Sensor for detecting the position of a mechanical component within a polar-
By designing a sensor equipped with a variety of sensors and data processing units, the position of mechanical components can be accurately detected in the polar spherical coordinate reference system, which solves the problem that traditional linear position sensors cannot detect the polar spherical coordinate position, and realizes small, efficient and low-cost position detection and action recognition functions.
Patent Information
- Application Number
- CN202380074103.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-20
- Filing Date
- 2023-10-17
- Publication Date
- 2025-06-13
AI Technical Summary
The existing linear position sensors can only perform linear position measurements and cannot effectively detect the position of mechanical components in the polar spherical coordinate reference system. The multi-sensor scheme is large in size, high in cost and high in complexity.
A sensor is designed, which includes a sensor body extending along the longitudinal expansion axis, equipped with a data processing unit, a memory unit, a linear sensor, an acceleration sensor and an angular velocity sensor, which can detect the position of the slider in the polar spherical coordinate reference system, and achieve accurate detection of the position of the mechanical component by measuring the polar spherical coordinates.
The precise detection of the position of mechanical components in the polar spherical coordinate reference system is achieved, and the limitations of traditional linear sensors are overcome. They are small in size, low in cost and wide in use. They can independently compensate for the misalignment of the installation steps, identify the movement of mechanical components and match them with the predefined model.
Smart Images
Figure CN120153224A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to sensors that can be used to detect movement between mechanical components, and more particularly to a sensor for detecting the position of a mechanical component within a polar spherical coordinate reference system. Background Art
[0002] Detecting movement between mechanical components (such as those of an excavator articulated arm) is a very important aspect of automation, which allows for accurate monitoring of the reliability of such movement during the service life of the mechanical components, thereby enabling intervention in maintenance and / or replacement activities to ensure an adequate level of performance and safety.
[0003] Today, such detection can be achieved by using linear self-supporting position sensors with a cylindrical body that are widely used in the field of automation.
[0004] They typically consist of a single-stage telescopic structure formed by a movable slider that slides relative to the body of the sensor, which represents the fixed part.
[0005] The free end of the movable slider is connected to the mechanical component whose position needs to be monitored, while the free end of the sensor body represents the origin of the measurement reference system.
[0006] The position measurement generated by such a linear sensor depends on the linear distance between the slider and the body of the sensor.
[0007] In fact, the movement of the mechanical component generates extension or compression of the telescopic structure, resulting in a change in the distance between the movable slider and the sensor body.
[0008] An obvious limitation of the above linear position sensors is that they can only generate linear position measurements because they transform a cylinder that can extend and compress in a single direction in space.
[0009] To overcome this limitation, the mechanical component can be equipped with multiple linear position sensors, which can generally ensure the robustness, reliability, and accuracy of the generated measurements.
[0010] However, the solution based on multiple independent sensors located on the same mechanical component is bulky, costly, complex, and not always feasible from a practical perspective. Summary of the Invention
[0011] The object of the present invention is to design and provide a sensor for detecting the position of a mechanical component within a polar spherical coordinate reference system, which allows at least partially overcoming the disadvantages of the above-mentioned prior art, and is small in size, low in manufacturing cost, and versatile for its possible intended implementation modes.
[0012] Such an object is achieved by the sensor according to claim 1.
[0013] The present invention relates to a method for detecting the position of a mechanical component in a polar spherical coordinate reference system. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other features and advantages of the sensor according to the present invention will become apparent from the following description of its preferred embodiments given by way of non-limiting indication with reference to the accompanying drawings, in which:
[0015] - Figure 1 schematically shows a sensor for detecting the position of a mechanical component in a polar spherical coordinate reference system according to an embodiment of the present invention;
[0016] - Figure 2 is schematically shown by a block diagram a sensor for detecting the position of a mechanical component in a polar spherical coordinate reference system according to the present invention;
[0017] - Figure 3 shows Figure 1 a longitudinal sectional view of the sensor in, for explaining the detection principle of the first linear position coordinate in the polar spherical coordinate reference system;
[0018] - Figure 4a and Figure 4b shows Figure 1 a side view of the sensor in, for explaining the detection principle of the second co-latitude coordinate in the polar spherical coordinate reference system;
[0019] - Figure 5a and Figure 5b shows Figure 1 a top view of the sensor in, for explaining the detection principle of the third longitude coordinate in the polar spherical coordinate reference system;
[0020] - Figure 6a and Figure 6b shows Figure 1 a use case of the sensor in;
[0021] - Figures 7a to 7f shows Figure 1 another use case of the sensor in;
[0022] - Figure 8 schematically shows the path traveled by a point of a mechanical component in a polar spherical coordinate reference system;
[0023] - Figure 9 schematically shows a sensor for detecting the position of a mechanical component in a polar spherical coordinate reference system according to another embodiment of the present invention;
[0024] - Figure 10 、Figure 11a , Figure 11b and Figure 12 The components of the sensor of the present invention for performing an action recognition method are shown by corresponding block diagrams. DETAILED DESCRIPTION
[0025] Referring to the above-mentioned drawings, the sensor 1 for detecting the position of a mechanical component within a polar spherical coordinate reference system S1 will now be described.
