TWI752699B - Coefficient of friction measuring device - Google Patents

Abstract

The present invention provides a machine with a sliding seat, a weight sensing unit arranged on the sliding seat, a platform for fixing the item to be tested, a motor positioned on the machine, and a microcontroller module. When the aforementioned item under test bears the instable normal force exerted by the object, it can be transmitted to the weight sensing unit through the platform. As for the motor, it can provide a frictional force to overcome the instable normal force to pull the sliding seat to move to calculate the coefficient of friction between the item to be measured and the object. The microcontroller module has a timer unit and a memory unit. The memory unit is planted with the allowable deviation of the instable normal force and the delay parameter of the timer unit. In the case of instable normal force is exerted on the item by the object, it can provide a signal to notify the microcontroller module to start the calculation process. When the instable normal force remains within the allowable deviation for a stabilization period preset as the delay parameter, the microcontroller module will start the motor to pull the sliding seat. And when the instable normal force deviates from the allowable deviation, the microcontroller module will command the motor to stop running or issue a retest signal so that the tester can know whether the measurement process is accurate.

Description

Friction coefficient measuring device

The present invention provides a technical field in which the friction coefficient between an object and a test object can be measured, especially when the object is a finger, a toe, a heel or other suitable parts of the human body, and the object to be tested is applied with an unstable positive force. When the force is applied, the present invention can still accurately measure the friction coefficient between each other, thereby greatly facilitating the selection and development of materials for wearable products, hand tools, hand-held appliances, game equipment control rods or sports equipment grips.

Press, the material selection of hand tools, hand-wearing products, hand-held appliances, game equipment joysticks or sports equipment grips is to match the fingers as much as possible, especially when precise touch is required with the fingertips, or with the belly of the fingers. When applying force to control, the maximum static friction coefficient and kinetic friction coefficient generated by the finger on the material are related to the overall use texture.

In addition, the finger lengths of users of different ages cannot be the same, so the grip angle of the ventral surface of the fingers is also different, resulting in the above-mentioned maximum static friction coefficient and dynamic friction coefficient. Conduct a large number of simulation experiments.

The reason is that there is no relevant measuring device, because the existing objects The friction coefficient measurement between the body and the object to be measured needs to be solved through the calculation of the friction force formula f (friction force) = u (friction coefficient) * N (normal force), the N (normal force) is usually directly The weight of the object itself is used. If the weight of the object itself is too light, it can be further responded by using a weight or a pressure applicator, so that the object can apply an effective rated force to the object to be measured, so as to facilitate the smooth measurement of the friction coefficient, but , when the object is a finger or other appropriate parts of the human body, the above-mentioned measurement technology cannot cope, because the finger or other appropriate parts of the human body exert an unstable positive force on the object to be measured.

In view of this, the previous patent case of my country's No. 098105007 "Testing method for the friction force and coefficient of the interface of the sole of the foot" came into being, which mainly placed the foot under a flat device, and the flat device was fastened with a hard Inelastic ropes or iron hooks allow the horizontal force gauge connected to a parallel platform to push the force gauge. The horizontal force gauge is then connected to a heavy object through a fixed pulley. When the heavy object gradually increases, the foot is affected by static friction. There is no movement with the plane device, until the plane device starts to move and then stops adding weight, and the pulling force indicated by the tension gauge can be read. This is the maximum static friction force, except for the standard constant force of pressing the plane device up and down and the plane device After the total weight of , the maximum static friction coefficient between the foot and the surface of the flat device can be calculated.

However, it is difficult to measure the friction coefficient between the finger and the object to be measured in the previous case of the patent, at least for the following reasons:

1. The previous case of the patent is to provide a normal force with a standard fixed force, but it is very likely that the finger will not consciously shake left and right or up and down at the moment when the object to be measured moves, resulting in the change of the positive force due to the inclination angle. The measured friction coefficient has a great error, but the tester has no clear knowledge from the experiment.

2. In the previous case of the patent, the foot was inverted for measurement. This operation is not only against ergonomics, but also when measuring the friction coefficient between the finger and the object to be measured, due to the insufficient contact area with each other, the flat device There will be a situation of overturning, which is not practical at all, and it is more difficult to provide a large number of fingers on the ventral surface to measure the friction coefficient at different angles.

