The present invention relates to a method and an apparatus for determining the position of at least one surface having patterned regions.
A plurality of optical sensors currently are used in vehicle applications to detect the positions of moveable components of the vehicle. Optical sensors replace a mechanical switching element and may allow the establishment of a digital communication concept within a vehicle. Optical sensors may be used to measure the revolutions of a crankshaft of an internal combustion engine or to count the revolutions of a vehicle driver's steering wheel to detect the angle of the front wheels of a vehicle with respect to the vehicle's body.
U.S. Pat. No. 5,930,905 discusses a method and device for angular measurement of a rotatable body. That rotatable body is mounted to be rotated by more than 360° and includes a number of uniform angular markers or teeth. The rotatable body cooperates with at least two further rotatable bodies, which have another number of uniform angular markers or teeth, that angles 0 and v of this two further rotatable bodies are determined and the angular position φ of the rotatable body whose angle is to be measured, is calculated from the angles 0 and ψ, taking into consideration the prevailing geometric conditions. In a first step the whole number k is determined by forming the difference between the number of the teeth M of a gear wheel, multiplied by the angle 0 and the number of teeth of the gear wheel multiplied by the angle ψ. This number is divided by the angle Ω whereas in a second step the angle φ which is to be tacted, is determined starting from this k-value by evaluating the equation
and, in case of negative angles φ, subsequently the full angle period is added to this value. German Published Patent Document No. 100 41 095 discusses a device for measuring the angle and/or a torque on a rotatable body. The angle of rotation is detected by means of magnetic or optical sensors. In an exemplary embodiment two devices are provided, each being provided with two optical readable code traces. The two code traces of each device are embodied in the same manner and are arranged in such a manner that said devices are off-set against each other to allow allocated sensors to output a digital signal. The angle of rotation is calculated from the off-set of two digital signals. In another exemplary embodiment a torsional element having a certain stiffness and is arranged between the two devices. A torque which is transmitted by the rotatable body may thus be calculated from the different angles of the two devices. The device according to the disclosure of German Published Patent Document No. 100 41 095 may be used in the steering column shaft of a motor vehicle.
International Published Patent Application No. WO 00/28285 discusses an optical sensor. This sensor is used for determining the position of a moveable surface having patterned regions of high and low reflectivity to EMR, the sensor including an application specific integrated circuit (ASIC) at least one lens and at least one EMR-source. The ASIC includes at least one array of EMR-sensitive detectors and processing arrangement, the EMR-source facilitating illumination of the surface and the at least one lens facilitating the focusing of reflected EMR from the surface and generating an image on the at least one array of EMR-sensitive detectors corresponding to the pattern on the surface. Said ASIC, the at least one lens and the at least one EMR-source are enclosed in a single housing providing for accurate optical alignment of these elements with respect to each other and integrated as a single replaceable module. The processing arrangement of the ASIC facilitates processing of the image to determine the position of the pattern on the surface.
For single turn applications (360°) torque and angle sensors (TAS) are frequently used. To detect a plurality of rotations, i.e. multiturns of the rotatable element this TAS is operated to electrically count the number of turns. That implies that the TAS is switched with respect to the battery voltage and, on ignition of the internal combustion engine of the vehicle, is connected to supply voltage. At ignition on, the sensor (TAS) measures in a approximately 500 μs an actual position and counts the number of turns. After ignition has been switched off the sensor works in an inactive mode (i.e. sleeping mode). In this inactive mode the refreshing time of said TAS increases to decrease the average of the supply current to operate the TAS. However, the TAS counts the turns in the inoperative mode as well.
The multiturn-operation strategy of the TAS provides that the supply current for the TAS, even in its inoperative mode, discharges the battery and decreases the time between two ignition-cycles which may cause motor starting problems. Thus, the recovery period for the vehicles battery is considerably decreased causing significant problems on ignition of the internal combustion engine, which is extremely critical at low ambient temperatures.
