A double-arm bridge pressure detector

Abstract

The present invention discloses a double-arm bridge pressure detector, comprising an upper panel, a lower panel, two strain gauge pressure sensors with cantilever beams, and a circuit board. The strain gauge pressure sensor comprises a pressure U-shaped frame, a cantilever beam located inside the U-shaped frame, and an electronic strain gauge is attached to the connection between the cantilever beam and the U-shaped frame. Two parallel first grooves are provided on the lower panel, and a second groove is also provided in the first groove. The strain gauge pressure sensor is embedded in the first groove, and the cantilever beam is located above the second groove. Two pressure blocks are fixed on the inner side of the upper panel, and the pressure blocks are respectively attached to the cantilever beams of the strain gauge pressure sensor. The double-arm bridge pressure detector of the present invention is modularly designed, and the outer surface of the module is flat, and can be directly attached to any plane for use. The internal circuit can be directly connected to a single-chip microcomputer to obtain accurate pressure measurement values ​​after filtering and analog-to-digital conversion, which is greatly convenient to use.

Description

Technical Field

[0001] The invention relates to a double-arm bridge type pressure detector. Background Art

[0002] In today's portable, lightweight, and miniaturized mobility devices, it has become a trend to control mobility devices by changing the center of gravity of the human body. At the same time, mobility devices controlled by other methods can automatically adjust their operating status by understanding the center of gravity position of the user. However, there is a lack of a universal pressure detector on the market, which needs to be directly installed on the pedal of any small mobility device, and can obtain the center of gravity position of various standing postures of the human body through combination. Summary of the invention

[0003] Purpose of the invention: In view of the above-mentioned prior art, a double-arm bridge pressure detector is proposed, which can be installed on the pedal of any small travel equipment as a universal device. Through combination, it can accurately detect the center of gravity position of the human body in different standing postures.

[0004] Technical solution: A double-arm bridge pressure detector, comprising an upper panel, a lower panel, two strain gauge pressure sensors with cantilever beams, and a circuit board; the strain gauge pressure sensor comprises a U-shaped frame, a cantilever beam located inside the U-shaped frame, the U-shaped frame and the cantilever beam are in the same horizontal plane, and an electronic strain gauge is affixed to the connecting portion between the cantilever beam and the U-shaped frame; two parallel first grooves are provided on the lower panel, and a second groove is also provided in the first groove; the strain gauge pressure sensor is embedded in the first groove, and the cantilever beam is located above the second groove; two pressure blocks are fixed on the inner side of the upper panel, the upper panel covers the lower panel, and the pressure blocks are respectively affixed to the cantilever beams of the strain gauge pressure sensor; the circuit board is arranged in a cavity formed by the upper panel and the lower panel, and is located between the two strain gauge pressure sensors with cantilever beams, and the circuit board is connected to the electronic strain gauge.

[0005] Furthermore, the cantilever beam is an inverted "mountain" shaped structure, including a "T" shaped main beam connected to the U-shaped frame, and two long strip sub-beams connected to the "T" shaped main beam, the two long strip sub-beams are symmetrically arranged about the "T" shaped main beam, the suspended end of the sub-beam is provided with a blind hole or a through hole, the pressure block is provided with four protrusions, and the protrusions are respectively embedded in the blind holes or through holes.

[0006] Furthermore, the U-shaped frame is glued into the first groove, and the pressing block is glued to the surface of the cantilever beam.

[0007] Furthermore, a mounting limit strip for the circuit board is provided on the lower panel between the two strain gauge pressure sensors with cantilever beams, and an opening for leading out wiring of the circuit board is provided on the lower panel.

[0008] Furthermore, the U-shaped frame and the cantilever beam are both made of hard aluminum, and are coated with insulating paint on the upper and lower surfaces.

[0009] Furthermore, the upper panel and the lower panel are made of aluminum alloy material and are coated with insulating paint on the relative inner sides.

[0010] A center of gravity detector of a double-arm bridge pressure detector comprises four double-arm bridge pressure detectors, two of which are arranged side by side at the front with a horizontal interval, and the other two are arranged side by side at the rear with a horizontal interval.

