MOTION CAPTURE DEVICE AND ASSOCIATED METHOD

• US 20090067678A1
• Filed: 02/16/2007
• Published: 03/12/2009
• Est. Priority Date: 02/17/2006
• Status: Active Grant

• Current Assignee: Commiissariat A L'Energie Atomique
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Godin, Christelle, Caritu, Yanis, David, Dominique
• Granted Patent: US 8,055,021 B2
• Time in Patent Office: Days
• US Class Current: 382/107
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00

Abstract

The invention concerns a device for capturing the motion of a structure consisting of N articulated segments, characterised in that it comprises:

• • first means (ML) that deliver at least one item of information able to restore an absolute acceleration vector {right arrow over (a)}₁ of a point on the segment of rank 1 in a reference frame forming a reference, at successive times t_k, k being an integer number greater than or equal to 1, and
  • second measuring means (MD₁, MD_n) distributed over the various segments and which deliver, for each segment of rank 1 to N, at each time t_k, a measurement (M₁, M_n) representing an orientation vector ({right arrow over (Θ)}₁, {right arrow over (Θ)}_n) of the segment in the reference frame.

Application to biomechanical analysis, telemanipulation, animation of characters, etc.

Claims

1-19. -19. (canceled)

20. Motion capture device of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater than or equal to 2, the segment of rank n (n=2, . . . , N) being articulated with the segment of rank n−

1 at an articulation point p_n, characterised in that it comprises;

first means (ML) that deliver information able to restore an absolute acceleration vector {right arrow over (a)}₁ of a point on the segment of rank 1 in a reference frame forming a reference, at successive times t_k, k being an integer number greater than or equal to 1,

second measuring means (MD₁) fixed to the segment of rank 1 and which deliver, at each time t_k, a measurement (M₁) representing an orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, and

supplementary measurement means (MD_n) fixed to each segment of rank n (n=2, . . . , N), and which deliver, at each time t_k, a measurement representing an orientation vector {right arrow over (Θ

)}_n of the segment of rank n.

21. Motion capture device according to claim 20, in which the second measuring means (MD₁) and the supplementary measuring means (MD_n) consist of an accelerometer and a sensor that delivers a measurement of a uniform physical field present in the space where the structure moves and with a known direction in the reference frame.

22. Motion capture device according to claim 21, in which the second measuring means (MD₁) and the supplementary measuring means (MD_n) further comprise at least one gyrometric axis.

23. Motion capture device according to claim 21, in which the sensor that delivers a measurement of a uniform physical field of known direction in the reference frame is a magnetometer.

24. Motion capture device according to claim 21, in which the sensor that delivers a measurement of a uniform physical field of known direction in the reference frame is a photoelectric cell.

25. Device according to claim 20, in which the first means (ML) are measuring means consisting of a velocity measurer so that the data item able to restore an absolute acceleration vector of the segment of rank 1 is the velocity of the point.

26. Device according to claim 20, in which the first means (ML) are measuring means consisting of a position measurer so that the data item able to restore an absolute acceleration vector of a point on the segment of rank 1 is the position of the point.

27. Device for reproducing the motion of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater or equal to 2, the segment of rank n (n=2, . . . , N) being articulated with the segment of rang n−

1 at an articulation point p_n, characterised in that it comprises;

a motion capture device according to claim 20 in which the supplementary measurement means (MD_n) of a segment of rank n are positioned close to the articulation point p_n so that the distance that separates the supplementary measuring means (MD_n) of a segment of rank n from the articulation point p_n is considered to be zero, and

calculation means (3) that calculate, at each time t_k;

a) the absolute acceleration vector {right arrow over (a)}₁ in the reference frame, from the information delivered by the first means,

b) the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, from the absolute acceleration vector {right arrow over (a)}₁ and the measurement (M₁) representing the orientation vector ({right arrow over (Θ

)}₁) of the segment of rank 1;

c) an acceleration vector {right arrow over (a)}_n (n≧

2) of the articulation point p_n in the reference frame, from the equation;

${\stackrel{\to <br><br>}{a}}_n={\stackrel{\to <br><br>}{a}}_{n-1}+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}}{<br><br>t}\right)<br><br>\mathrm{\Lambda <br><br>}<br><br>\stackrel{\to <br><br>}{L_{n-1}}+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br><br><br>\stackrel{\to <br><br>}{L_{n-1}}\right)$

where {right arrow over (ω

)}_n=d({right arrow over (Θ

)}_n)/dt, {right arrow over (L)}_n being a vector oriented from the articulation point p<sub>n−

1</sub> to the articulation point p_n and whose modulus has as its value the distance that separates the articulation point p_n from the articulation point p<sub>n−

1</sub>; and

d) the orientation vector {right arrow over (Θ

)}_n(n≧

2) of the segment of rank n from the acceleration vector {right arrow over (a)}_n and the measurement (M_n) representing the orientation of the segment of rank n.

