Rope tension measuring device with range protection function and measuring method

Abstract

The application relates to a rope tension measuring device with a range protection function and a measuring method, and the device structure comprises a pressure sensor, a roller is arranged on the pressure sensor, guide wheels are arranged on the two sides of the roller, the angle of rope bending can be adjusted by adjusting the positions of the two guide wheels relative to the roller, the tension acting on the rope can make the rope generate pressure on the roller; the pressure sensor is arranged in a support, a limiting part is arranged on the pressure sensor, the limiting part is matched with the upper end of the support to limit the movement range of the pressure sensor, an adjusting screw is arranged at the lower end of the support, the adjusting screw is connected with the limiting part through a spring, and the pre-tightening force of the spring can be adjusted through the adjusting screw. The measuring method can quantitatively determine the optimal elastic coefficient of the spring, and the accuracy of the range protection of the pressure sensor is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure measuring devices, in particular to a rope tension measuring device with range protection function and a measuring method. BACKGROUND

[0002] Exoskeleton is a kind of mechanical system which is parallel to the user's body outside, used for power assistance, walking aid or auxiliary rehabilitation treatment. Exoskeleton can be used as a power-assisted device, applied in military, enabling the wearer to carry much heavier equipment without any effort. Applied in industrial production, it can ensure that workers will not strain their backs, arms and legs when handling heavy loads of large volume, reduce work-related injuries and improve the work efficiency of workers. Applied in the field of medical rehabilitation, it helps people with paralysis or limb disabilities to stand up again. For patients with lower extremity motor dysfunction, the rehabilitation goal is to achieve normal standing, walking, squatting and other actions.

[0003] In the structure of lower limb rehabilitation exoskeleton, a rope tension measuring device is often provided. In the prior art, the rope tension measuring device has the following problems: first, a sensor is directly connected in series in the rope. When the rope is pulled, the force sensor will move, and the signal line on it will also move, which is not suitable for patients receiving rehabilitation treatment. Second, the sensor is easily damaged when the rope tension exceeds the sensor range. Third, the structure is complex and heavy, which is not suitable for patients receiving rehabilitation treatment to carry and use. For example, see the patent with publication number CN208591275U and the name "A precise tension measuring mechanism for a lower limb rehabilitation robot suspension system", which has a structure including a stand, an upper support plate, a hanging plate, a fixed pulley, a movable pulley, a winch, a rope and a power source. The upper end of the stand is fixedly connected to the upper support plate. The power source output end is provided with a movable pulley, which is driven by the power source to move up and down. The winch is fixed on the upper support plate. One end of the rope is wound around the winch, the other end passes through the movable pulley, changes direction through the fixed pulley installed on the upper support plate and is connected to the patient's body. The tension sensor is installed between the fixed pulley and the upper support plate. However, it has the following problems: not only is the structure complex and heavy, but also is inconvenient to carry, and sudden large impact may occur during use, such as when used on the knee joint to perform jumping action, the pressure sensor is stressed beyond the range, which is easy to cause damage to the sensor during long-term use, affecting the measurement accuracy and service life. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a rope tension measuring device with range protection function and a measuring method, which aims to quantitatively determine the parameters of the protection mechanism and improve the range protection accuracy of the pressure sensor.

[0005] The technical solution adopted by the present application is as follows:

[0006] The application provides a rope tension measuring device with a range protection function, comprising a pressure sensor, a roller mounted on the pressure sensor, and guide wheels arranged on both sides of the roller; the angle of rope bending can be adjusted by adjusting the positions of the two guide wheels relative to the roller, so that the tension acting on the rope can generate pressure on the roller; the pressure sensor is arranged in a bracket, a limiting part is mounted on the pressure sensor, the limiting part cooperates with the upper end of the bracket to limit the movement range of the pressure sensor, and an adjusting screw is arranged at the lower end of the bracket, the adjusting screw is connected with the limiting part through a spring, and the pre-tightening force of the spring can be adjusted through the adjusting screw.

