Multi-data synchronous sampling device
By designing a synchronous sampling device including a clock circuit, a collection circuit and a timing circuit, the problem of data time difference in flexible pressure sensor testing is solved, and the synchronous acquisition of physical quantity data and microstructure images is realized, and the testing accuracy is improved.
Patent Information
- Application Number
- CN202420578881.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-25
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-03-25
AI Technical Summary
In the functional testing of flexible pressure sensors, it is difficult for the prior art to realize the synchronous acquisition of physical quantity data and microstructure images, resulting in a large time difference between the time when the data is collected and the time when the host computer acquires the data, affecting the test accuracy.
Design a synchronous sampling device with multiple data, including a first clock circuit, a collection circuit and a timing circuit, and provides clock signals to the acquisition circuit and a timing circuit through the first clock circuit. The acquisition circuit is responsible for collecting physical quantity data and sending it to the upper computer, and timing it The circuit is responsible for determining the time when the microscope takes images and sending them to the microscope to ensure the time synchronization of the data.
Through this device, the upper computer can determine the shooting time of each microstructure image, avoiding the data congestion caused by single-port transmission, solving the problem of time difference, and improving the functional testing accuracy of the flexible pressure sensor.
Smart Images
Figure CN222441709U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of time synchronization, in particular to a synchronous sampling device for multiple data. Background Art
[0002] When performing functional testing on a device, it is usually necessary to test a variety of parameters of the device. For flexible pressure sensors, it is necessary to pay attention to physical quantity data such as the pressure load currently on the sensor, the current current value passing through the sensor, and the current compression of the sensor. When the flexible pressure sensor is contacted by other objects, the deformation of the flexible pressure sensor is directly related to the change in various physical quantities. In order to study the influence of the deformation on the physical quantity, it is necessary to use a microscope system to capture the microstructure image of the flexible pressure sensor so that the staff can directly observe the contact and deformation process of the flexible pressure sensor.
[0003] Image capture and physical quantity collection need to be carried out at the same time, and all these data need to be uploaded to the host computer. Due to the limited performance of the host computer, the transmission of a large amount of data at the same time is prone to bandwidth limitations or data congestion delays, resulting in a large time difference between the time when data is collected and the time when the host computer obtains the data, thereby affecting the functional test accuracy of the flexible pressure sensor. Utility Model Content
[0004] The purpose of the utility model is to provide a multi-data synchronous sampling device, which can enable a host computer to determine the shooting time of each microstructure image, and also avoid the data congestion problem caused by single-port transmission, thereby solving the time difference problem and improving the functional test accuracy of the flexible pressure sensor.
[0005] In order to solve the above technical problems, the utility model provides a synchronous sampling device for multiple data, comprising:
[0006] A first clock circuit, a collection circuit and a timing circuit;
[0007] The output end of the first clock circuit is connected to the clock end of the timing circuit and the clock end of the acquisition circuit respectively, and the first clock circuit is used to output a clock signal;
[0008] The data acquisition end of the acquisition circuit is connected to the data output end of the test system for collecting the physical quantity of the flexible pressure sensor, and the data output end is connected to the data input end of the host computer. The acquisition circuit is used to collect the physical quantity according to the clock signal and send it to the host computer;
[0009] The timing end of the timing circuit is connected to the timing end of the microscope system used to capture the microstructure image of the flexible pressure sensor. The timing circuit is used to determine the current time according to the clock signal and send it to the microscope system, so that the microscope system marks the shooting time of the structure image and sends it to the host computer.
[0010] In one aspect, a second clock circuit is also included;
[0011] The output end of the second clock circuit is connected to the clock end of the timing circuit and the clock end of the acquisition circuit respectively, and the second clock circuit is used to output the clock signal when the first clock circuit fails.
[0012] On the one hand, the first clock circuit is a crystal oscillator circuit.
[0013] On the one hand, it also includes the power supply;
[0014] The power supply is connected to the acquisition circuit and is used to provide power to the acquisition circuit.
