Method and control unit for performing an engine stop of an internal combustion engine

Abstract

Control unit (101) for a vehicle (100); wherein the vehicle (100) comprises an internal combustion engine (102) with a shaft (103, 203) that can be coupled to or disconnected from an electric machine (105); wherein the control unit (101) is configured, in the context of an engine stop of the internal combustion engine (102), - to couple the electric machine (105) with the internal combustion engine (102); - to cause the electric machine (105) to guide the shaft (103, 203) of the internal combustion engine (102); - to determine that a rotational speed of the guided shaft (103, 203) is equal to or less than a rotational speed threshold (304); - in response to this, to decouple the electric machine (105) from the internal combustion engine (102) so that the shaft (103, 203) of the internal combustion engine (102) comes to a standstill without being guided by the electric machine (105); and - during a final intake stroke of the internal combustion engine before standstill, at least one intake valve (204) of at least one cylinder (201) of the internal combustion engine (102) is actuated in order to adjust a gas spring within the cylinder, by which the shaft (103, 203) of the internal combustion engine (102) is turned back to a specific shutdown position (215) of the internal combustion engine (102).

Description

[0001] The invention relates to a method and a corresponding control unit for carrying out an engine stop of an internal combustion engine.

[0002] To enable the starting of an internal combustion engine (e.g., a direct-injection engine) without a starter motor, typically at least one piston of the engine is positioned in a specific shut-off position. This shut-off position can be defined such that, in conjunction with the air in the corresponding cylinder, it allows for the highest possible, and in particular maximum, torque during the combustion process of a subsequent engine start. In this way, a reliable engine start can be achieved even without a starter motor.

[0003] During the stopping process of an internal combustion engine, vibrations of the engine can occur, which may be perceived as unpleasant by a vehicle user.

[0004] DE 60 2004 012 838 T2 describes a control device for an internal combustion engine. DE 10 2004 062 940 A1 describes a method for operating a hybrid drive of a hybrid vehicle. DE 10 2010 032 087 A1 describes a method for stopping an internal combustion engine. US 2015 / 0 051 817 A1 describes a control device for a hybrid vehicle. DE 10 2006 028 334 A1 describes a method for controlling engine shutdown.

[0005] This document addresses the technical challenge of enabling precise adjustment of the stop position of a shaft or piston of an internal combustion engine in an efficient and convenient manner, particularly in a hybrid vehicle.

[0006] The problem is solved by the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim may not be valid without the features of the independent claim or only in combination with a subset thereof. During the stopping process of an internal combustion engine, vibrations of the engine may occur, which can be perceived as unpleasant by a vehicle user.

[0007] This document addresses the technical challenge of enabling precise adjustment of the stop position of a shaft or piston of an internal combustion engine in an efficient and convenient manner, particularly in a hybrid vehicle.

[0008] The problem is solved by the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims. It should be noted that additional features of a claim dependent on an independent claim, without the features of the independent claim itself or only in combination with a subset of the features of the independent claim, can constitute a separate invention independent of the combination of all features of the independent claim, which can be made the subject of an independent claim, a divisional application, or a subsequent application. This applies equally to technical teachings described in the description, which can constitute an invention independent of the features of the independent claims.

[0009] According to one aspect, a control unit for a vehicle, particularly a hybrid vehicle, is described. The vehicle includes an internal combustion engine with a shaft (especially a crankshaft) that can be coupled to or decoupled from an electric machine. In other words, the shaft of the internal combustion engine can be coupled to or decoupled from an electric machine. For example, the vehicle's drivetrain may have a disconnect clutch through which the shaft of the internal combustion engine can be coupled to or decoupled from the shaft of the electric machine. The electric machine may further be coupled to one or more of the vehicle's wheels via a transmission.

[0010] The control unit is configured to couple the electric motor to the combustion engine when the engine is stopped, so that the electric motor drives the combustion engine shaft until a speed threshold is reached. Specifically, the control unit can be configured to couple the electric motor to the combustion engine. For example, the control unit can cause the disconnect clutch to engage the electric motor shaft to the combustion engine shaft. Furthermore, the control unit can be configured to cause the electric motor to drive the combustion engine shaft. In this case, the combustion engine shaft can be driven from an initial speed (e.g., the idle speed) up to a (lower) speed threshold. This speed threshold is above zero, e.g., 50 rpm, 100 rpm, 200 rpm, or more.

