Mechanical device and method for determining the mutual position of a first and a second mechanical member belonging to a mechanical device

Abstract

Mechanical device provided with a first and a second mutually movable mechanical member, a track (1) formed by several optical sections (2) being obtained on the second member. The sections (2) are of two types with different optical contrast, distributed according to a predetermined bit number pseudo-random code. The mechanical device is provided with a sensor (3) comprising several optical transducers (5), spaced with a resolution (R) equal to or less than half the width (L) of a section (2) and arranged for framing a measurement window (6) on the track (1) extended for a number of sections (2) equal to the predetermined bit number and for each generating a measurement signal. Furthermore, the mechanical device comprises an electronic unit, configured for associating, with each section (2) in the measurement window (6), a corresponding group (G) formed by a first and a second optical transducer (5', 5") and by at least a third optical transducer (5"') interposed therebetween. The electronic unit is configured for associating, with the measurement signals of the first, second and third optical transducers (5', 5", 5"') at least a first, a second and a third comparison parameter, respectively. The electronic unit is configured for comparing these parameters in order to identify the coinciding ones and, if most of them are coinciding, to obtain, as a function of their measurement signals, a position binary number having a number of bits equal to the predetermined bit number, in which each bit corresponds to a group (G). Furthermore, the electronic unit is configured for associating the position binary number with a position of the second member.

Description

[0001] MECHANICAL DEVICE AND METHOD FOR DETERMINING THE MUTUAL POSITION OF A FIRST AND A SECOND MECHANICAL MEMBER BELONGING TO A MECHANICAL DEVICE

[0002] DESCRIPTION

[0003] Field of application

[0004] The present invention relates to a mechanical device and a method for determining the mutual position of a first and a second mechanical member belonging to a mechanical device.

[0005] The mechanical device and the method in question are part of the production sector of actuators (in particular linear, for example hydraulic or pneumatic cylinders) provided with movable members and optical sensors designed to detect, preferably continuously, the position (in particular absolute) of such movable members.

[0006] State of the art

[0007] Position sensors, in particular optical ones, are known in the state of the art and are used in mechanical devices, in particular linear actuators, for example hydraulic or pneumatic cylinders, to detect the position of the piston of the hydraulic cylinder with respect to the containment sleeve.

[0008] In particular, it is known to obtain a positioning track along the rod of a hydraulic cylinder and to fix a position sensor on the sleeve of the hydraulic cylinder, and such sensor is adapted to capture a given detection window on the positioning track.

[0009] In more detail, the position sensor is provided with a light source, for example an LED, adapted to emit a light radiation onto the positioning track, and an optical detector adapted to detect a reflected radiation coming from the positioning track itself.

[0010] The positioning track is provided with a succession of sectors having equal width, each of which consists of two sections with different optical contrast arranged one after the other.

[0011] In particular, each sector is provided with a first section, with a low reflection coefficient (for example black in color), and a second section with a high reflection coefficient (for example white in color).

[0012] In more detail, the piston rod is provided with a chrome -plated surface on which markings are obtained, for example by laser ablation, which constitute the first sections of the sectors of the positioning track, while the second sections are obtained from the unmachined areas of the chrome-plated surface of the rod.

[0013] In particular, the marked (machined) surface defining the first sections has a very low reflectivity (e.g. 20%) and the chrome-plated surface defining the second sections has a very high reflectivity (e.g. 100%). The position sensor is provided with a control processor which detects, as a function of the light radiation emitted by the optical emitter and the corresponding reflected radiation coming from the positioning track of the rod, a measurement of the reflectivity of the area of the positioning track hit by the light radiation.

[0014] In order to determine if such an area of the positioning track is occupied by a marked surface (first sections) or by a chrome-plated surface (second sections), the position sensor compares the reflectivity measurement with a given threshold value, preset to a reflectance value (e.g. 60%) such as to guarantee a good reliability in the identification of the section. In particular, if the reflectivity measurement is lower than the aforesaid threshold value, the position sensor will identify a marked surface (and therefore a first section), while if it is higher than such a threshold value, the position sensor will identify a chrome-plated surface (and therefore a second section).

[0015] In order to allow the control processor to absolutely determine the position of the piston rod with respect to the sleeve, the first and second sections of different optical contrast of each sector of the positioning track are different in width with respect to the first and second sections of each other sector of the same positioning track.

[0016] For example, the first section of each sector has a greater width with respect to the width of the first section of the previous sector and lower width with respect to the width of the first section of the next sector, so that each sector has a percentage of its overall width occupied by the first section that is different from the percentage of each other sector, thus allowing the control processor to uniquely identify the mutual position between the piston rod and sleeve as a function of the percentage of the width of the sector framed by the optical detector that is occupied by the first section.

[0017] The mechanical device with a known type of position sensor has, however, proved to be not free from drawbacks in practice.

[0018] In fact, the main drawback lies in the fact that in order to allow the optical detector to distinguish the different widths of each section of the sectors of the positioning track from each other, it is necessary for the first and second sections of the sectors to differ from each other by a width equal to or a multiple of one pixel of the optical detector.

[0019] Therefore, the maximum length of mutual movement between the movable members of the mechanical device that can be measured is limited by the maximum width of the sectors of the positioning track, which cannot have first sections that increase their width continuously from sector to sector but that differ in width from one another as a function of the width of the pixels of the optical detector.

[0020] Presentation of the invention

[0021] In this situation, the essential object of the present invention is therefore to overcome the drawbacks manifested by the known solutions, by providing a mechanical device and a method for detecting the mutual position of a first and a second mechanical member belonging to a mechanical device, which allow to provide the mutual position of the mechanical members along a very extended movement track of the aforesaid mechanical members.

[0022] A further object of the present invention is to provide a mechanical device and a method for detecting the mutual position of a first and a second mechanical member belonging to a mechanical device, which are particularly economical to produce.

[0023] A further object of the present invention is to provide a mechanical device and a method for detecting the mutual position of a first and a second mechanical member belonging to a mechanical device, which are simple to manufacture.

[0024] A further object of the present invention is to provide a mechanical device and a method for detecting the mutual position of a first and a second mechanical member belonging to a mechanical device, which are operatively completely reliable.

[0025] Brief description of the drawings

[0026] The technical features of the invention, according to the aforesaid objects, can be clearly seen from the contents of the claims set out below and the advantages thereof will become more evident in the detailed description which follows, made with reference to the attached drawings, which represent some purely exemplifying and non-limiting embodiments thereof, in which:

[0027] - Figure 1 shows a position sensor of a mechanical device which is the subject matter of the present invention;

[0028] - Figure 2 shows a schematic view of some components of the position sensor of Figure 1;

[0029] - Figure 3 shows a schematic view of the position sensor components illustrated in Figure 2 next to a positioning track obtained on a second mechanical member of the mechanical device which is the subject matter of the present invention.

[0030] Detailed description of a preferred embodiment example

[0031] The present invention relates to a mechanical device provided with a first mechanical member and a second mechanical member susceptible to relative motion with respect to the first mechanical member.

[0032] In more detail, this mechanical device can be applied to any type of machine, for example on agricultural machines and earth-moving machines.

[0033] For example, the first and the second mechanical member of the mechanical device are movable with linear motion with respect to each other.

[0034] In particular, the mechanical device is a linear actuator (for example a hydraulic or pneumatic cylinder) in which the first mechanical member is a sleeve and the second mechanical member is the rod slidably inserted in the sleeve and movable in translation with respect thereto along a straight direction.

[0035] Alternatively, the mechanical device can be a telescopic arm for machines such as tele-handlers or cranes in which the first mechanical member is a first telescopic section and the second member is a second telescopic section slidably associated with the first telescopic section.

[0036] In accordance with a different application example, the mechanical device can be provided with a first and second mechanical member which are movable with respect to each other with a rotary motion.