[0015] On the one hand, it also includes a first communication module;
[0016] The first communication module is arranged between the acquisition circuit and the test system;
[0017] The communication bandwidth of the first communication module is not less than the bandwidth required for transmitting the physical quantity.
[0018] On the one hand, the first communication module is an RS serial communication module.
[0019] On the one hand, it also includes a second communication module;
[0020] The second communication module is arranged between the host computer and the microscope system;
[0021] Wherein, the communication bandwidth of the second communication module is not less than the bandwidth required for transmitting the microstructure image.
[0022] On the one hand, the second communication module is an RJ45 communication module.
[0023] On the one hand, it also includes a wireless communication module;
[0024] The wireless communication module is connected to the host computer, and the wireless communication module is used for data transmission between the remote terminal and the host computer.
[0025] The beneficial effect of the present application is to provide a synchronous sampling device for multiple data, which relates to the field of time synchronization. By setting a first clock circuit, an acquisition circuit and a timing circuit, the first clock circuit is respectively connected to the timing circuit and the acquisition circuit and is used to output a clock signal; the acquisition circuit acquires various physical quantities according to the clock signal and sends it to the host computer; the timing circuit determines the current moment according to the clock signal and sends it to the microscope system, so that the microscope system can determine the shooting time of the structural image. The first clock circuit provides the same time signal for the physical quantity data and the microstructure image, so that the microscope system can mark the microstructure image with a time tag, allowing the host computer to determine the shooting time of each microstructure image; in addition, the physical quantity is sent to the host computer from another path through the acquisition circuit, avoiding the data congestion problem caused by single-port transmission. In this way, the problem of time difference is solved and the functional test accuracy of the flexible pressure sensor is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0027] Figure 1 A schematic diagram of the structure of a multi-data synchronous sampling device provided in this application;
[0028] Figure 2 A schematic diagram of the structure of another multi-data synchronous sampling device provided in the present application. DETAILED DESCRIPTION
[0029] The core of the utility model is to provide a multi-data synchronous sampling device, which can enable the host computer to determine the shooting time of each microstructure image and avoid the data congestion problem caused by single-port transmission, thereby solving the time difference problem and improving the functional test accuracy of the flexible pressure sensor.
[0030] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0031] The test system of the flexible pressure sensor includes the flexible pressure sensor to be tested, the test device, the grating ruler, the pressure transmitter, the industrial camera and other devices. Figure 2 , Figure 2 A structural schematic diagram of another multi-data synchronous sampling device provided for this application, wherein the test device is responsible for driving the operation of various other devices (the commonly used test device model is CDHD2-0061DEC2), the grating ruler is used to measure the displacement of the component, and the material compression of the flexible pressure sensor (the volume deformation of the material) is characterized according to the position data of the grating ruler; the pressure transmitter is used to apply pressure and load to the flexible pressure sensor to cause the flexible pressure sensor to deform, which is convenient for testing other devices; the industrial camera is used to photograph the microstructure of the flexible pressure sensor so that the staff can observe the deformation process of the microstructure of the flexible pressure sensor.
[0032] Since there are many physical quantities that need to be detected, and there is usually only one serial port connection between the test system and the host computer, all the data detected by the test system need to be transmitted to the host computer through the serial port. When the amount of data is not large, the existing test system can meet the real-time requirements of the test; however, when the amount of data is large, due to the limitation of the transmission bandwidth, data congestion and delay will occur during the data transmission process, and this situation will also occur when the host computer unpacks and calculates the data packet, resulting in a large time difference between the time when the data is collected and the time when the host computer obtains the data, and the real-time nature of the data cannot be reflected.
[0033] This is because the deformation of the flexible pressure sensor is directly related to the change in physical quantity. In the prior art, in order to study the specific impact of contact with other objects on the flexible pressure sensor, the test system is usually equipped with a microscope system to capture real-time image data of the microstructure of the flexible pressure sensor. Since the amount of real-time image data is large, when the real-time image data and various other physical quantity data are sent to the host computer at the same time, the above-mentioned data congestion and delay will occur.