[0026] A "mechanical component" refers to any mechanical component used in the industrial field, the position of which needs to be measured and monitored during its movement. For example, in the field of mobile hydraulics, sections of articulated arms of material handling machines, components of suspensions or power steering, components of agricultural tools and crawler earthmoving machinery, components of plastic molding machines, mold support frames, components of extractors or drums.
[0027] By way of example, Figure 6a and Figure 6b the mechanical component in Figures 7a to 7f is the wall (C1 or C2), while the mechanical component in
[0028] is a section (C1 or C2) of an articulated excavator arm.
[0029] The sensor body 4 extends along a longitudinal deployment axis d, which is shown by a dashed line in the drawings. Figure 6a , Figure 6b , Figures 7a to 7f as shown).
[0030] The free end O of the sensor body 4 represents the origin of the polar spherical coordinate reference system S1.
[0031] The sensor 1 includes a slider 2, which is operatively connected to the sensor body 4 so as to be able to slide coaxially with respect to the sensor body 4 along the longitudinal deployment axis d of the sensor body 4.
[0032] The slider 2 has a corresponding free end P, which is configured to be operatively connected to a second mechanical component C2 (for example, as also shown in Figure 6a , Figure 6b , Figures 7a to 7f ).
[0033] Specifically referring to Figure 2 , the sensor 1 further includes a data processing unit 9 housed inside the sensor body 4.
[0034] For example, the data processing unit 9 is a microcontroller, a microprocessor, or a programmable logic device such as an FPGA (Field Programmable Gate Array).
[0035] Furthermore, the sensor 1 includes a memory unit 8, which is operatively associated with the data processing unit 9.
[0036] The memory unit 8 is housed inside the sensor body 4.
[0037] The memory unit 8 is of a rewritable and permanent type of memory and is based on, for example, EEPROM, FRAM, or MRAM technology.
[0038] More specifically, as Figure 2 schematically shown in, it should be noted that the data processing unit 9 and the memory unit 8 are preferably mounted on an electronic board 5 (schematically shown in the figure) housed inside the sensor body 4.
[0039] The sensor 1 further includes linear sensors 6, 3, which are housed inside the sensor body 4 and are operatively connected to the data processing unit 9.
[0040] The linear position sensors 6, 3 are configured to detect a first linear coordinate position ρ of the free end P of the slider 2 in a polar spherical coordinate reference system S1.
[0041] The sensor 1 further includes acceleration sensors 7, 7a, which are housed inside the sensor body 4 and are operatively connected to the data processing unit 9.
[0042] The data processing unit 9 is configured to determine a second colatitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 based on the acceleration value experienced by the sensor body 4 The acceleration value can be detected by the acceleration sensors 7, 7a.
[0043] More specifically, as Figure 2 schematically shown in, it should be noted that the acceleration sensors 7, 7a are also preferably mounted on the electronic board 5 housed inside the sensor body 4.
[0044] The sensor 1 further includes angular velocity sensors 7, 7b, which are housed inside the sensor body 4 and are operatively connected to the data processing unit 9.
[0045] The data processing unit 9 is configured to determine a third longitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 based on the angular velocity value experienced by the sensor body 4 The angular velocity value can be detected by the angular velocity sensors 7, 7b.
[0046] More specifically, asFigure 2 is schematically shown. It should be noted that the angular velocity sensors 7, 7b are also preferably mounted on the electronic board 5 housed inside the sensor body 4.
[0047] According to the present invention, the data processing unit 9 is configured to store in the memory unit 8 multiple sets of three detected polar spherical coordinates.
[0048] Each set of three polar spherical coordinates includes at multiple consecutive instants t 1 , t 2 , …, t i , …t N the instant t i at which the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 is detected, the first linear coordinate ρ, the second co-latitude coordinate and the third longitude coordinate where 1 < i < N.
[0049] The multiple sets of three polar spherical coordinates stored in the memory unit represent the path PS traveled by the free end P of the slider 2 in the polar spherical coordinate reference system S1.
[0050] An example of the path PS is schematically shown in Figure 8 .
[0051] According to the embodiment shown in the figures, the linear position sensors 6, 3 include a sensing element 6 arranged on the sensor body 4 and an electrical or magnetic element 3 arranged on the slider 2.
[0052] According to an embodiment, in combination with the foregoing embodiment and as shown in Figure 1 and Figure 3 , the sensing element 6 is a resistive track extending along the longitudinal deployment axis d of the sensor body 4, and the electrical or magnetic element 3 is at least one sliding contact.
[0053] In this embodiment, the first linear coordinate ρ of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 (i.e., the relative position of the slider 2 with respect to the sensor body 4 (carrier radius)) depends on the resistance value of the resistive track, which can be measured between one end of the resistive track and the position of at least one sliding contact on the resistive track.
[0054] It should be noted that in this embodiment, the principle applied by the linear position sensors 6, 3 for detecting the first linear coordinate ρ of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 is the potential type principle.
[0055] According to a further embodiment, as an alternative to the foregoing embodiment and as shown in Figure 9As shown, the sensing element 6 is a magnetic field sensor, which is arranged in the sensor body 4 such that the corresponding mutually orthogonal sensing axes are further orthogonal to the longitudinal deployment axis d.