[0037] Furthermore, the second mechanical member is provided with a positioning track 1 extended along an extension line X and provided with a plurality of optical sections 2 having equal width L along the aforesaid extension line X, of which a part are first optical sections 2' and a part are second optical sections 2", and such first and second optical sections 2', 2" have different optical contrasts (i.e. in other words, the second optical sections 2" are in optical contrast with respect to the first optical sections 2').

[0038] In particular, the extension line X along which the positioning track 1 is extended is a straight line if the first and the second mechanical member are movable with respect to each other with a translational motion and is curved if the first and the second mechanical member are movable with respect to each other with a rotary motion. The aforesaid first and second optical sections 2', 2” are distributed along the positioning track 1 according to a predetermined bit number pseudo-random code.

[0039] In more detail, a predetermined bit number pseudo-random code shall be understood hereinafter to mean a binary code provided with a plurality of bits, each corresponding to an optical section 2 of the positioning track 1, in which each sequence formed by optical sections 2 adjacent to each other in a number equal to the predetermined bit number is different from any other sequence formed by optical sections 2 adjacent to each other in a number equal to the aforesaid predetermined bit number, the aforesaid sequences being able to also be at least partially overlapping each other with a part of their optical sections 2 in common.

[0040] In particular, the predetermined bit number pseudo-random code is provided with a maximum number of possible different sequences equal to 2n-l, wherein n is equal to the predetermined bit number and wherein each sequence is made, as previously exposed, by optical sections 2, adjacent to each other, in number equal to the predetermined bit number.

[0041] Therefore, for example, a twelve-bit pseudo-random code is a binary code in which every sequence formed by twelve optical sections 2 adjacent to each other is different from every other sequence formed by twelve optical sections 2 adjacent to each other, and such twelve-bit pseudo-random code has in particular a maximum number of possible different sequences equal to 212-1.

[0042] Furthermore, the mechanical device is provided with a position sensor 3 integral with the first mechanical member and comprising an optical emitter 4, which is arranged for projecting an incident radiation onto at least part of the positioning track 1 of the second mechanical member.

[0043] In more detail, the position sensor 3 integral with the first mechanical member can be directly fixed to the first mechanical member or be fixed to a part of the machine to which the first mechanical member of the mechanical device is fixed, so that in particular no mutual movement is possible between the position sensor 3 and the first mechanical member.

[0044] The position sensor 3 further comprises a plurality of optical transducers 5, which are distributed in succession along the extension line X and are arranged for framing, on the positioning track 1, at least one measurement window 6 extended for a number of optical sections 2 adjacent to each other that is equal to the predetermined bit number of the pseudo-random code.

[0045] That is, for example, if the first and second optical sections 2', 2" are distributed on the positioning track 1 according to a twelve-bit pseudo-random code, the measurement window 6 will extend for a number of adjacent optical sections 2 equal to twelve.

[0046] Without departing from the scope of the present invention, a part of the plurality of optical transducers 5 can frame further adjacent optical sections 2 outside the measurement window 6.

[0047] For example, if the first and second optical sections 2', 2” are distributed on the positioning track 1 according to a twelve-bit pseudo-random code, the optical transducers 5 of the position sensor 3 could frame a number of adjacent optical sections 2 greater than twelve, such as fifteen adjacent optical sections 2, so as to define four measurement windows 6 offset from each other by an optical section 2 and each formed by twelve adjacent optical sections 2, with the consequence that the method for determining the mutual position of the first and the second mechanical member of the mechanical device described below can be repeated simultaneously more than once, i.e. once for each framed measurement window 6, to increase the reliability of the position detected by the position sensor 3.

[0048] Alternatively, the optical transducers 5 of the position sensor 3 can frame a number of adjacent optical sections 2 greater than the number of optical sections 2 contained in the measurement window 6, the information associated with the optical sections 2 contained in the measurement window 6 is analyzed to perform the method for determining the mutual position of the first and the second mechanical member of the mechanical device described below and the information associated with the optical sections 2 outside the measurement window 6 can be analyzed to perform different types of control.

[0049] The optical transducers 5 are arranged for detecting a reflected radiation coming from the positioning track 1 hit by the incident radiation and to each generate a corresponding measurement signal.

[0050] Advantageously, since the first and second optical sections 2', 2” are distributed according to a pseudorandom code with a predetermined bit number in which all the sequences formed by adjacent optical sections 2 in a number equal to the predetermined bit number are different from each other, the position sensor 3 is able at any moment to determine the position of the second mechanical member with respect to the first mechanical member in an absolute manner since it is provided with optical transducers 5 which frame a measurement window 6 extended for a number of optical sections 2 equal to the aforesaid predetermined bit number.

[0051] Preferably, in order to be able to detect the reflected radiation coming from the positioning track 1 hit by the incident radiation emitted by the optical emitter 4, the optical transducers 5 are opposite a portion of the positioning track 1 so as to frame the measurement window 6 on such a portion of the positioning track 1, with the consequence that, when the second mechanical member moves with respect to the first mechanical member, the portion of the positioning track 1 opposite the optical transducers 5 changes gradually, allowing the position sensor 4 to determine the succession of mutual positions between the first and second mechanical members in movement with respect to each other.

[0052] In more detail, the first optical sections 2’ have a low reflectivity and the second optical sections 2” in optical contrast with the first optical sections 2’ have a high reflectivity.

[0053] According to a possible embodiment, the second mechanical member is provided with a chrome -plated surface on which the first optical sections 2' (for example black in color) of the positioning track 1 are obtained, for example by laser ablation, while the second optical sections 2" are obtained from the unmachined areas of the chrome-plated surface (for example white in color).

[0054] Advantageously, the optical transducers 5 are each arranged for generating a corresponding measurement signal having a difference in potential (expressed in Volts) or current (expressed in Amperes) proportional to the light intensity of the reflected radiation coming from the positioning track 1 hit by the incident radiation.

[0055] Thereby, the measurement signal generated by each optical transducer 5 has a difference in potential or current which is lower than a pre-established discrimination threshold if it is located at a first optical section 2' with low reflectivity and the measurement signal generated by each optical transducer 5 has a difference in potential or current that is higher than the aforesaid discrimination threshold if it is located at a second optical section 2" with high reflectivity.

[0056] Therefore, it is preferably possible to establish at each instant whether each optical transducer 5 detects a first or a second optical section 2', 2” by comparing the corresponding measurement signal with such a discrimination threshold, below which the difference in potential or current of the measurement signal is indicative of a first section 2' with low reflectivity and above which the difference in potential or current of the measurement signal is indicative of a second section 2" with high reflectivity.

[0057] Furthermore, each optical transducer 5 is (provided with a center thereof and is) spaced by an adjacent optical transducer 5 with a resolution R equal to or less than half the width L.

[0058] In more detail, resolution R is intended as the distance between the centers of two optical transducers 5 adjacent to each other.

[0059] Thereby, with resolution R equal to or less than half the width L of the optical sections 2, at each instant at least one optical transducer 5 is located at each optical section 2 contained in the measurement window 6.

[0060] Furthermore, the mechanical device is provided with an electronic control unit, which is operatively connected to the optical transducers 5 to receive the measurement signals.

[0061] Such an electronic control unit is configured to associate, with each optical section 2 contained in the measurement window 6, a corresponding group G of at least three consecutive optical transducers 5, of which a first lateral optical transducer 5', a second lateral optical transducer 5” and at least one central optical transducer 5'" interposed between the first and the second lateral optical transducer 5', 5".

[0062] Furthermore, the aforesaid electronic control unit is configured to associate the measurement signals of the optical transducers 5 with respective comparison parameters, in which at least a first comparison parameter is associated with the measurement signals of the first lateral optical transducers 5', at least a second comparison parameter is associated with the measurement signals of the second lateral optical transducers 5" and at least a third comparison parameter is associated with the measurement signals of the central optical transducers 5"'.