3. The former case of the patent can only measure the friction coefficient between the sole of the foot and the object to be measured, and it cannot distinguish the friction coefficient between the toe or heel and the object to be measured. Therefore, the scope of application of the former case of the patent is quite limited, resulting in the corresponding Wearing products (such as socks or sandals) cannot distinguish between the different friction coefficients of the toes and heels.

In view of this, the inventor of the present invention has developed the present invention based on years of professional experience and knowledge, and through continuous conception, innovation and research.

The main content of the present invention is to provide a technology for measuring the coefficient of friction between an object and the object to be measured, especially the object is a finger, toe, heel or other suitable parts of the human body, and the object to be measured is applied with an unstable positive force. When the force is applied, the friction coefficient between each other can still be accurately measured, and it is enough for the tester to immediately know whether the measurement is accurate, which at least includes:

A machine table, which is provided with a slide rail and a slide seat that can move along the slide rail;

A weight sensing unit is installed on the sliding seat, and a platform for fixing the object to be tested is installed above it. When the object to be tested is subjected to the unstable normal force exerted by the object, it can be transmitted to weight sensing unit;

A motor installed on the machine table, which can provide a friction force to overcome the above-mentioned unstable positive force, and is used to pull the sliding seat to move along the sliding rail, so as to calculate the friction coefficient between the object to be measured and the object;

A microcontroller module electrically connected to the weight sensing unit and the motor, which has a timing unit and a memory unit, the memory unit is set with the aforementioned allowable error of the unstable positive force, and a delay parameter of the timing unit is set, When an unstable positive force is applied to the object to be measured, it can provide a signal to notify the microcontroller module for operation processing. When the unstable positive force is kept within the allowable error and stabilized to the delay parameter, make The microcontroller module activates the motor traction carriage, and when the unstable positive force deviates from the allowable error, the microcontroller module commands the motor to stop running or sends a retest signal; and

A power supply module, which provides the electric power required by the motor and the microcontroller module.

The second aspect of the present invention is to further define that the aforementioned motor is a servo motor, a current sensor is electrically connected between the servo motor and the microcontroller module, and a data table of the linear relationship between the motor current and the load of the tension gauge is stored in the memory unit. , and then a display device is electrically connected to the microcontroller module, so that the display device can display the corresponding load of the servo motor.

The third aspect of the present invention is to further define that the aforementioned weight sensing unit is composed of at least one normally closed pressure switch and one normally open pressure switch, so that the normally closed pressure switch defines the upper limit of the permissible error of the unstable positive force, the normally closed pressure switch Open the pressure switch to define the lower limit of the allowable error of the unstable positive force. When the unstable positive force is kept between the upper limit and the lower limit, the microcontroller module will start the motor to pull the slip. If the microcontroller module senses that the unstable positive force deviates from the upper limit or lower limit, the microcontroller module can control the motor to stop running or send a retest signal.

The fourth aspect of the present invention is to further define the space between the motor and the slider, and the intermediate load is installed with a tension gauge capable of visually measuring the change of friction force, and the tension gauge is electrically connected to the microcontroller module.

W: object to be tested

10: Machine

11: Slide rail

12: Slider

20: Bracket

21: Column

22: Adjustment slot

23: Auxiliary lever

24: Screw

25: Nut

30: Weight Sensing Unit

30A: normally closed pressure switch

30B: Normally open pressure switch

31: The first screw

40: Platform

41: Limit slot

42: Longitudinal guide rod

43: Pilot hole

50: Motor

51: Motor seat

52: Spindle

53: Pulley

54: Cables

60: Tensile Gauge

61: Second screw

70: Microcontroller Module

C: shell

71: Timing Unit

72: Memory Unit

73: Communication port

74: Display device

75: Voice output device

76: Wireless transmission module

80: Power supply module

90: Current sensor

Figure 1 is an exploded schematic view of the present invention.

Figure 2 is a schematic diagram of the combination of the present invention.

Figure 3 is a schematic front view of the present invention after combination.

FIG. 4 is a schematic diagram of the measurement implementation of the present invention.

FIG. 5 is a schematic diagram of a circuit block of the present invention.

FIG. 6 is a schematic diagram of a second embodiment of the present invention.

FIG. 7 is a schematic diagram of a third embodiment of the present invention.