[0011] At the beginning of the engine shutdown, the supply (especially the injection) of fuel to one or more cylinders of the internal combustion engine can be stopped. During the shutdown, the internal combustion engine then typically pumps essentially fuel-free air. Specifically, during an intake stroke, air can be drawn into a cylinder of the internal combustion engine via an intake valve. Furthermore, during a compression stroke, air can be pumped out of a cylinder of the internal combustion engine via an exhaust valve.

[0012] At the start of the engine stop, the internal combustion engine's crankshaft has an output speed higher than the speed threshold. This output speed can correspond to the engine's idle speed. Between the output speed and the speed threshold, there may be a vibration-relevant speed range of the internal combustion engine (which, for example, includes at least one resonant frequency). The electric machine can thus guide, and in particular decelerate, the internal combustion engine's crankshaft from the output speed down to the speed threshold in a controlled manner.

[0013] The control unit can be configured to cause the electric motor to guide the internal combustion engine shaft according to a target speed profile, a target torque profile, and / or a target shaft position profile. The target speed profile can represent, or be, a target speed profile over time. The target torque profile can represent, or be, a target torque profile over time applied to the shaft by the electric motor. The target shaft position profile can represent, or be, a target position profile over time (in particular, a rotational angle or angular position) of the internal combustion engine shaft.

[0014] Thus, the internal combustion engine shaft can be guided in a defined manner (i.e., according to a specific target profile) up to a certain speed threshold during a control phase of the engine stop. This reduces or eliminates vibrations of the internal combustion engine during engine stop. Furthermore, it ensures that the internal combustion engine shaft is in a defined state upon reaching the speed threshold (i.e., at the end of the control phase). In particular, the kinetic energy and / or the position (i.e., the rotation angle or angular position) of the internal combustion engine shaft at the end of the control phase can be precisely adjusted. This facilitates precise shutdown of the internal combustion engine shaft in a specific shutdown position (i.e., with a specific rotation angle or angular position).

[0015] The control unit is further configured to decouple the electric machine from the internal combustion engine when the speed threshold is reached, so that the shaft of the internal combustion engine comes to a standstill, or can come to a standstill, without being driven by the electric machine. In particular, the control unit can be configured to determine that the speed of the driven shaft of the internal combustion engine is equal to or less than the speed threshold. In response to this (i.e., when it has been determined that the driven shaft of the internal combustion engine is equal to or less than the speed threshold), the electric machine can be decoupled from the internal combustion engine, so that the shaft of the internal combustion engine is no longer driven by the electric machine. The shaft of the internal combustion engine is then typically driven exclusively by the aforementioned electric machine.The pump operation is slowed down, and thus comes to a standstill without being guided by the electric machine.

[0016] Once the speed threshold is reached, the guided phase can be terminated and a freewheeling phase can begin, in which the combustion engine shaft is decelerated and brought to a standstill without the influence of the electric motor (solely by the combustion engine's pumping action). Due to the preceding guided phase, which extends up to a defined speed threshold, it is possible to ensure that the combustion engine shaft comes to a standstill in a defined shutdown position even without guidance from the electric motor.

[0017] The control unit thus enables low-vibration shutdown of the shaft of an internal combustion engine at a defined shutdown position by combining a guidance phase and a subsequent freewheeling phase. A cost-effective electric motor can be used during the guidance phase, as this phase ends when a speed threshold greater than zero is reached (e.g., between 100 rpm and 400 rpm), thus eliminating the need for an electric motor with stepper motor functionality, for example.

[0018] The control unit can be configured to cause the electric motor to set, and in particular regulate, an actual shaft speed and / or shaft position depending on the target speed profile and / or shaft position profile. The actual speed and / or position can be detected directly or indirectly via one or more vehicle sensors.

