CN108261189A - Method and device for non-invasive continuous real-time accurate measurement of arterial blood pressure - Google Patents

Abstract

The present invention relates to a method and device for measuring arterial blood pressure in a non-invasive, continuous, real-time and accurate manner. The method comprises: pressing down the tissues on both sides of the arterial blood vessel to highlight the arterial blood vessel, and then vertically pressing down the arterial blood vessel from above the arterial blood vessel with a manometry sensor until flat state, using a pressure sensor to measure arterial blood pressure; the device includes a sensor assembly, a controller assembly and a motor unit, the sensor assembly includes a pressure measurement sensor and two positioning sensors, the motor unit is used to drive the movement of the sensor assembly, and the sensor assembly will The signal is transmitted to the controller component, and the controller component controls the operation of the motor unit. In the present invention, the tendons and other tissues around the blood vessels are driven down, and the blood vessels are highlighted from the covered tissues, so that the interference factors of the blood pressure measurement are smaller, and the loss of the pressure signal in the arteries during the transfer process is reduced, so that Measurements are more accurate, even stronger arterial pulses can be detected in the superficial layers of the skin.

Description

Method and device for noninvasive, continuous, real-time and accurate measurement of arterial blood pressure

technical field

The invention relates to the technical field of arterial positioning and blood pressure measurement, in particular to a method and device for non-invasive, continuous, real-time and accurate measurement of arterial blood pressure.

Background technique

In clinical large-scale surgery and emergency medical occasions such as ICU, accurate and continuous stroke-per-beat measurement of the patient's blood pressure is required. By observing the blood pressure in real time, doctors can judge the parameters of the blood circulation system, so as to carry out targeted treatment. The current common clinical method is to use continuous arterial puncture catheter method to measure blood pressure, and the measurement result of this method is the gold standard for measuring blood pressure in the medical field. Although this method is accurate, it will cause damage to the human body, and the requirements for operators are relatively high. The medical community has a strong demand for equipment that can measure blood pressure non-invasively, continuously and accurately in real time, and it has always been a hot spot in medical science research.

Regarding noninvasive blood pressure measurement methods, there are auscultation measurement method, vibration measurement method, ultrasonic measurement method, arterial tonometry method, and constant volume measurement method.

Auscultatory measurement, vibration measurement, and ultrasonic measurement determine the systolic and diastolic blood pressure of the patient's heart by detecting the Korotkoff sounds. To accurately measure the pressure value, the systolic and diastolic blood pressure cannot be measured in continuous time, and the actual blood pressure waveform of the patient cannot be reproduced, so continuous stroke-per-stroke blood pressure measurement cannot be realized by these methods.

Two blood pressure measurement methods, tonometry and constant volume measurement, are the main methods of non-invasive continuous real-time blood pressure measurement. Since the blood pressure measurement method of the constant volume method is to maintain the blood oxygen parameters of fingers or other parts of the body in a stable range by applying dynamic pressure from the outside, the blood pressure parameters obtained by indirectly measuring the dynamic pressure have large measurement errors and High R&D difficulty.

Arterial tension measurement method, through the pressure sensor, placed on the skin above the artery, measured according to the theory of arterial tension, this method directly converts the measured pressure value to obtain the blood pressure value, in this way for continuous detection The blood pressure measurement method is very popular, and this patent uses the principle of the arterial tension measurement method to realize accurate measurement of the blood pressure value of the human body.

According to the principle of tension method, the pressure in superficial arteries with sufficient skeletal support (such as dorsalis pedis, radial artery) may be accurately recorded when the transmural pressure is zero, that is, the blood vessel is in a flattened state. In the state of applanation, the arterial vessel is compressed into a dog-bone shape. Under the action of this pressure, it is generally considered that the obtained pressure is the maximum peak-to-peak value. The obtained pressure at this time corresponds to zero transmural pressure. The waveform obtained by the pressure sensor on the skin surface just above the blood vessel is the waveform of ambulatory blood pressure.

Tension measurement systems are usually also sensitive to the direction of the pressure sensor on the site to be measured, so the sensor needs to be pressed vertically above the center of the arterial vessel during measurement. Therefore, it is especially important to find the position of the blood vessel and press the sensor in the correct direction and precisely on the blood vessel.

