Methods and systems for providing control stability in a vacuum generation system using an override proportional-integral-derivative (PID) controller

Abstract

Certain embodiments provide a vacuum generation system having an override PID controller, a proportional valve, and a vacuum generator. The override PID controller allows the vacuum generation system to control an operating range of supply air pressure provided to the vacuum generator. By controlling the operating range of supply air pressure, the vacuum generation system is able to avoid entering a decreasing region or non-monotonic region of the vacuum generator.

Description

[0001] CLAIM OF PRIORITY

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 077,757, filed September 14, 2020, entitled “METHODS AND SYSTEMS FOR PROVIDING CONTROL STABILITY IN A VACUUM GENERATION SYSTEM USING AN OVERRIDE PROPORTIONAL-INTEGRAL-DERIVATIVE (PID) CONTROLLER,” having inventor Brian T. Chiem, the entirety of which is incorporated by reference herein as if fully set forth herein. TECHNICAL FIELD

[0003] The present disclosure relates generally to methods and systems for providing control stability in a vacuum generation system using an override proportional-integral-derivative (PID) controller. BACKGROUND

[0004] During small incision surgery, particularly during ophthalmic surgery, a small probe is inserted into a surgical site to cut, remove, or otherwise manipulate tissue. During these surgical procedures, fluid and tissue can be aspirated from the surgical site.

[0005] Examples of ophthalmic surgery in which fluid and tissue are aspirated include vitreoretinal surgery. Vitreoretinal surgery can include various procedures performed to restore, protect, and enhance vision. Vitreoretinal surgery can be indicated for the treatment of many serious disorders of the back of the eye. Vitreoretinal surgery can treat disorders such as age-related macular degeneration (AMD), diabetic retinopathy and diabetic vitreous hemorrhage, macular hole, retinal detachment, epiretinal membrane, CMV retinitis, and many other ophthalmic disorders. To treat certain disorders of the back of the eye, a vitrectomy can be performed first as part of an ongoing vitreoretinal surgery by a physician. Vitrectomy refers to surgical removal of the vitreous, which is a clear, gel-like substance in the center of the eye. The vitreous can occupy about two-thirds of the volume of the eye, giving it shape and form before birth.

[0006] Removal of the vitreous can involve a vitreous cutter (also referred to as a “cutter” or “vitreous cutter”). In some examples, the vitreous cutter can be powered by a pneumatic vitreous cutter machine (e.g., a “surgical console”) that includes one or more pneumatic valves (also referred to as drive valves). In such examples, the vitreous cutter can work like a microkeratome, with an oscillating microcutter used to remove the vitreous gel in a controlled manner. In some other examples, the vitreous cutter can use a laser or some other technology such as ultrasound to cut the vitreous. In addition to cutting the vitreous, the cutter can also be configured to aspirate the vitreous cut away by surgery. The aspiration can be provided by a vacuum generator (e.g., a Venturi vacuum) that is coupled to the cutter by a tube that provides an aspiration passageway.

[0007] Other examples of ophthalmic surgery in which fluids and tissue are aspirated include phacoemulsification, which refers to a cataract surgery in which a diseased lens is emulsified and aspirated from the lens capsule. In some examples, a phacoemulsification probe can break up the lens by ultrasound (or other technology, such as a laser, etc.). To aspirate the broken-up lens, the phacoemulsification probe can be powered by a vacuum generator (e.g., a Venturi vacuum) that is coupled to the phacoemulsification probe by a tube that provides an aspiration passageway.

[0008] Certain existing vacuum generators, such as certain existing Venturi vacuum generators, operate using a flow of compressed air through an orifice to create a vacuum pressure. However, one common characteristic of these vacuum generators is that beyond a certain amount of supply pressure, as the supply pressure increases, the vacuum generator becomes less efficient and the vacuum pressure generated becomes smaller. For example, the vacuum pressure increases as the supply air pressure increases in the range of 0-60 psig (pounds per square inch gauge). However, as the supply air pressure increases in the range of 60-87 psig, the vacuum pressure starts to decrease. More specifically, when the supply air pressure reaches around 60 psig or higher, for example, the vacuum pressure starts to decrease, causing a standard PID controller used to regulate the supply air pressure to become unstable. In such examples, the vacuum generator can be referred to as operating in a monotonic region when the supply air pressure is in the range of 0-60 psig. On the other hand, the vacuum generator can be referred to as operating in a non-monotonic region or a decreasing region when the supply air pressure is higher than 60 psig, for example. While 60 psig is used in the above example, it should be understood that other supply air pressure values can also be considered. SUMMARY

[0009] The present disclosure relates generally to methods and systems for providing control stability in a vacuum generation system using an override proportional-integral-derivative (PID) controller.

[0010] Certain embodiments provide a method of controlling a vacuum pressure in a vacuum generation system. The method includes receiving a vacuum pressure sensor reading of a vacuum pressure sensor. The method further includes calculating a first error between the vacuum pressure sensor reading and a vacuum pressure setpoint. The method further includes calculating a first voltage level for controlling a proportional valve based on the first error. The method further includes receiving a supply air pressure sensor reading of a supply air pressure sensor. The method further includes calculating a second error between the air pressure sensor reading and a supply air pressure setpoint. The method further includes calculating a second voltage level for controlling the proportional valve based on the second error. The method further includes determining a lower voltage level of the first voltage level and the second voltage level. The method further includes providing the lower voltage level to the proportional valve. The method further includes providing, using the proportional valve, a supply air pressure to a vacuum generator based on the lower voltage level. The method further includes providing, using the vacuum generator, a vacuum pressure to a surgical tool based on the supply air pressure.