[0019] During the control phase, the speed and / or position of the shaft can be regulated. For this purpose, the control unit can be configured to adjust the torque applied to the shaft by the electric motor depending on the actual speed and / or position of the shaft (in particular, depending on a difference between the actual speed and the target speed (from the target speed profile) and / or depending on a difference between the actual position and the target position (from the target position profile)). By regulating the speed and / or position of the shaft, vibrations during a motor stop can be further reduced and / or the accuracy of setting a defined stop position can be further increased.

[0020] The target speed profile, target torque profile, and / or target shaft position profile preferably depend on the target stop position of the shaft when the shaft is stationary. In particular, the target speed profile, target torque profile, and / or target shaft position profile can be defined such that the internal combustion engine shaft has a defined state (especially with respect to kinetic energy and / or position) at the end of the engagement phase, such that the shaft comes to a standstill in the defined stop position during the subsequent freewheeling phase. The target speed profile, target torque profile, and / or target shaft position profile can be experimentally determined for a specific internal combustion engine.

[0021] The target speed profile, target torque profile, and / or target shaft position profile can depend on the internal combustion engine's temperature, the ambient air pressure, and / or the engine's age. For example, different profiles can be provided for different temperature values, air pressure values, and / or age values ​​(e.g., as maps and / or lookup tables). The control unit can then determine the current temperature value, air pressure value, and / or age value for a specific engine stop and, based on this, select a target speed profile, a target torque profile, and / or a target shaft position profile for the engine stop control phase. This allows vibrations during an engine stop to be further reduced and / or the accuracy of setting a defined shutdown position to be further increased.

[0022] As explained above, the internal combustion engine and / or the vehicle may have a vibration-relevant speed range. The speed threshold is preferably set such that the vibration-relevant speed range lies between the initial speed (at the beginning of the engine stop) and the speed threshold. The shaft rotating at a speed outside the vibration-relevant speed range can cause resonance in the internal combustion engine and / or the vehicle (which may be perceived as unpleasant by a vehicle user).

[0023] The internal combustion engine can be designed in such a way that the shaft of the internal combustion engine would traverse the vibration-relevant speed range in a reference time without the influence of the electric machine.

[0024] In other words, a free-running shaft could traverse the vibration-relevant speed range within the reference time. On the other hand, the target speed profile, the target torque profile, and / or the target shaft position profile can be defined such that the vibration-relevant speed range is traversed in a shorter time, particularly in a time 2, 3, 5, 10 times shorter or more than the reference time. By guiding the internal combustion engine shaft, it is thus possible to accelerate the passage through the vibration-relevant speed range. In this way, vibrations can be suppressed particularly reliably when the engine is stopped.

[0025] The control unit can be configured to determine position information regarding the actual position of the internal combustion engine shaft (e.g., using a suitable sensor on the shaft). The electric motor can then be controlled based on this position information. In particular, the position information can be used to determine that the shaft has a predefined target position. In response, the electric motor can then be instructed to guide the internal combustion engine shaft. The guidance phase of the internal combustion engine shaft can thus begin at a predefined target position. This allows for increased accuracy in ensuring that the shaft is in a specific position when the speed threshold is reached. This, in turn, has a positive effect on the accuracy of the shaft's shut-off position.

[0026] The control unit can be configured (particularly during the final intake stroke of the internal combustion engine before shutdown) to actuate at least one valve (especially an intake valve) of at least one cylinder of the internal combustion engine in order to set the engine's shutdown position. Specifically, actuating the valve can adjust a gas spring within the cylinder. The gas spring can then cause the cylinder piston, and thus the recording device shaft, to rotate back to a specific shutdown position. This further increases the accuracy of setting the shutdown position of the internal combustion engine shaft.

[0027] According to another aspect, a method for performing an engine stop of a vehicle's internal combustion engine is described. The internal combustion engine includes a shaft that can be coupled to or disconnected from an electric machine. The method includes coupling the electric machine to the internal combustion engine (e.g., via a disconnect clutch). Furthermore, the method includes guiding the shaft of the internal combustion engine by means of the electric machine. The shaft of the internal combustion engine is typically guided in such a way that its rotational speed is steadily and / or continuously reduced. The method also includes determining or detecting that the rotational speed of the guided shaft of the internal combustion engine is equal to or less than a speed threshold, and / or that the rotational speed of the guided shaft of the internal combustion engine has reached or is approaching a speed threshold.Furthermore, in response to the determination, the procedure includes decoupling the electric machine from the combustion engine, so that the combustion engine is no longer guided by the electric machine (and thus comes to a standstill without guidance from the electric machine).