In the following embodiments, "a" or "a group" is used to describe the units or components described herein, which is only for the convenience of description and provides a general meaning to the scope of the present invention, and such description should be understood as Including one or more than one, more importantly, the "object" shown in Figure 4 is a finger, which can also be replaced by toes, heels or other suitable parts of the human body, as long as it can output unstable positive force, belong to it.

In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail by the following specific embodiments and the accompanying drawings. Please refer to Figures 1 to 5. The present invention at least includes: :

A machine table 10 is fixedly provided with a set of sliding rails 11 erected along the left and right horizontal directions, and a sliding seat 12 matched with the sliding rail 11, so that the sliding seat 12 can be limited and horizontally moved between the left and right ends of the sliding rail 11, The sliding rail 11 and the sliding seat 12 can also be equivalently made of standardized linear sliding rails;

A bracket 20 is arranged on the machine table 10 , which is connected to the front and rear of the machine table 10 and extends symmetrically with upright columns 21 . The top edges of the two upright columns 21 are respectively provided with adjustment grooves 22 for spanning an auxiliary rod above the sliding seat 12 . 23. The two ends of the auxiliary rod 23 are installed in the matching adjustment slot 22 through the cooperation of the screw 24 and the nut 25, so that the auxiliary rod 23 can adjust the height and rotation angle according to the needs of the object, so as to meet the needs of the human body. Learn to support the object to press on the upper surface of the object to be tested W, so that when the friction coefficient between the object and the object to be tested W is measured, the object will not be shaken out of alignment. As shown in Figure 4, the support 20 For experiments that require a large number of ventral angles of fingers or toes, its operability is quite convenient;

a weight sensing unit 30 disposed on the sliding seat 12 and fixed on the top surface of the sliding seat 12 by protruding through the first screw 31;

A platform 40 located above the weight sensing unit 30 has a concave limit groove 41 on the top surface for the object to be measured W to be fixed in abutment. The W is integrally combined with the top surface of the platform 40, and the upper surface of the object to be tested W is maintained for the object to slide; the platform 40 and the sliding seat 12 are further provided with matching longitudinal guide rods 42 and guide holes 43 for the purpose of guiding the platform 40 to ascend and descend, so that the weight sensing unit 30 can accurately sense the downward pressure of the object through the platform 40 and apply the unstable positive force to the object to be tested W;

A motor 50 installed on the machine table 10 is erected on the left side of the slide rail 11 through the motor base 51 , and a pulley 53 is installed on the main shaft 52 of the motor 50 . The pulley 53 can be linked with a cable 54 to wind up or release;

A tension gauge 60 has one end fixed to the left end of the sliding seat 12 through the second screw 61 , and the other end is fixed to the free end of the cable 54 , so that the tension gauge 60 can be installed between the sliding seat 12 and the sliding seat 12 with an intermediate load. Between the motors 50, the aforementioned motor 50 adopts a servo motor that rotates at a certain speed, so that when the motor 50 winds the cable member 54, the frictional force can be gradually increased until the aforementioned unstable positive force is overcome, so as to pull the carriage 12 Move along the slide rail 11, the tester has to visually observe the change of the friction force of the tension meter 60, so as to use the friction force formula f (friction force)=u (friction coefficient)*N (normal force), and then calculate the object to be tested The friction coefficient between W and the object, the friction coefficient includes the sliding friction coefficient and the maximum static friction coefficient. Specifically, when the friction force adopts the maximum value of 60 of the tension meter, the maximum static friction coefficient can be calculated. When the friction force adopts the tensile force When the stable value of 60 is counted, the sliding friction coefficient can be calculated;

