RU199568U1 - ANGULAR POSITION SENSOR - Google Patents

Abstract

The utility model relates to the field of measuring technology and is designed to measure the angular position of structural elements of machines and devices, including medical technology. To determine the absolute angular position of rotating structural elements, a device is used that includes a housing, a rotating shaft, support bearings, a movable mounting plate fixed on the shaft with two microelectromechanical accelerometers, a fixed mounting plate with an accelerometer and a microcontroller mounted on it. In this case, the accelerometers on the movable circuit board are installed so that they are at an equal distance from the axis of rotation, the angle between their centers is 180 °, the sensitivity axes in the plane of the circuit board are multidirectional, and the sensitivity axes perpendicular to the circuit board are co-directed. As the initial data when calculating the angular position, the differences in the modules of the acceleration vector of the entire structure, including the moving and stationary parts, the calculation of the angle of deviation of the moving part (board) relative to the stationary one, as well as compensation for the influence on the measurement of centripetal acceleration, carried out by mathematical algorithms implemented by the embedded software are used microcontroller.

Description

The utility model relates to the field of measuring technology and is designed to measure the angular position of structural elements of machines and devices, including medical technology.

The essence of the proposed solution lies in the fact that to determine the absolute angular position of rotating structural elements, a device is used that includes accelerometric micromechanical sensors installed both on the stationary part of the device (body) and on the rotating part (shaft).

Methods and devices for measuring the angular orientation of rotating objects are known in the art, based, in particular, on the use of accelerometers and inclinometers that record the deviation of the gravity vector. So, there is a known method for determining the angular orientation of an object [US Pat. 2414685 Russian Federation, IPC G01C 21/10 (2006.01). Method for determining the angular orientation of an object / Bogdanov M.B., Prokhortsov A.V., Saveliev V.V., Vlasov A.Yu., Danilov M.B .; applicant and patentee State educational institution of higher professional education "Tula State University" - No. 2010107038/28, App. 02/25/2010; publ. 03/20/2011, Bul. No. 8], which implements the determination of the angular orientation of an object using data from a GPS receiver, as well as a block of three accelerometers, the measuring axes of which are mutually perpendicular and coincide with the axes of the coordinate system associated with the object. Object orientation parameters are determined by solving a matrix equation from data from accelerometers and information about the heading angle received from a GPS receiver.

The closest analogue of the proposed utility model, taken as a prototype, is a measuring device for the angular position of the product [US Pat. 2491507 Russian Federation, IPC G01C 21/10 (2006.01). Measuring instrument of the angular position of the product / Blokin-Mechtalin Yu.K., Sudakov V.A., Zalivako V.Yu., Malyutin V.A .; applicant and patent holder Federal State Unitary Enterprise “Central Aerohydrodynamic Institute named after Professor N.Ye. Zhukovsky "- No. 2011153917/28, app. 12/29/2011; publ. 08/27/2013, Bul. No. 24], containing analog-to-digital converters, a microcontroller and two-axis micromechanical accelerometers, installed so that their like axes of sensitivity are directed horizontally and perpendicularly, and opposite in opposite directions, while dissimilar outputs of accelerometers are connected to differential inputs of amplifiers through buffer operational amplifiers.

The prototype has the following disadvantages:

- the ability to determine the angular position only in a static state (not during rotation).

The technical result is the ability to measure the angular position of rotating structural elements not only in a static state, but also during rotation or linear movement.

The technical result is achieved due to the fact that the device for measuring the angular position of the object, consisting of housing 1 (figure 1), shaft 2 (figure 1), support bearings 3 and 4 (figure 1), circuit board 5 (figure 1), fixed on shaft with two microelectromechanical accelerometers 6 and 7 (figure 1), the second mounting wiring board 8 (figure 1) with accelerometer 9 fixed on it (figure 1) and microcontroller 10 (figure 1), differs from the device taken as a prototype in that it is used integral three-axis accelerometers, two of which are mounted on a circuit board rigidly fixed to the device shaft so that they are at an equal distance from the axis of rotation, the angle between their centers is 180 degrees, the sensitivity axes in the plane of the circuit board are multidirectional, and the sensitivity axes are perpendicular circuit board - co-directional (Figure 2).

Thanks to these distinctive features, the following technical result is achieved - the ability to determine the angular position of an object fixed on a shaft or connected to a device shaft during rotation and during linear movement of structures on which the angular position measuring device is fixed.

The arrangement of two accelerometers on a circuit board fixed to the shaft of the device, shown in figure 2, makes it possible to exclude the influence of the centripetal acceleration on the measurement result, in the event that the measurement is made while the shaft of the device is rotating. So, when the shaft 2 (figure 1) and the board 5 (figure 1), fixed on it, rotate, the accelerometers 11 and 12 will experience accelerations, as shown in figure 2, while the centripetal acceleration a is directed towards the axis of rotation, and the acceleration g directed vertically downward. Then the projections of accelerations on the X-axis of both sclerometers can be written as follows:

X ₁ = g-a

X ₂ = -g-a

where X ₁ is the sum of the acceleration projections on the X-axis of the accelerometer 12, X ₂ is the sum of the acceleration projections on the X-axis of the accelerometer 11. Having solved this system of equations for the acceleration g we get:

In general, to determine the gravitational acceleration vector, it is necessary to use the acceleration projections along all three axes of sensitivity of both accelerometers. If we take some values of R _x , R _y and R _z as:

then the following mathematical relationship can be used to determine the angular position of the object:

where A _x1 , A _y1 , A _z1 - acceleration accelerometer 9 (figure 1), mounted on a circuit board, fixed on the device body motionless.

The described mathematical dependence is implemented in the form of an algorithm in the program of the microcontroller 10 (figure 1).

Considering that all accelerometers are under the same external conditions and experience the same values of accelerations, both linear, caused by the movement of the entire structure, and the acceleration of gravity, the only differences in the readings of accelerometers will be caused by the displacement of the axes of their sensitivity relative to each other. Thus, using the difference between the projections of the gravitational acceleration vector on each of the axes of the same name of both accelerometers, the angle of rotation of the movable plate 5 fixed on the shaft 2 relative to the fixed plate 8 fixed on the body of the device 1 can be determined.

Claims (1)

A device for measuring the angular position of an object, consisting of a housing, a rotating shaft, support bearings, a movable mounting plate fixed on a shaft with two microelectromechanical accelerometers, a fixed mounting plate with an accelerometer and a microcontroller attached to it, characterized in that integrated three-axis accelerometers are used, two of which are installed on a circuit board rigidly fixed to the device shaft so that they are at an equal distance from the axis of rotation, the angle between their centers is 180 °, the sensitivity axes in the plane of the circuit board are multidirectional, and the sensitivity axes perpendicular to the circuit board are co-directed.

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