An experimental system for detecting the kinematic characteristics of a mechanism

Abstract

An experimental system for detecting the motion characteristics of a mechanism, comprising a camera, a lighting device, an experimental bracket provided with support columns, and a base. A camera adjustment bracket for mounting the camera and a light source adjustment bracket for mounting the lighting device are slidably mounted on the support columns. The experimental bracket is mounted on the base, and a speed reduction and frequency conversion motor for providing a power source for the experimental detection system, a synchronous belt drive system connected to the output end of the speed reduction and frequency conversion motor, and a to-be-tested mechanism mounting plate for mounting the to-be-tested mechanism and located above the synchronous belt drive system are also mounted on the base. The invention has accurate measurement, simple structure, convenient operation, low-speed safety, and low cost, and can be used for teaching experiments and engineering tests, and is convenient for popularization and use.

Description

Technical Field

[0001] The present invention relates to an experimental teaching instrument for mechanical principles, and particularly to an experimental system for detecting the motion characteristics of a mechanism. Background Art

[0002] The course of mechanical principles is a core course for mechanical engineering majors. Mechanism design is the main content of the mechanical principles course. Detecting and analyzing the motion characteristics of planar mechanisms is an important part of mechanism design. Due to the abstract content and complex calculation and analysis of the motion characteristics of planar mechanisms, it is very difficult for students to understand the motion characteristics of planar mechanisms. Currently, there is no experimental device and related experimental content for mechanism motion detection in China.

[0003] The current experimental method is to learn about the mechanism by measuring the mechanism model, drawing the mechanism motion sketch, and calculating the degrees of freedom. This experimental method not only has few experimental contents and old experimental methods, but also cannot achieve the motion analysis of the mechanism. Summary of the Invention

[0004] The purpose of the present invention is to provide an experimental system for detecting the motion characteristics of a mechanism. This device can detect and analyze the motion of any point on the mechanism, including real-time detection and drawing of motion characteristic curves such as displacement (angular displacement), velocity (angular velocity), and acceleration (angular acceleration) of any point. This device solves the problems of short experimental process and little student participation in current mechanism design. And it has the characteristics of scientific design, compact structure, convenient operation, high precision, safety and reliability. It not only fills the gap in the experimental aspect of mechanism motion analysis, but also is suitable for popularization in engineering practice or practical teaching in universities and vocational colleges.

[0005] The purpose of the present invention is achieved by the following technical solutions. An experimental system for detecting the motion characteristics of a mechanism according to the present invention includes a camera 1, a lighting device 4, an experimental bracket 5 provided with a support column 51, and a base 9. A camera adjustment bracket 2 for installing the camera 1 and a light source adjustment bracket 3 for installing the lighting device 4 are slidably installed on the support column 51. The experimental bracket 5 is installed on the base 9. A speed reduction and frequency conversion motor 6 for providing a power source for this experimental detection system, a synchronous belt drive system 7 connected to the output end of the speed reduction and frequency conversion motor 6, and a to-be-tested mechanism mounting plate 8 for installing the to-be-tested mechanism are also installed on the base 9 above the synchronous belt drive system 7;

[0006] Preferably, the adjustment bracket 2 includes a camera clamping plate 21 slidably mounted on the support column 51, a first screw 22 for locking the position of the camera clamping plate 21, and a camera vertical adjustment base 23 slidably mounted on the camera clamping plate 21. The two ends of the camera vertical adjustment base are also slidably mounted with camera horizontal adjustment beams 26 and a second screw 27 for locking the position of the camera horizontal adjustment beams 26. Both of the two camera horizontal adjustment beams 26 are connected to a camera mounting bracket 29 for mounting the camera 1.

[0007] Preferably, the light source adjustment bracket 3 includes a lighting lamp adjustment base 31 slidably sleeved on the support column 51, a second screw 32 for locking the lighting lamp adjustment base 31 on the support column 51. The two sides of the lighting lamp adjustment base 31 are both slidably mounted with lighting lamp placement cross beams 33, and a lighting device 4 is mounted at the end of each lighting lamp placement cross beam 33.