[0063] The electronic control unit is further configured to compare the comparison parameters to identify, among them, coinciding comparison parameters and, if most of the comparison parameters are coinciding comparison parameters, to obtain, based on the measurement signals associated with such coinciding comparison parameters, a position binary number having a bit number equal to the predetermined bit number of the pseudo-random code, where each bit corresponds to a group G of at least three optical transducers 5.

[0064] Therefore, if the first and second optical sections 2', 2" are distributed for example according to a twelvebit pseudo-random code, the position binary number will advantageously have twelve bits, each of which corresponding to a group G of at least three adjacent optical transducers 5, where in particular each group G has been associated by the electronic control unit with a corresponding optical section 2 contained in the measurement window 6, which is extended for a number of adjacent optical sections 2 equal to the predetermined bit number of the pseudo-random code, i.e. twelve.

[0065] Furthermore, the electronic control unit is configured for associating the position binary number with a position of the second mechanical member with respect to the first mechanical member.

[0066] Thereby, the position of the second mechanical member with respect to the first mechanical member is determined absolutely as a function of the position binary number, where each bit of such a position binary number is representative of an optical section 2, which is contained in the measurement window 6 and is adapted to form with the other optical sections 2 contained in the same measurement window 6 a unique and never repeated sequence within the pseudo-random code.

[0067] Furthermore, the mechanical device according to the invention allows to detect the position of the second mechanical member with respect to the first mechanical member by means of the position sensor 3 in a very reliable manner. In fact, advantageously, since the optical transducers 5 are each spaced from adjacent optical transducers 5 with a resolution R equal to or less than half the width L of an optical section 2, in use, in most cases, two optical transducers 5 of each group G are simultaneously located at the same optical section 2 and one optical transducer 5 of each group G is located at a different optical section 5. Therefore, the value of each bit of the position binary number, in most cases, depends on a comparison between comparison parameters in which the comparison parameter obtained from the measurement signal generated by an optical transducer 5 that detects a reflected radiation coming from an optical section 2 different from the optical section 2 that projects the reflected radiation thereof on the at least two other optical transducers 5 belonging to the same group G is discarded.

[0068] In use, however, cases may occur in which the at least one central optical transducer 5'" is positioned exactly in front of an edge interposed between two adjacent optical sections 2 and the first and the second optical transducer 5', 5" are each located in one of the aforesaid two adjacent optical sections 2. In this case, the central optical transducer 5'" could generate a measurement signal that is not indicative of either of the two adjacent optical sections 2 and, therefore, the electronic control unit might not be able to identify coinciding control parameters.

[0069] Therefore, advantageously, if most of the comparison parameters are not coinciding comparison parameters, the electronic control unit is configured to obtain at least two provisional position binary numbers each having a bit number equal to the predetermined bit number of the pseudo-random code, in which each bit of both provisional position binary numbers corresponds to a group G of at least three optical transducers 5 and in which one of the two provisional position binary numbers is obtained as a function of the at least a first comparison parameter and the other of the two provisional position binary numbers is obtained as a function of the at least a second comparison parameter.

[0070] Furthermore, the electronic control unit is advantageously configured to associate each of the two aforesaid provisional position binary numbers with a hypothetical position of the second mechanical member with respect to the first mechanical member and, if the hypothetical positions associated with the two provisional position binary numbers are representative of adjacent positions, to select one of the two aforesaid hypothetical positions as the position of the second mechanical member with respect to the first mechanical member.

[0071] In more detail, “adjacent positions” is intended as positions associated with two sequences of optical sections 2 on the positioning track 1 which are offset with respect to each other by only one optical section 2 and which are each formed by a number of optical sections 2 equal to the predetermined bit number of the pseudo-random code (i.e. a number equal to the number of optical sections 2 contained in the measurement window 6).

[0072] Thereby, the determination of the position of the second mechanical member with respect to the first mechanical member is still very reliable. Operatively, in fact, the provisional position binary number associated with the at least a first comparison parameter depends on the measurement signals generated by the first lateral optical transducers 5' which detect a sequence of adjacent optical sections 2 in a number equal to the predetermined bit number of the pseudo-random code and the provisional position binary number associated with the at least a second comparison parameter depends on the measurement signals generated by the second lateral optical transducers 5" which detect a sequence of adjacent optical sections 2 in a number equal to the predetermined bit number which is offset with respect to the other sequence of an optical section 2. Therefore, when the electronic control unit verifies that the hypothetical positions associated with the two provisional position binary numbers are representative of adjacent positions, the reliability of the reading of the positioning track 1 by the optical transducers 5 is essentially confirmed.

[0073] Furthermore, the mechanical device according to the invention allows the position of the second mechanical member to be detected with respect to the first mechanical member by means of the position sensor 3 even when the maximum possible mutual movement between the first and second mechanical member is very large (for example in the order of several meters of translation, compatible for example with the relative translation between sections of a telescopic arm belonging to a crane or a tele -handler). In fact, to make the mechanical device having the certainty of being able to determine the mutual position between the first and second mechanical member on very high maximum amplitudes of mutual movement, it is sufficient to:

[0074] - select the maximum range of mutual movement (e.g. 4000 mm),

[0075] - divide this maximum range by the smallest displacement which is to be detected in order to determine the number of mutual positions between first and second mechanical members that must be able to be identified by the position sensor 3 (for example, dividing a maximum range of 4000 mm by a smallest detectable displacement of 1 mm, four thousand mutual positions are obtained between the first and second mechanical members, identifiable by the position sensor 3),

[0076] - select the first power of the two whose result subtracted by one is greater with respect to the number of identifiable mutual positions (for example, with four thousand identifiable mutual positions, the first power of two, whose result subtracted by one is greater than four thousand, is two raised to an exponent of twelve, or four thousand ninety-six, from which one is subtracted to obtain four thousand ninety-five),

[0077] - generate (in particular by means of algorithms known to those skilled in the art and therefore not better described below) a predetermined bit number pseudo-random code that is equal to the exponent of the first power of two whose result subtracted by one is greater than the number of distinguishable mutual positions (for example, with four thousand identifiable mutual positions, the first power of two, whose result subtracted by one is greater than this number of identifiable mutual positions, is two raised to the power of twelve and therefore a twelve-bit pseudo-random code will be generated), and

[0078] - obtain on the second mechanical member a positioning track 1 in which the first and second optical sections 2', 2" are distributed according to the aforesaid pseudo-random code and each have a width L equal to the smallest detectable displacement (so that, by using a number of optical sections 2 in sequence equal to the number of identifiable mutual positions increased by one, for example four thousand-one optical sections 2 for four thousand identifiable mutual positions, it is possible to distinguish four thousand different sequences of twelve optical sections 2 adjacent to each other, in which such a positioning track 1 is therefore extended on the second mechanical member for a length substantially equal to the maximum amplitude of the mutual movement between the first and second mechanical members);

[0079] - arrange the optical transducers 5 on the position sensor 3 so that they frame a measurement window 6 on the positioning track 1, extended over a number of adjacent optical sections 2 equal to the predetermined bit number of the pseudo-random code (in accordance with the example, therefore, the measurement window 6 will extend over twelve adjacent optical sections 2 and therefore at any moment it will frame a sequence of twelve optical sections 2 that is unique and not repeated within the positioning track 1, so that the position of the second mechanical member can be detected in an absolute manner).

[0080] Advantageously, at least one of the first and the second lateral optical transducers 5', 5" of each group G is in common with another adjacent group G, so that, in particular, it is possible to reliably compare the comparison parameters even with a reduced cost of the position sensor 3.

[0081] As can be seen in the example in Figure 3 where the groups G are formed by three adjacent spaced optical transducers 5 with resolution R equal to half the width L, the groups G at the optical sections 2 contained in a lateral position within the measurement window 6 have only one of the first and the second lateral optical transducer 5', 5" in common with the group G adjacent to them, while the groups G at the optical sections 2 contained in the most central positions within the measurement window 6 have both the first and the second lateral optical transducer 5', 5" in common with the two groups G adjacent thereto.