[0007] Further technical solutions are as follows:

[0008] The two guide wheels are located at the same horizontal height, the roller is arranged on the perpendicular bisector of the center line of the two guide wheels, and the pressure generated by the rope on the roller can drive the roller to move along the perpendicular bisector of the center line of the two guide wheels.

[0009] The length direction of the spring is parallel to the movement direction of the pressure sensor.

[0010] The spring and the adjusting screw are arranged in two groups and symmetrically arranged on both sides of the pressure sensor.

[0011] The application also provides a measuring method of the rope tension measuring device with the range protection function, comprising the following steps:

[0012] The rope to be measured is wound around the lower part of the first guide wheel, the upper part of the roller, and the lower part of the second guide wheel in sequence.

[0013] A spring with a suitable elastic coefficient is selected, the pre-tightening force of the spring is adjusted through the adjusting screw, and the pre-tightening force of the spring is equal to the maximum measuring pressure of the pressure sensor.

[0014] The position of the pressure sensor is adjusted to eliminate the gap between the rope and the roller, so that the rope is in close contact with the guide wheels and the roller.

[0015] When the tension is generated on the rope, the rope can generate pressure on the roller, the pressure sensor detects the pressure acting on the roller, calculates the tension acting on the rope, and when the rope tension is too large and exceeds the range of the pressure sensor, the excessive pressure can compress the pressure sensor to overcome the pre-tightening force of the spring, thereby protecting the pressure sensor.

[0016] Further technical solutions are as follows:

[0017] The selection method of the elastic coefficient of the spring is as follows:

[0018] When the force N of the pressure sensor is not greater than the pre-tightening force F of the spring, the function relationship between the rope tension T and N is N=2T sinθ, θ is the included angle between the inner common tangent of the guide wheel and the horizontal direction, wherein F=k*Δl, k and Δl are the elastic coefficient and the compression amount of the spring (6) in the pre-tightening state respectively.

[0019] Determine the tension T of the rope corresponding to the maximum range of the pressure sensor max According to the geometric relationship of the guide wheel and the guide wheel, when T>T max , the function relationship between the rope tension T and N is N=2T sinθ', θ' is the included angle between the inner common tangent of the guide wheel and the guide wheel (1) after the pressure sensor moves down by Δy and the horizontal direction, the relationship between the moving distance Δy of the pressure sensor (4) and T is calculated as Δy=f(T), the relationship curve two between Δy and N when Δy=0 is obtained, and the relationship curve three between Δy and N when Δy>0 is obtained, the spring elastic force F' of the pressure sensor (4) when moving down by Δy is k*(Δl+Δy), the function relationship is straight line one, and F'=N;

[0020] The intersection point of the straight line one and the curve three corresponds to the N value close to the intersection point of the straight line one and the curve two: reduce the slope k of the straight line one;

[0021] Quantitative acquisition of the optimal k value: select the initial value of k and Δl, select different T values and substitute them into Δy=f(T) to obtain Δy, substitute it into F'=k*(Δl+Δ.y) to obtain F' which is the N value, change the value of k, repeat the calculation, obtain the trend graph of N and T under different k values, and obtain the optimal elastic coefficient k according to the trend graph.

[0022] The beneficial effects of the present application are as follows:

[0023] The measuring device of the present application can protect the sensor when the rope tension exceeds the sensor range, effectively avoid damage to the sensor, has small volume and occupies small space, and is convenient for lightweight design of the exoskeleton and convenient to use and carry.

[0024] The measuring device of the present application does not move with the rope during measurement of the rope tension, which is convenient for arrangement of the sensing circuit.

[0025] The measuring method of the present application can quantitatively determine the optimal elastic coefficient of the spring, and improve the accuracy of the pressure sensor range protection.

