moved to a different position relative to mechanical ground than the other stick, at least one of the first and second feedback positions are adjusted to cause the first and second sticks to remain substantially at a same relative position relative to the mechanical ground.
18. The method of claim 17, further comprising the step of passively biasing the first stick when the first stick is displaced from a feedback neutral position of the first feedback assembly and passively biasing the second stick when the second stick is displaced from a feedback neutral position of the second feedback assembly.
19. The method of claim 16, further comprising the step of initiating a priority mode to prioritize the second stick, and performing the following steps when in the priority mode:
sensing the first stick position;
sensing the first feedback position;
sensing a second stick position which is the position of a second stick relative to the mechanical ground;
determining a first stick relative error which is the second stick position minus the first stick position; and
adjusting the first feedback position by adding the first stick relative error to the first feedback position.
20. The method of claim 19, further comprising the step of always maintaining the second feedback position fixed when there is a difference between the first and second stick positions.
21. The method of claim 16, further comprising reciprocally vibrating the first stick by reciprocally adjusting the first feedback position when the first stick position is not equal to a second stick position.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An argon condensation system for an air separation unit having an argon column, a lower pressure column and a higher pressure column, said argon condensation system comprising:
a plurality of once-through heat exchangers connected to an argon column such that argon-rich vapor streams composed of argon-rich vapor column overhead are condensed within condensation passages of the once-through heat exchangers to produce an argon-rich liquid product stream and an argon-rich liquid reflux stream that is returned to the argon column as reflux;
a phase separator configured to separate a partially vaporized crude oxygen feed stream into at least one crude oxygen vapor stream and one or more crude liquid oxygen streams, wherein the partially vaporized crude oxygen feed stream originates as a crude liquid oxygen column bottoms from the higher pressure column that is partially vaporized as it is directed to the phase separator;
one or more crude liquid oxygen feed conduits disposed between the phase separator and vaporization passages of the once-through heat exchangers and configured to direct the one or more crude liquid oxygen streams to the plurality of once-through heat exchangers and wherein the one or more crude liquid oxygen streams are partially vaporized in the vaporization passages of the once-through heat exchangers through indirect heat exchange with the argon-rich vapor streams to produce partially vaporized crude liquid oxygen streams; and
one or more crude oxygen vapor conduits disposed between the phase separator and the lower pressure column and configured to direct the at least one crude oxygen vapor stream from the phase separator to the lower pressure column;
wherein the argon-rich vapor column overhead is produced through distillation of a crude argon feed stream and is fed from the lower pressure column to the argon column.
2. The argon condensation system of claim 1 further comprising:
one or more crude liquid oxygen flow transducers disposed downstream of the higher pressure column and upstream of the phase separator at a location where the crude liquid oxygen column bottoms stream is in a substantially liquid state and configured to sense liquid flow rates of the crude liquid oxygen column bottoms stream, and to produce flow signals corresponding thereto;
one or more crude oxygen flow control valves positioned downstream of the flow transducers to control the liquid flow rates of the crude liquid oxygen column bottoms stream; and
crude liquid oxygen flow controllers responsive to the flow signals and configured to control the flow control valves such that the flow rates of the crude liquid oxygen column bottoms stream are controlled to attain flow rate set points proportional to vaporization surface areas provided by the vaporization passages of each of the one-through heat exchangers.
3. The argon condensation system of claim 2 further comprising:
one or more control subsystems for controlling a feed stream flow rate of the crude argon feed stream in response to air flow rate into the air separation unit and for controlling a product flow rate of the argon-rich liquid product stream in response to the feed stream flow rate of the crude argon feed stream.
4. The argon condensation system of claim 3 wherein:
a level transducer is connected to the higher pressure column to sense a level of the crude liquid oxygen column bottoms in the higher pressure column and to generate a level signal referable to the level of the crude liquid oxygen column bottoms; and
a level controller is responsive to the level signal and configured to generate the flow rate set points such that the flow rate set points decrease as the level of the crude liquid oxygen bottoms decreases and vice-versa and the level is maintained at a constant height within the higher pressure column.
5. The argon condensation system of claim 3 wherein:
temperature transducers are positioned to sense temperatures of the partially vaporized crude liquid oxygen streams that are indicative of quality of the partially vaporized crude liquid oxygen streams; and
the controller for controlling the feed stream flow rate are responsive to the temperature transducers such that feed stream flow rate and product flow rate decreases when the temperatures of the partially vaporized crude liquid oxygen streams are above a predetermined level indicative of dry out within the vaporization passages.
6. The argon condensation system of claim 5, wherein the crude liquid oxygen flow controllers are responsive to the temperature transducers such that when the temperatures are unequal, the flow rate set points are biased so as to maintain the temperatures at an equal level.
7. The argon condensation system of claim 1 wherein phase separator is disposed at a prescribed height above the once-through heat exchangers such that the liquid level in the phase separator provides the liquid head required to drive flow of the crude liquid oxygen streams through the once-through heat exchangers.