[0082] Obviously, embodiments are also possible in which the groups G are formed by more than three adjacent optical transducers 5 and in which more than one optical transducer 5 of each group G is in common with another adjacent group G (with five optical transducers 5 it is for example possible that the groups G in the most central positions within the measurement window 6 have two optical transducers 5 in common with an adjacent group G and two optical transducers 5 in common with another adjacent group G). Advantageously, the optical transducers 5 are phototransistors, which preferably do not require amplifiers to provide the control electronics with a measurement signal that can be analyzed and are particularly low-cost.

[0083] Alternatively, the optical transducers 5 may be of another type, such as photodiodes, which are more expensive with respect to phototransistors because they require the use of amplifiers, but have a much higher acquisition frequency with respect to that of phototransistors and therefore the possibility of using the position sensor 3 on a mechanical device in which the first and the second mechanical member can move with respect to each other with a high speed.

[0084] The optical emitter 4 advantageously comprises a plurality of light sources 7 (for example of the LED type), each of which corresponds to a group G of at least three optical transducers 5 and is arranged for emitting the incident radiation on a part of the positioning track 1 contained in the measurement window 6 and susceptible of reflecting the reflected radiation towards the optical transducers 5 of the group G corresponding to the light source 7 itself.

[0085] In more detail, each light source 7 is arranged substantially centered with respect to the at least one central optical transducer 5"' of the corresponding group G, so that the reflected radiation coming from the optical section 2 hit by the incident radiation emitted by the same light source 7 hits the central optical transducer 5"' of the corresponding group G and the first and second lateral optical transducers 5', 5” belonging to the same group G.

[0086] Preferably, the electronic control unit is operatively connected to the light sources 7 of the optical emitter 4 and is configured for separately actuating each light source 7 to emit a corresponding incident radiation. Thereby, by separately actuating each light source 7 corresponding to a group G, the three or more optical transducers 5 of each group G together generate the corresponding measurement signals without these measurement signals being affected by background noise due to any reflected radiation coming from the optical sections 2 hit by the incident radiation emitted by a different light source 7.

[0087] This advantageously allows the use of a particularly economical position sensor 3 which does not require the integration of components, such as lenses and / or septa and / or collimators and / or optical filters and / or mirrors, to prevent the reflected radiations coming simultaneously from different optical sections 2 from interfering with each other, thus mutually disturbing the measurement signals generated by the optical transducers 5 of the two groups G opposite thereto.

[0088] Advantageously, the electronic control unit comprises a microcontroller operatively connected to the optical transducers 5 to receive the measurement signals and to the light sources 7 to control the switching on thereof.

[0089] Furthermore, the absence of such components of the position sensor 3 (i.e. lenses and / or septa and / or collimators and / or optical filters and / or mirrors mentioned above) advantageously allows the optical transducers 5 and the light sources 7 to be positioned particularly close to the positioning track 1, ensuring that the image generated starting from the measurement signals of the optical transducers 5 faithfully reproduces the optical sections 2 present on the framed portion of the positioning track 1.

[0090] Furthermore, the fact that the light sources 7 are separately actuated does not affect the ability of the position sensor 3 to correctly determine the position of the second mechanical member with respect to the first mechanical member, since the frequency with which the light sources 7 can be actuated to emit the incident radiation thereof and the frequency with which the optical transducers 5 acquire are sufficiently high to allow, at normal operating speeds with which the second mechanical member is actuated to move with respect to the first mechanical member, to consider the second mechanical member substantially stationary between one acquisition of the optical transducers 5 and the next and between the actuation of one light source 7 and the next.

[0091] For example, by using optical transducers 5 capable of acquiring all the optical sections 2 within the measurement window 6 with a frequency around 1 kHz (with the consequence that an acquisition of the optical sections 2 is performed in 1 ms), such as phototransistors, and by using LED type light sources 7, the position sensor 3 is able to correctly determine the position of the second mechanical member with respect to the first mechanical member with the second mechanical member moving with a speed of up to 1000 mm / s (i.e. a speed compatible for example with the normal operation of mechanical devices belonging to earth-moving machines, such as the telescopic arms of tele-handlers or cranes), if the accuracy required in identifying the position of the second mechanical member is substantially equal to 1 mm.

[0092] In particular, the electronic control unit is configured to sequentially actuate the light sources 7 to emit corresponding incident radiation (i.e. in other words, the electronic control unit is configured to actuate each light source 7 to emit the corresponding incident radiation individually, after having actuated an adjacent light source 7 to emit the incident radiation thereof).

[0093] Thereby, it is possible to use light sources 7 arranged for emitting the incident radiation thereof within a particularly restricted emission volume, and such light sources 7, by means of the corresponding reflected radiation, completely illuminate the central optical transducer 5"' of the respective group G and only partially the first and the second lateral optical transducer 5', 5”. Furthermore, the fact that the first and the second lateral optical transducer 5', 5” are only partially illuminated by the light source 7 corresponding to the group G thereof does not constitute an obstacle to the generation of a precise measurement signal by the first or the second lateral optical transducer 5', 5”, by means of which it is possible to distinguish a first from a second optical section 2', 2”. In fact, in this case, the measurement signal will have an intensity dependent on the overlapping of the partial illumination due to the actuation of the light source 7 of a group G and the partial illumination due to the actuation of the light source 7 of an adjacent group G, given that advantageously the first lateral optical transducer 5' of a group G is also the second lateral optical transducer 5” of an adjacent group G and that advantageously the light sources 7 are actuated in sequence.

[0094] The electronic control unit is advantageously configured to separately actuate each light source 7 and to simultaneously disable the optical transducers 5 belonging exclusively to groups G not corresponding to the separately actuated light source 7.

[0095] In more detail, the electronic control unit disables the optical transducers 5 that belong only to groups G different from the one corresponding to the light source 7 actuated at that moment and does not disable the optical transducers 5 that belong to both the group G corresponding to the light source 7 actuated at that moment and to an adjacent group G, i.e. it does not disable the optical transducers 5 that belong to the group G corresponding to the light source 7 actuated at that moment and that are in common with another adjacent group G.

[0096] Thereby, even in the case in which the reflected radiation due to the actuation of a light source 7 goes to partially illuminate the optical transducers 5 belonging to a group G different from that corresponding to the actuated light source 7, no problems related to the generation of disturbed light signals occur.

[0097] Furthermore, thanks to the fact that the optical emitter 4 advantageously comprises a plurality of light sources 7 (in particular separately actuatable and each substantially centered with respect to the at least one central optical transducer 5'" of the corresponding group G), the position sensor 3 is able to correctly determine whether an optical section 2 is a first or a second optical section 2', 2” even in the rare cases in which the at least one central optical transducer 5'" of the group G associated therewith is located exactly at the center of such an optical section 2 and the first and the second optical transducer 5', 5" belonging to the same group G are located at the edge between the aforesaid optical section 2 and an adjacent one. In fact, the incident radiation emitted by each light source 7 never has a perfectly planar wavefront, but can be assimilated to a slightly conical light beam. Therefore, in use, the first and the second lateral optical transducer 5', 5” which are located exactly in front of the edges between two adjacent optical sections 2 generate a measurement signal starting from a reflected radiation which does not come from the edge in front of them, but from a point adjacent to the same edge and inside the optical section 2 at which the central optical transducer 5"' of the same group G is located (due to a part of the incident radiation which does not hit the positioning track 1 perfectly orthogonally, but with a small inclination) and, thereby, the measurement signal generated by such first and second lateral optical transducers 5', 5" is identical to the measurement signal generated by the central optical transducer 5'" of the same group G and it is therefore possible to compare the comparison parameters, identifying those which coincide with each other. In essence, therefore, the first and second lateral optical transducers 5’, 5” tend to provide a reading which converges toward the center.