[0011] Certain embodiments provide a vacuum generation system. The vacuum generation system includes a first proportional-integral-derivative (PID) controller configured to receive a first error between a vacuum pressure sensor reading associated with a vacuum generator and a vacuum pressure setpoint and calculate a first voltage level for controlling a proportional valve based on the first error. The vacuum generation system further includes a second PID controller configured to receive a second error between a supply air pressure sensor reading and a supply air pressure setpoint and calculate a second voltage level based on the second error. The vacuum generation system includes determining a lower voltage level of the first voltage level and the second voltage level. The vacuum generation system further includes a proportional valve configured to receive the lower voltage level and cause a supply air pressure to be provided to the vacuum generator based on the voltage level. The vacuum generation system further includes a vacuum generator configured to provide a vacuum pressure to a surgical tool based on the supply air pressure.

[0012] Certain embodiments provide a vacuum generation system comprising: a memory comprising executable instructions; a processor in data communication with the memory and configured to execute the instructions, the processor configured to: receive a first error between a vacuum pressure sensor reading associated with a vacuum generator and a vacuum pressure setpoint; calculate a first voltage level based on the first error; receive a second error between a supply air pressure sensor reading and a supply air pressure setpoint; calculate a second voltage level based on the second error; determine a lower voltage level of the first voltage level and the second voltage level and provide the lower voltage level to a proportional valve. The vacuum generation system further comprises the proportional valve configured to cause a supply air pressure to be provided to the vacuum generator based on the lower voltage level. The vacuum generation system further comprises the vacuum generator configured to provide a vacuum pressure to a surgical tool based on the supply air pressure.

[0013] The following description and associated drawings set forth certain illustrative features of one or more embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings are only intended to depict examples of certain embodiments of the present disclosure and therefore should not be thought to limit the scope of the present disclosure.

[0015] Figure 1 FIGURE 1 illustrates an exemplary surgical console in accordance with certain embodiments.

[0016] Figure 2 FIGURE 2 illustrates an exemplary vitrectomy probe in accordance with certain embodiments.

[0017] Figure 3 FIGURE 3 illustrates a side view of the vitrectomy probe of Figure 2 FIGURE 4 illustrates an exemplary cutting mechanism of the vitrectomy probe of

[0018] Figure 4 FIGURE 5 illustrates a side view of the vitrectomy probe of Figure 2 FIGURE 6 illustrates a prior art vacuum generation system in accordance with certain embodiments.

[0019] Figure 5 FIGURE 7 illustrates an exemplary schematic vacuum generation system with an override PID controller in accordance with certain embodiments.

[0020] FIGURE 6 illustrates a prior art vacuum generation system in accordance with certain embodiments.

[0021] Figure 7 FIGURE 7 illustrates an exemplary schematic vacuum generation system with an override PID controller in accordance with certain embodiments.

[0022] Figure 8 FIGURE 7 illustrates an exemplary schematic vacuum generation system with an override PID controller in accordance with certain embodiments. FIGURE 7 illustrates an exemplary schematic vacuum generation system with an override PID controller in accordance with certain embodiments.

[0023] Figure 9 FIG. 1 illustrates an exemplary schematic vacuum generating system having an override PID controller, in accordance with certain embodiments.

[0024] Figure 10 FIG. 1 illustrates an exemplary schematic vacuum generating system having an override PID controller, in accordance with certain embodiments. Figure 8 exemplary operation of the vacuum generating system of FIG. 1.

[0025] For ease of understanding, the same reference numbers will be used in different drawings to designate the same or similar elements. It is contemplated that elements and features of one embodiment can be beneficially incorporated into other embodiments without further recitation. DETAILED DESCRIPTION

[0026] While features of the present disclosure can be discussed with respect to certain embodiments and drawings below, one or more of the advantageous features discussed herein can be incorporated into all embodiments of the application. In other words, while one or more embodiments can be discussed as having certain advantageous features, one or more of such features can be used in accordance with the various embodiments discussed herein. In a similar manner, while exemplary embodiments can be discussed below as devices, instruments or methods, it is contemplated that such exemplary embodiments can be implemented in various devices, instruments and methods.

[0027] Figure 1 FIG. 1 illustrates an exemplary schematic vacuum generating system having an override PID controller, in accordance with certain embodiments.

[0028] The surgical console 101 can include a display 109 for displaying information to a user (which display can also incorporate a touch screen for receiving user input). The surgical console 101 can also include a vacuum generator coupled to the port 107. The tool 103 is operably coupled to the vacuum generator by a tubing 105 connected to the port 107. The vacuum generator creates a vacuum at the tip of the tool 103, which causes surgically cut or emulsified material or tissue to be drawn into the tool 103 with the vacuum and transported along the tubing 105 to the surgical console 101. It should be noted that the tubing 105 can represent a plurality of tubes that can couple the tool 103 with the surgical console 101. For example, the tubing 105 can represent pneumatic tubing or fiber optic cables for powering the tool 103 for cutting purposes as well as suction tubing or vacuum tubing for transporting the suctioned material back to the surgical console 101.