[0056] In this embodiment, the electrical or magnetic element 3 is a cylindrical magnetic helix wound around the slider 2 along the longitudinal deployment axis d.
[0057] In this embodiment, the first linear coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 depends on the direction of the magnetic field generated by the cylindrical magnetic helix according to the cylindrical helix deployment.
[0058] More specifically, the magnetic field sensor is preferably arranged on an electronic board 5 housed inside the sensor body 4 so as to have corresponding mutually orthogonal sensing axes, which are further orthogonal to the longitudinal deployment axis d, so as to be able to measure the angular direction α of the magnetic field generated by the cylindrical magnetic helix.
[0059] The angular direction measurement α detected by the magnetic field sensor varies at most within the range of 0° to 360°, and since it coincides with the value 0°, the extreme values of this range are not included.
[0060] Therefore, the magnetic field sensor represents a detection sensor for a single-turn absolute angular direction.
[0061] By way of example, assume that:
[0062] - The cylindrical magnetic helix has a constant pitch;
[0063] - The angular direction measurement α is detected and provided by the magnetic field sensor in a manner relative to the increasing extension, which is the extension of the slider 2 relative to the sensor body 4;
[0064] - At the rest position ρ 0 (fully compressed) of the sensor 1, the magnetic field sensor provides an angular direction value α≈0°;
[0065] - At the bottom scale position FS (fully extracted) of the sensor 1, the magnetic field sensor provides an angular direction value α≈360°;
[0066] - The connection of the sensor body 4 to the free end O of the first mechanical component C1 represents the origin of the polar spherical coordinate reference system S1,
[0067] - The free end P of the slider 2 is connected to the second mechanical component C2;
[0068] The relative position of the slider 2 with respect to the sensor body 4 (i.e., the first linear coordinate ρ of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1, also called the carrier radius) can be associated with the measurement of the angular direction value α of the magnetic field generated by the cylindrical magnetic helix according to the unfolding of the cylindrical helix, as shown by the following mathematical relationship:
[0069]
[0070] According to a further embodiment, the sensing element 6 is a magnetic field sensor made of a Hall effect integrated circuit, or giant magnetoresistance or tunneling.
[0071] According to a further embodiment, the sensing element 6 of the linear position sensors 6, 3 can be a wire of magnetostrictive material, and the electrical or magnetic element 3 of the linear position sensors 6, 3 can be a magnet.
[0072] According to an embodiment, in combination with any of the above, as Figure 2 , Figure 4a and Figure 4b shown, the acceleration sensors 7, 7a include at least one accelerometer 7a having a corresponding set of three mutually orthogonal sensing axes x, y, z (as Figure 4a and Figure 4b shown).
[0073] For example, at least one accelerometer 7b employs MEMS technology.
[0074] The second colatitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 depends on the acceleration value to which the sensor body 4 is subjected, which can be detected by at least one accelerometer 7a along each of the sensing axes x, y, z of the corresponding set of three sensing axes.
[0075] Specifically referring to Figure 4a and Figure 4b , the second colatitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 is represented by the inclination of the sensing axes x and y of a set of three sensing axes of at least one accelerometer 7a with respect to the plane in which the direction g of the gravitational acceleration lies.
[0076] For example, in this embodiment, the second colatitude coordinate can be calculated, for example, by the following mathematical relationship:
[0077]
[0078] where:
[0079] g xis the projection of the acceleration due to gravity g along the sensing axis x of at least one accelerometer 7a;
[0080] g y is the projection of the acceleration due to gravity g along the sensing axis y of at least one accelerometer 7a;
[0081] g z is the projection of the acceleration due to gravity g along the sensing axis z of at least one accelerometer 7a.
[0082] According to a further embodiment, in combination with the foregoing embodiments, the angular velocity sensors 7, 7b include at least one gyroscope 7b having a corresponding set of three mutually orthogonal sensing axes x, y, z.
[0083] The data processing unit 9 is configured to determine the second co-latitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 The second co-latitude coordinate depends on the acceleration value and the angular velocity value to which the sensor body 4 is subjected. The acceleration value can be detected by at least one accelerometer 7a along each of the sensing axes x, y, z in the corresponding set of three sensing axes, and the angular velocity value can be detected by at least one gyroscope 7b along each of the sensing axes x, y, z in the corresponding set of three sensing axes.
[0084] According to a further embodiment, in combination with any one of the foregoing embodiments, as Figure 2 、 Figure 5a and Figure 5b shown, the angular velocity sensors 7, 7b include at least one gyroscope 7b having a corresponding set of three mutually orthogonal sensing axes x, y, z.
[0085] The data processing unit 9 is configured to determine the third longitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 The third longitude coordinate depends on the angular velocity value to which the sensor body 4 is subjected and the initial inclination value of the longitudinal deployment axis d with respect to a set of three sensing axes of at least one gyroscope 7b. The angular velocity value can be detected by at least one gyroscope 7b along each of the sensing axes in the corresponding set of three sensing axes.
[0086] Specifically, the longitudinal deployment axis d is inclined with respect to the initial inclination value θ 0 、with respect to a set of three sensing axes of at least one gyroscope 7b on the plane where the sensing axes x, y in the set of three sensing axes x, y, z of at least one gyroscope 7b are located.