[0026] Other features and advantages of the present application will be set forth in the following description, and some will become apparent from the description, or will be understood from the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the measuring device of the present application.

[0028] Figure 2 This is a schematic diagram of the geometric model of the guide wheel and roller when the force on the pressure sensor of the measurement system of the present invention is no greater than the spring preload.

[0029] Figure 3 This is a schematic diagram of the geometric model of the guide wheel and roller when the pressure sensor of the measurement system of the present invention is subjected to a force greater than the spring preload.

[0030] Figure 4 This is a graph showing the relationship between N and T obtained by the measurement method of this invention.

[0031] Figure 5 This is a graph showing the relationship between N and Δy obtained by the measurement method of this invention.

[0032] Figure 6 This is a trend graph of N and T under different k values ​​obtained by the measurement method of the present invention. Detailed Implementation

[0033] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0034] like Figure 1 As shown, this embodiment provides a rope tension measuring device with range protection function, including a pressure sensor 4, a roller 2 mounted on the pressure sensor 4, and guide wheels 1 located on both sides of the roller 2. By adjusting the position of the two guide wheels 1 relative to the roller 2, the bending angle of the rope 3 can be adjusted so that the tension acting on the rope 3 can cause the rope 3 to exert pressure on the roller 2. The pressure sensor 4 is set in a bracket 8, and a limiting part 5 is mounted on the pressure sensor 4. The limiting part 5 cooperates with the upper end of the bracket 8 to limit the movement range of the pressure sensor 4. An adjusting screw 7 is provided at the lower end of the bracket 8. The adjusting screw 7 is connected to the limiting part 5 by a spring 6. The preload of the spring 6 can be adjusted by adjusting the adjusting screw 7.

[0035] Two guide wheels 1 are located at the same horizontal height, and roller 2 is located on the perpendicular bisector of the line connecting the centers of the two guide wheels 1. The pressure generated by the rope 3 on roller 2 can cause roller 2 to drive pressure sensor 4 to move along the perpendicular bisector of the line connecting the centers of the two guide wheels 1.

[0036] The length direction of spring 6 is parallel to the movement direction of pressure sensor 4.

[0037] Two sets of springs 6 and adjusting screws 7 are provided and are symmetrically arranged on both sides of pressure sensor 4.

[0038] In practical use, the bracket 8 can be fixed to the corresponding bone joint.

[0039] This embodiment also provides a measurement method for the rope tension measuring device with range protection function, including:

[0040] The rope 3 to be measured is wound around the lower part of the first guide wheel 1, the upper part of the roller 2, and the lower part of the second guide wheel 1 in sequence;

[0041] The spring 6 with a proper elastic coefficient is selected, and the pre-tightening force of the spring 6 is adjusted by adjusting the screw 7, so that the pre-tightening force of the spring 6 is equal to the maximum measuring pressure of the pressure sensor 4;

[0042] The position of the pressure sensor 4 is adjusted to eliminate the gap between the rope 3 and the roller 2, so that the rope 3 is in close contact with the guide wheels 1 and the roller 2;

[0043] When the rope 3 generates a pulling force, the rope 3 can generate a pressure on the roller 2, and the pressure sensor 4 calculates the pulling force on the rope 3 by detecting the pressure acting on the roller 2. When the pulling force of the rope 3 is too large and exceeds the range of the pressure sensor 4, the excessive pressure can compress the pressure sensor 4 to overcome the pre-tightening force of the spring 6, thereby protecting the pressure sensor 4.

[0044] In the pre-tightening state, the pre-tightening force F of the spring 6 is k x Δl, k and Δl are the elastic coefficient and the compression amount of the spring 6 in the pre-tightening state respectively. When the force N acting on the pressure sensor 4 is less than or equal to F, i.e., when the pulling force T of the rope 3 is small, the pressure sensor 4 does not move and can normally measure the pressure N acting on it, and then the corresponding pulling force T is obtained.

