Absolute value transmitter acting as a rotation transmitter for registration of a steering angle of a motor vehicle

• US 6,226,569 B1
• Filed: 10/20/1999
• Issued: 05/01/2001
• Est. Priority Date: 12/02/1996
• Status: Expired due to Term

• Current Assignee: TRW Automotive Electronics & Components GmbH & Co. KG
• Original Assignee: TRW Automotive Electronics & Components GmbH & Co. KG
• Inventors: Huber, Wolfgang, Stewart, Trevor, Caratto, Danilo, Peter, Cornelius, Pavlis, Zdenek
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Marc, McDieunel, Marc, McDieunel
• Application Number:
  US09/331,145
• Time in Patent Office: 559 Days
• Field of Search: 700/261, 700/260, 700/254, 700/255, 700/275, 700/302, 341/13, 341/2, 341/15, 318/587, 701/224, 701/24
• US Class Current: 700/302
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2495 Pseudo-random code
• CPC Class Codes: G01D 5/2497 Absolute encoders G01D5/2454 takes precedence
• CPC Class Codes: G01D 5/34776 Absolute encoders with analogue or digital scales

Abstract

A rotary transmitter for registration of the steering angle of a motor vehicle, with a transmitter component (49) on which is provided a coding (51) of a predetermined number n of locally sequentially digital words (W_i) with a width of m bits (b₁, b₂, . . , B_m) in m adjacent to each other tracks, at least one detector (55) for essentially simultaneous registration of the individual bits (b₁, b₂, . . . , B_m) of a digital word (W_i), whereby the transmitter component (49) and at least the one detector (55) are movable relative to each other, and with an evaluation unit (11) to which is conducted the signal of at least the one detector (55). The evaluation unit (11) ascertains the absolute position of the transmitter component (49) relative to at least the one detector (55), at least one time, by evaluation of a predetermined number (p) of sequentially detected digital words (W_i), whereby the evaluation unit (11) assigns to a detected p-measure (W_i, W_i+1, . . . , W_i+p−1), consisting of the predetermined number (p) of sequentially detected digital words (W_i), a defined position value of the transmitter component (49) relative to at least the one detector (55). The coding is hereby designed in such manner that all sequences (W_i, W₁₊₁, . . . , W_i+p−1) from among the sequential words (W_i) consisting of the predetermined number (p) are uniquely defined at least within a predetermined uniquely defined area (I. II) of coding (51) and that within each uniquely defined area (I, II) the digital words (W_i) are not uniquely defined.

Claims

1. An absolute value transmitter, comprising:

a transmitter component including a coding having a predetermined number n of locally sequential digital words (W_i), each having a width of m individual bits (b₁, b₂, . . . b_m) in adjacent tracks;

at least one detector simultaneously registering the individual bits (b₁, b₂, . . . b_m) defining one of the digital words (W_i), the transmitter component being movable with respect to the at least one detector; and

an evaluation unit for receiving respective signals from the at least one detector and determining an absolute position of the transmitter component relative to at least the one detector, at least for a first time, by evaluating a predetermined number p of the sequentially detected digital words (W_i), the evaluation unit assigning to a detected p-tuple (W_i, W_i+1, W<sub>i+p−

1</sub>), including a predetermined number p of the sequentially detected digital words (W_i), a defined position value of the transmitter component relative to the at least one detector, all of the sequences (W_i, W_i+1, W<sub>i+p−

1</sub>) from the predetermined number p including the sequential words (W_i) being uniquely defined within at least one predetermined uniquely defined area (I, II) of the coding, and the digital words (W_i) not being uniquely defined within each of the at least one uniquely defined areas (I, II).

2. The absolute value transmitter as set forth in claim 1, wherein the coding satisfies at least one of a group of conditions including:

a) two of the respective adjacent words (W_i, W_i+1) having different values;

b) each of the words (W<sub>i−

1</sub>) and (W_i+1), respectively adjacent to the word (W_i), having different values; and

c) no sequence (W_i, W_i+1, . . . , W<sub>i+p−

1</sub>) existing as a mirror-image sequence (W<sub>i+p−

1</sub>, . . . , W_i+1, W_i), within at least the one uniquely defined area (I, II) of the coding.

3. The absolute value transmitter as set forth in claim 2, wherein the evaluation unit ascertains a direction of an absolute movement by comparing one of the detected p-tuples with a stored image of the coding for complying with the condition c).