[0087] For example, the third longitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 can be obtained by the sensor body 4 with respect to the initial inclination value It is calculated by integrating the angular velocity Ω with respect to time, using the following mathematical relationship:
[0088]
[0089] where the angular velocity Ω is determined by the data processing unit 9 as its components Ω x 、Ω y and Ω z in combination, i.e., the projection of the angular velocity Ω along the respective sensing axes x, y, z of a set of three sensing axes of at least one gyroscope 7.
[0090] According to an embodiment, in combination with each of the foregoing embodiments and as shown in the figures, the respective free ends O of the sensor body 4 include self-aligning joints.
[0091] According to an embodiment, in combination with each of the foregoing embodiments and as shown in the figures, the respective free ends P of the slider 2 include self-aligning joints.
[0092] According to an embodiment, in combination with each of the above embodiments, as Figure 2 shown, the sensor 1 further includes a bus communication module 10 operatively connected to the data processing unit 9, which allows for the exchange of electrical signals between the data processing unit 9 and a field bus used in the control system of the mechanical component to which the sensor 1 is connected.
[0093] According to an embodiment, in combination with the foregoing embodiments, as shown in the figures, the sensor 1 further includes a connector 12 adapted to provide an electrical connection (power supply voltage and electrical signals) to a field bus used in the control system of the mechanical component to which the sensor 1 is connected.
[0094] The connector 12 is also operatively connected to the data processing unit 9 via the bus communication module 10.
[0095] In an embodiment, in combination with the foregoing embodiments, as Figure 2 shown, the sensor 1 further includes a power management module 11 operatively connected to the connector 12, which is adapted to generate a voltage level required for the operation of the electronic devices housed inside the sensor body 4 starting from the power supply voltage provided to the field bus.
[0096] Now also referring to Figure 6a and Figure 6b , the first mechanical component C1 includes a first surface, and the second mechanical component C2 includes a second surface.
[0097] The first surface and the second surface face each other.
[0098] In an embodiment, in combination with any of the above embodiments, the data processing unit 9 is configured to determine a first linear coordinate ρ and a second co-latitude coordinate of a position of the free end P of the slider 2 in a polar spherical coordinate reference system S1 that belong to a detected set of three polar spherical coordinates, to determine a true distance OP between the first surface and the second surface.
[0099] For example, the actual distance OP between the first surface and the second surface can be determined by the data processing unit 9 by employing the following mathematical relationship:
[0100]
[0101] Furthermore, according to an embodiment, in combination with the foregoing embodiments, the data processing unit 9 is configured to determine a misalignment between the free end P of the slider and the free end O of the sensor body 4 based on the first linear coordinate ρ and the second co-latitude coordinate of a position of the free end P of the slider 2 in a polar spherical coordinate reference system S1 that belong to a detected set of three polar spherical coordinates. to determine a misalignment between the free end P of the slider and the free end O of the sensor body 4.
[0102] Determining the misalignment advantageously allows obtaining whether the sensor 1 is correctly installed between the first surface and the second surface.
[0103] For example, the misalignment between the free end P of the slider and the free end O of the sensor body 4 can be determined by the data processing unit 9 by employing the following mathematical relationship:
[0104]
[0105] Therefore, the misalignment error generated during the installation of the sensor 1 is non-linear and increases with the cosine of the second co-latitude coordinate .
[0106] According to an embodiment, according to any of the above embodiments, a path PS traveled by the free end P of the slider 2 represented by a plurality of sets of three polar spherical coordinates stored in the memory unit 8 in a polar spherical coordinate reference system S1 represents a set of actions performed by a first mechanical component C1 and a second mechanical component C2 and usable as a reference recognition model executed in a motion model recognition algorithm.
[0107] In fact, the recognition of the actions performed by the mechanical components can be performed in different ways, including using a set of three polar spherical coordinates ρ, i (1 < i < N, N is an integer) measured at a set time t and as input of the raw data in the set, and extracting different features that can be used as input of the recognition method that can be implemented.
[0108] By analyzing the evolution of a separate set of three spherical polar coordinates generated by the sensor 1 of the present invention, it is indeed possible to identify a unique combination that describes the performance of a specific action performed by a mechanical component.
[0109] Reference Figures 7a to 7f , the articulated arms C1, C2 of the excavator 100 are hereinafter referred to.
[0110] For example, assume Figure 7a that the articulated arms of the excavator shown in are in their initial state in the plane XZ of the spherical polar coordinate reference system S1. Then, the actions of extending the articulated arms C1, C2 are uniquely defined in the following cases:
[0111] - The first linear coordinate ρ approaches the maximum extension FS;
[0112] - The second co-latitude coordinate is almost orthogonal to the horizontal line (for the frequency of the function atan = 90°);
[0113] - The third longitude coordinate is equal to zero because the initial condition is assumed to be moving in the plane XZ of the spherical polar coordinate reference system S1.
[0114] Figure 7b The bucket standing action in the material loading area shown in is uniquely defined in the following cases:
[0115] - The first linear coordinate ρ has a downward trend;
[0116] - The second co-latitude coordinate has exceeded the discontinuity of the periodicity of the function atan and has a gradually increasing negative value;
[0117] - The third longitude coordinate is equal to zero because the initial condition is assumed to be moving in the plane XZ of the spherical polar coordinate reference system S1.