[0034] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a multi-data synchronous sampling device provided in this application includes:
[0035] A first clock circuit 1, a collection circuit 2 and a timing circuit 3;
[0036] The output end of the first clock circuit 1 is connected to the clock end of the timing circuit 3 and the clock end of the acquisition circuit 2 respectively, and the first clock circuit 1 is used to output a clock signal;
[0037] The data acquisition end of the acquisition circuit 2 is connected to the data output end of the test system for collecting the physical quantity of the flexible pressure sensor, and the data output end is connected to the data input end of the host computer. The acquisition circuit 2 is used to collect the physical quantity according to the clock signal and send it to the host computer;
[0038] The timing end of the timing circuit 3 is connected to the timing end of the microscope system used to capture the microstructure image of the flexible pressure sensor. The timing circuit 3 is used to determine the current time according to the clock signal and send it to the microscope system so that the microscope system marks the shooting time of the structure image.
[0039] In the present application, in order to solve the problem that the real-time performance of the data cannot be reflected, the acquisition circuit 2 and the timing circuit 3 are set to respectively acquire the physical quantity data and the image data, and send them to the host computer through two interfaces to avoid data congestion. In addition, the first clock circuit 1 is combined to provide the same clock signal to the acquisition circuit 2 and the timing circuit 3, so that the data collected by the two circuits can be synchronized in time, and even if there is a delay when the host computer obtains the data, the acquisition time of each data can be determined.
[0040] Specifically, the function of the first clock circuit 1 is to provide a clock signal. The clock signal is a level signal (or a pulse signal) or a specific time signal. The acquisition circuit 2 and the timing circuit 3 both perform corresponding actions according to the clock signal.
[0041] The function of the timing circuit 3 is to provide time for the microscopic system. A preset time point is stored in the timing circuit 3. The preset time point is preset by the staff before the test starts (for example, the real time of starting the test is used as the preset time point). The timing circuit 3 updates the preset time point (real time) according to the clock signal, and sends the preset time point as the current time to the microscopic system. The microscopic system can know the shooting time of the currently captured microstructure image according to the current time. In addition, the timing circuit 3 actually used can be any single-chip microcomputer, FPGA (Field Programmable Gate Array) or CPLD (Complex Programmable logic device) that can provide accurate time to the microscopic system, and the EQ6HL130 structure can be selected as the timing circuit 3.
[0042] The function of the acquisition circuit 2 is to collect all other physical quantity data except the microstructure image, because other physical quantity data are a small amount of text data or character data, and the total amount of these physical quantity data is smaller than that of the microstructure image, so the acquisition circuit 2 can simply and effectively collect real-time physical quantity data. In addition, the actual acquisition circuit 2 can be any single-chip microcomputer, controller or processor that can realize the acquisition function. The EQ6HL9 sampling board can be selected as the acquisition circuit 2.
[0043] Taking the clock signal as a level signal (or pulse signal) as an example, every time the level flips to a specific level (or every time a pulse is received), the acquisition circuit 2 collects physical quantity data once and sends it to the host computer; the timing circuit 3 updates the current moment once and sends it to the microscope system, the microscope system determines the shooting moment of the microstructure image according to the current moment, and sends the microstructure image and its shooting moment to the host computer. It should be noted that the amplitude of the timing circuit 3 updating the current moment needs to be set according to the period of the level signal or pulse signal. If the period of the level signal or pulse signal is 1ms, the timing circuit 3 only adds 1ms to the previous moment as the current moment each time.
[0044] Taking the clock signal as a specific time signal, every time the time passes a preset time (for example, 1ms), the acquisition circuit 2 acquires physical quantity data once; the timing circuit 3 synchronously updates the current time. In this case, it is necessary to ensure that the performance of the acquisition circuit 2 and the timing circuit 3 is good enough, otherwise it is easy for the two circuits to analyze the time signal in different times and generate a time difference.