According to the present invention, a torque and angle module (TAS) is disclosed for detection of multiturns of a moveable component in a vehicle which does not discharge the battery of the respective vehicle. Instead, a gear is provided between a standard code disk having patterned surface regions thereon and a further additional code disk. By means of one sensor element, packaged within the TAS-module, at least two code carriers such as disks may be surveyed contactless, transferring optical signals from the respective surface patterned regions of the code carriers into digital processable information. The number of multiturns of a moveable vehicle component, such as a steering wheel and its associated steering column shaft are detected by means of a modified nonius-calculation or an n-dimensional nonius calculation.
An optical system and an illumination system are arranged within a TAS-module's housing. The illumination system may allow for sequential illumination of different code carriers such as code disks, being arranged on a rotating shaft or another rotating component. Due to the small size of ASIC and sensor, said components fit into a housing of small size as well, which may be packaged close to the movable component the number of turns of which are to be detected. According to different exemplary embodiments of the present invention, a sequential illumination of input code-carrier and a multiturn information carrier may be achieved as well as a sequential illumination of output code carrier and a multiturn information carrier, depending on the respective spatial conditions. The multiturn disk-element may be arranged either assigned to a bearing's side on a shaft or on a shaft's circumferential torsion in a distance from a bearing or at a side of the torsion bar.
The TAS-multiturn imaging and illumination principle according to the present invention provides for measurement of three different code carriers such as code disks, having 12 tracks, by means of two detective arrays (8 tracks) on the ASIC's surface. The respective carriers provided with code patterns include different reflectivity characteristics to enhance contrast-generation of the ASIC, provided on top of the TAS-module's housing.
Maximum contrast generation is important to enhance distinction between non-symmetrical turning marks and surfaces of laser marks.
To increase robustness of the measurement principle, sequential measurement of two code carriers such as code disks may be performed at the same time. This improves reliability of the TAS-module-application.
The movement principle as disclosed may be used for single turn sensor arrangements, as well as electrical multiturns sensors. Further, the measurement principle according to the present invention may be used in connection with a mechanical multiturn sensor.
As may be seen from
Reference numerals 19, 20, respectively, identify a first turning mark and a second turning mark. The first turning mark 19 and the second turning mark 20 are shaped in a saw-teeth-profile 21 including a curved surface 22. The profile 21 further includes an inclined surface 23. A first beam 24 results in a reflected first beam 25. A second beam 26 reaching the curved surface 22 of the profile 21 results in a reflected second beam 27. The reflected first beam 25 and the reflected second beam 27 generate a optical ASIC-information 28 on the surface 5 of the ASIC 4 mounted between the first LED 2 and the second LED 3. The optical ASIC-information 28 includes bright/dark-profile 29 on the respective first array 6 and the second array 7 on the ASIC's surface 5. By means of the ASIC 4, the bright/dark-profile 29 is turned into digital information which may be processed further in components not given in greater detail in
An optical ASIC information 31 given on the left hand side of
The printed circuit board 1 is mounted within a TAS-module 40, including the ASIC 4 having a surface 5 oriented towards the lens 8. On a shaft 45 an output-code-disk 46 and an input-code-disk 47 are arranged, defining a detection area 48. Within the detection area 48, the surfaces of the output-code-disk 46 and the input-code-disk 47, respectively, are detected and focused by means of the lens 8 on the respective first array 6 and the second array 7 on the surface 5 of the ASIC 4.
Within the hollow interior 44 of the shaft 45 a torsion element 43 is mounted. Said shaft 45 is rotatably mounted by means of a first ball bearing 41 and a second ball bearing 42.
The arrangement of
In
Due to the different gear ratios 103 and 104 in relation to the multiturn code signal sequences 102 and 105, the single multiturn signals 111 of the sequence 105 in
The bright images on the ASIC are produced at positions in which the light may reach the ASIC. This happens, when the light is reflected at the turning marks and focused by the lens. The dark images on the ASIC are produced when the light is reflected at a laser mark and does not reach the lens and the ASIC.