[0011] Further, when one foot of a human body crosses over the two front double-arm bridge-type pressure detectors, and the other foot crosses over the two rear double-arm bridge-type pressure detectors, the four double-arm bridge-type pressure detectors are set to detect that the user makes a left front tilt, a front tilt, and a right front tilt posture, and are defined as a forward tilt acceleration state, the double-arm bridge-type pressure detectors detect that the user makes a left rear tilt, a rear tilt, and a right rear tilt posture, and are defined as a rear tilt deceleration state, and the four double-arm bridge-type pressure detectors detect that the user makes a left tilt, an upright position, and a right tilt posture, and are defined as an upright uniform speed state; when a new user weight is detected by the four double-arm bridge-type pressure detectors, a parameter adjustment step is performed, including:

[0012] Step 1: collecting the output values ​​of the four double-arm bridge pressure detectors when the user's body makes nine postures, namely, left front tilt, front tilt, right front tilt, left tilt, upright, right tilt, left rear tilt, rear tilt, and right rear tilt, and calibrating the center of gravity tilt percentage of the forward tilt acceleration state as 100%, the center of gravity tilt percentage of the upright uniform speed state as 0%, and the center of gravity tilt percentage of the backward tilt deceleration state as -100%;

[0013] Step 2: According to the output values ​​of the four double-arm bridge pressure detectors collected in step 1, the front-to-back tilt pressure difference pfb and the left-to-right tilt pressure difference plr in the nine postures are calculated respectively, and the calculation method is:

[0014] Front and rear tilt pressure difference pfb = (x1 + x4) - (x2 + x3)

[0015] Left and right tilt pressure difference plr = (x1 + x2) - (x4 + x3)

[0016] Among them, x1 is the output value of the double-arm bridge pressure detector at the left front, x2 is the output value of the double-arm bridge pressure detector at the left rear, x3 is the output value of the double-arm bridge pressure detector at the right rear, and x4 is the output value of the double-arm bridge pressure detector at the right front;

[0017] Step 3: According to the 9*2 matrix data of the front-to-back tilt pressure difference and the left-to-right tilt pressure difference obtained in step 2, the least square method is used to fit the plane z=a*pfb+b*plr+c, where a, b, c are plane fitting parameters;

[0018] Step 4: When the center of gravity detector is used to control the device to move forward, the x1, x2, x3, and x4 values ​​output in real time by the four double-arm bridge pressure detectors are input into the model obtained in step 3, and the model output value is converted into a percentage, which is the center of gravity inclination percentage.

[0019] Beneficial effects: The double-arm bridge pressure detector of the present invention is modularly designed, and the outer surface of the module is flat, and can be directly attached to any plane for use, and does not require separate measurement and zeroing. The internal circuit can be directly connected to the single-chip microcomputer to obtain accurate pressure measurement values ​​after filtering and analog-to-digital conversion, which is very convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the main cross-section of a double-arm bridge pressure detector;

[0021] Figure 2 It is the overall left view of the double-arm bridge pressure detector;

[0022] Figure 3 The schematic diagram of the cross section of the double-arm bridge pressure detector after removing the upper panel;

[0023] Figure 4 This is the left view of the double-arm bridge pressure detector after removing the upper panel;

[0024] Figure 5 The top view of the double-arm bridge pressure detector after removing the upper panel;

[0025] Figure 6 It is a schematic cross-sectional view of the lower panel of the double-arm bridge pressure detector;

[0026] Figure 7 It is the left view of the lower panel of the double-arm bridge pressure detector;

[0027] Figure 8 It is a top view of the lower panel of the double-arm bridge pressure detector;

[0028] Fig. 9A schematic diagram of a pressure detector arrangement of a center of gravity detector based on the above-mentioned double-arm bridge pressure detector;

[0029] Fig.10 This is a schematic diagram showing the matrix data obtained by adjusting the parameters in the embodiment in two-dimensional coordinates. DETAILED DESCRIPTION

[0030] The present invention will be further explained below in conjunction with the accompanying drawings.