[0045] For the physical quantity data collected by the acquisition circuit 2, because the data volume of the physical quantity data is relatively small, and the physical quantity data and the microstructure image are sent to the host computer from two different ports, there is no problem of data congestion and bandwidth limitation between the acquisition circuit 2 and the host computer. The host computer can quickly obtain these physical quantity data and perform unpacking calculations. When the unpacking calculations are completed, the host computer can determine the collection time of these physical quantity data.
[0046] For the microstructure image captured by the microscope system, although the amount of data of the microstructure image is large, the timing circuit 3 provides the microscope system with the current moment, and the microscope system can determine the shooting moment of the microstructure image according to the current moment, and write the shooting moment into the data of the microstructure image as the attribute parameter of the microstructure image. In practical applications, even if there is a bandwidth limitation or data congestion, resulting in the microstructure image at a certain moment being acquired by the host computer at another subsequent moment, at this time, the host computer can simply determine the real shooting moment of the microstructure image according to the shooting moment recorded in the attribute parameter.
[0047] In this way, the host computer can give priority to obtaining physical quantity data to ensure its real-time performance, and then obtain the microstructure image when the bandwidth is sufficient. Therefore, only the transmission and unpacking of physical quantity data will produce time difference, and the transmission of microstructure images will not produce time difference, which significantly improves the functional test accuracy of the flexible pressure sensor.
[0048] In summary, by setting the first clock circuit 1, the acquisition circuit 2 and the timing circuit 3, the output end of the first clock circuit 1 is connected to the clock end of the timing circuit 3 and the clock end of the acquisition circuit 2 respectively, and the first clock circuit 1 is used to output the clock signal; the data acquisition end of the acquisition circuit 2 is connected to the data output end of the test system, and the data output end of the acquisition circuit 2 is connected to the data input end of the host computer, and the acquisition circuit 2 is used to collect physical quantities according to the clock signal and send it to the host computer; the timing end of the timing circuit 3 is connected to the timing end of the microscope system for shooting the microstructure image of the flexible pressure sensor, and the timing circuit 3 is used to determine the current time according to the clock signal and send it to the microscope system, so that the microscope system can determine the shooting time of the structure image. Since the physical quantity data and the microstructure image are transmitted to the host computer through different ports, the host computer can effectively determine the time of each physical quantity data. In addition, the first clock circuit 1 provides the same time signal for the physical quantity data and the microstructure image, so that the microscope system can mark the microstructure image with a time tag, and the host computer can determine the shooting time of each microstructure image. In this way, the problem of a large time difference between the time when data is collected and the time when the host computer obtains the data is solved, and the functional test accuracy of the flexible pressure sensor is improved.
[0049] Based on the above embodiments:
[0050] In some embodiments, further comprising a second clock circuit;
[0051] The output end of the second clock circuit is connected to the clock end of the timing circuit 3 and the clock end of the acquisition circuit 2 respectively. The second clock circuit is used to output a clock signal when the first clock circuit 1 fails.
[0052] In order to improve practicality, in this application, please refer to Figure 2 , Figure 2 A structural diagram of another multi-data synchronous sampling device provided for the present application, in addition to the first clock circuit 1, a second clock circuit is also reserved. Under normal circumstances, the second clock circuit generates a clock signal that is exactly the same as the first clock circuit 1, but the second clock circuit does not send the clock signal generated by itself to the timing circuit 3 and the acquisition circuit to prevent clock signal conflicts.