4. The absolute value transmitter as set forth in claim 2, wherein the coding on the transmitter component includes the at least two connected areas (I, II), each of the at least two connected areas (I, II) having the predetermined number n of the digital words (W_i).

5. The absolute value transmitter as set forth in claim 4, wherein the group of conditions are satisfied, at least at one of two interfaces of the two areas (I, II).

6. The absolute value transmitter as set forth in claim 1, wherein the evaluation unit determines the absolute position of the transmitter component relative to at least the one detector by respectively assigning the corresponding position value to the detected p-tuple (W_i, W_i+1, . . . , W_i+p−

1).

7. The absolute value transmitter as set forth in claim 6, wherein the evaluation unit determines, after a one-time determination of the absolute position, a future absolute position of the transmitter component relative to at least the one detector via at least one of incrementing and decrementing the one-time determined position value.

8. The absolute value transmitter as set forth in claim 1, wherein the evaluation unit ascertains a change in a rotational direction by comparing the digital words W_p−

3 and W<sub>p−

1</sub> of the detected p-tuple and detects, if W<sub>p−

3</sub> and W<sub>p−

1</sub> are equal, a change in the rotational direction following an over-travel of the digital word W<sub>p−

2</sub>.

9. The absolute value transmitter as set forth in claim 1, wherein the evaluation unit determines the absolute position by:

1) generating a first output via incrementing/decrementing a prior value; and

2) generating a second output via evaluating an appropriate detected p-tuple, the evaluation unit generating an error signal if the first and second outputs are not equal.

10. The absolute value transmitter as set forth in claim 1, wherein:

the width m of the digital words (W_i) equals three; and

the predetermined number p of the sequential words for the position determination equals three.

11. The absolute value transmitter as set forth in claim 1, wherein for recognizing at least one of a rotational direction, a change in the rotational direction, and a step, one of a) a supplemental track is provided, in addition to the adjacent tracks for the digital words (W_i), having a sequential series of values including logical “

zeros” and

logical “

ones”

, and b) one of the adjacent tracks includes the sequential series of values including the logical “

zeros” and

the logical “

ones”

.

12. The absolute value transmitter as set forth in claim 11, wherein:

two detectors, staggered by a half step, are provided for scanning the track including the alternating sequences of the logical “

zeros” and

the logical “

ones”

; and

the evaluation unit determines at least one of the rotational direction and the change in the rotational direction from a phase displacement of respective ones of the signals.

13. The absolute value transmitter as set forth in claim 12, wherein:

within the at least one uniquely defined area (I, II), a respective mirror-image sequence (W<sub>i+p−

1</sub>, . . . , W_i+1, W_i) exists for at least one of the sequences (W_i, W_i+1, . . . , W<sub>i+p−

1</sub>) of coding; and

the evaluation unit determines the absolute value from the rotational direction and the detected p-tuple.

14. The absolute value transmitter as set forth in claim 1, wherein:

a registration device determines an approximate registration of the absolute position, the approximate registration being more accurate than a difference of values corresponding to two limits for each of at least the two areas (I, II); and

the evaluation unit, for determining the absolute position within the entire coding, determining an approximate absolute position value via the registration device and determining the absolute position value as a function of the respective signals provided by the at least one detector, the absolute position value being multi-valued.

15. The absolute value transmitter as set forth in claim 14, wherein the evaluation unit:

determines an actual signal (S_T) of the registration device indicating an approximate registration of a corresponding position value (α

_a);

determines a lower barrier (α

_a−

δ

) and an upper barrier (α

_a+δ

) of a permissible tolerance range for the corresponding position value (α

_a), a width (2δ

) of the tolerance area being smaller than each of the uniquely defined areas (I, II) of the coding of the transmitter component;

determines a multi-valued position value (α

_r) by evaluating the respective signals of the at least one detector registering the coding; and

determines a corrected absolute value (α

_r,corr) according to;