[0118] Figure 7c The material loading action shown in is uniquely defined in the following cases:
[0119] - The first linear coordinate ρ approaches the minimum extension ρ 0 ;
[0120] - Near the discontinuity points + / - 90°, the second co-latitude coordinate becomes horizontal again;
[0121] - The third longitude coordinate is equal to zero because the initial condition is assumed to be moving in the plane XZ of the spherical polar coordinate reference system S1.
[0122] Figure 7dThe loading bucket lifting movement shown in the figure is uniquely defined in the following cases:
[0123] - The first linear coordinate ρ is close to the minimum extension ρ 0 ;
[0124] - The second colatitude coordinate has exceeded the discontinuity of the periodicity of the function atan and has a gradually decreasing positive value;
[0125] - The third longitude coordinate is equal to zero because it is assumed that the initial condition is to move in the plane XZ of the polar spherical coordinate reference system S1.
[0126] Towards Figure 7e The rotation movement towards the material unloading area shown in the figure is uniquely defined in the following cases:
[0127] - The first linear coordinate ρ is close to the minimum extension ρ 0 ;
[0128] - The second colatitude coordinate has exceeded the discontinuity of the periodicity of the function atan and has a gradually decreasing positive value;
[0129] - The third longitude coordinate has a gradually increasing positive value.
[0130] Figure 7f The material unloading movement shown in the figure is uniquely defined in the following cases:
[0131] - The first linear coordinate ρ is close to the maximum extension FS;
[0132] - The second colatitude coordinate has exceeded the discontinuity of the periodicity of the function atan and has a gradually decreasing positive value;
[0133] - The third longitude coordinate has a gradually increasing positive value.
[0134] Therefore, the excavation activity is formed by a series of movements that correspond to the specific movements performed by the surveyor in space by tracing the characteristic path PS, an example of which is shown in Figure 8 the figure.
[0135] According to the present invention, according to the Figure 10 embodiment shown in the figure, a method for action recognition that can be executed by the data processing unit 9 of the sensor 1 will now be described.
[0136] This method implements the concept of mobile model recognition (motion pattern recognition) known per se.
[0137] According to this method, the reference time ti The polar spherical coordinates ρ, and Input 90 is provided to the recognition algorithm 91, which can distinguish the corresponding actions at this precise moment with extremely high accuracy.
[0138] For example, the recognition algorithm 91 is a pattern matching algorithm or neural network of the RNN (recurrent neural network) type, for example.
[0139] Pattern matching is a form of model recognition in which data is represented as a series of carriers of features and / or parameters called models, as Figure 10 shown by the reference numeral 81 in the drawings.
[0140] Each action (model 81) is stored as a separate model in the memory unit 8.
[0141] Input 90 is organized among the models 81 stored before the recognition process is performed.
[0142] At the start of the recognition process, input 90 is compared with the models 81 stored in the memory unit 8 (as Figure 10 shown).
[0143] The stored model 81 that best corresponds to the model corresponding to input 90 is recognized as the action, and the selected model 92 will be the best match for input 90.
[0144] Model matching is performed at the path level associated with the movement of the mechanical components.
[0145] The matching process involves a frame-by-frame comparison of the spectral models and generates an overall similarity assessment for each model.
[0146] The comparison does not need to produce an exact match to establish overall similarity, because individual actions and the movement of the same mechanical component are affected by the surrounding environment.
[0147] This variation can be caused by a series of factors, including different speeds of performing the action, or different orientations of the reference frame axes.
[0148] Regardless of the reason for the variation between the stored model 81 and input 90, there needs to be a method to minimize the time difference between the models so that the fastest or slowest actions of the same movement are not recognized as different movements.
[0149] In this regard, the process of minimizing the time difference known in the literature is called time alignment.
[0150] The most commonly used method for performing time alignment in model matching is a pattern matching technique called dynamic time warping (DTW).
[0151] Most model matching systems have a predetermined acceptability threshold.
[0152] Its function is to avoid noise and situations not included in the stored model 81 from being wrongly identified as acceptable inputs.
[0153] If no model match exceeds the acceptability threshold, the recognition is not registered.
[0154] Model matching is very effective for short and unique actions and requires at least all the models that can represent almost all actions.
[0155] As an alternative to the pattern matching algorithm, a Recurrent Neural Network (RNN) can be used, which is a neural network specialized for using sequence data or time series.
[0156] Like all neural networks, recurrent neural networks also use training data to learn.
[0157] They stand out for their "memory" because they obtain information from previous inputs to influence the current input and output.
[0158] In this regard, while traditional networks assume that the inputs and outputs are independent of each other, the output of a recurrent neural network depends on the elements before the sequence.
[0159] By way of example, it should be regarded as a sequence of determined movements.
[0160] For it to make sense, such a sequence must be represented in a specific order.
[0161] Therefore, the recurrent neural network must consider the form and use this information to predict the successive actions in the sequence.