[0008] Preferably, the synchronous belt drive system 7 includes an upper base plate 73, a lower base plate 74, a plurality of second belt pulleys 72 mounted between the upper base plate 73 and the lower base plate 74 through shafts, and a first belt pulley 71 mounted on the output shaft of the speed reduction and frequency conversion motor 6. A synchronous belt 75 is mounted between the first belt pulley 71 and the second belt pulleys 72.

[0009] The mechanism motion characteristic detection experimental system proposed by the present invention has the following advantages:

[0010] 1. By taking the motion images of the mechanism and analyzing them by the digital speckle method, the present invention draws the displacement (angular displacement) curve, velocity (angular velocity) curve, and acceleration (angular acceleration) curve of any point on the mechanism, realizing the analysis of the motion characteristics of any point on the mechanism.

[0011] 2. The present invention can realize the motion analysis of various planar mechanisms, such as four-bar mechanisms, jaw crushers, shaper mechanisms, etc.

[0012] 3. The present invention has accurate measurement and can be used for teaching experiments and engineering tests.

[0013] 4. The present invention has a simple structure, convenient operation, low speed and safety, low cost, and is convenient for popularization and use.

[0014] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given and described in detail in conjunction with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the front view of the present invention;

[0016] Figure 2 Left view of the present invention;

[0017] Figure 3 Top view of the synchronous belt drive system of the present invention after removing the mechanism to be tested.

[0018] Figure 4 Top view of the camera adjustment bracket of the present invention installed on the support column.

[0019] Figure 5 Installation schematic diagram of the mechanism to be tested mounting plate and the synchronous belt drive system of the present invention.

[0020] Reference numerals

[0021] 1 - Camera; 2 - Adjustment bracket, 21 - Camera clamping plate, 22 - First screw, 23 - Camera vertical adjustment seat, 24 - Cylindrical gear, 25 - Rack, 26 - Camera horizontal adjustment beam, 27 - Third screw, 28 - Through hole; 3 - Light source adjustment bracket, 31 - Lighting lamp adjustment seat, 32 - Second screw, 33 - Lighting lamp placement cross beam; 4 - Lighting equipment; 5 - Experiment bracket, 51 - Support column; 6 - Deceleration and frequency conversion motor; 7 - Synchronous belt drive system; 71 - First pulley, 72 - Second pulley, 73 - Upper bottom plate, 74 - Lower bottom plate, 75 - Synchronous belt; 8 - Mechanism to be tested mounting plate, 81 - Positioning pin; 9 - Base. Detailed implementation manners

[0022] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined purpose, the following, in combination with the attached drawings and preferred embodiments, details the specific implementation manners, structures, features and effects of a mechanism motion characteristic detection experimental system proposed according to the present invention as follows.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship in the attached drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0024] Please refer to Figures 1 to 5 , a mechanism motion characteristic detection experimental system, including a camera 1, a lighting equipment 4, an experiment bracket 5 provided with a support column 51 and a base 9. The experiment bracket 5 is installed on the base 9, and the camera 1 is slidably installed on the support column 51 through a camera adjustment bracket 2;