[0029] Figure 2 and Figure 3 respectively illustrate perspective and side views of an exemplary vitreous cutter 203 in accordance with certain embodiments described herein. Thus, for the sake of clarity, the following description Figure 2 and Figure 3 The vitreous cutter 203 is an example of the tool 103. As depicted in Figure 2 and Figure 3 The vitreous cutter 203 includes a probe 210 and a base unit 220. The probe 210 is partially and longitudinally threaded through a distal end 221 of the base unit 220 and can be directly or indirectly attached to the distal end within an internal chamber of the base unit 220. The probe 210 can be inserted into an eye for vitreous cutting. It should be noted that as described herein, a distal end or distal portion of a component refers to an end or portion that is closer to a patient’s body during its use. On the other hand, a proximal end or proximal portion of a component refers to an end or portion that is further away from a patient’s body.

[0030] The base unit 220 further provides a port 223 at its proximal end 225 for one or more supply tubing to be laid into the internal chamber of the base unit 220. In certain embodiments, the port 223 can represent two or more ports. In certain embodiments, the port 223 can provide the base unit 220 with a tube or vacuum tubing (e.g., a tube or vacuum tubing of the vacuum generator in the surgical console 101) for creating a vacuum at the tip of the probe 210. In certain embodiments, the port 223 can provide the base unit 220 with a tube or vacuum tubing for creating a vacuum at the tip of the probe 210 and a tube or vacuum tubing for transporting the suctioned material back to the surgical console 101. Figure 1port 223 can provide a connection to a fiber optic cable coupled to one or more laser sources (e.g., in the surgical console 101) to provide a laser used by the vitreous cutter 203 to cut vitreous. In certain embodiments, the port 223 can provide a connection to a pneumatic line coupled to a pneumatic module (e.g., in the surgical console 101) that uses compressed gas, such as nitrogen, to power the vitreous cutter 203 to cut vitreous. It should be noted that other techniques, as would be appreciated by one of ordinary skill in the art, can be used to power the vitreous cutter 203. As described in further detail below, the vitreous cutter 203 includes a cutting port 216 at a distal portion of the probe 210. In certain embodiments, the vitreous cutter 203 is capable of cutting vitreous and aspirating vitreous through this port 216. Figure 4 Further described below, the vitreous cutter 203 includes a cutting port 216 at a distal portion of the probe 210. In certain embodiments, the vitreous cutter 203 is capable of cutting vitreous and aspirating vitreous through this port 216.

[0031] Figure 4 FIGS. 1-4 illustrate examples of cutting mechanisms used by the vitreous cutter 203 in conjunction with Figure 2 and Figure 3 More specifically, Figure 4 FIG. 4 illustrates a distal end of the probe 210 of the vitreous cutter 203 that houses a probe cutter 425 used as a cutting device. The probe cutter 425 reciprocates within the probe 210. In certain embodiments, the probe cutter 425 is a hollow tube with a sharp tip. In certain embodiments, the probe cutter 425 includes a cutter port that is similar to and interacts with the cutter port 216 of the probe cutter 425 to improve cutting efficiency and effectiveness. As the probe cutter 425 moves back and forth, the probe cutter 425 can alternately open and close the cutter port 216 with the sharp tip of the probe cutter 425. Each cycle of the probe cutter 425 through the distal end of the probe 210 can cut through material (such as vitreous) in the cutter port 216 as the probe cutter 425 is closing. The surgically cut vitreous is then aspirated through the probe 210. In certain embodiments, the surgically cut vitreous is aspirated from a circular area between an outer surface of the probe cutter 425 and an inner surface of the probe 210. In certain embodiments, additionally or instead, the surgically cut vitreous is aspirated through the probe cutter 425 (e.g., through a hollow compartment therein).

[0032] It should be noted that Figure 2 and Figure 3 only one example of a vitreous cutter is illustrated. Also, Figure 4Only one example of a cutting mechanism that can be used as part of a vitreous cutter is illustrated. As noted above, a laser or other mechanism can be used instead. Further, the tool 103 can be a phacoemulsification probe, such as Figure 5 the phacoemulsification probe shown in FIG. 5.

[0033] Figure 5 An exemplary phacoemulsification probe 503 is illustrated, which includes a handpiece body 520 and a probe 510 that can be inserted into an eye for phacoemulsification. A cutting tip 516 extends beyond a distal end of the probe 510. The cutting tip 516 is a hollow cylindrical tube or shaft that propagates ultrasonic waves provided by an ultrasonic power line 524. The ultrasonic waves emulsify the lens. The cutting tip 516 also provides an aspiration port 518 through which emulsified lens is aspirated due to vacuum pressure provided by an aspiration line 523. The probe 510 also has an irrigation port for irrigating the lens during phacoemulsification. It should be noted that, Figure 5 Only one example of a phacoemulsification probe is illustrated. Also, Figure 5 Only one example of an emulsification mechanism that can be used as part of a phacoemulsification probe is illustrated.

[0034] As noted above, some existing vacuum generators that can be used to enable the tool 103 (e.g., the vitreous cutter 203, the phacoemulsification probe 503, etc.) to aspirate material from a surgical site (e.g., a patient's eye) operate using compressed air flowing through an orifice to create a vacuum pressure. However, one common characteristic of these vacuum generators is that beyond a certain amount of supply air pressure, as the supply air pressure increases, the vacuum generator becomes less efficient and the vacuum pressure generated becomes smaller. FIG. 6 illustrates exemplary operation of these vacuum generators.