[0162] Reference Figure 11a The scroll view of the recurrent neural network RNN including nodes 96, 97, and 98 shown in represents the entire neural network, and in the case of the proposed sensor, it represents the entire predicted action of the mechanical component described by the determined input sequence 90.
[0163] Figure 11b The unfolded view shown in shows a single layer or time phase of the recurrent neural network.
[0164] Each layer including nodes 96, 97, and 98 corresponds to a single piece of information of the sequence at a given moment t i in, so each layer corresponds to a single variable ρ, o, o,
[0165] In the third stage, the input at the previous moment is shown as a hidden state to predict the output of the ongoing action or continuous sequence.
[0166] Another remarkable feature of the recurrent neural network is the sharing of parameters in each layer of the network.
[0167] Similar to the pattern matching algorithm, a training path for creating a reference dataset is also provided for the training of the recurrent neural network RNN.
[0168] In this regard, the storage model 81 is learned by the sensor 1 during a dedicated training session.
[0169] The learned model is registered in the memory unit 8 in a step called registration and will constitute a reference dataset for the pattern matching algorithm.
[0170] The overall architecture of the training step is shown in Figure 12 .
[0171] The analysis of the actions autonomously performed by the data processing unit 9 of the sensor 1 also enables the identification of how the actions are performed.
[0172] In this case, the subject of study is the identification of specific fault conditions.
[0173] To achieve this function, it is sufficient to input a registration related to the fault condition to be identified into the reference dataset of the storage model 81.
[0174] Once identified, the data processing unit 9 of the sensor 1 can recommend maintenance activities based on the specified interventions for each cause.
[0175] Now a method for detecting the position of a mechanical component within the polar spherical coordinate reference system S1 is described.
[0176] The method includes the step of providing a sensor body 4 extending along a longitudinal deployment axis d. The sensor body 4 has a corresponding free end O, which is configured to be operatively connected to a first mechanical component. The free end O of the sensor body 4 represents the origin of the polar spherical coordinate reference system S1.
[0177] The method further includes the step of providing a slider 2, which is operatively connected to the sensor body 4 so as to be able to slide coaxially along the longitudinal deployment axis d of the sensor body 4 relative to the sensor body 4. The slider 2 has a corresponding free end P, which is configured to be operatively connected to a second mechanical component C2.
[0178] The method further includes the step of providing a data processing unit 9, which is housed inside the sensor body 4.
[0179] The method further includes the step of providing a memory unit 8, which is operatively associated with the data processing unit 9. The memory unit 8 is housed inside the sensor body 4.
[0180] The method further includes the steps of providing linear sensors 6, 3, which are housed inside the sensor body 4 and operatively connected to the data processing unit 9.
[0181] The method further includes the steps of providing acceleration sensors 7, 7a, which are housed inside the sensor body 4 and operatively connected to the data processing unit 9.
[0182] The method further includes the steps of providing angular velocity sensors 7, 7b, which are housed inside the sensor body 4 and operatively connected to the data processing unit 9.
[0183] For each of a plurality of consecutive instants t 1 、t 2 、…、t i 、…、t N where 1 < i < N and N is an integer, the method includes the following steps: i
[0184] - Detecting, by the linear sensors 6, 3, a first linear coordinate ρ of the free end P of the slider 2 in the polar spherical coordinate reference system S1;
[0185] - Determining, by the data processing unit 9, based on the acceleration value experienced by the sensor body 4, a second colatitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 The acceleration value is detected by the acceleration sensors 7, 7a;
[0186] - Determining, by the data processing unit 9, based on the angular velocity value experienced by the sensor body 4, a third longitude coordinate of the position of the free end P of the slider 2 in the polar spherical coordinate reference system S1 The angular velocity value is detected by the angular velocity sensors 7, 7b;
[0187] - Storing, by the data processing unit 9, in the memory unit 8 a set of three polar spherical coordinates, which include the first linear coordinate ρ of the position of the free end P, the second colatitude coordinate and the third longitude coordinate
[0188] The multiple sets of three polar spherical coordinates stored in the memory unit 8 represent the path PS traveled by the free end P of the slider 2 in the polar spherical coordinate reference system S1.
[0189] As shown in the figure, the object of the present invention is fully realized because the sensors just described have several advantages.
[0190] The self - supporting position sensor of the present invention having a cylindrical body (composed of a movable slider and a fixed sensor body, with the end of the movable slider connected to a first mechanical component and the free end of the fixed sensor body representing the origin of the polar - spherical coordinate system) can be defined as multivariable because it includes a plurality of sensing elements suitable for measuring linear movement as well as rotation and inclination with respect to the horizontal plane.
[0191] A specific data - processing unit included in the sensor body combines linear movement, rotation, and inclination measurements to determine polar - spherical coordinates, thereby identifying the position of the first mechanical component within the polar - spherical coordinate system.
[0192] The time evolution of the polar - spherical coordinates is recorded in a specific memory unit always included in the sensor body and represents the path traveled by the first mechanical component during the measurement.
[0193] From a metrological point of view, the sensor advantageously autonomously compensates for any residual misalignment of the installation steps, which may compromise the accuracy of the position measurement.
[0194] From a functional point of view, by analyzing the path traveled by the mechanical component under test, the sensor autonomously identifies the actions performed by the mechanical component and compares them with the stored action models learned during a previous training step.