The pressure in the arteries is transmitted up through human tissues, and there will inevitably be transfer losses. Especially when measuring the blood pressure of the dorsalis pedis artery, because the tendons at the foot artery are very rich and cover part of the blood vessels, when measuring, the blood pressure pulsation felt on the skin is slightly lighter than the pulsation felt when pressed on the wrist . Similarly, when measuring the radial artery at the wrist, because the thicker fat layer has a buffering effect on the pressure of the blood vessel, the pulse measured on the surface of the skin of obese people is often relatively weak.

Precise positioning of the vessel and placing the sensor vertically above the vessel and reducing tissue loss of pressure on the vessel are critical for accurate measurement of relevant arterial parameters by arterial tonometry. Regarding the precise positioning of blood vessel positions, existing products basically scan horizontally and vertically to position the sensor at different positions. The position where the waveform measured by the detector has the largest peak-to-peak value is the position of the blood vessel. With regard to reducing the pressure loss due to the intermediate tissue, the existing common practice is to bend the wrist outward when taking the radial artery measurement of the wrist, so that the radial artery is exposed more from the tissue, so that the surface of the skin The perceived arterial pulse is stronger, but bending the wrist at an angle for a long time can be very uncomfortable for the subject or patient.

In particular, no suitable method has been found for reducing the loss caused by tissue pressure penetration caused by arterial pulsation, which will cause the detected blood pressure signal to be on the low side and cause the blood pressure measurement error to be too large. Moreover, the above-mentioned outward bending of the wrist can only have an effect on some subjects.

Contents of the invention

The present invention aims to provide a non-invasive, continuous, real-time and accurate method and device for measuring arterial blood pressure, so as to solve the two problems of precisely locating arterial blood vessels and reducing the loss caused by tissue pressure penetration generated by arterial pulses.

The term "transverse scanning" and "vertical scanning" are involved in this article, and the horizontal scanning refers to the process in which the pressure sensor moves away from the human artery to directly above the artery, and then leaves the artery. The "scanning" here generally refers to linear position changes, and can also be in any other way.

Vertical scanning is the process in which the pressure sensor applies downward pressure perpendicular to the arterial vessel. During this scanning process, the arterial vessel changes from no change to a flattened state and then to an over-compressed state, and the pressure sensor returns to the position at the moment when the arterial vessel is compressed into a flattened state.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

By accurately and repeatably (if necessary) disposing the sensor assembly on the physiological tissue of the individual to be measured, the sensor assembly includes at least three or more pressure sensors, at least one of which is a sensor for measuring the subject's blood pressure or other parameters , which is called a pressure sensor; the other two pressure sensors are used to accurately locate the arterial blood vessels, and they are called positioning sensors.

Non-invasive, continuous, real-time and accurate measurement of arterial blood pressure. The tissue on both sides of the arterial vessel is pressed down to highlight the arterial vessel, and then the manometry sensor is vertically pressed down the arterial vessel from above the arterial vessel to a flat state, and the arterial blood pressure is measured using the manometry sensor. Take measurements. When the blood vessel is flat, the arterial transmural pressure is zero. At this time, the arterial blood vessel is compressed into a dog-bone shape. At this time, the waveform obtained by the pressure sensor pressed on the skin surface directly above the blood vessel is the waveform of ambulatory blood pressure. Specifically include the following steps:

Step 1, determining the position of the artery, said step 1 comprises the following steps:

Sub-step 1.1, scan the patient's skin laterally with the sensor assembly, record the pulse pressure collected by the positioning sensor and the position corresponding to the pulse pressure during the scanning process, the sensor assembly includes two positioning sensors arranged side by side laterally;

Sub-step 1.2, stop scanning, retrieve the maximum value of the pulse pressure sum collected by the two positioning sensors and the position corresponding to the maximum value;

Sub-step 1.3, laterally moving the sensor assembly to the position corresponding to the maximum value;

Step 2, highlighting arterial vessels, said step 2 includes the following steps:

Sub-step 2.1, move the two positioning sensors laterally respectively, and stop moving when the pulse pressure collected by the positioning sensors is 0, and the moving directions of the two positioning sensors are opposite;

Sub-step 2.2, move the two positioning sensors vertically downward for a certain distance to highlight the arterial vessel from the covered tissue; the pressing distance can be set according to the experience of those skilled in the art, and will not be repeated here.