[0045] Referring to Figure 2 and Figure 3 , when the pulling force T of the rope 3 increases to a certain extent to T max , N > F, the spring 6 is compressed, the roller 2 moves downward, and θ (θ is the included angle between the inner common tangent of the roller 2 and the guide wheel 1 and the horizontal direction) becomes smaller to θ'. Since N = 2T sinθ and T does not change, when θ decreases, even if T is large, N is small. In this state, the corresponding pulling force T cannot be obtained by the pressure sensor, i.e., the measurement fails, thereby protecting the pressure sensor. Figure 2 and Figure 3 In the figures, O1 and O2 are the centers of the roller and the guide wheel respectively, a is the center distance, and R and r are the radii of the roller and the guide wheel respectively.

[0046] Referring to Figure 4 , it is a graph of the relationship between N and T. It can be understood that N is the vertical component of T, and T > T max . In the ideal state, the relationship between N and T is shown by straight line ①, but the actual relationship between N and T is shown by straight line ②. In order to achieve a better protection effect, it is necessary to make straight line ② as close to straight line ① as possible. Therefore, the elastic coefficient of the spring 6 is optimized in this embodiment, and the selection method is as follows:

[0047] When the force N on the pressure sensor 4 is not greater than the preload F of the spring, the functional relationship between the tension T of the rope 3 and N is: N = 2T sinθ, where θ is the angle between the common internal tangent of the roller 2 and the guide wheel 1 and the horizontal direction, and F = k × Δl, where k and Δl are the elastic coefficient of the spring 6 and the compression under the preload state, respectively.

[0048] Determine the tension T in rope 3 corresponding to the maximum range of pressure sensor 4. max Based on the geometric relationship between roller 2 and guide wheel 1, see [reference needed]. Figure 3 Calculate T > T mａｘ The functional relationship between the tension T and N of rope 3 is N = 2T sinθ′, where θ′ is the angle between the internal common tangent of roller 2 and guide wheel 1 and the horizontal direction after the pressure sensor 4 moves down Δy. The relationship between the downward movement distance Δy of pressure sensor 4 and T is calculated as: Δy = f(T), and its specific expression is:

[0049] Where a′ 2 =a ２ +Δy ２

[0050] like Figure 5 As shown, based on Δy=f(T), we obtain the second curve of the relationship between Δy and N when Δy=0, and the third curve of the relationship between Δy and N when Δy>0. We calculate the spring force F′=k×(Δl+Δy) when the pressure sensor 4 moves down by Δy. The functional relationship is the first line, and F′=N.

[0051] Specifically,

[0052]

[0053] The relationship between line 1, curve 2, and curve 3 is shown in [reference]. Figure 5 To make the N value corresponding to the intersection of line 1 and curve 3 as close as possible to the N value corresponding to the intersection of line 1 and curve 2: that is, to reduce the slope k of line 1.

[0054] Based on the idea of ​​reducing the slope of line one, we can further quantitatively obtain the optimal value of k:

[0055] Select initial values ​​for k and Δl, substitute different values ​​of T into Δy = f(T) to obtain Δy, substitute this into F′ = k × (Δl + Δy) to obtain F′, which is the value of N. Change the value of k and repeat the calculation to obtain a trend graph of N vs. T for different values ​​of k. See [reference needed]. Figure 6 The optimal elastic coefficient k is obtained from the trend graph. As can be seen from the graph, when k=5 is selected in this embodiment, the aforementioned straight line ② is closest to straight line ①. That is, the more gradual the increase of N, the smaller and smoother the force on the pressure sensor, and the better the protective effect.