[0035] FIG. 6 illustrates a high-level diagram that illustrates operation of an exemplary prior art vacuum generation system 600. As shown, the vacuum generation system 600 includes a vacuum generator 650, such as a Venturi vacuum, that generates a vacuum pressure. As noted above, the vacuum generation system 600 can be positioned in a surgical console (e.g., the surgical console 101) that is coupled to the tool 103. As such, the vacuum pressure provided by the vacuum generation system 600 can be used for the aspiration processes described above. The vacuum generation system 600 also includes a proportional valve 652. The vacuum generator 650 takes as input supply air and generates a vacuum having a certain vacuum pressure 657, the pressure of which (i.e., the supply air pressure 651) is set by the proportional valve 652. In certain embodiments, the vacuum generator 650 is a Venturi vacuum generator that generates a vacuum by the supply air flowing through a pump. Those of ordinary skill in the art are aware of the internal workings of a Venturi vacuum generator, and thus, for the sake of brevity, details related to such internal workings are not described herein.

[0036] As described above, the proportional valve 652 sets the supply air pressure 651 of the supply air provided to the vacuum generator 650. The proportional valve provides a change in output pressure or flow at the same ratio as the change in input. For example, if the input is doubled, the output will also double. In FIG. 6, the proportional valve 625 is operatively coupled to an air compressor or air source reservoir 658. The proportional valve 625 takes compressed air as input and adjusts the pressure (by providing less or more air) based on the input voltage 653 provided to the proportional valve 652. The higher the voltage 653, the higher the supply air pressure 651. The vacuum generation system 600 further includes a PID controller 654 for controlling the vacuum pressure 657. Generally, the PID controller provides a calculation for driving an actuator (e.g., the proportional valve 652) based on an error amount of an error trend (calculated as the difference between a desired setpoint and a last sensor reading), an integral, and a derivative.

[0037] To illustrate the operation of the PID controller 654 with a simple example, the PID controller 654 takes as input an error value corresponding to the difference between the current vacuum pressure and the vacuum pressure setpoint 656. The PID controller 654 then calculates the derivative and the integral of this error value with respect to time. Based on such calculations, the PID controller 654 then provides an output (e.g., in the form of a voltage value). The output can be calculated in different ways as would be appreciated by one of ordinary skill in the art. In one example, the output can equal a proportional gain (Kp) times the magnitude of the error plus an integral gain (Ki) times the integral of the error plus a derivative gain (Kd) times the derivative of the error. P i d

[0038] The vacuum pressure setpoint 656 refers to some vacuum pressure that a user of the corresponding tool 103 (e.g., the vitreous cutter 203, the phacoemulsification probe 503, etc.) can desire. The user can change the vacuum pressure setpoint 656 by providing input to the surgical console 101 through a graphical user interface displayed on the display 109 of the surgical console 101, a foot pedal of the surgical console 101, or through some other mechanism. The current vacuum pressure refers to the last sensor reading of the vacuum pressure provided by the vacuum pressure sensor 659 to the PID controller 654. For example, the vacuum pressure sensor 659 can sense the current vacuum pressure periodically or continuously.

[0039] ​​​Accordingly, the PID controller 654 periodically or continuously calculates an amount of voltage 653 that should be provided to the proportional valve 652 (e.g., using a drive circuit) to help the vacuum generating system 600 eventually reach the vacuum pressure setpoint 656. As noted above, the higher the voltage 653, the higher the supply air pressure 651, and thus the higher the vacuum pressure 657. As such, by controlling the voltage 653 based on the error calculated by the PID controller 654, the vacuum generating system 600 is able to control the vacuum pressure 657.

[0040] However, in the vacuum generating system 600, beyond a certain amount of supply air pressure 651, as the supply air pressure increases 651, the vacuum generator 650 becomes less efficient and the resulting vacuum pressure 657 becomes smaller.

[0041] Figure 7 A vacuum generation performance graph 700 for a prior art vacuum generating system, such as the vacuum generating system 600, is illustrated. As shown in the graph 700, the vacuum pressure (measured in mmHg, which refers to millimeters of mercury) increases as the supply air pressure increases in a range from 0 to a certain threshold (e.g., 60 psig (pounds per square inch gauge)). However, as the supply air pressure increases above the threshold, the vacuum pressure begins to decrease. For example, as the supply air pressure reaches and increases above about 60 psig, the vacuum pressure begins to decrease, causing a standard PID controller (e.g., the PID controller 654) to drive unstable. It should be noted that 60 psig is just an example, and the threshold can be different for different vacuum generators. For example, the supply air pressure setpoint can be in a range of about 40 psig to 60 psig.

[0042] Accordingly, if the system reaches the decreasing region or non-monotonic region (e.g., 60-87 psig), using a single PID controller (such as in the manner described in connection with vacuum generation system 600) can cause vacuum generation system 600 to become unstable. For example, in such a case, PID controller 654 senses that vacuum pressure 657 is lower than vacuum pressure setpoint 656, which causes PID controller 654 to increase voltage 653. The increased voltage causes proportional valve 652 to open even more, allowing more supply air (i.e., higher supply air pressure 651), which causes vacuum generator 650 to lower vacuum pressure 657 even more. The additional lowering of vacuum pressure 657 causes PID controller 654 to again increase voltage 653, and the cycle repeats. In such a case, vacuum generation system 600 is driven to its limits and becomes unstable. To recover from this instability, vacuum pressure setpoint 656 must be lowered below current vacuum pressure 657, which causes PID controller 654 to lower voltage 653 until vacuum generation system 600 returns to the monotonic region (e.g., 0-60 psig of supply air pressure). As such, vacuum generation system 600 can experience an initial increase and then decrease in vacuum pressure until the vacuum pressure setpoint 656 is reached. As a result, in the above-described case, vacuum generation system 600 can perform sluggishly or slowly in reaching the desired vacuum pressure setpoint.