[0053] In actual application, if the first clock circuit 1 used is a circuit capable of realizing self-detection of faults, the first clock circuit 1 can be connected to the second clock circuit, and the first clock circuit 1 sends a fault signal to the second clock circuit after its own fault occurs, and the second clock circuit then sends the clock signal generated by itself to the timing circuit 3 and the acquisition circuit 2. In addition, the host computer can also be used to detect whether the first clock circuit 1 is faulty, such as detecting whether the clock cycle of the first clock circuit 1 is abnormal. When a fault is detected, the host computer sends an instruction to the second clock circuit, and the second clock circuit then sends the clock signal generated by itself to the timing circuit 3 and the acquisition circuit 2.
[0054] In addition, the second clock circuit actually used may be a circuit that generates a GPS second pulse signal, or may introduce an external time system as the second clock circuit, or may use a crystal oscillator circuit, and this application does not limit this.
[0055] In this way, after the first clock circuit 1 fails, it can still provide a synchronous clock signal to the acquisition circuit 2 and the timing circuit 3, thereby improving the practicality of the entire synchronous sampling device.
[0056] In some embodiments, the first clock circuit 1 is a crystal oscillator circuit.
[0057] The crystal oscillator circuit can generate an accurate and high-frequency clock signal, is not easily disturbed by the external environment, has high stability, and can ensure the time synchronization between the acquisition circuit 2 and the timing circuit 3 during the sampling test process; in addition, the crystal oscillator circuit is very small in size, low in cost, and can be directly connected to other circuits, and can be simply integrated into the entire synchronous sampling device. Therefore, using the crystal oscillator circuit as the first clock circuit 1 can simply and reliably achieve the purpose of providing a clock signal to the timing circuit 3.
[0058] In addition, in addition to the crystal oscillator circuit, according to the above embodiments, a circuit that generates a GPS second pulse signal can also be used as the first clock circuit 1.
[0059] In some embodiments, a power source is also included;
[0060] The power supply is connected to the acquisition circuit 2 and is used to provide power to the acquisition circuit 2.
[0061] When setting the power supply, it is necessary to set it according to the working voltage of the acquisition circuit 2 to ensure that the power supply can provide a stable working voltage to the acquisition circuit 2. As for the type of power supply, a battery or a storage battery such as a super capacitor can be used as the power supply; or a voltage stabilizing circuit can be used as the power supply, the input of the voltage stabilizing circuit is connected to the external power supply, and the external power supply voltage is stabilized to the working voltage of the acquisition circuit 2 by the voltage stabilizing circuit, and then output to the acquisition circuit 2 as power supply.
[0062] In some embodiments, further comprising a first communication module;
[0063] The first communication module is arranged between the acquisition circuit 2 and the test system;
[0064] The communication bandwidth of the first communication module is not less than the bandwidth required for transmitting the physical quantity.
[0065] The first communication module is an RS serial communication module.
[0066] In order to simply obtain other physical quantity data in addition to the microstructure image data, in the present application, a first communication module is provided between the acquisition circuit 2 and the test system, and the first communication module is responsible for sending various physical quantity data detected by the test system to the acquisition circuit 2. The first communication module specifically used is an RS serial communication module. Since the amount of physical quantity data is relatively small, even if serial communication is used to send multiple physical quantity data to the acquisition circuit 2 in sequence, the real-time nature of the data can be guaranteed. On this basis, in order to ensure the accuracy of the data, serial communication with a lighter protocol complexity is used, which can also ensure that the physical quantity data will not be interfered with in a long-distance transmission environment and various external environments. The use of RS serial communication, such as RS485, RS232 and other modules, can further improve the anti-interference ability of the data and ensure the accuracy of the data.
[0067] Based on this, because the physical quantity data and the microstructure image are transmitted separately, the pressure of simply transmitting the physical quantity data is relatively small, so a serial communication module is used to ensure the real-time nature of the data while also ensuring the accuracy of the data.
[0068] In some embodiments, further comprising a second communication module;
[0069] The second communication module is arranged between the host computer and the microscope system;
[0070] The communication bandwidth of the second communication module is not less than the bandwidth required for transmitting the microstructure image.
[0071] The second communication module is an RJ45 communication module.