[0056] Those skilled in the art can understand that the above only describes the preferred embodiments of the present application and is not used to limit the present application, and although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rope tension measuring device with range protection function, characterized in that, The measuring device includes a pressure sensor (4), on which a roller (2) is mounted. Guide wheels (1) are provided on both sides of the roller (2). By adjusting the position of the two guide wheels (1) relative to the roller (2), the bending angle of the rope (3) can be adjusted so that the tension acting on the rope (3) can cause the rope (3) to exert pressure on the roller (2). The pressure sensor (4) is set in the bracket (8). A limiting part (5) is mounted on the pressure sensor (4). The limiting part (5) cooperates with the upper end of the bracket (8) to limit the movement range of the pressure sensor (4). An adjusting screw (7) is provided at the lower end of the bracket (8). The adjusting screw (7) is connected to the limiting part (5) by a spring (6). The preload of the spring (6) can be adjusted by adjusting the adjusting screw (7). Two guide wheels (1) are at the same horizontal height, and the roller (2) is located on the vertical line of the line connecting the centers of the two guide wheels (1). The pressure generated by the rope (3) on the roller (2) can cause the roller (2) to drive the pressure sensor (4) to move along the vertical line of the line connecting the centers of the two guide wheels (1). The length direction of the spring (6) is parallel to the direction of motion of the pressure sensor (4); The spring (6) and adjusting screw (7) are provided in two sets and are symmetrically arranged on both sides of the pressure sensor (4); The method for selecting the spring constant of the spring (6) is as follows: When the force N on the pressure sensor (4) is not greater than the preload F of the spring, the functional relationship between the tension T of the rope (3) and N is: N = 2Tsinθ, where θ is the angle between the inner common tangent of the roller (2) and the guide wheel (1) and the horizontal direction, and F = k × Δl, where k and Δl are the elastic coefficient of the spring (6) and the compression under the preload state, respectively. Determine the tension T on the rope (3) corresponding to the maximum range of the pressure sensor (4). max Based on the geometric relationship between roller (2) and guide wheel (1), calculate T>T max The functional relationship between the tension T and N of the rope (3) is N = 2Tsinθ′, where θ′ is the angle between the inner common tangent of the roller (2) and the guide wheel (1) and the horizontal direction after the pressure sensor (4) moves down Δy. The relationship between the downward movement distance Δy of the pressure sensor (4) and T is calculated as: Δy = f(T). The relationship curve between Δy and N when Δy = 0 and the relationship curve between Δy and N when Δy > 0 are obtained. The spring force F′ = k × (Δl + Δy) when the pressure sensor (4) moves down Δy is calculated. The functional relationship is a straight line and F′ = N. Make the N value corresponding to the intersection of line 1 and curve 3 as close as possible to the N value corresponding to the intersection of line 1 and curve 2: reduce the slope k of line 1. Quantitatively obtain the optimal k value: Select initial values ​​of k and Δl, substitute different T values ​​into Δy=f(T) to obtain Δy, substitute into F′=k×(Δl+Δy) to obtain F′, which is the N value, change the k value, repeat the calculation, obtain the trend graph of N and T under different k values, and obtain the optimal elastic coefficient k based on the trend graph.

2. A method for measuring rope tension measuring device with range protection function as described in claim 1, characterized in that, include: The rope (3) whose tension is to be measured is passed around the lower part of the first guide wheel (1), the upper part of the roller (2), and the lower part of the second guide wheel (1) in sequence; Select a spring (6) with a suitable elastic coefficient, and adjust the preload of the spring (6) by adjusting the screw (7) so that the preload of the spring (6) is equal to the maximum measuring pressure of the pressure sensor (4); Adjust the position of the pressure sensor (4) to eliminate the gap between the rope (3) and the roller (2) so that the rope (3) is in close contact with both the guide wheel (1) and the roller (2); When tension is generated on the rope (3), the rope (3) can generate pressure on the roller (2). The pressure sensor (4) calculates the tension acting on the rope (3) by detecting the pressure acting on the roller (2). When the tension of the rope (3) is too large and exceeds the range of the pressure sensor (4), the excessive pressure can cause the pressure sensor (4) to overcome the preload of the spring (6) and compress, thus protecting the pressure sensor (4).

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