Step 3, measure arterial blood pressure, described step 3 comprises the following steps:

Sub-step 3.1, make the pressure measuring sensor perform vertical scanning between the two positioning sensors, record the pulse pressure collected by the pressure measuring sensor and the position information corresponding to the pulse pressure during the scanning process;

Sub-step 3.2, stop scanning, and retrieve the maximum value of the pulse pressure collected by the pressure sensor and the position corresponding to the maximum value;

Sub-step 3.3, vertically move the manometry sensor to the position corresponding to the maximum pulse pressure, and use the manometry sensor to measure the arterial blood pressure.

Further, the sensor assembly is reset before step 1; in the reset state, the two positioning sensors are in contact, and the load cell is located directly above the two positioning sensors.

Further, the above method is processed by using a device for non-invasive continuous real-time accurate measurement of arterial blood pressure, the device includes a sensor assembly, a controller assembly and a motor unit, the sensor assembly includes a pressure sensor and two positioning sensors, the The motor set is used to drive the sensor assembly to move laterally and vertically, and the sensor assembly transmits signals to the controller assembly, and the controller assembly controls the operation of the motor set.

Further, the signal acquisition frequency of the controller component is 50 Hz.

Further, the movement of each positioning sensor is respectively driven by two motors, the movement of the load cell is respectively driven by two motors, and the controller component controls the operation of each motor. Of course, only 5 motors can be used, 3 of which control the lateral movement of the 3 sensors respectively; the other 1 motor controls the vertical movement of the load cell, and the other 1 motor controls the vertical movement of the two positioning sensors.

A device for non-invasive, continuous, real-time and accurate measurement of arterial blood pressure, comprising a sensor assembly, a controller assembly, and a motor set, the sensor assembly includes a manometric sensor and two positioning sensors, and the motor set is used to drive the sensor assembly to move laterally and vertically , the sensor component transmits the signal to the controller component, and the controller component controls the operation of the motor unit.

Preferably, the two positioning sensors are parallel and arranged on the same horizontal plane, the two positioning sensors are in contact, and the load cell is located directly above the two positioning sensors.

Further, it also includes a measuring device body and a fixing belt arranged on the measuring device body, and the sensor assembly, the controller assembly and the motor assembly are arranged in the measuring device body.

Further, the measuring device body is provided with a measuring chamber, the bottom of which is open, and the sensor assembly is located in the measuring chamber.

Further, the controller assembly and the motor assembly are located above the sensor assembly.

Further, the motor group includes six motors, the lateral movement and vertical movement of the load cell are respectively controlled by two motors, the lateral movement and vertical movement of the positioning sensor are respectively controlled by two motors, and the positioning The lateral movement and vertical movement of the sensor are respectively controlled by two motors.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention can accurately locate the position of the arterial blood vessel, and the downward pressure of the positioning sensor can drive down the tendon and other tissues around the blood vessel, so that the blood vessel can be highlighted from the covered tissue as much as possible, so that the surface layer of the skin can be detected more Strong arterial pulses. In the application of tonometry, the present invention can make the measurement of blood pressure less disturbed, and reduce the loss of the pressure signal in the arterial vessel during the transfer process, making the measurement result more accurate, even when the pulse is relatively weak There are also good measurements at the dorsalis pedis artery.

Description of drawings

Fig. 1 is the flowchart of method among the present invention;

Fig. 2 is the structural representation of device among the present invention;

Fig. 3 is a structural schematic diagram of the device worn on the foot in the present invention;

Fig. 4 is the structural representation of sensor assembly among the present invention;

In the figure: 101-right foot, 102-dorsalis pedis artery, 200-measuring device body, 201-fixing belt, 202-fixing bracket, 203-sensor component, 204-motor unit, 205-controller component, 206-measurement cavity Chamber, 232 - first positioning sensor, 233 - second positioning sensor.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

It should be noted that this specific embodiment mainly describes the method and device for accurately finding the dorsalis pedis artery at the instep of the human body, but the present invention is also applicable to finding arteries in other parts of the human body, such as accurately locating the radial artery and the brachial artery. , femoral artery, carotid artery, etc.