${\mathrm{\alpha <br><br>}}_{\left(r,\mathrm{corr}\right)}=\left(\mathrm{INT}<br><br>\frac{\left[{\mathrm{\alpha <br><br>}}_a+\mathrm{\delta <br><br>}\right]}{{\mathrm{\alpha <br><br>}}_{r,m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}}\times <br><br>{\mathrm{\alpha <br><br>}}_{r,m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}\right)+{\mathrm{\alpha <br><br>}}_r<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{for}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_r<<br><br>\frac{{\mathrm{\alpha <br><br>}}_{r,\text{\hspace{1em}<br><br>}<br><br>m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}}{2},\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_{\left(r,\mathrm{corr}\right)}=\left(\mathrm{INT}<br><br>\frac{\left[{\mathrm{\alpha <br><br>}}_a-\mathrm{\delta <br><br>}\right]}{{\mathrm{\alpha <br><br>}}_{r,m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}}\times <br><br>{\mathrm{\alpha <br><br>}}_{r,m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}\right)+{\mathrm{\alpha <br><br>}}_r<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{for}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_r<<br><br>\frac{{\mathrm{\alpha <br><br>}}_{r,\text{\hspace{1em}<br><br>}<br><br>m<br><br>\text{\hspace{1em}<br><br>}<br><br>a<br><br>\text{\hspace{1em}<br><br>}<br><br>x}}{2}.$

16. The absolute value transmitter as set forth in claim 15, wherein:

the evaluation unit determines if the corrected absolute value (α

_r,corr) is within the permissible tolerance range; and

if an error occurs, the evaluation unit generates an error signal and compensates the registration device for the approximate registration of the absolute position.

17. The absolute value transmitter as set forth in claim 16, wherein:

the evaluation unit determines a difference between the determined absolute value (α

_a,corr) and the corresponding position value (α

_a); and

the evaluation unit writes the corresponding position value (α

_a) in a non-volatile memory, the corresponding position value (α

_a) being read from the non-volatile memory as a corrective value for subsequent determinations of the corresponding position value (α

_a).

18. The absolute value transmitter as set forth in claim 1, wherein the transmitter component is formed as a ring.

19. The absolute value transmitter as set forth in claim 18, wherein:

the transmitter component is rotatably joined with a component, having an angle of rotation to be registered;

the coding arranged on the transmitter component is endless on an outer circumference of the transmitter component; and

each interface satisfies the group of conditions.

20. A rotation transmitter for registering a steering angle of a motor vehicle, comprising:

a rotatable transmitter mechanically connected to a steering wheel;

a coding, included on the transmitter, having a predetermined number n of locally sequential digital words (W_i), each having a width of m individual bits (b₁, b₂, . . . b_m), in adjacent tracks;

at least one detector simultaneously registering the individual bits (b₁, b_{2, . . . bm}) defining one of the digital words (W_i), the transmitter being movable with respect to the at least one detector;

a plunger device, mechanically connected to the steering wheel, a rotational movement of the steering wheel causing a corresponding translational movement of the plunger device, for indicating an approximate registration of the absolute steering angle; and

an evaluation unit for receiving a signal from the plunger device and respective signals from the at least one detector for determining an absolute position of the transmitter relative to the at least one detector, at least for a first time, by evaluating a the approximate registration of the absolute steering angle anti the predetermined number p of the sequentially detected digital words (W_i), the evaluation unit assigning to a detected p-tuple (W_i, W_i+1, W<sub>i+p−

1</sub>), including a predetermined number p of the sequentially detected digital words (W_i), a defined position value of the transmitter relative to the at least one detector, all of the sequences (W_i, W_i+1, W<sub>i+p−

1</sub>) from the predetermined number p including the sequential words (W_i) being uniquely defined within at least one predetermined uniquely defined area (I, II) of the coding, and the digital words (W_i) not being uniquely defined within each of the at least one uniquely defined areas (I, II).

21. A method for registering a steering angle of a motor vehicle, comprising:

determining a coding on a transmitter component using at least one detector for simultaneously registering individual bits (b₁, b₂, . . . b_m) defining respective digital words (W_i), the transmitter component being movable with respect to the at least one detector, the coding including a predetermined number n of locally sequential digital words (W_i), each having a width of the m individual bits (b₁, b₂, . . . b_m), in adjacent tracks;

receiving respective signals from the at least one detector into an evaluation unit; and

determining an absolute position of the transmitter component relative to at least the one detector, at least for a first time, by evaluating a predetermined number p of the sequentially detected digital words (W_i), the evaluation unit assigning to a detected p-tuple (W₁, W_i+1, W<sub>i+p−

1</sub>), including a predetermined number p of the sequentially detected digital words (W_i), a defined position value of the transmitter component relative to the at least one detector, all of the sequences (W_i, W_i+1, W<sub>i+p−

1</sub>) from the predetermined number p including the sequential words (W_i) being uniquely defined within at least one predetermined uniquely defined area (I, II) of the coding, and the digital words (W_i) not being uniquely defined within each of the at least one uniquely defined areas (I, II).