[0025] Please refer to Figure 2 , Figure 4, the adjustment bracket 2 includes a camera clamping plate 21 sleeved on the support column 51 and capable of vertically moving on the support column 51. A first screw 22 is provided on the camera clamping plate 21. When the camera clamping plate 21 slides to a specified position, the sliding clamping plate 21 can be fixed on the support column 51 by tightening the first screw 22. When the first screw 22 is loosened, the camera clamping plate 21 can move up and down in the axial direction of the support column 51. A camera vertical adjustment base 23 is also slidably mounted on the camera clamping plate 21. A cylindrical gear 24 is provided on the camera clamping plate 21, and a rack 25 extending in the vertical direction and meshing with the cylindrical gear 24 is provided on the camera vertical adjustment base 23. Through the cooperation of the gear and the rack, the camera vertical adjustment base 23 moves along the vertical direction of the camera clamping plate 21. Through holes 28 are provided at both ends of the camera vertical adjustment base 23, and a camera horizontal adjustment beam 26 is slidably mounted in each through hole 28. A third screw 27 for locking the position of the camera horizontal adjustment beam 26 is also provided on the camera vertical adjustment base 23. The end of the horizontal adjustment beam 26 is provided with a camera 1 through a camera mounting bracket 29. The camera is connected to a computer through a camera data output line to transmit the image on the camera to the computer, and the computer uses the digital speckle correlation method to calculate and analyze the image.

[0026] When it is necessary to adjust the height of the camera 1, first, loosen the first screw 22, move the position of the camera clamping plate 21 to roughly adjust the height of the camera, tighten the first screw 22, and then adjust the position of the camera vertical adjustment base 23 through the gear and rack to finely adjust the height of the camera. Then loosen the third screw 27 and pull the camera horizontal adjustment beam 26 to drive the camera 1 to move horizontally. When the camera moves to a suitable position, tighten the third screw 27 to lock the camera horizontal adjustment beam 26 on the camera vertical adjustment base 23.

[0027] Please refer to Figure 1 , Figure 2 , a light source adjustment bracket 3 for fixing the lighting device 4 is also installed on the support column 51. The lighting device 4 can adjust the angle of the light by changing its own angle. The lighting device 4 is a prior art and will not be introduced in detail here. The light source adjustment bracket 3 is located below the camera adjustment bracket 2. The light source adjustment bracket includes a lighting lamp adjustment seat 31 slidably sleeved on the support column 51 and a second screw 32 for locking the lighting lamp adjustment seat 31 on the support column 51. Lighting lamp placement cross beams 33 are slidably mounted on both sides of the lighting lamp adjustment seat 31, and a lighting device 4 is installed at the end of each lighting lamp placement cross beam 33. When adjusting the height of the lighting device 4, loosen the second screw 32 to move the light source adjustment bracket 3 up and down in the axial direction of the support column 51, then tighten the second screw 32, and then move the lighting lamp placement cross beam 33 to move the lighting lamp 4 horizontally to an appropriate position.

[0028] Please refer toFigures 1 to 3 On the base 9, a speed reduction and frequency conversion motor 6 and a synchronous belt drive system 7 connected to the output end of the speed reduction and frequency conversion motor 6 are also installed. The speed reduction and frequency conversion motor 6 is the power source, and the output speed of the frequency conversion motor 6 is adjusted through a control button. The synchronous belt drive system 7 includes an upper base plate 73, a lower base plate 74, a plurality of second pulleys 72 installed between the upper base plate 73 and the lower base plate 74 through a shaft 76, and a first pulley 71 installed on the output shaft of the speed reduction and frequency conversion motor 6. A synchronous belt 75 is installed between the first pulley 71 and the plurality of second pulleys 72. At the top of the shaft 76, a test mechanism mounting plate 8 for mounting the test mechanism is also installed.

[0029] The test mechanism is a model made according to the planar motion schematic diagrams of various different mechanisms, such as four-bar mechanisms, shaper machines, jaw crushers, etc. Select one of the models and install it on the test mechanism mounting plate 8. The speed reduction and frequency conversion motor 6 drives the synchronous drive system 7 to rotate. The speed reduction and frequency conversion motor 6 is the power output mechanism, and the multiple pulleys are the output mechanisms. According to the position of the prime mover of the test mechanism, any one or any two of the shafts 76 of the plurality of second pulleys 72 are selected as the input shafts of the test mechanism, and the shaft of the test mechanism is installed on this input shaft. The test mechanism can be various different types of planar mechanisms, such as crank-slider mechanisms, crank-rocker mechanisms, jaw crusher mechanisms, shaper mechanisms, inertial screen mechanisms, press mechanisms, etc. According to the type and geometric parameters of the test mechanism, the test mechanism is installed on the test mechanism mounting plate 8, positioning pins 81. Please refer to Figure 5 Both sides of the test mechanism mounting plate 8 are provided with holes for installing the positioning pins 81. The test mechanism is positioned through the positioning pins 81 and thus sleeved on the shaft 76, so that the test mechanism can be installed together with the shaft of the second pulley 72 that is the active part of the test mechanism.