[0028] According to another aspect, a road motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described that includes the control unit described in this document.

[0029] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor (e.g., on a vehicle's control unit) and thereby execute the procedure described in this document.

[0030] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0031] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

[0032] The invention will now be described in more detail using exemplary embodiments. Fig. 1. Exemplary components of a hybrid vehicle; Fig. 2 an exemplary piston of an internal combustion engine; Fig. 3 an exemplary time course of the rotational speed of an internal combustion engine during an engine stop; and Fig. 4 A flowchart of an exemplary procedure for performing an engine stop of an internal combustion engine.

[0033] As stated at the outset, this document deals with the reliable and convenient setting of the piston's stop position in a vehicle's internal combustion engine during an engine shutdown. At the beginning of the engine shutdown, the fuel supply to the engine is typically cut off. The engine can then coast to a stop and / or be braked until the engine shaft comes to a standstill at a specific stop position. Once this stop position is reached, the engine shutdown is complete.

[0034] Fig. Figure 1 shows exemplary components of a (powertrain of a) vehicle 100. In particular, it shows Fig. 1. The internal combustion engine (IM) 102 of a vehicle 102, which is coupled to a transmission 106 via a drive shaft 103 to transmit torque to at least one axle or at least one wheel of the vehicle 100 (not shown). Furthermore, the vehicle 100 comprises at least one electric machine (EM) 105, which can be coupled to or decoupled from the IM 102 via a clutch 104. For example, the vehicle 100 can comprise a P2 hybrid drive with an IM 102 and an EM 105. The IM 102, the EM 105, the clutch 104, and / or the transmission 106 can be controlled and / or regulated by a control unit 101 of the vehicle 100.

[0035] A VM 102 typically comprises a plurality of cylinders (e.g., 4, 6, or 8 cylinders). Fig. Figure 2 shows an example of a cylinder 201 of a VM 102. A piston 202 is movably arranged within the cylinder 201, and its movement drives the crankshaft 203 of the VM 102 (which in turn drives the drive shaft 103). The piston 202 moves back and forth through different positions 210 (in particular, angles) between a top dead center 211 and a bottom dead center 212. These different positions 210 can be defined as angles between 0° and 360°. The top dead center can be at 0° or 360°, and the bottom dead center 212 at 180°.

[0036] On the way from top dead center 211 to bottom dead center 212, air and / or a fuel-air mixture is drawn into cylinder 201 via an intake valve 204 (intake stroke). Conversely, the air and / or fuel-air mixture in cylinder 201 is compressed when the piston 201 moves from bottom dead center 212 to top dead center 211 (compression stroke). During this time, air and / or a (combusted) fuel-air mixture can be expelled from cylinder 201 via the exhaust valve 205.

[0037] At the beginning of an engine stop, fuel injection into cylinder 201 of the VM 102 is typically terminated, and the VM 102 can then coast to a stop. Upon reaching the final intake stroke (i.e., upon reaching the final movement of a piston 202 of the VM 102 from top dead center 211 to bottom dead center 212) before the VM 102 comes to a standstill, a defined quantity of air can be drawn in during the intake stroke (via the intake valve 204). The quantity of air drawn in typically depends on boundary conditions such as the desired stop position of the piston 202, the current rotational speed of the VM 102, and / or the temperature of the VM 102. The amount of air can be adjusted by the VVT ​​(Variable Valve Timing) stroke. In particular, by adjusting the degree of opening and / or the opening time of the inlet valve 204, the amount of air drawn into a cylinder 201 of the VM 102 in the last intake stroke can be adjusted.

[0038] In the following compression stroke, the air is compressed, forming a gas spring 206 in cylinder 201. By enclosing a specific amount of air in cylinder 201, i.e., by adjusting the gas spring 206, the crankshaft 203 can be caused to rotate backward before reaching top dead center 211 due to the expanding gas spring 206. Furthermore, enclosing a specific amount of air in cylinder 201 can cause the crankshaft 203, or the piston 202, to come to a standstill at a defined stopping position 215. This facilitates a subsequent engine start.