[0031] like Figure 1 , Figure 2 As shown, a double-arm bridge pressure detector is composed of an upper panel 1, a lower panel 2, two strain gauge pressure sensors 3 with cantilever beams, and a circuit board 4. The upper panel 1 and the lower panel 2 are made of aluminum alloy material and are coated with insulating paint on the relative inner sides. The strain gauge pressure sensor 3 includes a U-shaped frame 31, a cantilever beam located inside the U-shaped frame 31, and the U-shaped frame 31 and the cantilever beam are in the same horizontal plane. The U-shaped frame 31 and the cantilever beam are both made of hard aluminum and are coated with insulating paint on the upper and lower surfaces. An electronic strain gauge 33 is attached to the connection between the cantilever beam and the U-shaped frame 31. Among them, the cantilever beam is an inverted "mountain" shaped structure, including a "T" shaped main beam 321 connected to the U-shaped frame 31, and two long strip-shaped secondary beams 322 connecting the "T" shaped main beam 321. Two long strip-shaped auxiliary beams 322 are symmetrically arranged about the “T”-shaped main beam 321 , and blind holes or through holes 323 are arranged at the suspended ends of the auxiliary beams 322 .

[0032] like Figure 6-8 As shown, the lower panel 2 is provided with two parallel first grooves 21, and a second groove 22 is further provided in the first groove 21. Figure 3-5 As shown, the strain type pressure sensor 3 is embedded in the first groove 21, and the cantilever beam is located above the second groove 22. The U-shaped frame 31 is consistent in size with the first groove 21, and is glued in the first groove 21. Two pressing blocks 11 are fixed on the inner side of the upper panel 1, and four protrusions 111 are provided on the pressing blocks 11. The upper panel 1 is covered on the lower panel 2, and the pressing blocks 11 are respectively attached to the cantilever beams of the strain type pressure sensor 3, and the protrusions 111 are respectively embedded in the blind holes or through holes 323 at the ends of each sub-beam 322. Before installation, glue is applied on the surface of the pressing block 11 so that it can be attached to the surface of the cantilever beam.

[0033] The lower panel 2 located between the two strain type pressure sensors 3 with cantilever beams is provided with a mounting limit strip 23 for the circuit board 4, and an opening for wiring the circuit board 4 is provided on the lower panel 2. The circuit board 4 is arranged in a cavity formed by the upper panel 1 and the lower panel 2, and is located between the two strain type pressure sensors 3 with cantilever beams. The circuit board 4 is connected to the electronic strain gauge 33.

[0034] When the upper panel 1 is stressed, the pressure is completely transmitted to one end of the cantilever beam, causing the cantilever beam and the U-shaped frame 31 to bend relative to each other, driving the electronic strain gauge 33 to deform and generate an electrical signal to realize the conversion between pressure and electron. This conversion relationship is a nonlinear relationship, and there are slight differences in the production process. The material of the U-shaped frame 31 and the cantilever beam is hard aluminum, which is characterized by high resistance to metal fatigue. Within the range, the vertical height of the bending of one end of the force arm is less than 0.5mm.

[0035] The A / D conversion, voltage stabilization, filtering and other tasks of the pressure data are completed in the circuit board, and the circuit board is encapsulated in a double-arm bridge pressure detector. The double-arm bridge pressure detector is led out by a cable consisting of three wires. The double-arm bridge pressure detector can be directly connected to the digital circuit for use, which greatly increases the versatility of the module and reduces the design complexity of the external circuit.

[0036] The existing cantilever beam strain gauge pressure sensor has the following disadvantages when used for detection: the force point is strictly regulated and must be on the plane of one end of the cantilever beam. When multiple sensors are used together, once the force point is inconsistent, the force arm length will be different. Each sensor needs to be debugged separately, which is extremely time-consuming and labor-intensive. When the force is applied, the cantilever beam will bend significantly. When the cantilever beam bends and touches the pressure surface, the force will be transmitted and cannot be accurately measured.