[0043] Accordingly, certain embodiments described herein relate to a vacuum generation system having a first PID controller and a second override PID controller, which correspond to a first feedback loop and a second feedback loop in parallel with the first feedback loop, respectively. The first PID controller is configured to perform calculations based on an error between a current vacuum pressure and a vacuum pressure setpoint, while the second override PID controller is configured to perform calculations based on an error between a current supply air pressure and a supply air pressure setpoint. The calculations performed by the first and second feedback loops are then compared to determine a lower or minimum voltage for driving the vacuum generation system.

[0044] Figure 8A high-level diagram is illustrated, showing exemplary operation of the vacuum generation system 800, in accordance with certain embodiments. As shown, the vacuum generation system 800 includes a first feedback loop 810 having a first PID controller 868 configured to take as input a first loop vacuum pressure error (“first loop error”) 880, which corresponds to a difference between a current vacuum pressure 857 (corresponding to a latest sensor reading provided by the vacuum pressure sensor 659) and a vacuum pressure setpoint 656. Using the first loop error 880, the first PID controller 868 is then configured to calculate a derivative and an integral of the first loop error 880 with respect to time. The first PID controller 868 further uses the first loop error to calculate a proportional term. Based on such calculations, the PID controller 868 is configured to provide as output a first voltage 886, which corresponds to a control value for minimizing the difference between the current vacuum pressure 857 and the vacuum pressure setpoint 656.

[0045] The vacuum generation system 800 further includes a second feedback loop 820 having a second override PID controller 866 taking as input an override loop error 884, where the override loop error 884 corresponds to a difference between a supply air pressure setpoint 882 (as determined or provided by a user) and a current supply air pressure 851. The current supply air pressure 851 corresponds to a latest sensor reading provided by the supply air pressure sensor 860. In certain embodiments, the supply air pressure setpoint 882 can be set in a range of 0-60 psig (e.g., corresponding to a monotonic region of the vacuum generator 650). For example, the supply air pressure setpoint 882 can be set to a maximum supply air pressure (e.g., 60 psig, which can be unchanging (e.g., constant) or static during use) that corresponds to a maximum vacuum pressure of the monotonic region of the vacuum generator 650. As further described below, limiting the range of the supply air pressure helps to ensure stability of the vacuum generation system 800.

[0046] Using the override loop error 884, the override PID controller 866 is then configured to calculate a derivative and an integral of the override loop error 884 with respect to time. The override PID controller 866 further uses the override loop error 884 to calculate a proportional term. Based on such calculations, the override PID controller 866 is configured to determine as output a second voltage 890, which corresponds to a control value for minimizing the difference between the current supply air pressure 851 and the supply air pressure setpoint 882.

[0047] The minimum control force analyzer 894 compares the first voltage 886 computed by the first PID controller 868 and the second voltage 890 computed by the override PID controller 866 to determine a minimum voltage 898 corresponding to the lower voltage level of the first voltage 886 and the second voltage 890. The minimum voltage 898 is then provided to the proportional valve 652, which then sets the supply air pressure 851 based on the provided minimum voltage 898. As previously mentioned, the vacuum generator 650 takes the supply air as input and generates a vacuum having a certain vacuum pressure 857, the pressure of which (i.e., the supply air pressure 851) is set by the proportional valve 652. In some embodiments, an integral value calculated by the loop using the lower voltage level (i.e., the integral value determined by the first PID controller 868 if the first voltage 886 is less than the second voltage 890, or the integral value determined by the override PID controller 866 if the second voltage 890 is less than the first voltage 886) is provided to the first PID controller 868 and the override PID controller 866 for use as the integral value at the next voltage computation.

[0048] The use of both the first PID controller 868 and the override PID controller 866 at the same time allows the vacuum generation system 800 to control the vacuum pressure 857 by limiting the range of the supply air pressure 851 provided into the vacuum generator 650, thereby eliminating or reducing the likelihood of the vacuum generator 650 operating in its decreasing and non-monotonic range. More specifically, the first PID loop involving the first PID controller 868 uses vacuum pressure feedback including the current vacuum pressure 857 (e.g., the primary parameter) and the desired vacuum pressure setpoint 656 to output the first voltage 886. On the other hand, the override PID loop involving the override PID controller 866 employs the supply air pressure setpoint 882 and supply air pressure feedback including the current supply air pressure 851 (e.g., the secondary parameter) to output the second voltage 890.

[0049] In operation, in certain embodiments, the first feedback loop 810 generally controls the vacuum generating system 800 when the supply air pressure 851 is below the supply air pressure setpoint 882 (e.g., 60 psig). In such examples, the first voltage 886 generated by the first PID controller 868 is lower than the second voltage 890 generated by the override PID controller 866 and is provided to the proportional valve 652 to control the supply air pressure 851. However, when the supply air pressure 851 approaches, equals, or exceeds the supply air pressure setpoint 882, the second feedback loop 820 takes over control of the vacuum generating system 800 by providing the second voltage 890 to the proportional valve 652 at a point lower than the first voltage 886. Thus, the second feedback loop 820 functions to monitor the supply air pressure 851 and take over control of the system 800 from the first feedback loop 810 when the supply air pressure 851 approaches, equals, or exceeds the supply air pressure setpoint 882, thereby preventing the vacuum generating system 800 from entering a non-monotonic region or minimizing the amount of time the vacuum generating system 800 operates in a non-monotonic region. Further, by utilizing the minimum control effort analyzer 984, there is a seamless transition between control by the first feedback loop 810 and the second feedback loop 820.