As shown in Figure 1, the non-invasive, continuous, real-time and accurate method for measuring arterial blood pressure disclosed by the present invention, presses down the tissues on both sides of the arterial blood vessel to highlight the arterial blood vessel, and then presses the manometry sensor vertically from above the arterial blood vessel to the arterial blood vessel. In a flat state, the arterial blood pressure is measured using a manometry sensor. Specifically include the following steps:

Step 1, determining the position of the artery, said step 1 comprises the following steps:

Sub-step 1.1, scan the patient's skin laterally with the sensor assembly, record the pulse pressure collected by the positioning sensor and the position corresponding to the pulse pressure during the scanning process, the sensor assembly includes two positioning sensors arranged side by side laterally;

Sub-step 1.2, stop scanning, retrieve the maximum value of the pulse pressure sum collected by the two positioning sensors and the position corresponding to the maximum value;

Sub-step 1.3, move the sensor assembly laterally to the position corresponding to the maximum value; align the midline of the sensor assembly with the position corresponding to the maximum value, and set the two positioning sensors symmetrically about the midline.

Step 2, highlighting arterial vessels, said step 2 includes the following steps:

Sub-step 2.1, move the two positioning sensors laterally respectively, and stop moving when the pulse pressure collected by the positioning sensors is 0, that is, stop when the two positioning sensors do not feel the pulse pressure signal; the moving directions of the two positioning sensors are opposite;

Sub-step 2.2, move the two positioning sensors vertically downward for a certain distance to highlight the arterial vessel from the covered tissue; the pressing distance can be set according to the experience of those skilled in the art, and will not be repeated here.

Step 3, measure arterial blood pressure, described step 3 comprises the following steps:

Sub-step 3.1, make the pressure measuring sensor perform vertical scanning between the two positioning sensors, record the pulse pressure collected by the pressure measuring sensor and the position information corresponding to the pulse pressure during the scanning process;

Sub-step 3.2, stop scanning, and retrieve the maximum value of the pulse pressure collected by the pressure sensor and the position corresponding to the maximum value;

Sub-step 3.3, vertically move the manometry sensor to the position corresponding to the maximum pulse pressure, and use the manometry sensor to measure the arterial blood pressure.

Further, the sensor assembly is reset before step 1; in the reset state, the two positioning sensors are in contact, and the load cell is located directly above the two positioning sensors. The method of the present invention utilizes a non-invasive, continuous, real-time and accurate device for measuring arterial blood pressure.

As shown in Figures 2 and 3, the device for non-invasive continuous real-time and accurate measurement of arterial blood pressure disclosed by the present invention includes a sensor assembly 203, a controller assembly 205, and a motor unit 204, and the sensor assembly 203 includes a pressure measuring sensor 231 and a first positioning sensor 232 and the second positioning sensor 233 , the motor unit 204 is used to drive the sensor unit 203 to move laterally and vertically, the sensor unit 203 transmits a signal to the controller unit 205 , and the controller unit 205 controls the operation of the motor unit 204 . The controller component 205 collects 50 signals per second, that is, the signal collection frequency is 50 Hz. Preferably, the two positioning sensors are elongated pressure sensors with the same size and material, and the pressure sensor is a pressure sensor with a diameter of 2 to 6 mm. As shown in Figure 4, the cross section of the first positioning sensor 232 and the second positioning sensor 233 is rectangular, the load cell 231 is cylindrical, and the axis of the load cell 231 is perpendicular to the first positioning sensor 232 and the second positioning sensor 233 .

The movement of each positioning sensor is driven by two motors respectively, and the movement of the pressure measuring sensor is driven by two motors respectively. Further, the motor group 204 includes six motors, and the lateral movement and vertical movement of the pressure measuring sensor 231 are respectively driven by two motors. Motor control, the lateral movement and vertical movement of the first positioning sensor 232 are respectively controlled by two motors, and the lateral movement and vertical movement of the second positioning sensor 233 are respectively controlled by two motors.