[0037] The double-arm bridge pressure detector of the present invention is modularly designed. The outer surface of the module is flat and can be directly attached to any plane for use, and does not require separate measurement and zeroing. The internal circuit can be directly connected to a single-chip microcomputer to obtain accurate pressure measurement values ​​after filtering and analog-to-digital conversion, which is very convenient to use. Specifically:

[0038] The first groove 21 on the lower panel 2 is used to limit the strain gauge pressure sensor 3 with the cantilever beam, so as to facilitate the installation of the strain gauge pressure sensor 3. After the strain gauge pressure sensor 3 is installed in the first groove 21, the U-shaped frame 31 and the groove are fixedly connected with glue. There is a second groove 22 in the first groove 21, the size of which is just the same as the cantilever beam of the strain gauge, leaving space for the cantilever beam to bend downward, so as to prevent the cantilever beam from contacting the bottom surface when bending up and down, resulting in inaccurate detection data.

[0039] There are two protruding pressure blocks 11 of exactly the same size corresponding to the force points of the cantilever beam of the strain type pressure sensor 3. The pressure blocks 11 are used to press tightly on the cantilever beam, and are fixedly connected to the strain gauge sensor by glue. The pressure blocks 11 have two functions: 1. Ensure that the pressure is completely borne on the cantilever beam of the strain gauge sensor. 2. Make a certain height gap between the upper panel 1 and the lower panel 2, so that the circuit board can be placed inside and the upper part of the strain gauge can be routed. There are two protrusions 111 on the pressure block 11, which are used to insert into the corresponding blind holes or through holes 323 on the cantilever beam. During installation, the protrusions 111 can play the role of alignment and limit, which is convenient for installation.

[0040] A center of gravity detector based on the above double-arm electric bridge pressure detector comprises four double-arm electric bridge pressure detectors located on the pedal of the walking device, the double-arm electric bridge pressure detectors are arranged side by side at the front with a spacing therebetween, and the other two double-arm electric bridge pressure detectors are arranged side by side at the rear with a spacing therebetween. Fig. 9 Four double-arm bridge pressure detectors are connected to a controller, and the controller controls the acceleration or deceleration of the mobility device according to the difference between the front and rear pressure detectors.

[0041] Each user has different operating habits when using a mobility device, which is mainly reflected in the posture amplitude control during acceleration and deceleration control. Although the four sets of pressure detectors have the same pressure unit and sensitivity, it cannot guarantee that each set of pressure detectors will have the same pressure response after the user steps on it. For example, when the user stands steadily on the mobility device, even if there is no leaning forward, left, right, or backward, due to the difference between the soles and heels, the values ​​of the two pairs of sensors, pressure detector A1 and pressure detector A4, or pressure detector A2 and pressure detector A3, must not be exactly the same, and such differences are also different for users with different usage habits. In order to avoid the problem of sudden acceleration and deceleration of the mobility device due to different usage habits of users, a parameter adjustment step is performed for the first use by a new user, and the adjusted parameters are stored in the non-volatile memory of the controller. The parameter adjustment step does not need to be repeated when the user uses it next time. Specifically:

[0042] When one foot of a human body crosses over the two front double-arm bridge pressure detectors, and the other foot crosses over the two rear double-arm bridge pressure detectors, the four double-arm bridge pressure detectors are set to detect that the user makes a left front tilt, a front tilt, and a right front tilt posture, which are all defined as a forward tilt acceleration state, and the double-arm bridge pressure detectors are set to detect that the user makes a left rear tilt, a rear tilt, and a right rear tilt posture, which are all defined as a rear tilt deceleration state, and the four double-arm bridge pressure detectors are set to detect that the user makes a left tilt, an upright position, and a right tilt posture, which are all defined as an upright uniform speed state. When a new user weight is detected by the four double-arm bridge pressure detectors, the parameter adjustment steps are executed, including:

[0043] Step 1: Collect the output values ​​of four double-arm bridge pressure detectors when the user's body makes nine postures, namely, left front tilt, front tilt, right front tilt, left tilt, upright, right tilt, left rear tilt, rear tilt, and right rear tilt, and calibrate the center of gravity tilt percentage of the forward tilt acceleration state to 100%, the center of gravity tilt percentage of the upright uniform speed state to 0%, and the center of gravity tilt percentage of the backward tilt deceleration state to -100%. The above nine postures are maintained for 1 to 2 seconds respectively, and the average value of multiple outputs of the pressure detector is also taken in the step.