[0030] Taking the crank-slider mechanism as an example in this experimental process, the crank-slider mechanism is a prior art and will not be elaborated here. The active part of the crank-slider mechanism is the crank. The rotation center of the crank is installed on the shaft 76 of the second pulley 72 of the test bench. The crank is driven to rotate by the shaft 76 of the second pulley 72. The crank drives the slider to move linearly through a connecting rod. The sensor is adsorbed on the slider and moves with the slider. The sensor is a disc-shaped metal part with fluorescent paint smeared on its surface and a magnetic metal material welded to its back. The sensor is adsorbed at the test position. The industrial camera tracks the movement of the part adsorbed by the sensor, and finally obtains a motion curve graph and takes an image of the mechanism movement. Subsequently, the image is imported into the computer detection system, and the speckle correlation method is used for data analysis to calculate the displacement, speed, and acceleration of the sensor and the slider, and the calculation results are output in the form of images and data.

[0031] The measurement working principle of this device is as follows:

[0032] (1) Adjust the instrument

[0033] According to the characteristics of the mechanism to be measured, adjust the settings such as the light source angle, focal length, aperture, and exposure rate to make the captured image clear.

[0034] (2) Shoot the motion image

[0035] Start the variable-frequency motor switch and set the speed at 50 - 100 r / min. Start the test system and record the test.

[0036] (3) Principle of digital speckle analysis

[0037] The digital speckle correlation method converts the collected image into a digital gray field through an analog-to-digital converter and imports it into the detection system. The detection system transforms the displacement measurement problem into a numerical calculation process of correlation search and correlation recognition. By searching for the movement information of the sub-region, the displacement information of its center point is obtained. The main determination basis for the search is to calculate the correlation coefficient between the target image sub-region and the reference image sub-region, and judge the similarity of the two sub-regions by calculating the extreme value of the correlation coefficient.

[0038] The specific steps are as follows:

[0039] S1. Install the mechanism to be measured on the mounting plate 8 of the mechanism to be measured. Turn on the camera 1, lighting device 4, and the monitor of the computer. Adjust the position and angle of the camera adjustment bracket 2 and the light source adjustment bracket 3, as well as the camera aperture and focal length, so that the image of the mechanism to be measured can be clearly displayed;

[0040] S2. Start the switch of the deceleration variable-frequency motor 6, adjust the knob, and adjust the speed of the deceleration variable-frequency motor 6 to an appropriate value, and observe whether the movement of the mechanism is stable.

[0041] S3. Stop the machine and conduct the first experiment. According to the movement process, survey the basic parameters of the mechanism, draw a planar motion sketch and calculate the degree of freedom.

[0042] S4. Conduct the second experiment to detect the movement of the mechanism. Place the sensor on the mounting plate 8 of the mechanism to be measured, start the switch, the mechanism starts to move, start the test system of the computer, set the target parameters according to the system prompts, the camera shoots for a period of time, import the photos into the detection system, and the computer uses the digital speckle correlation method to calculate and analyze the photos. The test system of the computer outputs and displays the calculation results and images.

[0043] S5. Observe whether the displacement curve and velocity curve in the image conform to the motion law. Compare and summarize according to the experimental data and the data calculated theoretically, and analyze the reasons for the experimental errors. Analyze the abnormal phenomena among them.

[0044] S6. According to the experimental requirements, install another mechanism to be tested on the mounting plate of the mechanism to be tested, and then repeat the above process.