Further, it also includes a measuring device body 200 and a fixing belt 201 arranged on the measuring device body 200 , and fixing brackets 202 are arranged on both sides of the measuring device body 200 , and the fixing belt 201 is connected to the fixing bracket 202 . The sensor assembly 203 , the controller assembly 205 and the motor assembly 204 are arranged in the measuring device body 200 . The measurement device body 200 is provided with a measurement chamber 206 , the bottom of which is open, and the sensor assembly 203 is located in the measurement chamber 206 , wherein the bottom surfaces of the two positioning sensors are flush with the bottom surface of the measurement chamber 206 . Controller assembly 205 and motor pack 204 are located above sensor assembly 203 . The fixing belt 201 and the fixing bracket 202 are mainly used to firmly fix the device on the instep, so as to ensure that the blood pressure and other parameters of the subject can be accurately measured even with little interference.

The controller component 205 is the core of the entire measurement device, plays a control role, and includes various control chips such as MCU and their circuits. The controller component is used for communication with the upper computer, signal detection and logic processing, and motor control. In this specific embodiment, the controller component adopts the MCU system, but is not limited to the MCU, and can be embedded chips such as DSP, CPLD, and FPGA according to the needs of different occasions. The controller component reads the real-time data measured by the sensor component through the interface, and sends a control signal to control the operation of the motor in the brake component. In the present invention, the logic of condition judgment and corresponding action execution is carried out by this component, and the specific implementation is written by the developer and burnt into the MCU.

Before the detection starts, place the device of the present invention at a suitable position near the arterial vessel to be measured. If the sensor cannot detect a signal, you can properly adjust the wearing position, reset the system settings, reset the motor rotation state, and reset the position of the sensor. In the reset state, as shown in FIG. 4 , the first positioning sensor 232 and the second positioning sensor 233 are pasted together side by side in parallel, and are located on the left side of the measuring device body 200; the load cell 231 is located on the top of the two positioning sensors. right in the middle.

The device is started, and under the control of the controller assembly 205, the motor drives the sensor assembly to move laterally as a whole and scan back and forth for one round. During the scanning process, the controller component 205 reads the detected pulse pressure data from the two positioning sensors at a certain frequency, records the sum of the pulse pressure of the two positioning sensors and the position at this time, and the preferred frequency is 50HZ .

After the scan ends, the pulse pressure sum value of the two positioning sensors is the largest and the corresponding position is retrieved. The controller component 205 controls the motor unit 204 to drive the sensor component 203, and the center of the two closed positioning sensors corresponds to the position corresponding to the above-mentioned maximum sum value.

The first positioning sensor 232 is gradually moved outward, the controller assembly 205 detects that the signal of the first positioning sensor 232 is zero, and stops the outward movement. The second positioning sensor 233 performs the same operation. It should be noted that at this time, the pressure measuring sensor 231 above the positioning sensor remains in its original position, and the dorsalis pedis artery is between the two positioning sensors at this moment.

Immediately afterwards, the motor controls the two positioning sensors to press down vertically, and stops when the dorsalis pedis artery in the middle is obviously protruded. When this protrusion is obvious, it can be controlled by the pressing distance, which can be set according to the experience of those skilled in the art, and will not be repeated here.

After the positioning sensor is fixed, the pressure sensor 231 is still directly above the dorsalis pedis artery, and the controller component 205 outputs a control signal to control the corresponding motor in the motor unit to drive the pressure sensor 231 to scan vertically for one round. Record the maximum value detected by the pressure sensor 231 and the corresponding position during the scanning process, and then press the pressure sensor 231 vertically down to the position corresponding to the maximum value. Measure the subject's blood pressure and other parameters.

When accurately looking for the dorsalis pedis artery, the controller component 205 outputs a control signal to the motor group 204, and the corresponding motor in the motor group 204 starts to run after receiving the control signal, and drives the first positioning sensor 232 and the second positioning sensor 233 to scan horizontally to find Then control the first positioning sensor 232 and the second positioning sensor 233 to press down vertically at the position where the sum of the pulse pressure values detected by the two sensors is the largest, so that the dorsalis pedis artery 102 in the middle is highlighted. After the positioning sensor is fixed, the manometry sensor 231 is still directly above the dorsalis pedis artery, and the manometry sensor 231 is driven to press the dorsalis pedis artery 102 into a flat state, and the manometry sensor 231 starts to measure the subject's blood pressure and other parameters. The present invention can accurately locate the position of the arterial blood vessel, press down the positioning sensor, and can push down the tendon and other tissues around the blood vessel, so that the blood vessel can be highlighted from the covered tissue as much as possible, so that the surface layer of the skin can be detected to a stronger arterial pulse. In the application of the tension measurement method, the present invention can make the measurement of the blood pressure less disturbed, and reduce the loss of the pressure signal in the arterial blood vessel during the transfer process, so that the measurement result is more accurate. Good measurements even at the dorsalis pedis artery, where the pulse is relatively weak.