[0044] Step 2: According to the output values ​​of the four double-arm bridge pressure detectors collected in step 1, the front-to-back tilt pressure difference pfb and the left-to-right tilt pressure difference plr in the nine postures are calculated respectively, and the calculation method is:

[0045] Front and rear tilt pressure difference pfb = (x1 + x4) - (x2 + x3)

[0046] Left and right tilt pressure difference plr = (x1 + x2) - (x4 + x3)

[0047] Among them, x1 is the output value of the double-arm bridge pressure detector at the left front of the pedal, x2 is the output value of the double-arm bridge pressure detector at the left rear of the pedal, x3 is the output value of the double-arm bridge pressure detector at the right rear of the pedal, and x4 is the output value of the double-arm bridge pressure detector at the right front of the pedal. In this embodiment, the nine groups of pressure detector output data obtained by the test are:

[0048]

[0049] The 9*2 matrix data of the front-to-back tilt pressure difference and the left-to-right tilt pressure difference are displayed in two-dimensional coordinates, such as Fig.10 As shown, it can be found that it is not a regular distribution.

[0050] Step 3: Based on the 9*2 matrix data of the front-to-back tilt pressure difference and the left-to-right tilt pressure difference obtained in step 2, use the least squares method to fit the plane z=a*pfb+b*plr+c, where a, b, and c are plane fitting parameters.

[0051] Step 4: When the device is controlled to move forward by the center of gravity detector, the x1, x2, x3, and x4 values ​​output by the four double-arm bridge pressure detectors in real time are input into the model obtained in step 3. The value range of the model output z value is between -1 and +1, which is a measure of the center of gravity tilt. The model output value is converted into a percentage, which is the center of gravity tilt percentage, indicating the degree of the user's center of gravity tilt.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A double-arm bridge pressure detector, characterized in that: The invention comprises an upper panel (1), a lower panel (2), two strain type pressure sensors (3) with cantilever beams, and a circuit board (4); the strain type pressure sensor (3) comprises a U-shaped frame (31), a cantilever beam located inside the U-shaped frame (31), the U-shaped frame (31) and the cantilever beam are located at the same horizontal plane, and an electronic strain gauge (33) is attached to the connecting portion between the cantilever beam and the U-shaped frame (31); the lower panel (2) is provided with two first grooves (21) arranged in parallel, and a second groove (22) is further provided inside the first groove (21); the strain type pressure sensor (3) comprises a U-shaped frame (31), a cantilever beam located inside the U-shaped frame (31), and a second groove (22) is provided inside the first groove (21); the strain type pressure sensor (3) comprises a U-shaped frame (31), a cantilever beam located inside the U-shaped frame (31), and a cantilever beam located inside the U-shaped frame (31) and a cantilever beam located inside the U-shaped frame (31). The force sensor (3) is embedded in the first groove (21), and the cantilever beam is located above the second groove (22); two pressing blocks (11) are fixed to the inner side of the upper panel (1), the upper panel (1) covers the lower panel (2), and the pressing blocks (11) are respectively attached to the cantilever beams of the strain type pressure sensor (3); the circuit board (4) is arranged in a cavity formed by the upper panel (1) and the lower panel (2), and is located between the two strain type pressure sensors (3) with cantilever beams, and the circuit board (4) is connected to the electronic strain gauge (33); The cantilever beam is an inverted "mountain" shaped structure, comprising a "T" shaped main beam (321) connected to the "U" shaped frame (31), and two long strip-shaped secondary beams (322) connected to the "T" shaped main beam (321), the two long strip-shaped secondary beams (322) are symmetrically arranged with respect to the "T" shaped main beam (321), a blind hole or a through hole (323) is provided at a suspended end of the secondary beam (322), and four protrusions (111) are provided on the pressing block (11), and the protrusions (111) are respectively embedded in the blind holes or through holes (323).