[0039] A disadvantage is that when the crankshaft 203 slows down below idle speed, the VM 102 typically passes through a vibration-relevant speed range in which vibrations are excited within the VM 102 and / or within the vehicle 100, which can be perceived as unpleasant by a user of the vehicle 100.

[0040] An alternative method for performing an engine stop, particularly in a hybrid vehicle 100, is to use the EM 105 to bring the crankshaft 203 of the VM 102 to a standstill. For this purpose, the VM 102 and the EM 105 can be coupled to each other via the disconnect clutch (K0) 104. A target speed profile (or a target torque profile) can be specified to the EM 105, according to which the VM 102 is to be decelerated by the EM 105. Since the VM 102 and the EM 105 are coupled to each other via the disconnect clutch 104, the VM 102 follows the target speed profile specified by the EM 105.

[0041] The target speed profile can be such that the speed range in which the one or more vibration resonances of the VM 102 and / or the vehicle 100 lie is traversed as quickly as possible (especially faster than during the unguided coasting of the crankshaft 203). This can increase comfort during an engine stop, as the excitation of vibrations can be avoided. On the other hand, the use of an EM 105 to brake the crankshaft 203 of the VM 102 typically does not allow for the precise setting of a stop position 215 of a piston 202 of the VM 102. Furthermore, the EM 105 must not be coupled to the one or more wheels of the vehicle 100 (e.g., via the transmission 106), especially when the VM 102 reaches relatively low speeds, as otherwise the EM 105 would be driven by the one or more wheels of the vehicle 100, and thus the crankshaft 203 of the VM 102 could not be brought to a standstill.

[0042] Precise adjustment of the VM 102's stop position 215 can be achieved, for example, by using an electric stepper motor, such as an additional stepper motor or a stepper motor for the EM 105. However, this involves additional costs.

[0043] Fig. Figure 3 shows an exemplary time course 310 of the rotational speed of the crankshaft 203 of the VM 102 during an engine stop. The crankshaft 203 of the VM 102 is guided in a guide area 301 by the EM 105. The rotational speed profile 311 in the guide area 301 can be determined by the EM 105.

[0044] Upon reaching a speed threshold of 304, the EM 105 can be decoupled from the VM 102 by the clutch 104. For speeds below the speed threshold of 304, i.e., in ranges 302 and 303, this results in an unguided speed profile 312. The unguided speed profile 312 in ranges 302 and 303 depends on the mechanical resistances within the VM 102. Upon reaching the last intake stroke of the VM 102, a precise adjustment of the shut-off position 215 can be achieved in range 303 (as described above) by a gas spring 206.

[0045] In a first step, the crankshaft 203 can be guided by an EM 105 according to a predefined target speed profile until a speed threshold 304 (e.g., at approximately 300 rpm) is reached. By setting a relatively large time gradient 305 of the target speed profile, it can be ensured that the vibration-relevant speed range of the VM 102 or the vehicle 100 is traversed as quickly as possible. The speed threshold 304 is preferably located below the vibration-relevant speed range. In a second step, i.e., for speeds below the speed threshold 304, the VM 102 can then coast to a stop without guidance. If necessary, the stop position 215 can also be precisely adjusted by adjusting the gas spring 206 of at least one cylinder 201.

[0046] In other words, the VM 102 can be guided by the EM 105 up to a speed threshold of 304. Furthermore, the VM 102 can be rotated into a desired parking position 215 using the gas spring 206. This allows for both a high level of comfort when setting down the VM 102 and precise adjustment of the parking position 215. Additionally, a cost-effective EM 105 (without step function) can be used. Moreover, the EM 105 can be coupled to the wheels of the vehicle 100, at least temporarily.