[0098] Furthermore, in use, in the case in which the at least one central optical transducer 5'" of a group G is located exactly in front of an edge between two adjacent optical sections 2 and the first and the second lateral optical transducer 5', 5” of the same group G are each located in one of the aforesaid two adjacent optical sections 2, it is still possible to establish the position of the second mechanical member substantially without errors. In fact, the measurement signals generated by the at least three optical transducers 5 of each group G can be substantially considered equal to each other in shape but offset in time, since the first and second lateral optical transducers 5', 5” pass from one section 2 to another adjacent section 2, during the motion of the second mechanical member relative to the first mechanical member, one early and the other delayed with respect to the central optical transducer 5'", depending on the movement direction of the second mechanical member. Therefore, even when the central optical transducer 5"' is located at an edge between two adjacent optical sections 2, it is possible to fictitiously establish that it is located at one of the aforesaid two adjacent optical sections 2 by taking into account the potential or current difference of the measurement signal generated by an adjacent and delayed optical transducer 5.

[0099] As an alternative to such a verification which provides for considering the measurement signal generated by an adjacent and delayed optical transducer 5, if the case occurs in which the at least one central optical transducer 5"' is not able to generate a measurement signal indicative of either the first or the second optical sections 2', 2” because it is located at a given moment exactly in front of an edge between two adjacent optical sections 2, the electronic control unit can operatively proceed as described above to obtain the two provisional position binary numbers and perform the verification on the hypothetical positions associated therewith.

[0100] In accordance with an embodiment different from the one diagrammed in the attached figures in which the resolution R is equal to half the width L and in which each group G is formed by three optical transducers 5, the optical transducers 5 can each be advantageously spaced by an adjacent optical transducer 5 with a resolution R equal to the width L divided by a first whole number greater than two (for example four) and, in this case, the electronic control unit is advantageously configured to associate with each optical section 2 contained in the measurement window 6 a corresponding group G composed of a second whole number of consecutive optical transducers 5, in which this second whole number is equal to the aforesaid first whole number increased by one (equal to five if the first whole number is four). In more detail, in the aforesaid embodiment not shown, each group G comprises a first lateral optical transducer 5', a second lateral optical transducer 5" and more than one central optical transducer 5'" interposed between the first and the second lateral optical transducer 5', 5” (and therefore three central optical transducers 5"' if the resolution R is equal to the width L divided by four and if therefore five optical transducers 5 are provided for each group G). In accordance with this embodiment, the electronic control unit is also advantageously configured to associate the measurement signals of the optical transducers 5 with respective comparison parameters, in which at least a first comparison parameter is associated with the measurement signals of the first lateral optical transducers 5', at least a second comparison parameter is associated with the measurement signals of the second lateral optical transducers 5” and a number of third comparison parameters equal to at least the number of central optical transducers 5'" is associated with the measurement signals of the central optical transducers 5"'.

[0101] Advantageously, in accordance with a preferred embodiment, the electronic control unit is configured to generate the comparison parameters in the form of corresponding comparison binary numbers, each of which has one bit corresponding to each of the groups G of at least three optical transducers 5.

[0102] Therefore, if the pseudo-random code is twelve-bit and the measurement window 6 extends over twelve adjacent optical sections 2 framed by twelve corresponding groups G of at least three optical transducers 5, the comparison parameters in the form of comparison binary numbers are each provided with twelve bits.

[0103] In more detail, the bits of the first comparison parameter each have a value that depends on the measurement signal generated by the first lateral optical transducer 5' of the corresponding group G, the bits of the second comparison parameter each have a value that depends on the measurement signal generated by the second lateral optical transducer 5" of the corresponding group G and the bits of the third comparison binary number each have a value that depends on the measurement signal generated by the at least one central optical transducer 5'" of the corresponding group G.

[0104] In particular, therefore, the number of comparison parameters in the form of comparison binary numbers is equal to the number of optical transducers 5 forming each group G.

[0105] Thereby, the first comparison parameter is advantageously a binary comparison number formed by a number of bits equal to the number of optical sections 2 contained in the measurement window 6 and representative of the reading of such optical sections 2 generated only by the first lateral optical transducers 5', which in particular are the optical transducers 5 on the left in each group G with reference to Figure 3.

[0106] Furthermore, the second comparison parameter is advantageously a comparison binary number formed by a number of bits equal to the number of optical sections 2 contained in the measurement window 6 and representative of the reading of such optical sections 2 generated only by the second lateral optical transducers 5", which in particular are the optical transducers 5 on the right in each group G with reference to Figure 3.

[0107] Furthermore, the third comparison parameter is advantageously a comparison binary number formed by a number of bits equal to the number of optical sections 2 contained in the measurement window 6 and representative of the reading of such optical sections 2 generated only by the central optical transducers 5'", which in particular are the optical transducers 5 at the center in each group G with reference to Figure 3.

[0108] In accordance with the aforesaid preferred embodiment, the electronic control unit is advantageously configured to compare at least one of the comparison parameters with a positioning matrix saved in a memory, in which each possible position of the second mechanical member with respect to the first mechanical member is associated with a binary number, and to verify if in such a positioning matrix there is a binary number identical to the aforesaid comparison parameter (for example, the electronic control unit is configured to compare the third comparison parameter which, depending on the measurement signals generated by the central optical transducers 5"', is more likely coinciding with one of the other two comparison parameters obtained from measurement signals generated by optical transducers 5 which are located to the right and left with respect to the aforesaid central optical transducer 5'", with reference to the example diagram of Figure 3).

[0109] In more detail, if there is no binary number identical to the selected comparison parameter in the positioning matrix, the electronic comparison unit is preferably configured to compare one other comparison parameter at a time with the positioning matrix, in particular until a binary number identical to a comparison parameter is found in the positioning matrix (i.e. if there is no binary number identical to the third comparison parameter in the positioning matrix, for example, the electronic control unit is configured to compare the first comparison parameter with the positioning matrix and, if there is no binary number identical to the first comparison parameter in this case either, the same electronic control unit is configured to compare the second comparison parameter with the positioning matrix).

[0110] Furthermore, if there is no binary number identical to one of the comparison parameters in the positioning matrix, the electronic control unit is preferably configured to emit an error signal, which is in particular indicative of the impossibility of correctly determining the position of the second mechanical member with respect to the first mechanical member (for example, the impossibility of correctly determining the position could be caused by dirt covering part of the positioning track 1 or by damage to the optical transducers 5 and / or the optical emitter 4).

[0111] If there is a binary number in the positioning matrix that is identical to a comparison parameter, the electronic control unit is preferably configured to compare the aforesaid comparison parameter with at least part of the other comparison parameters to check if most of the comparison parameters are coinciding.

[0112] In particular, if the comparison parameter identical to one of the binary numbers of the positioning matrix is compared with a part of the other comparison parameters and it is verified that they are coinciding and that they constitute most of all the comparison parameters, then it is not necessary to proceed with comparing the aforesaid comparison parameter identical to one of the binary numbers of the positioning matrix with all the other comparison parameters (for example, always with reference to the diagram of Figure 3, if the third comparison parameter is identical to one of the binary numbers of the positioning matrix, the aforesaid third comparison parameter is then compared with another comparison parameter, such as the first comparison parameter, and if such third and first comparison parameters are coinciding with each other it is not necessary to perform a comparison also with the second comparison parameter to verify if most of the comparison parameters are coinciding with each other).

[0113] In fact, if most of the comparison parameters are coinciding, the electronic comparison unit is preferably configured to set one of the coinciding comparison parameters as a position binary number and associate the position binary number with a position of the second mechanical member with respect to the first mechanical member by means of the positioning matrix.

[0114] If most of the comparison parameters are not coinciding, the electronic control unit is preferably configured to compare the first and the second comparison parameters with the positioning matrix and check whether there are two different binary numbers in the positioning matrix that are identical to the first comparison parameter and the second comparison parameter.