[0195] Moreover, since the sensor of the present invention is actually of the stand - alone type, it undoubtedly improves the drawbacks in the prior art regarding poor resolution, large size, high cost, and complexity.
[0196] In fact, the sensor of the present invention is a self - supporting contact sensor having a cylindrical body and including the possibility of simultaneously generating and storing several types of position measurements (linear, angular, inclination).
[0197] In addition, the sensor of the present invention meets the requirements of a position sensor, namely:
[0198] - A maximum measurement range for articulated - arm extensions in the meter range;
[0199] - Low cost;
[0200] - Robust, resistant to extreme temperatures from - 40°C to + 85°C, thermal shocks and mechanical shocks up to 50g, vibrations, corrosion, and solar radiation;
[0201] - Improved reliability level according to functional - safety standards.
[0202] To meet possible requirements, those skilled in the art can make changes and adjustments to the above-described embodiments of the sensor and replace elements with other functionally equivalent elements without departing from the scope of the appended claims.
[0203] Each of the features described above that belongs to a possible embodiment can be implemented independently of the other embodiments described.
Claims
1. A sensor (1) for detecting the position of a mechanical component within a polar spherical coordinate reference system (S1), comprising: - A sensor body (4) extending along a longitudinal deployment axis (d), the sensor body (4) having a respective free end (O) configured to be operatively connected to a first mechanical component (C1), the free end (O) of the sensor body (4) representing the origin of the polar spherical coordinate reference system (S1); - A slider (2) operatively connected to the sensor body (4) so as to slide coaxially with respect to the sensor body (4) along the longitudinal deployment axis (d) of the sensor body (4), the slider (2) having a respective free end (P) configured to be operatively connected to a second mechanical component (C2); The sensor (1) further comprises: - A data processing unit (9) housed inside the sensor body (4); - A memory unit (8) operatively associated with the data processing unit (9), the memory unit (8) being housed inside the sensor body (4); - A linear position sensor (6, 3) housed inside the sensor body (4) and operatively connected to the data processing unit (9), the linear sensor (6, 3) being configured to detect a first linear coordinate (ρ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1); - An acceleration sensor (7, 7a), housed inside the sensor body (4) and operatively connected to the data processing unit (9), the data processing unit (9) being configured to determine a second colatitude coordinate of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) based on the acceleration value experienced by the sensor body (4) The acceleration value can be detected by the acceleration sensor (7, 7a); - An angular velocity sensor (7, 7b) housed inside the sensor body (4) and operatively connected to the data processing unit (9), the data processing unit (9) being configured to determine a third longitude coordinate (θ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) based on an angular velocity value experienced by the sensor body (4), the angular velocity value being detectable by the angular velocity sensor (7, 7b); The data processing unit (9) is configured to store in the memory unit (8) multiple sets of three detected polar spherical coordinates, each set of three polar spherical coordinates including the first linear coordinate, the second colatitude coordinate, and the third longitude coordinate of the position of the free end (P) of the slider (2) detected in the polar spherical coordinate reference system (S1) at multiple consecutive moments t 1 , t 2 , …, t i , …, t N in the moments t i where 1 < i < N and N is an integer. The multiple sets of three polar spherical coordinates stored in the memory unit (8) represent the path (PS) traveled by the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1).
2. The sensor (1) according to claim 1, wherein, The linear position sensor (6, 3) comprises a sensing element (6) arranged on the sensor body (4) and an electrical or magnetic element (3) arranged on the slider (2).
3. The sensor (1) according to claim 2, wherein, The sensing element (6) is a resistance track extending along the longitudinal deployment axis (d) of the sensor body (4), and the electrical or magnetic element (3) is at least one sliding contact, the first linear coordinate (ρ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) depending on the resistance value of the resistance track, the resistance value being measurable between one end of the resistance track and the position of the at least one sliding contact on the resistance track.
4. The sensor (1) according to claim 2, wherein, The sensing element (6) is a magnetic field sensor which is arranged in the sensor body (4) such that corresponding mutually orthogonal sensing axes are in turn orthogonal to the longitudinal deployment axis (d), and the electrical or magnetic element (3) is a cylindrical magnetic helix wound around the slider (2) along the longitudinal deployment axis (d), and the first linear coordinate (ρ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) depends on the direction of the magnetic field generated by the cylindrical magnetic helix according to the cylindrical helix unfolding.
5. The sensor (1) according to claim 4, wherein, the sensing element (6) is a magnetic field sensor made of a Hall effect integrated circuit, or giant magnetoresistance or tunneling.
6. The sensor (1) according to claim 2, wherein, the sensing element (6) is a magnetostrictive material wire, and the electrical or magnetic element (3) is a magnet.
7. The sensor (1) according to any one of the preceding claims, wherein, The acceleration sensors (7, 7a) include at least one accelerometer (7a) having a respective set of three mutually orthogonal sensing axes x, y, z, and the second colatitude coordinate of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) depends on the acceleration value to which the sensor body (4) is subjected, and the acceleration value can be detected by the at least one accelerometer (7a) along each of the sensing axes x, y, z in the respective set of three sensing axes.