8. The argon condensation system of claim 1 wherein the pressure in the phase separator is maintained at a pressure above the pressure of the lower pressure column and at or above the pressure required to drive flow of the crude liquid oxygen streams through the heat exchangers.
9. The argon condensation system of claim 1 wherein phase separator is disposed at a prescribed height relative to the once-through heat exchangers and the phase separator is maintained at a prescribed pressure such that the liquid head in the phase separator combined with the maintained pressure of the phase separator drives the flow of the crude liquid oxygen through the heat exchangers.
10. The argon condensation system of claim 1 wherein the one or more partially vaporized crude liquid oxygen streams exiting the plurality of once-through heat exchangers each comprise about 10% or more crude liquid oxygen so as to prevent dry-out within the vaporization passages of the heat exchangers.
11. The argon condensation system of claim 1 wherein the one or more partially vaporized crude liquid oxygen streams exiting the plurality of once-through heat exchangers collectively comprise about 20% or more crude liquid oxygen so as to prevent dry-out within the vaporization passages of the once-through heat exchangers.
12. The argon condensation system of claim 1 wherein the vaporization surface areas of the once-through heat exchangers are of equal size.
13. A method of condensing argon reflux within an air separation unit having an argon column, a lower pressure column and a higher pressure column, said method comprising the steps of:
condensing argon-rich vapor streams within condensation passages of a plurality of once-through heat exchangers connected to the argon column such that argon-rich vapor streams composed of argon-rich vapor column overhead are condensed within condensation passages of the once-through heat exchangers to produce an argon-rich liquid product stream and an argon-rich liquid reflux stream that is returned to the argon column as reflux, the argon-rich vapor column overhead being produced through distillation of a crude argon feed stream fed from the lower pressure column to the argon column;
partially vaporizing a stream of crude liquid oxygen column bottoms from the higher pressure column as it is directed toward the plurality of once-through heat exchangers;
separating the partially vaporized crude oxygen feed stream in a phase separator into at least one crude oxygen vapor stream and one or more crude liquid oxygen streams;
introducing the one or more crude liquid oxygen streams from the phase separator into vaporization passages of the plurality of once-through heat exchangers to partially vaporize the crude liquid oxygen streams through indirect heat exchange with the argon-rich vapor streams;
directing the partially vaporized crude liquid oxygen streams produced in the vaporization passages of the plurality of once-through heat exchangers into the lower pressure column; and
directing the at least one separated crude oxygen vapor stream from the phase separator into the lower pressure column.
14. The method of claim 13 further comprising the steps of:
sensing liquid flow rates of the crude liquid oxygen column bottoms from the higher pressure column at locations downstream of the higher pressure column and upstream of the phase separator where the crude liquid oxygen column bottoms stream is in a substantially liquid state;
controlling the liquid flow rates of the crude liquid oxygen column bottoms from the higher pressure column such that the liquid flow rates of the crude liquid oxygen streams are in proportion to vaporization surface areas provided by the vaporization passages of each of the one-through heat exchangers;
controlling a feed stream flow rate of the crude argon feed stream in response to an air flow rate into the air separation unit; and
controlling a product flow rate of the argon-rich liquid product stream in response to the feed stream flow rate of the crude argon feed stream.
15. The method of claim 14 further comprising the steps of:
sensing temperatures of the partially vaporized crude liquid oxygen streams that are indicative of quality of the partially vaporized crude liquid oxygen streams; and
controlling the crude argon feed stream flow rate in response to the sensed temperature of the partially vaporized crude liquid oxygen streams wherein the crude argon feed stream flow rate and argon product flow rate decrease when the temperatures of the partially vaporized crude liquid oxygen streams are above a predetermined level indicative of dry out within the vaporization passages of the once through heat exchangers.
16. The method of claim 13 wherein the liquid level in the phase separator is maintained at a prescribed level to provide the liquid head required to drive flow of the crude liquid oxygen streams through the once-through heat exchangers.
17. The method of claim 13 wherein the pressure in the phase separator is maintained at a prescribed level required to drive flow of the crude liquid oxygen streams through the once-through heat exchangers.
18. The method of claim 13 wherein the liquid level in the phase separator and the pressure in the phase separator are maintained at prescribed levels to drive flow of the crude liquid oxygen streams through the once-through heat exchangers.
19. The method of claim 14 wherein the liquid flow rates of the crude liquid oxygen column bottoms from the higher pressure column are controlled such that the one or more partially vaporized crude liquid oxygen streams exiting the plurality of once-through heat exchangers each comprise about 10% or more crude liquid oxygen so as to prevent dry-out within the vaporization passages of the once-through heat exchangers.
20. The method of claim 14 wherein the liquid flow rates of the crude liquid oxygen column bottoms from the higher pressure column are controlled such that the one or more partially vaporized crude liquid oxygen streams exiting the plurality of once-through heat exchangers collectively comprise about 20% or more crude liquid oxygen so as to prevent dry-out within the vaporization passages of the once-through heat exchangers.