[0050] Accordingly, in certain embodiments, due to transient effects, the vacuum generating system 800 can enter a non-monotonic region as a result of the supply air pressure 851 exceeding the supply air pressure setpoint 882. In such cases, the second feedback loop 820 becomes the active controller to drive the vacuum generating system 800 back towards the supply air pressure setpoint 882, thereby making the presence of the vacuum generating system 800 in the non-monotonic region temporary, rather than permanent. In other words, in the non-monotonic region, the second voltage 890 can be greater than the first voltage 886 for a short period of time, but the override PID controller 866 will quickly lower the second voltage 890 so that the second feedback loop 820 takes control and the proportional valve 652 will lower the supply air pressure 851 until the supply air pressure reaches the supply air pressure setpoint 882.

[0051] In other words, as described herein, the simultaneous use of the first PID controller 868 and the override PID controller 866 allows the vacuum generating system 800 to control the operating range of a secondary parameter (e.g., supply air pressure) based on which the vacuum generating system 800 is able to avoid entering a decreasing or non-monotonic region of the vacuum generator 650. Preventing the vacuum generating system 800 from experiencing unintended suction and entering a decreasing and non-monotonic region of the vacuum generator 650 improves the performance responsiveness (e.g., performance speed) of the vacuum generating system 800 because the system does not need to recover from instability.

[0052] It is further noted that the override PID controller designs described herein can be implemented in various other systems that operate with a primary parameter (e.g., vacuum pressure) and a secondary parameter (e.g., supply air pressure) such that the primary parameter is calculated based on the secondary parameter. By implementing the override PID controller designs described herein in such systems, the secondary parameter can be controlled based on a minimum output (e.g., voltage value) corresponding to the smaller of a first output (e.g., first voltage 886) and a second output (e.g., second voltage 890), where the first output is calculated based on a current primary parameter (e.g., vacuum pressure 857) and a primary parameter setpoint (e.g., vacuum pressure setpoint 656), and the second output (e.g., second voltage 890) is calculated based on a current secondary parameter (e.g., supply air pressure 851) and a secondary parameter setpoint (e.g., supply air pressure setpoint 882).

[0053] In other words, any system that operates with primary and secondary parameters like those described above can benefit from the override PID controller designs described herein.

[0054] It is further noted that the ranges set forth herein for inputs, outputs, or setpoints are exemplary. In other words, these ranges can be adjusted based on manufacturing and / or user preferences, as well as the types and characteristics of the system components. For example, a vacuum generating system can use a vacuum generator that enters a non-monotonic operating range when the supply air pressure reaches 90 psig. In this case, the range for the supply air pressure setpoint can be defined as 0-90 psig. In another example, a different type of vacuum generator can enter its non-monotonic operating range when the supply air pressure reaches 40 psig. In this case, the range for the supply air pressure setpoint can be defined as 0-40 psig. Other ranges for inputs, outputs, or setpoints can be similarly changed depending on the above factors, as well as other factors as would be appreciated by one of ordinary skill in the art.

[0055] It should also be noted that while two feedback loops are described above, more than two feedback loops can be used in combination. For example, the vacuum generation system 800 can further include a third feedback loop having a second override PID controller configured to take as input a third loop error corresponding to a difference between the current supply air pressure and a second supply air pressure setpoint (determined or provided by the user). In certain embodiments, the second supply air pressure setpoint can be set to a minimum supply air pressure corresponding to a minimum vacuum pressure of the monotonic region of the vacuum generator 650 (e.g., which can be constant during use). Using the third loop error, the second override PID controller can be configured to determine a third voltage as output, which the maximum control force analyzer can then compare to the first voltage 886 before the minimum control force analyzer 894 or to the minimum voltage 898 after the minimum control force analyzer 894. Upon comparison, the maximum control force analyzer can then provide as output the higher of the two interval voltage levels (e.g., the maximum). Accordingly, a minimum operating range of the vacuum generation system 800 can be established with the same system architecture but including an additional feedback loop. In some embodiments, using the second override loop can not require the use of a minimum output. For example, a minimum comparator can be used between the vacuum pressure and the first override loop, and a maximum comparator can be used between the result of the minimum comparator and the output of the second override loop. In some embodiments, the same sensors can be used. For example, when using supply pressure, the second override loop can be used to prevent the supply air pressure from being too low or too high.

[0056] As will be appreciated by one of ordinary skill in the art, the vacuum generation system 800 can have a variety of implementations. For example, in certain embodiments, all of the components of the system can be configured for digital communication. In such embodiments, the use of digital-to-analog converters (DACs) or analog-to-digital converters (ADCs) can not be required. In certain other embodiments, all of the components of the system can be analog. Similarly, in such embodiments, the use of digital-to-analog converters (DACs) or analog-to-digital converters (ADCs) can not be required. In certain other embodiments, some of the components of the system can be analog and some other components can be digital. For example, in certain other embodiments, the first PID controller 868, the override PID controller 866, and the minimum control force analyzer 894 can correspond to software instructions that can be retrieved from memory and then executed by a processor. In such embodiments, because any output provided by the processor is digital, a digital-to-analog converter (DAC) can be used to allow the processor to communicate with some of the analog components of the system (e.g., the driver circuit, the proportional valve 652, etc.). Similarly, an ADC can be used by certain components, such as the supply air pressure sensor 860 and the vacuum pressure sensor 659, to communicate with the processor.