8. The sensor (1) according to claim 7, wherein, The angular velocity sensors (7, 7b) include at least one gyroscope (7b) having a respective set of three mutually orthogonal sensing axes x, y, z, and the data processing unit (9) is configured to determine the second co-latitude coordinate of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1). The second co-latitude coordinate depends on the acceleration value to which the sensor body (4) is subjected and the angular velocity value to which the sensor body (4) is subjected, the acceleration value being detectable by the at least one accelerometer (7a) along each of the sensing axes x, y, z of the respective set of three sensing axes, and the angular velocity value being detectable by the at least one gyroscope (7b) along each of a set of three sensing axes x, y, z of the respective set of three sensing axes.
9. The sensor (1) according to any one of the preceding claims, wherein, The longitude sensor (7, 7b) includes at least one gyroscope (7b) having a corresponding set of three mutually orthogonal sensing axes x, y, z, and the data processing unit (9) is configured to determine the third longitude coordinate (θ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1), and the third longitude coordinate depends on the angular velocity value experienced by the sensor body (4) and the initial inclination value of the longitudinal deployment axis (d) relative to a set of three sensing axes of the at least one gyroscope (7b), and the angular velocity value can be detected by the at least one gyroscope (7b) along each of a set of three sensing axes in a corresponding set of three sensing axes.
10. The sensor (1) according to any one of the preceding claims, wherein, The corresponding free end (O) of the sensor body (4) includes a self-aligning joint.
11. The sensor (1) according to any one of the preceding claims, wherein, The corresponding free end (P) of the slider (2) includes a self-aligning joint.
12. The sensor (1) according to any one of the preceding claims, wherein, The first mechanical component (C1) includes a first surface, and the second mechanical component (C2) includes a second surface, and the first surface and the second surface face each other. The data processing unit (9) is configured to determine a true distance (OP) between the first surface and the second surface based on a first linear coordinate (ρ) and a second co-latitude coordinate of a position of a free end (P) of the slider (2) in the polar spherical coordinate reference system (S1), the first linear coordinate (ρ) and the second co-latitude coordinate being from a detected set of three polar spherical coordinates. 13. The sensor (1) according to claim 12, wherein, The data processing unit (9) is configured to determine the misalignment between the free end (P) of the slider (2) and the free end (O) of the sensor body (4) based on the first linear coordinate (ρ) and the second colatitude coordinate of the position of the free end (P) of the slider in the polar spherical coordinate reference system (S1), the first linear coordinate (ρ) and the second colatitude coordinate being part of a detected set of three polar spherical coordinates. 14. The sensor (1) according to any one of the preceding claims, wherein, The path (PS) traveled by the free end (P) of the slider (2) represented by multiple sets of three polar spherical coordinates stored in the memory unit represents a set of actions performed by an element that can be used as an identification model in a motion model identification algorithm.
15. A method for detecting the position of a mechanical component within a polar spherical coordinate reference system (S1) Comprising the following steps: - Providing a sensor body (4) extending along a longitudinal deployment axis (d), the sensor body (4) having a respective free end (O) configured to be operatively connected to a first mechanical component, the free end (O) of the sensor body (4) representing the origin of the polar spherical coordinate system (S1); - Providing a slider (2) operatively connected to the sensor body (4) so as to slide coaxially with respect to the sensor body (4) along the longitudinal deployment axis (d) of the sensor body (4), the slider (2) having a respective free end (P) configured to be operatively connected to a second mechanical component (C2); - Providing a data processing unit (9) housed inside the sensor body (4); - Providing a memory unit (8) operatively associated with the data processing unit (9), the memory unit (8) being housed inside the sensor body (4); - Providing a linear sensor (6, 3) housed inside the sensor body (4) and operatively connected to the data processing unit (9); - Providing an acceleration sensor (7, 7a; 7, 7a, 7b), the acceleration sensor being housed inside the sensor body (4) and operatively connected to the data processing unit (9); - Providing an angular velocity sensor (7, 7b), the angular velocity sensor being housed inside the sensor body (4) and operatively connected to the data processing unit (9); For multiple consecutive instants t 1 、t 2 、…、t N for each instant t i in which 1 < i < N, N being an integer: - Detecting, by the linear sensor (6, 3), a first linear coordinate (ρ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate system (S1); - A second colatitude coordinate of the position of the free end (P) of the slider (2) in the polar spherical coordinate reference system (S1) is determined by the data processing unit (9) based on the acceleration value experienced by the sensor body (4). The acceleration value is detected by the acceleration sensors (7, 7a); - Determining, by the data processing unit (9), based on the angular velocity value experienced by the sensor body (4), a third longitude coordinate (θ) of the position of the free end (P) of the slider (2) in the polar spherical coordinate system (S1), the angular velocity value being detected by the angular velocity sensor (7, 7b); - The data processing unit (9) stores a set of three polar spherical coordinates in the memory unit (8), the three polar spherical coordinates including the first linear coordinate (ρ) of the position of the free end (P), the second colatitude coordinate and the third longitude coordinate (θ); Storing, in the memory unit (8), multiple sets of three polar spherical coordinates representing the path traveled by the free end (P) of the slider (2) in the polar spherical coordinate system (S1).