Certainly, the present invention also can have other multiple implementation modes, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes All changes and modifications should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. The method for non-invasive continuous real-time accurate measurement of arterial blood pressure is characterized in that: the tissue on both sides of the arterial blood vessel is pressed down to highlight the arterial blood vessel, and then the manometry sensor is vertically pressed down the arterial blood vessel from above the arterial blood vessel to a flat state, using The manometry transducer measures arterial blood pressure. 2. The method according to claim 1, characterized in that: comprising the following steps: Step 1, determining the position of the artery, said step 1 comprises the following steps: Sub-step 1.1, scan the patient's skin laterally with the sensor assembly, record the pulse pressure collected by the positioning sensor and the position corresponding to the pulse pressure during the scanning process, the sensor assembly includes two positioning sensors arranged side by side laterally; Sub-step 1.2, stop scanning, retrieve the maximum value of the pulse pressure sum collected by the two positioning sensors and the position corresponding to the maximum value; Sub-step 1.3, laterally moving the sensor assembly to the position corresponding to the maximum value; Step 2, highlighting arterial vessels, said step 2 includes the following steps: Sub-step 2.1, move the two positioning sensors laterally respectively, and stop moving when the pulse pressure collected by the positioning sensors is 0, and the moving directions of the two positioning sensors are opposite; Sub-step 2.2, moving the two positioning sensors vertically downward for a certain distance to highlight the arteries from the covered tissue; Step 3, measure arterial blood pressure, described step 3 comprises the following steps: Sub-step 3.1, make the pressure measuring sensor perform vertical scanning between the two positioning sensors, record the pulse pressure collected by the pressure measuring sensor and the position information corresponding to the pulse pressure during the scanning process; Sub-step 3.2, stop scanning, retrieve the maximum value of the pulse pressure collected by the pressure sensor and the position corresponding to the maximum value; Sub-step 3.3, vertically move the manometry sensor to the position corresponding to the maximum pulse pressure, and use the manometry sensor to measure the arterial blood pressure. 3. The method according to claim 2, wherein the sensor assembly is reset before step 1; in the reset state, the two positioning sensors are in contact, and the pressure sensor is located directly above the two positioning sensors. 4. The method according to claim 2 or 3, characterized in that: it is processed by a device for non-invasive, continuous and real-time accurate measurement of arterial blood pressure, said device comprising a sensor assembly, a controller assembly and a motor unit, said sensor assembly It includes a pressure measuring sensor and two positioning sensors. The motor unit is used to drive the sensor unit to move laterally and vertically. The sensor unit transmits signals to the controller unit, and the controller unit controls the operation of the motor unit. 5. The method according to claim 4, characterized in that: the signal acquisition frequency of the controller component is 50 Hz. 6. the device of non-invasive continuous real-time accurate measurement of arterial blood pressure, it is characterized in that: comprise sensor assembly, controller assembly and motor set, described sensor assembly comprises pressure measuring sensor and two positioning sensors, and described motor set is used to drive sensor assembly The sensor assembly transmits signals to the controller assembly, and the controller assembly controls the operation of the motor unit. 7. The device according to claim 6, wherein the two positioning sensors are parallel and arranged on the same horizontal plane, the two positioning sensors are in contact, and the pressure measuring sensor is located directly above the two positioning sensors. 8. The device according to claim 6, characterized in that it further comprises a measuring device body and a fixing belt arranged on the measuring device body, the sensor assembly, the controller assembly and the motor unit are arranged in the measuring device body. 9. The device according to claim 8, wherein the measuring device body is provided with a measuring chamber, the bottom of which is open, and the sensor assembly is located in the measuring chamber. 10. The apparatus of claim 9, wherein the controller assembly and motor assembly are located above the sensor assembly.