[0115] If the positioning matrix contains a binary number identical to the first comparison parameter and another binary number identical to the second comparison parameter, the electronic control unit is preferably configured to set the aforesaid first and second comparison parameters as provisional position binary numbers and, as previously described above, to associate, by means of the positioning matrix, each of such provisional position binary numbers with a hypothetical position of the second mechanical member with respect to the first mechanical member.

[0116] Furthermore, if the hypothetical positions associated with the two provisional position binary numbers are representative of adjacent positions, the electronic control unit is further configured to select one of the aforesaid two hypothetical positions as the position of the second mechanical member with respect to the first mechanical member.

[0117] In particular, the checks just described above are applicable when the comparison parameters are not coinciding with each other, for example because the at least one central optical transducer 5"' is located at a given moment exactly in front of an edge between two adjacent optical sections 2.

[0118] Advantageously, the electronic control unit is also configured to calculate the movement speed of the second mechanical member with respect to the first mechanical member as a function of a sequence of positions determined in a pre-established time interval.

[0119] A further object of the present invention is a method for determining the mutual position of a first and a second mechanical member belonging to a mechanical device.

[0120] The aforesaid method provides for a step of arranging the mechanical device, which is provided with a first mechanical member and a second mechanical member susceptible to relative motion with respect to the first mechanical member.

[0121] Such a second mechanical member is provided with a positioning track 1 extended along an extension line X and provided with a plurality of optical sections 2 having equal width L along the aforesaid extension line X.

[0122] A part of such optical sections 2 are first optical sections 2' and a part are second optical sections 2", and such first and second optical sections 2', 2” have different optical contrasts (i.e. in other words, the second optical sections 2" are in optical contrast with respect to the first optical sections 2').

[0123] Furthermore, the first and second optical sections 2', 2" are distributed along the positioning track 1 according to a predetermined bit number pseudo-random code.

[0124] In more detail, the predetermined bit number pseudo-random code is a binary code provided with a plurality of bits each corresponding to an optical section 2 of the positioning track 1, in which each sequence formed by the optical sections 2 adjacent to each other in a number equal to the predetermined bit number is different from any other sequence formed by optical sections 2 adjacent to each other in a number equal to the aforesaid predetermined bit number, the aforesaid sequences being able to also be at least partially overlapping each other with a part of their optical sections 2 in common.

[0125] Furthermore, the aforesaid mechanical device comprises a position sensor 3, which is integral with the first mechanical member and comprises an optical emitter 4 and a plurality of optical transducers 5.

[0126] The aforesaid optical transducers 5 are distributed in succession along the extension line X, are arranged for framing, on the positioning track 1, at least one measurement window 6 extended for a number of optical sections 2 adjacent to each other, equal to the predetermined bit number of the pseudo-random code and are each spaced by an adjacent optical transducer 5 with a resolution R equal to or less than half the width L (and are each provided with a center thereof).

[0127] In particular, resolution R is intended as the distance between the centers of two optical transducers 5 adjacent to each other.

[0128] The method in question further provides for an acquisition step, in which the optical emitter 4 projects, on at least part of the positioning track 1 of the second mechanical member, an incident radiation and in which the optical transducers 5 detect a reflected radiation coming from the positioning track 1 hit by the incident radiation and each generate a corresponding measurement signal.

[0129] In particular, the first optical sections 2' are optical sections 2 with low reflectivity and the second optical sections 2” are optical sections 2 with high reflectivity, so that the measurement signal generated by each optical transducer 5 has a difference in potential or current lower than a pre-established discrimination threshold if the optical transducer 5 is located at a first optical section 2' and has a difference in potential or current higher than the pre-established discrimination threshold if the optical transducer 5 is located at a second optical section 2".

[0130] Furthermore, the method in question comprises an association step, in which each optical section 2 contained in the measurement window 6 is associated with a corresponding group G of at least three consecutive optical transducers 5, of which a first lateral optical transducer 5', a second lateral optical transducer 5" and at least one central optical transducer 5"' interposed between the first and the second lateral optical transducer 5', 5".

[0131] The method according to the present invention also provides a comparison step, in which the measurement signals of said optical transducers 5 are associated with respective comparison parameters, so that at least a first comparison parameter is associated with the measurement signals of the first lateral optical transducers 5', at least a second comparison parameter is associated with the measurement signals of the second lateral optical transducers 5" and at least a third comparison parameter is associated with the measurement signals of said central optical transducers 5”', and in which the aforesaid comparison parameters are compared with each other to identify, among them, coinciding comparison parameters.

[0132] The method in question further provides a calculation step, in which, if most of the comparison parameters are coinciding comparison parameters, a position binary number having a bit number equal to the predetermined bit number of the pseudo-random code is obtained, as a function of the measurement signals associated with the coinciding comparison parameters, in which each bit corresponds to a group G of at least three said optical transducers 5.

[0133] The method according to the invention finally comprises a determination step, in which the position binary number is associated with a position of the second mechanical member with respect to the first mechanical member.

[0134] If in the comparison step it is not verified that most of the comparison parameters are coinciding comparison parameters, in the calculation step at least two provisional position binary numbers are advantageously derived, each having a bit number equal to the predetermined bit number of the pseudo- random code, in which each bit of both provisional position binary numbers corresponds to a group G of at least three optical transducers 5 and in which one of the two provisional position binary numbers is obtain as a function of the at least a first comparison parameter and the other of the two provisional position binary numbers is obtained as a function of the at least a second comparison parameter.

[0135] Furthermore, if in the calculation step the aforesaid provisional position binary numbers are obtained, in the determination step each of the two aforesaid provisional position binary numbers is advantageously associated with a hypothetical position of the second mechanical member with respect to the first mechanical member and, if the hypothetical positions associated with the two provisional position binary numbers are representative of adjacent positions, one of the two aforesaid hypothetical positions is selected as the position of the second mechanical member with respect to the first mechanical member.

[0136] In more detail, “adjacent positions” is intended as positions associated with two sequences of optical sections 2 on the positioning track 1 which are offset with respect to each other by only one optical section 2 and which are each formed by a number of optical sections 2 equal to the predetermined bit number of the pseudo-random code (i.e. a number equal to the number of optical sections 2 contained in the measurement window 6).

[0137] It is thereby possible to reliably determine the position of the second mechanical member with respect to the first mechanical member even when the comparison parameters generated starting from the measurement signals of the optical transducers 5 are not coinciding with each other, for example because at a given moment the at least one optical transducer 5'" of each group G is positioned exactly in front of an edge interposed between two adjacent optical sections 2 without being able to generate a measurement signal either indicative of a first optical section 2' or of a second optical section 2”.

[0138] Advantageously, in the position sensor 3 used in the method in question, at least one among the first and the second lateral optical transducer 5', 5” of each group G is in common with another adjacent group G. Preferably, in particular in the embodiment in which each group G is formed by three adjacent optical transducers 5, the groups G arranged in a lateral position with respect to the measurement window 6 have only one of the first and the second lateral optical transducer 5', 5" in common with an adjacent group G and the groups G arranged in the central positions with respect to the measurement window 6 have both the first and the second lateral optical transducer 5', 5” in common with their two adjacent groups G.

[0139] Preferably, in order to make the position sensor 3 as economical as possible and not have to use amplifiers arranged to amplify the measurement signals generated by the optical transducers 5, the optical transducers 5 are phototransistors.

[0140] Advantageously, the optical emitter 4 comprises a plurality of light sources 7, each of which corresponds to a group G of at least three optical transducers 5 and is arranged for emitting the incident radiation thereof on a part of the positioning track 1 contained in the measurement window 6 and susceptible of reflecting the reflected radiation towards the optical transducers 5 of the group G corresponding to the light source 7 itself.

[0141] In more detail, in the acquisition step, the light sources 7 are actuated to each separately emit the incident radiation thereof, in particular in sequence.