[0057] Figure 9 A vacuum generation system 900 is illustrated that corresponds to the example implementation of the vacuum generation system 800. The vacuum generation system 900 includes a processor and memory (collectively, "processor and memory 980") to perform the calculations of the first loop error 880 and the override loop error 884 and the PID calculations of the first PID controller 868 and the override PID controller 866. The processor and memory 980 can also calculate the minimum voltage 898 that corresponds to the lesser of the first voltage 886 and the second voltage 890. The processor is configured to fetch and execute programmed instructions stored in the memory. The processor can include a single CPU (central processing unit), multiple CPUs, a single CPU with multiple processing cores, etc. The memory can be one or more readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, solid state, flash memory, magnetic storage, or any other form of local or remote digital storage. In certain embodiments, the memory includes instructions that, when executed by the processor, perform the calculations of the first loop error 880 and the override loop error 884, the PID calculations of the first PID controller 868 and the override PID controller 866, and the calculation of the minimum voltage 898. In certain embodiments, the processor and memory 980 can be the main processor and memory of the surgical console 101, which can implement or include the vacuum generation system 900.

[0058] As described above, one or more DACs and ADCs can be used for communication between the processor and other components in the system. For example, the processor can indicate the calculated minimum voltage value to the interface 862, which can include a DAC as well as a driver circuit. When the driver circuit receives an analog signal from the DAC indicating the calculated minimum voltage value, the driver circuit will provide a corresponding amount of voltage to the proportional valve 652. The use of a DAC and a driver circuit is merely exemplary. Other types of interfaces can alternatively be used as appreciated by one of ordinary skill in the art. Further, in certain embodiments, the supply air pressure sensor 860 and the vacuum pressure sensor 659 are analog components. As such, the supply air pressure sensor 860 can communicate with the processor using an interface 870 that can be an ADC. Similarly, the vacuum pressure sensor 659 can communicate with the processor using an interface 864 that can be an ADC.

[0059] Figure 10 An example operation 1000 of a vacuum generation system according to some embodiments is illustrated. In certain embodiments, the operation 1000 is performed by the vacuum generation system 800 of Figure 8 described herein with reference to Figure 8 and components thereof.

[0060] At 1002, a vacuum generating system (e.g., vacuum generating system 800) receives a vacuum pressure sensor reading of a vacuum pressure sensor (e.g., vacuum pressure sensor 659).

[0061] At 1004, the vacuum generating system calculates a first loop error (e.g., first loop error 880) between the vacuum pressure sensor reading (e.g., vacuum pressure sensor 659) and a vacuum pressure setpoint (e.g., vacuum pressure setpoint 656).

[0062] At 1006, the vacuum generating system calculates (e.g., using a first PID controller 868) a first voltage level for controlling a proportional valve (e.g., proportional valve 652) based on the first loop error.

[0063] At 1008, the vacuum generating system receives a supply air pressure sensor reading of a supply air pressure sensor (e.g., supply air pressure sensor 860).

[0064] At 1010, the vacuum generating system calculates an override loop error (e.g., override error 884) between the supply air pressure sensor reading and a supply air pressure setpoint 882.

[0065] At 1012, the vacuum generating system calculates (e.g., using a second PID controller (e.g., override PID controller 866)) a second voltage level or value for controlling the proportional valve (e.g., proportional valve 652), the second voltage value based on the override loop error.

[0066] At 1014, the vacuum generating system determines a minimum voltage level corresponding to the lower of the first voltage level and the second voltage level. The minimum voltage level is associated with an input of the proportional valve.

[0067] At 1016, the vacuum generating system provides the minimum voltage level to the proportional valve.

[0068] At 1018, the vacuum generating system uses the proportional valve to provide a supply air pressure to a vacuum generator (e.g., vacuum generator 650) based on the minimum voltage level.

[0069] At 1020, the vacuum generating system uses the vacuum generator to provide a vacuum pressure to a surgical tool (e.g., surgical tool 103) based on the supply air pressure. Figure 1 In some embodiments, an integral value calculated by the loop using the lower voltage level (i.e., the integral value determined by the first PID controller 868 if the first voltage 886 is less than the second voltage 890, or the integral value determined by the override PID controller 866 if the second voltage 890 is less than the first voltage 886) is provided to the first PID controller 868 and the override PID controller 866 as the integral value for the next voltage calculation.

[0070] The preceding description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the language of the claims.

[0071] Example Embodiments

[0072] Example 1 : A method of controlling a vacuum pressure in a vacuum generating system, the method comprising: receiving a first parameter sensor reading of a first parameter sensor; calculating a first error between the first parameter sensor reading and a first parameter setpoint; determining a first voltage value based on the calculated first error; receiving a secondary parameter sensor reading of a secondary parameter sensor; calculating a second error between the secondary parameter sensor reading and a secondary parameter setpoint; determining a second voltage value based on the calculated second error; determining a lower value of the first voltage value and the second voltage value; providing an input having the lower value to an actuator; providing, using the actuator, a secondary parameter to a device based on the input.

[0073] Example 2: A method of controlling a vacuum pressure in a vacuum generating system, the method comprising: receiving a first parameter sensor reading of a first parameter sensor; calculating a first error between the first parameter sensor reading and a first parameter setpoint; calculating, using a first proportional-integral-derivative (PID) controller, a first value associated with a first input to an actuator based on the first error; receiving a secondary parameter sensor reading of a secondary parameter sensor; calculating a second error between the secondary parameter sensor reading and a secondary parameter setpoint; calculating, using a second PID controller, a second value associated with a second input to the actuator based on the second error; determining a lower value of the first value and the second value; providing the first input or the second input having the lower value to the actuator; providing, using the actuator, a secondary parameter to a device based on the provided input; providing, using the device, a first parameter based on the secondary parameter to a tool.