A microcontroller module 70 electrically connected to the weight sensing unit 30 and the motor 50 is installed inside a hollow casing C, and the casing C is fixed to the proper position of the sliding seat 12. The aforementioned microcontroller The device module 70 has a timing unit 71 and a memory unit 72. The memory unit 72 stores the allowable error set with the aforementioned unstable positive force, and stores the delay parameter set with the timing unit 71 (the delay parameter can be 5 seconds, 6 seconds, 7 seconds or other appropriate seconds), when the weight sensing unit 30 is triggered by an unstable positive force applied to the object to be measured W, it can provide a signal to notify the microcontroller module 70 for calculation processing. The unsteady positive force remains within the tolerance, and after stabilizing to the delay parameter, the microcontroller The module 70 starts the motor 50 to pull the carriage 12 to carry out the experiment. If the object is unstable due to shaking and the microcontroller module 70 senses that the unstable positive force deviates from the allowable error, it can further control the motor 50 to stop running or Send a re-measurement signal to facilitate the re-measurement after stopping the machine, so that the tester can accurately measure the friction coefficient of the object to be measured W; Then, the microcontroller module 70 and the weight sensing unit 30, the motor 50 and the tension meter 60 can be electrically connected to the intermediary. For the same reason, the communication port 73 can also be extended to provide a positive force that can indicate instability. The display device 74, a voice output device 75 capable of sending out a re-measurement signal, and a wireless transmission module 76 are electrically connected, and the wireless transmission module 76 can integrate the measured unstable normal force and frictional force. Output to an electronic device (such as a computer or mobile phone) for recording and calculation, in addition, there may be several buttons outside the casing C to respond to the operation of the tester during the entire experimental process; and

A power supply module 80, which can provide the electric power required for the experiment of the motor 50 and the microcontroller module 70 by the commercial power or the battery.

Please observe with reference to Figures 4 and 5. During the experiment of the present invention, when the object is a finger, the tester can place his arm or palm against the auxiliary rod 23 of the bracket 20 to greatly improve the overall measurement stability. Then, Make the finger ventral surface exert downward instability positive force on the upper surface of the object to be tested W, and display the instability positive force through the display device 74, so that the tester can gradually control the instability by hand feeling When the positive force reaches the allowable error range stored in the memory unit 72, the microcontroller module 70 can automatically start the motor 50 after the continuous memory unit 72 stores the set delay parameter (for example, 5 seconds) to make the object to be tested W The top surface slides over the ventral surface of the finger at the same speed, and the tester can record the maximum static friction force and dynamic friction through the visual tension meter 60 force, and then divided by the aforementioned unstable normal force, so that the friction coefficient of the object to be measured W on the ventral surface of the finger is calculated.

Please refer to FIG. 6 , which is a second embodiment of the present invention. This embodiment further illustrates that a current sensor 90 can be electrically connected between the motor 50 and the microcontroller module 70 , and the memory unit 72 stores a current sensor 90 . The data table of the linear relationship between the motor current and the load of the dynamometer can simplify the dynamometer 60 disclosed in Figs. In the process of applying the force, the current sensor 90 can continuously transmit the motor driving current signal to the microcontroller module 70 for calculation and processing, and then the display device 74 displays the corresponding motor load.

Please refer to FIG. 7, which is a third embodiment of the present invention. This embodiment further illustrates that the weight sensing unit 30 disclosed in FIGS. 1 to 5 can be composed of at least one normally closed pressure switch 30A and one normally open pressure switch 30B , let the normally closed pressure switch 30A set the upper limit of the allowable error of the aforementioned unstable positive force, and the normally open pressure switch 30B to set the lower limit value of the aforementioned unsteady positive force allowable error. When the stability positive force is maintained between the upper limit and the lower limit, the microcontroller module 70 will start the motor 50 to pull the carriage. If the microcontroller module 70 senses that the instability positive force deviates When the upper limit or lower limit is reached, the microcontroller module 70 can further control the motor 50 to stop running or send a re-measurement signal, so that the present invention can accurately measure the friction coefficient of the object to be measured W on the ventral surface of the finger.

According to the foregoing, the present invention clearly has the following advantages:

1. In the present invention, the overall cooperation of the weight sensing unit, the motor, the slide, the platform, the timing unit and the memory unit is sufficient to apply a Instability Normal Force The friction coefficient can still be accurately measured, and the tester can immediately know whether the measurement is accurate, which completely overcomes the shortcomings of the previous patent.

2. In the present invention, when the object is a finger or a toe, such as measuring the ventral surface of the finger or toe, the stability of the object can be provided through the auxiliary rod of the bracket, so that the unstable situation of left and right or up and down shaking when the object to be measured is moved instantly is reduced. At the lowest level, the measurement error rate is greatly reduced, and it can provide a large number of measurement applications for different angles of the ventral surface of the finger, and the overall operation is very simple.