[0045] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any person skilled in the relevant art can make any simple modifications, equivalent changes and decorations to the above embodiments without departing from the technical solution of the present invention, and still fall within the scope of the technical solution of the present invention.

Claims

1. An experimental system for detecting the kinematic characteristics of a mechanism, characterized in that: It includes a camera (1), a lighting device (4), an experimental bracket (5) provided with a support column (51), and a base (9). A camera adjustment bracket (2) for installing the camera (1) and a light source adjustment bracket (3) for installing the lighting device (4) are slidably mounted on the support column (51). The experimental bracket (5) is mounted on the base (9). The camera is connected to a computer. A speed reduction and frequency conversion motor (6) providing a power source for the experimental detection system, a synchronous belt drive system (7) connected to the output end of the speed reduction and frequency conversion motor (6), and a test mechanism mounting plate (8) mounted above the synchronous belt drive system (7) and used for installing the test mechanism are also mounted on the base (9). The synchronous belt drive system (7) includes an upper base plate (73), a lower base plate (74), a plurality of second pulleys (72) installed between the upper base plate (73) and the lower base plate (74) through shafts, and a first pulley (71) installed on the output shaft of the speed reduction and frequency conversion motor (6). A synchronous belt (75) is installed between the first pulley (71) and the second pulleys (72). One or two shafts (76) of the plurality of second pulleys serve as the input shaft of the test mechanism. The measurement steps of the mechanism motion characteristic detection experimental system include: S1. Install the test mechanism on the test mechanism mounting plate. Turn on the camera, the lighting device, and the monitor of the computer. Adjust the positions and angles of the camera adjustment bracket and the light source adjustment bracket, as well as the aperture and focal length of the camera, so that the image of the test mechanism can be clearly displayed. S2. Start the speed reduction and frequency conversion motor switch, adjust the knob, and adjust the speed of the speed reduction and frequency conversion motor to an appropriate value, and observe whether the mechanism moves smoothly. S3. Stop the machine and conduct the first experiment. According to the motion process, survey the basic parameters of the mechanism, draw a planar motion sketch, and calculate the degree of freedom. S4. Conduct the second experiment to detect the motion of the test mechanism: Place the sensor at the test position of the test mechanism, start the switch, the test mechanism starts to move, start the test system of the computer, set the target parameters according to the system prompt steps, the camera takes pictures for a period of time, import the photos into the detection system, and the computer uses the digital speckle method to calculate and analyze the photos. The test system of the computer outputs and displays the calculation results and images. S5. Observe whether the displacement curve and speed curve in the image conform to the motion law. Compare and summarize according to the experimental data and the data calculated theoretically, analyze the reasons for the experimental errors, and analyze the abnormal phenomena among them. S6. According to the experimental requirements, install another test mechanism on the test mechanism mounting plate, and then repeat the above process.

2. The experimental system for detecting the kinematic characteristics of a mechanism according to claim 1, wherein: The adjustment bracket (2) includes a camera clamping plate (21) slidably mounted on the support column (51), a first screw (22) for locking the position of the camera clamping plate (21), and a camera vertical adjustment base (23) slidably mounted on the camera clamping plate (21). Camera horizontal adjustment beams (26) are also slidably mounted at both ends of the camera vertical adjustment base, and a third screw (27) for locking the position of the camera horizontal adjustment beam (26). Both camera horizontal adjustment beams (26) are connected to a camera mounting bracket (29) for mounting the camera (1).

3. An experimental system for detecting the motion characteristics of a mechanism according to claim 1, characterized in that: The light source adjustment bracket (3) includes a lighting lamp adjustment base (31) slidably sleeved on the support column (51), a second screw (32) for locking the lighting lamp adjustment base (31) on the support column (51). Lighting lamp placement cross beams (33) are slidably mounted on both sides of the lighting lamp adjustment base (31), and a lighting device (4) is mounted at the end of each lighting lamp placement cross beam (33).

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