[0074] Example 3: The method as recited in the above Example 2, further comprising: receiving a third parameter sensor reading of a third parameter sensor; calculating a third error between the third parameter sensor reading and a third parameter setpoint; calculating, using a third PID controller, a third value associated with a third input to the actuator based on the third error; determining a lowest value of the first value, the second value, and the third value; and providing the first input, the second input, or the third input having the lowest value to the actuator.

[0075] Example 4: The method as recited in Example 3 above, wherein the third parameter is a temperature limit that prevents the proportional valve from overheating by limiting the voltage provided to the proportional valve.

Claims

1. A method for controlling vacuum pressure in a vacuum generating system, the method comprising: Receive vacuum pressure sensor readings from the vacuum pressure sensor; Calculate the first error between the vacuum pressure sensor reading and the vacuum pressure setpoint; A first voltage level for controlling the proportional valve is calculated based on the first error. Receive supply air pressure sensor readings from the supply air pressure sensor; Calculate the second error between the air pressure sensor reading and the supply air pressure setpoint; A second voltage level for controlling the proportional valve is calculated based on the second error; Determine the lower voltage level between the first voltage level and the second voltage level; The proportional valve is supplied with an input voltage level corresponding to the lower voltage level; Using the proportional valve, supply air pressure is provided to the vacuum generator based on the lower voltage level; as well as The vacuum generator is used to provide a vacuum pressure to the surgical instruments based on the supply air pressure.

2. The method as described in claim 1, wherein, A first proportional-integral-derivative controller calculates the first voltage level, and a second proportional-integral-derivative controller calculates the second voltage level.

3. The method as described in claim 2, wherein, The first proportional-integral-derivative (PID) controller determines a first integral value, and wherein the second PID controller determines a second integral value, and wherein the integral value determined by the PID controller using the lower of the first voltage level or the second voltage level is provided to the first PID controller and the second PID controller for use as the integral value for subsequent voltage determination.

4. The method of claim 1, wherein, Calculating the second voltage level based on the second error includes limiting the supply air pressure setpoint to a range corresponding to the monotonic operating range of the vacuum generator.

5. The method of claim 4, wherein, The supply air pressure setpoint is constant, and the supply air pressure setpoint is set to be equal to the maximum supply air pressure within the range.

6. The method of claim 3, wherein, The first proportional-integral-derivative controller is the main driver of the vacuum generating system and drives the vacuum generating system when the first voltage level is lower than the second voltage level.

7. The method of claim 6, wherein, When the second voltage level is less than the first voltage level, the second proportional-integral-derivative controller drives the vacuum generating system.

8. A vacuum generating system, comprising: The first proportional-integral-derivative controller is configured as follows: Receive the first error between the vacuum pressure sensor reading associated with the vacuum generator and the vacuum pressure setpoint; and Calculate the first voltage level based on the first error; The second proportional-integral-derivative controller is configured as follows: Receive a second error between the supply air pressure sensor reading and the supply air pressure setpoint; and Calculate the second voltage level based on the second error; The minimum control force analyzer is configured as follows: Determine the lower voltage level between the first voltage level and the second voltage level; and The lower voltage level is transmitted to the proportional valve; The proportional valve is configured as follows: Based on the lower voltage level, the supply air pressure is provided to the vacuum generator; and The vacuum generator is configured as follows: Vacuum pressure is supplied to the surgical instruments based on the supply air pressure.

9. The vacuum generating system of claim 8, further comprising: A vacuum pressure sensor configured to provide readings from the vacuum pressure sensor; as well as A supply air pressure sensor is configured to provide the supply air pressure sensor reading.

10. The vacuum generating system as claimed in claim 8, wherein, When the supply air pressure is equal to or exceeds the supply air pressure setpoint of the second proportional-integral-derivative controller, the second proportional-integral-derivative controller controls the proportional valve.

11. The vacuum generating system as claimed in claim 10, wherein, The supply air pressure setpoint can be between 40 psig and 60 psig.

12. A vacuum generating system, comprising: Memory, which includes executable instructions; A processor that communicates data with memory and is configured to execute the instructions, wherein the processor is configured as follows: Receive the first error between the vacuum pressure sensor reading associated with the vacuum generator and the vacuum pressure setpoint; Calculate the first voltage level based on the first error; Receive the second error between the supply air pressure sensor reading and the supply air pressure setpoint; Calculate the second voltage level based on the second error; The lower voltage level between the first voltage level and the second voltage level is provided to the proportional valve; The proportional valve is configured as follows: Based on the lower voltage level, the supply air pressure is provided to the vacuum generator; The vacuum generator is configured as follows: Vacuum pressure is supplied to the surgical instruments based on the supply air pressure.

13. The vacuum generating system of claim 12, further comprising: A vacuum pressure sensor configured to provide readings from the vacuum pressure sensor; as well as A supply air pressure sensor is configured to provide the supply air pressure sensor reading.

14. The vacuum generating system as claimed in claim 12, wherein, Calculating the second voltage level based on the second error includes limiting the supply air pressure setpoint to a range corresponding to the monotonic operating range of the vacuum generator.

15. The vacuum generating system as claimed in claim 14, wherein, Calculating the second voltage level based on the second error includes limiting the supply air pressure setpoint to a range of 0-60 psig.

Images