According to the first solution given in
On the bottom of a printed circuit board the ASIC 4 is mounted in between a first port 128 and a second port 129. Below that first port 128 and said second port 129 a first angled light guide 122 and a second angled light guide 123 is arranged. By means of the second angled light guide 123 the turning mark profile 120 of the multiturn disk 149, 155 is detected. The reflected arrays from the turning mark profile 120 arranged on the surface of the multiturn-code-disks 149, 155, respectively, is focused by a first lens 125 of the lens combination 124 on an array—not given in greater detail here—of ASIC 4. The reflected arrays of the light, emitted by the first angled light guide 122 is focused by a second lens 126 of the lens combination 124 on respective arrays on the surface of the ASIC 4 oriented towards the lens combination 124.
According to the measurement arrangement given in
The first lens 125 focuses the reflected rays from the code pattern of the surface of multi-turn-code-disk 149, 155, respectively, on of an assigned array of ASIC 4. The reflections of the surfaces of the input-code-disk 47, and the output-code-disk 46 are focused by second lens 126 on the surface 131 of the ASIC 4.
The structure of the code of the multiturn-code disc and the input-code disc have the same orientation in relation to the angle based laser marks. The orientation of the turning marks are not afflicted therefrom. The turning marks only shall reflect the light to the lens. The angle of the turning marks only depends on the light guide and the position of the LED and the positions of the lenses. That means, that in the solutions 1, 2 and 3 the code disks including the code are imaged to the same region of the ASIC by the two lenses. Therefore the ASIC is able to read both codes, the code of the turning mark and the code of the laser mark or the combination thereof.
Assigned to the outer circumference of the steering wheel shaft 152 is the input-code-disk 47 a distance 150 from the output-code-disk 46, also arranged on the outer circumference of the steering wheel shaft 152. Further, according to the first exemplary embodiment of the present invention a first multiturn disk 149 is mounted to or assigned with respect to the outputcode-disk 46.
The first multiturn-code-disk 149 includes an inner gearing 143, having arranged a plurality of teeth 153 on its circumference. The inner gearing 143 cooperates with an outer gearing 144 having a plurality of outer teeth 154 arranged thereon. A meshing zone of the inner teeth 153 with the respective outer teeth 154 is identified with reference numeral 145. Opposite the meshing zone 145, reference numeral 146 identifies the maximum eccentricity 146 of the gearing 142 assigned to the first multiturn-code-disk 149. Said gearing 142 is integrated into a combined bearing 141 which is arranged on the outer circumference of the steering-wheel-axle 152. A sealing element 147 (O-ring) is mounted on the respective side of the gearing 142 which is oriented to the output-code-disk 46. This may be derived from
According to the exemplary embodiment given in
On the right hand side of
According to the first and second exemplary embodiment of the present invention given in
This exemplary embodiment of the present invention distinguishes over the first and second exemplary embodiments of the present invention as given in
Within the housing of the modified TAS-module 140 a lens combination 124 is arranged, which cooperates with ASIC 4 arranged on the sealing of the respective housing. Below said lens arrangement 124 the light reflections of the circumferential surfaces 156, 157 of the input-code-disk 47 and the output-code-disk 46 are focused and transferred to the ASIC 4 arranged in the modified TAS-module 140. The code structure of the multiturncode-disk 160 (angle based transmission holds) and the respective input-code-disk 47 (having angle-based laser mark) is the same. In the arrangement according to
According to the present invention the nonius-principle with phase-angle behavior is based on the modified nonius calculation of the multiturn-code-disk 149, 155 using 2 code-disk's information. The n-dimensional nonius calculation principle makes use of 3-code-disks in information, i.e. the pattern information of the input-code-disk 47, the output-code-disk 46 and the multiturn-code-disk 149, 155, respectively. The modified nonius calculation using 2-code-disk information is performed by sequential measurement of the respective 2-code-disks 47, 46 or 47, 149, 155 or 46, 149, 155, respectively. The first multiturn-code-disk 149 and the second multiturn-code-disk 155 may be assembled on an steering-wheel axle of a vehicle having three laser marks assigned thereto. The sequential measurement of the patterned regions of the different code disks 46, 47, 149, 155 is performed by sequential illumination of the respective disks the surfaces of which are detected in different sequential modes.
Filing Document | Filing Date | Country | Kind |
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PCT/EP02/01312 | 2/8/2002 | WO |