[0142] Thereby, it is not necessary for the position sensor 3 to be provided with components such as lenses and / or septa and / or collimators and / or optical filters and / or mirrors to prevent the measurement signals generated by optical transducers 5 belonging to a specific group G from being disturbed by interference due to the reflected radiation coming from the optical sections 2 hit by the incident radiation emitted by the light source 7 corresponding to a different group G.

[0143] In particular, in the acquisition step, the light sources 7 are actuated to each separately emit the incident radiation thereof and the optical transducers 5 belonging exclusively to groups G not corresponding to the light source 7 separately actuated (at that particular moment) are simultaneously disabled.

[0144] Furthermore, in the association step, the comparison parameters are advantageously generated in the form of corresponding comparison binary numbers, each of which has one bit corresponding to each of the groups G of at least three said optical transducers 5, in which the bits of the first comparison parameter each have a value that depends on the measurement signal generated by the first lateral optical transducer 5' of the corresponding group G, the bits of the second comparison parameter each have a value that depends on the measurement signal generated by the second lateral optical transducer 5” of the corresponding group G, and the bits of the third binary comparison number each have a value that depends on the measurement signal generated by the at least one central optical transducer 5"' of the corresponding group G.

[0145] In other words, in the association step, comparison parameters are generated in the form of comparison binary numbers equal to the number of optical transducers 5 forming each group G. That is, if each group G is formed by three optical transducers 5 as schematically shown in Figure 3, three comparison parameters are generated in the association step. Furthermore, each comparison parameter in the form of a comparison binary number is advantageously composed of a number of bits equal to the number of optical sections 2 contained in the measurement window 6, since the number of groups G corresponds to the number of optical sections 2 in the measurement window 6, each group G corresponding to an optical section 2 of the measurement window 6. Therefore, if for example the pseudo-random code is twelve-bit and the measurement window 6 is extended for twelve optical sections 2, each comparison parameter in the form of a comparison binary number is composed of twelve bits. Furthermore, with reference to the diagram in Figure 3, considering how the comparison parameters are advantageously generated in the association step, the first comparison parameter in the form of a comparison binary number is representative of a reading of the optical sections 2 contained in the measurement window 6 which is performed by the optical transducers 5 on the left in each group G, the second comparison parameter in the form of a comparison binary number is representative of a reading of the optical sections 2 contained in the measurement window 6 which is performed by the optical transducers 5 on the right in each group G and, furthermore, the third comparison parameter in the form of a binary comparison number is representative of a reading of the optical sections 2 contained in the measurement window 6 which is performed by the optical transducers 5 in the center in each group G. Advantageously, in the comparison step, at least one of the comparison parameters (in the form of a comparison binary number) is compared with a positioning matrix saved in a memory, in which each possible position of the second mechanical member with respect to the first mechanical member is associated with a binary number.

[0146] Preferably, in the comparison step, if it is verified that there is no binary number identical to the aforesaid comparison parameter in the positioning matrix, another comparison parameter is compared with the positioning matrix.

[0147] Furthermore, preferably, if there is no binary number in the positioning matrix that is identical to any of the comparison parameters, an error signal is generated.

[0148] In this case, the position sensor 3 was unable to determine the position of the second mechanical member because, for example, the positioning track 1 could be dirty or because the light sources 7 and / or the optical transducers 5 were subject to damage such as to affect the correct generation of the measurement signals.

[0149] Advantageously, in the comparison step, if it is verified that there is a binary number in the positioning matrix that is identical to a comparison parameter, the aforesaid comparison parameter is compared with at least part of the other comparison parameters to verify if most of the comparison parameters are coinciding.

[0150] Preferably, in the aforesaid comparison step, the third comparison parameter is first compared with the positioning matrix, since it is more likely to coincide with one of the other two between the first and the second comparison parameter (since the aforesaid third comparison parameter depends on the measurement signals generated by the central optical transducers 5”’ of each group G) and, if the third comparison parameter is not identical to any of the binary numbers of the positioning matrix, one between the first and the second comparison parameter is compared with the positioning matrix.

[0151] Furthermore, when performing the method in question, it is frequently not necessary to compare all the comparison parameters with each other to verify if most of them coincide, since if one out of, for example, three of the comparison parameters is identical to another comparison parameter, then it has already been verified that most of the comparison parameters coincide with each other, without therefore needing to also compare the last of the comparison parameters.

[0152] Furthermore, in the calculation step, if most of said comparison parameters coincide with each other, one of the coinciding comparison parameters is advantageously set as the position binary number.

[0153] Therefore, in the determination step, the position binary number is advantageously associated with a position of the second mechanical member with respect to the first mechanical member by means of the positioning matrix, since such a position binary number is in particular one of the comparison parameters coinciding with each other, which is identical to one of the binary numbers of the positioning matrix in light of the comparison step in which it was verified if in the positioning matrix there is a binary number identical to one of the comparison parameters before verifying whether such comparison parameter is coinciding with most of the comparison parameters. If it is not verified in the comparison step that most of the comparison parameters are coinciding comparison parameters, in this comparison step the first and the second comparison parameter are preferably compared with the positioning matrix to check if there are two different binary numbers in the positioning matrix that are identical to the first comparison parameter and the second comparison parameter.

[0154] Furthermore, if in the comparison step it is verified that in the positioning matrix there is a binary number identical to the first comparison parameter and another binary number identical to the second comparison parameter, in the calculation step the first and the second comparison parameter are advantageously set as temporary position binary numbers.

[0155] Furthermore, if in the calculation step the first and the second comparison parameter are set as temporary position binary numbers, in the determination step each of the two aforesaid temporary position binary numbers is advantageously associated, by means of the positioning matrix, with a hypothetical position of the second mechanical member with respect to the first mechanical member and, if the hypothetical positions associated with the two temporary position binary numbers are representative of adjacent positions, one of the aforesaid two hypothetical positions is selected as the position of the second mechanical member with respect to the first mechanical member.

[0156] Advantageously, the association step, the comparison step, the calculation step and the determination step are performed by a logic control unit, which in particular has the positioning matrix saved in a memory. Preferably, the electronic control unit is operatively connected to the optical transducers 5 to receive the measurement signals therefrom and to the optical emitter 4 (in particular to the light sources 7) to actuate it to emit the incident radiation.

[0157] Therefore, the invention thus conceived achieves the pre-set objects.