3. In addition to measuring the coefficient of friction of fingers, the present invention can also measure the coefficient of friction of toes or heels, respectively. For the same reason, the present invention can also measure the coefficient of friction of pet fingers and toes through man-made forced manipulation. Its scope of application is extremely wide enough to support the material selection or development of corresponding products.

To sum up, the core technology of the present invention has completely broken through the shortcomings of the previous patent case. However, the above is only a preferred embodiment of the present invention, and should not be used to limit the scope of implementation of the present invention. within the scope of coverage.

30: Weight Sensing Unit

50: Motor

60: Tensile Gauge

70: Microcontroller Module

71: Timing Unit

72: Memory Unit

73: Communication port

74: Display device

75: Voice output device

76: Wireless transmission module

80: Power supply module

Claims (10)

A friction coefficient measuring device, which at least includes: A machine table, which is provided with a slide rail and a slide seat that can move along the slide rail; A weight sensing unit is installed on the sliding seat, and a platform for fixing the object to be tested is installed above it, so that the object to be tested can be transmitted through the platform when it is subjected to the unstable normal force exerted by the object. to the weight sensing unit; A motor installed on the machine table, which can provide a friction force to overcome the above-mentioned unstable positive force, and is used to pull the sliding seat to move along the sliding rail, so as to calculate the friction coefficient between the object to be measured and the object; A microcontroller module electrically connected to the weight sensing unit and the motor, which has a timing unit and a memory unit, and the memory unit is set with the allowable error of the aforementioned unstable positive force, and a delay parameter of the timing unit is set, When an unstable positive force is applied to the object to be measured, it can provide a signal to notify the microcontroller module for calculation processing. When the unstable positive force is kept within the allowable error and stabilized to the delay parameter, make The microcontroller module activates the motor traction carriage, and when the unstable positive force deviates from the allowable error, the microcontroller module commands the motor to stop running or sends a retest signal; and A power supply module, which provides the electric power required by the motor and the microcontroller module. According to the friction coefficient measuring device of claim 1, the motor is a servo motor, further a current sensor is electrically connected between the servo motor and the microcontroller module, and the memory unit additionally stores the motor current and pulling force Calculate the load Then, a display device is electrically connected to the microcontroller module, so that the display device can display the corresponding load of the motor. According to the friction coefficient measuring device of claim 1, the weight sensing unit is composed of at least one normally closed pressure switch and one normally open pressure switch, so that the normally closed pressure switch defines the upper limit of the allowable error of the unstable normal force value, the normally open pressure switch defines the lower limit of the allowable error of the unstable positive force. According to the friction coefficient measuring device of claim 1, a tension gauge is installed between the motor and the sliding seat, and an intermediate load is installed, and the tension gauge is electrically connected to the microcontroller module. If the friction coefficient measuring device of claim 4, the slide rails are erected along the left and right horizontal directions, so as to provide the sliding seat can move in a limited position between the left and right ends of the slide rails; the motor is erected on the left side of the slide rails, and is connected to the motor spindle A pulley is installed, the pulley can be linked with a cable, and the intermediary of the tension gauge is installed between the left end of the sliding seat and the free end of the cable. For the friction coefficient measuring device of claim 1, 2, 3, 4 or 5, the machine table is further provided with a bracket, the bracket is fastened above the sliding seat and spans an auxiliary rod, and the auxiliary rod can be further controlled according to actual needs The height and rotation angle are adjusted to support the measurement of the friction coefficient of the object. According to the friction coefficient measuring device of claim 6, the bracket is connected to the front and rear of the machine table with uprights extending symmetrically, and the top edges of the two uprights are respectively provided with adjustment grooves for spanning an auxiliary rod above the sliding seat. The two ends of the auxiliary rod are combined with the matching adjustment groove through the combination of the screw rod and the nut. For the friction coefficient measuring device of claim 1, 2, 3, 4 or 5, matching longitudinal guide rods and guide holes are provided between the platform and the sliding seat to guide the platform to rise and fall. For the friction coefficient measuring device of claim 1, 2, 3, 4 or 5, the microcontroller module is further electrically connected with a voice output device capable of sending out a re-measurement signal. For the friction coefficient measuring device of claim 1, 2, 3, 4 or 5, the microcontroller module is further electrically connected to a wireless transmission module, and the wireless transmission module can obtain the unstable normal force and The integrated output of the friction force is sent to an electronic device.

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