2. The double-arm bridge pressure detector according to claim 1, characterized in that: The U-shaped frame (31) is glued into the first groove (21), and the pressing block (11) is glued to the surface of the cantilever beam.

3. The double-arm bridge pressure detector according to claim 1, characterized in that: A mounting limit strip (23) for the circuit board (4) is provided on the lower panel (2) located between the two strain gauge pressure sensors (3) with cantilever beams, and an opening for leading out wiring of the circuit board (4) is provided on the lower panel (2).

4. The double-arm bridge pressure detector according to claim 1, characterized in that: The U-shaped frame (31) and the cantilever beam are both made of hard aluminum and are coated with insulating paint on the upper and lower surfaces.

5. The double-arm bridge pressure detector according to claim 1, characterized in that: The upper panel (1) and the lower panel (2) are made of aluminum alloy material and are coated with insulating paint on the relative inner sides.

6. A center of gravity detector based on the double-arm bridge pressure detector according to claim 1, characterized in that: It comprises four double-arm bridge pressure detectors, two of which are arranged side by side at the front with a lateral spacing, and the other two are arranged side by side at the rear with a lateral spacing.

7. The center of gravity detector according to claim 6, characterized in that: When one foot of a human body crosses over the two front double-arm bridge-type pressure detectors, and the other foot crosses over the two rear double-arm bridge-type pressure detectors, it is set that when the four double-arm bridge-type pressure detectors detect that the user makes a left front tilt, a front tilt, and a right front tilt gesture, they are all defined as a forward tilt acceleration state, when the double-arm bridge-type pressure detectors detect that the user makes a left rear tilt, a rear tilt, and a right rear tilt gesture, they are all defined as a backward tilt deceleration state, and when the four double-arm bridge-type pressure detectors detect that the user makes a left tilt, an upright position, and a right tilt gesture, they are all defined as an upright uniform speed state; When a new user weight is detected by the four double-arm bridge pressure detectors, a parameter adjustment step is performed, including: Step 1: collecting the output values ​​of the four double-arm bridge pressure detectors when the user's body makes nine postures, namely, left front tilt, front tilt, right front tilt, left tilt, upright, right tilt, left rear tilt, rear tilt, and right rear tilt, and calibrating the center of gravity tilt percentage of the forward tilt acceleration state as 100%, the center of gravity tilt percentage of the upright uniform speed state as 0%, and the center of gravity tilt percentage of the backward tilt deceleration state as -100%; Step 2: According to the output values ​​of the four double-arm bridge pressure detectors collected in step 1, the front-to-back tilt pressure difference pfb and the left-to-right tilt pressure difference plr in the nine postures are calculated respectively, and the calculation method is: Front and rear tilt pressure difference pfb = (x1 + x4) - (x2 + x3) Left and right tilt pressure difference plr = (x1 + x2) - (x4 + x3) Among them, x1 is the output value of the double-arm bridge pressure detector at the left front, x2 is the output value of the double-arm bridge pressure detector at the left rear, x3 is the output value of the double-arm bridge pressure detector at the right rear, and x4 is the output value of the double-arm bridge pressure detector at the right front; Step 3: According to the 9*2 matrix data of the front-to-back tilt pressure difference and the left-to-right tilt pressure difference obtained in step 2, the least square method is used to fit the plane z=a*pfb+b*plr+c, where a, b, c are plane fitting parameters; Step 4: When the center of gravity detector is used to control the device to move forward, the x1, x2, x3, and x4 values ​​output in real time by the four double-arm bridge pressure detectors are input into the model obtained in step 3, and the model output value is converted into a percentage, which is the center of gravity inclination percentage.

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