Claims

CLAIMS1. Mechanical device provided with:- a first mechanical member;- a second mechanical member, which is susceptible to relative motion with respect to said first mechanical member and is equipped with a positioning track (1) extended along an extension line (X) and provided with a plurality of optical sections (2) having equal width (L) along said extension line (X), of which a part are first optical sections (2') and a part are second optical sections (2"), and such first and second optical sections (2', 2”) have different optical contrasts and are distributed along said positioning track (1) according to a predetermined bit number pseudo-random code;- a position sensor (3) integral with said first mechanical member and comprising:- An optical emitter (4), which is arranged for projecting an incident radiation on at least part of the positioning track (1) of said second mechanical member;- a plurality of optical transducers (5), which:- are distributed in succession according to said extension line (X) and are arranged for framing, on said positioning track (1), at least one measurement window (6) extended for a number of said optical sections (2), adjacent to each other, equal to the predetermined bit number of said pseudo-random code,- are arranged for detecting a reflected radiation coming from said positioning track (1) hit by said incident radiation and for each generating a corresponding measurement signal;- are each spaced by an adjacent said optical transducer (5) with a resolution (R) equal to or less than half of said width (L), wherein said resolution (R) is the distance between the centers of two said optical transducers (5) adjacent to each other;- an electronic control unit, which is operatively connected to said optical transducers (5) in order to receive said measurement signals and is configured for:- associating, with each said optical section (2) contained in said measurement window (6), a corresponding group (G) of at least three consecutive said optical transducers (5), of which a first lateral optical transducer (5'), a second lateral optical transducer (5") and at least one central optical transducer (5'") interposed between said first and second lateral optical transducers (5', 5”); at least one between the first and second lateral optical transducers (5', 5") of each said group (G) being in common with another adjacent said group (G);- associating, with the measurement signals of said optical transducers (5), respective comparison parameters, wherein at least a first comparison parameter is associated with the measurement signals of said first lateral optical transducers (5'), at least a second comparison parameter is associated with the measurement signals of said second lateral optical transducers (5") and at least a third comparison parameter is associated with the measurement signals of said central optical transducers (5"'); said electronic control unit being configured to generate said comparison parameters in the form of corresponding binary comparison numbers, each of which has a bitcorresponding to each of said groups (G) of at least three said optical transducers (5); the bits of said first comparison parameter each having a value that depends on the measurement signal generated by the first lateral optical transducer (5') of the corresponding group (G), the bits of said second comparison parameter each having a value that depends on the measurement signal generated by the second lateral optical transducer (5") of the corresponding group (G) and the bits of said third binary comparison number each having a value that depends on the measurement signal generated by the at least one central optical transducer (5"') of the corresponding group (G);- comparing said comparison parameters in order to identify, between said comparison parameters, coinciding comparison parameters;- if most of said comparison parameters are coinciding comparison parameters, obtaining, as a function of the measurement signals associated with said coinciding comparison parameters, a position binary number having a number of bits equal to the predetermined bit number of said pseudo-random code, in which each bit corresponds to a group (G) of at least three said optical transducers (5);- associating said position binary number with a position of said second mechanical member with respect to said first mechanical member; said optical emitter (4) comprising a plurality of light sources (7), each of which corresponding to a group (G) of at least three optical transducers (5) and arranged for emitting said incident radiation on a part of said positioning track (1) contained in said measurement window (6) and susceptible of reflecting said reflected radiation towards the optical transducers (5) of said group (G) corresponding to the light source (7) itself; said electronic control unit being operatively connected to the light sources (7) of said optical emitter (4) and configured for separately actuating each said light source (7) to emit a corresponding incident radiation.

2. Mechanical device according to claim 1, characterized in that said optical transducers (5) are phototransistors.

3. Mechanical device according to claim 1 or 2, characterized in that each said light source (7) is arranged substantially centered with respect to the at least one central optical transducer (5"') of the corresponding said group (G).

4. Mechanical device according to any of the preceding claims, characterized in that said electronic control unit is configured to separately actuate each said light source (7) and to simultaneously disable the optical transducers (5) belonging exclusively to groups (G) not corresponding to said separately actuated light source (7).

5. Mechanical device according to any one of the preceding claims, characterized in that said electronic control unit is configured to sequentially actuate said light sources (7) to emit corresponding incident radiation.

6. Mechanical device according to any one of the preceding claims, characterized in that said electroniccontrol unit is configured for:- comparing at least one of said comparison parameters with a positioning matrix saved in a memory, in which each possible position of said second mechanical member with respect to said first mechanical member is associated with a binary number, and verifying if, in said positioning matrix, there is a binary number identical to said comparison parameter;- if in said positioning matrix there is a binary number identical to a said comparison parameter, comparing said comparison parameter with at least part of the other said comparison parameters in order to verify if most of said comparison parameters are coinciding;- if most of said comparison parameters are coinciding, setting one of said coinciding comparison parameters as a position binary number and associating said position binary number with a position of said second mechanical member with respect to said first mechanical member by means of said positioning matrix.

7. Method for determining the mutual position of a first and a second mechanical member belonging to a mechanical device, which provides for:- a step of arranging said mechanical device provided with:- a first mechanical member;- a second mechanical member, which is susceptible to relative motion with respect to said first mechanical member and is equipped with a positioning track (1) extended along an extension line (X) and provided with a plurality of optical sections (2) having equal width (L) along said extension line (X), of which a part are first optical sections (2') and a part are second optical sections (2"), and such first and second optical sections (2', 2”) have different optical contrasts and are distributed along said positioning track (1) according to a predetermined bit number pseudorandom code;- a position sensor (3) integral with said first mechanical member and comprising an optical emitter(4) and a plurality of optical transducers (5), which are distributed in succession according to said extension line (X), are arranged for framing, on said positioning track (1), at least one measurement window (6) extended for a number of said optical sections (2) adjacent to each other equal to the predetermined bit number of said pseudo-random code and are each spaced from an adjacent said optical transducer (5) with a resolution (R) equal to or less than half of said width (L), where said resolution (R) is the distance between the centers of two said optical transducers(5) adjacent to each other;- an acquisition step, in which said optical emitter (4) projects, on at least part of the positioning track (1) of said second mechanical member, an incident radiation and said optical transducers (5) detect a reflected radiation coming from said positioning track (1) hit by said incident radiation and each generate a corresponding measurement signal;- an association step, in which, with each said optical section (2) contained in said measurement window (6), a corresponding group (G) of at least three consecutive optical transducers (5) isassociated, of which a first lateral optical transducer (5'), a second lateral optical transducer (5”) and at least one central optical transducer (5"') interposed between said first and second lateral optical transducers (5', 5"); at least one between the first and second lateral optical transducers (5', 5") of each said group (G) is in common with another adjacent said group (G);- a comparison step, in which, with the measurement signals of said optical transducers (5), respective comparison parameters are associated, such that at least a first comparison parameter is associated with the measurement signals of said first lateral optical transducers (5'), at least a second comparison parameter is associated with the measurement signals of said second lateral optical transducers (5") and at least a third comparison parameter is associated with the measurement signals of said central optical transducers (5"'), and said comparison parameters are compared with each other in order to identify, among them, coinciding comparison parameters; in said association step, said comparison parameters being generated in the form of corresponding binary comparison numbers, each of which has a bit corresponding to each of said groups (G) of at least three said optical transducers (5), in which the bits of said first comparison parameter each have a value that depends on the measurement signal generated by the first lateral optical transducer (5”) of the corresponding group (G), the bits of said second comparison parameter each have a value that depends on the measurement signal generated by the second lateral optical transducer (5”) of the corresponding group (G) and the bits of said third binary comparison number each have a value that depends on the measurement signal generated by the at least one central optical transducer (5'") of the corresponding group;- a calculation step, in which, if most of said comparison parameters are coinciding comparison parameters, a position binary number having a number of bits equal to the predetermined bit number of said pseudo-random code is obtained, as a function of the measurement signals associated with said coinciding comparison parameters, in which each bit corresponds to a group (G) of at least three said optical transducers (5);- a determination step, in which said position binary number is associated with a position of said second mechanical member with respect to said first mechanical member; said optical emitter (4) comprising a plurality of light sources (7), each of which corresponding to a group (G) of at least three optical transducers (5) and arranged for emitting said incident radiation on a part of said positioning track (1) contained in said measurement window (6) and susceptible of reflecting said reflected radiation towards the optical transducers (5) of said group (G) corresponding to the light source (7) itself; in said acquisition step, said light sources (7) being actuated to each separately emit a corresponding said incident radiation.

8. Method according to claim 7, characterized in that, in said acquisition step, said light sources (7) are actuated to each separately emit the incident radiation thereof, in sequence.

9. Method according to claim 7 or 8, characterized in that, in said acquisition step, said light sources (7) are actuated to each separately emit the incident radiation thereof and the optical transducers (5)belonging exclusively to groups (G) not corresponding to said separately actuated light source (7) are simultaneously disabled.

10. Method according to any one of the preceding claims, characterized in that, in said comparison step, at least one of said comparison parameters is compared with a positioning matrix saved in a memory, in which each possible position of said second mechanical member with respect to said first mechanical member is associated with a binary number, and, if in said positioning matrix there is a binary number identical to one said comparison parameter, said comparison parameter is compared with at least part of the other said comparison parameters in order to verify if most of said comparison parameters are coinciding; in said calculation step, if most of said comparison parameters are coinciding with each other, one of said comparison parameters that coincide with each other is set as the position binary number.

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