[0072] In order to effectively obtain the data of the microstructure image, in this application, a second communication module is also provided between the host computer and the microscope system. Since the amount of data of the microstructure image is large, it is necessary to consider whether it meets the transmission bandwidth requirement of the microstructure image when selecting the second communication module. For this reason, this application adopts the RJ45 communication module to realize the transmission of the microstructure image. Since the protocol of the RJ45 communication module can support a data transmission rate of up to 1Gbps, even microstructure images with a larger resolution can be quickly sent to the host computer through the RJ45 communication module. In addition, the RJ45 communication module itself also has an error detection mechanism on the physical layer and the link layer. Even if the microstructure image generates data errors due to interference during the transmission process, the RJ45 communication module can correct the errors, thereby improving the reliability of the microstructure image.
[0073] In some embodiments, further comprising a wireless communication module;
[0074] The wireless communication module is connected to the host computer, and the wireless communication module is used to realize data transmission between the remote terminal and the host computer.
[0075] In order to improve practicality, a wireless communication module is also provided in the present application. The wireless communication module is used to wirelessly receive instructions from other user terminals and send them to the host computer. For example, when the user is not near the synchronous sampling device, a remote terminal is used to send a control instruction, and the control instruction is sent to the host computer through the wireless communication module, so that the host computer enables the entire synchronous sampling device and the microscopic system to realize sampling. After the host computer collects physical quantity data and microstructure images, these data can also be sent to the remote user terminal through the wireless communication module to achieve the purpose of remote control and remote monitoring.
[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0077] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.
[0078] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A synchronous sampling device for multiple data, characterized in that: include: A first clock circuit, a collection circuit and a timing circuit; The output end of the first clock circuit is connected to the clock end of the timing circuit and the clock end of the acquisition circuit respectively, and the first clock circuit is used to output a clock signal; The data acquisition end of the acquisition circuit is connected to the data output end of the test system for collecting the physical quantity of the flexible pressure sensor, and the data output end is connected to the data input end of the host computer. The acquisition circuit is used to collect the physical quantity according to the clock signal and send it to the host computer; The timing end of the timing circuit is connected to the timing end of the microscope system used to capture the microstructure image of the flexible pressure sensor. The timing circuit is used to determine the current time according to the clock signal and send it to the microscope system, so that the microscope system marks the shooting time of the structure image and sends it to the host computer.
2. The synchronous sampling device for multiple data as claimed in claim 1, characterized in that: Also comprising a second clock circuit; The output end of the second clock circuit is connected to the clock end of the timing circuit and the clock end of the acquisition circuit respectively, and the second clock circuit is used to output the clock signal when the first clock circuit fails.
3. The synchronous sampling device for multiple data as claimed in claim 1, characterized in that: The first clock circuit is a crystal oscillator circuit.
4. The synchronous sampling device for multiple data as claimed in claim 1, characterized in that: Also includes a power supply; The power supply is connected to the acquisition circuit and is used to provide power to the acquisition circuit.
5. The synchronous sampling device for multiple data as claimed in claim 1, characterized in that: Also includes a first communication module; The first communication module is arranged between the acquisition circuit and the test system; The communication bandwidth of the first communication module is not less than the bandwidth required for transmitting the physical quantity.
6. The synchronous sampling device for multiple data as claimed in claim 5, characterized in that: The first communication module is an RS serial communication module.
7. The synchronous sampling device for multiple data as claimed in claim 1, characterized in that: Also comprising a second communication module; The second communication module is arranged between the host computer and the microscope system; Wherein, the communication bandwidth of the second communication module is not less than the bandwidth required for transmitting the microstructure image.
8. The synchronous sampling device for multiple data as claimed in claim 7, characterized in that: The second communication module is an RJ45 communication module.
9. The synchronous sampling device for multiple data according to any one of claims 1 to 8, characterized in that: Also included is a wireless communication module; The wireless communication module is connected to the host computer, and the wireless communication module is used for data transmission between the remote terminal and the host computer.