[0047] By specifying a particular target speed profile until reaching the speed threshold 304, the VM 102 can be made to possess a defined kinetic energy at the beginning of the coasting or freewheeling phase 302. Thus, the VM 102 has a defined energy state at the beginning of the coasting or freewheeling phase 302. During the coasting or freewheeling phase 302, this defined kinetic energy is dissipated in a defined manner, leading to a defined shutdown position 210 of the VM 102. By adjusting the target speed profile, the shutdown position 215 of the VM 102 can therefore be influenced. The use of a defined target speed profile in a guide phase 301 of the motor stop thus makes it possible to increase the accuracy of setting a defined shutdown position 215.

[0048] To further increase the accuracy of the stop position 215, when the VM 102 is guided by the EM 105, i.e., during the guide phase 301, the target speed profile can be triggered at a defined angle or at a defined position 210 of the crankshaft 203. This ensures that the crankshaft 203 comes to a reproducible stop in a defined stop position 215.

[0049] To further increase the accuracy of the stop position 215, the target speed profile can be superimposed on a controller when guiding the VM 102 with the EM 105, i.e., during the guiding phase 301. For this purpose, the actual speed of the VM 102 can be measured using a speed sensor (not shown). The EM 105 can then be controlled based on the difference between the measured actual speed and the specified target speed (from the target speed profile) to regulate the actual speed of the VM 102 according to the specified target speed profile.

[0050] Alternatively or additionally, a specific crankshaft position 210 can be set (in particular, regulated). If the crankshaft position deviates from a target position (from a target position profile) at a specific engine speed, a controller can slow down or accelerate the VM 102 by adjusting the EM torque, so that a predetermined speed-crankshaft angle profile is set during the guiding phase 301, which then leads to a desired shut-off position 215 in the subsequent freewheeling phase 302.

[0051] Fig.Figure 4 shows a flowchart of an exemplary method 400 for performing an engine stop of an internal combustion engine 102 of a vehicle 100. The method 400 can be executed, for example, by a control unit 101 or a control device, such as an engine control unit, of the vehicle 100. The internal combustion engine 102 comprises a shaft 103, 203, in particular a crankshaft 203 and / or a drive shaft 103 mechanically coupled to the crankshaft 203, which can be coupled to or decoupled from an electric machine 105 (e.g., by means of a clutch 104). In particular, the vehicle 100 can have a drive system configured as a P2 hybrid.

[0052] Method 400 comprises coupling the electric machine 105 with the internal combustion engine 102. Furthermore, method 400 comprises guiding the shaft 103, 203 of the internal combustion engine 102 by means of the electric machine 105. The electric machine 105 can define a target speed profile or a target speed profile over time. In other words, after the injection and / or fuel supply to the internal combustion engine 102 has ceased, the shaft 103, 203 of the internal combustion engine 102 can be decelerated by means of the electric machine 105. The electric machine 105 can guide the shaft 103, 203 relatively quickly through a vibration-relevant speed range of the internal combustion engine 102, so that resonances of the internal combustion engine 102 during engine shutdown can be avoided. Typically, shaft 103, 203 exhibits a specific output speed at the beginning of the engine stop (i.e., when the fuel supply is interrupted) (e.g.the idle speed), which can be in the range of 800 rpm to 1500 rpm, for example. The speed threshold is below the output speed and above zero (e.g., between 400 rpm and 100 rpm, around 300 rpm).

[0053] Furthermore, the method 400 includes determining 403 that the rotational speed of the guided shaft 103, 303 is equal to or less than a rotational speed threshold 304. In other words, it can be determined that the rotational speed of the guided shaft 103, 303 of the internal combustion engine 102 has reached the rotational speed threshold 304 or may already have (typically slightly) fallen below it.

[0054] Method 400 further comprises, in response to determination 403, decoupling 402 of the electric machine 105 from the internal combustion engine 102 upon reaching the speed threshold 304, so that the internal combustion engine 102 comes to a standstill without being driven by the electric machine 105. In other words, from the speed threshold onwards, the shaft 103, 203 of the internal combustion engine 102 can coast freely. This allows for precise stopping of the shaft 103, 203 in a specific stopping position 215 (e.g., by using a gas spring 206 during the last intake stroke of the internal combustion engine 102).

[0055] The measures described in this document make it possible to bring the shaft 103, 203 of an internal combustion engine 102 to a standstill with minimal vibration and in a precise manner at a specific stopping position 215 using an electric machine 105.

[0056] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems.

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