28. Device for reproducing the motion of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater than or equal to 2, the segment of rank n (n=2, . . . , N) being articulated with the segment of rank n−

1 at an articulation point p_n, characterised in that it comprises;

a motion capture device according to claim 20 in which the supplementary measuring means (MD_n) of a segment of rank n are distant from the articulation point p_n, and

calculation means (3) that calculate, at each time t_k;

a) the absolute acceleration vector {right arrow over (a)}₁ in the reference frame, from the information delivered by the first means,

b) the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, from the absolute acceleration vector {right arrow over (a)}₁ and the measurement (M₁) representing the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1;

c) an acceleration vector {right arrow over (a)}_n (n≧

2) of the articulation point p_n in the reference frame, from the equation;

${\stackrel{\to <br><br>}{a}}_n={\stackrel{\to <br><br>}{a}}_{n-1}+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}}{<br><br>t}\right)<br><br>\mathrm{\Lambda <br><br>}<br><br>\stackrel{\to <br><br>}{L_{n-1}}+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br><br><br>\stackrel{\to <br><br>}{L_{n-1}}\right)$

where {right arrow over (ω

)}_n=d({right arrow over (Θ

)}_n)/dt, {right arrow over (L)}_n being a vector oriented from the articulation point p<sub>n−

1</sub> to the articulation point p_n and whose modulus has as its value the distance that separates the articulation point p_n from the articulation point p<sub>n−

1</sub>; and

d) the orientation vector {right arrow over (Θ

)}_n (n≧

2) and an acceleration vector {right arrow over (b)}_n of the measuring point of the supplementary measuring means fixed on the segment of rank n from the acceleration vector {right arrow over (a)}_n, the measurement (M_n) representing the orientation of the segment of rank n, and the orientation vectors of the segment of rank n at least two times that precede the time t_k, with {right arrow over (b)}_n such that;

${\stackrel{\to <br><br>}{b}}_n={\stackrel{\to <br><br>}{a}}_n+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n}{<br><br>t}\right)\bigwedge <br><br>{\stackrel{\to <br><br>}{D}}_n+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n\bigwedge <br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n\bigwedge <br><br>{\stackrel{\to <br><br>}{D}}_n\right)$

where {right arrow over (D)}_n is a vector oriented from the articulation point p_n to the supplementary measuring means of the segment of rank n and whose modulus is substantially equal to the distance that separates the articulation point p, from the supplementary measuring means of the segment of rank n.

29. Motion reproduction device according to claim 27, in which radio transmission means transmit elementary electrical signals (RD_n, RL_m) representing the measurements delivered by the first measuring means (ML) and the second measuring means (MD_n) to the calculation means (3).

30. Motion reproduction device according to claim 29, in which the transmission means comprise an intermediate unit (DEM) that receives the elementary electrical signals (RD₁, . . . , RD_X, RL₁, . . . , RL_Y) and that retransmits an electrical signal (RF) representing elementary electrical signals to the calculation means (3).

31. Motion reproduction device according to claim 28, in which radio transmission means transmit elementary electrical signals (RD_n, RL_m) representing the measurements delivered by the first measuring means (ML) and the second measuring means (MD_n) to the calculation means (3).

32. Motion reproduction device according to claim 31, in which the transmission means comprise an intermediate unit (DEM) that receives the elementary electrical signals (RD₁, . . . , RD_X, RL₁, . . . , RL_Y) and that retransmits an electrical signal (RF) representing elementary electrical signals to the calculation means (3).

33. Device according to claim 20, in which storage means store the measurements delivered by the first measuring means (ML) and the second measuring means (MD_n).

34. Device according to claim 33, in which the storage means are placed on the structure.

35. Method of capturing the motion of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater than or equal to 2, the segment of rang n (n=2, . . . , N) being articulated with the segment of rank n−

1 at an articulation point p_n, characterised in that it comprises;

at least one determination of an item of information able to restore an absolute acceleration vector {right arrow over (a)}₁ of a point on the segment of rank 1 in a reference frame, at successive times t_k, k being an integer number greater than or equal to 1,

at least one measurement representing an orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, at each of the successive times t_k, and

for each segment of rank n, at least one supplementary measurement of an orientation vector {right arrow over (Θ

)}_n of the segment of rank n in the reference frame, at each of the successive times t_k.

36. Motion capture method according to claim 35, in which the measurement representing the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame and the measurement representing the orientation vector {right arrow over (Θ

)}_n of the segment of rank n are each a measurement of a uniform field present in the space where the structure moves and with a known direction in the reference frame.

37. Motion capture method according to claim 35, in which the information able to restore an absolute acceleration vector {right arrow over (a)}₁ of a point on the segment of rank 1 in a reference frame is the velocity of the point in the reference frame.

38. Motion capture method according to claim 35, in which the information able to restore an absolute acceleration vector {right arrow over (a)}₁ of a point on the segment of rank 1 in a reference frame is the position of the point in the reference frame.

39. Method for reproducing the motion of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater than or equal to 2, the segment of rang n (n=2, . . . , N) being articulated with the segment of rank n−

1 at an articulation point p_n, characterised in that it uses;

a motion capture method according to claim 35, and

a calculation, at each time t_k;

a) of the absolute acceleration vector {right arrow over (a)}₁ in the reference frame, from the measurement able to restore an absolute acceleration vector {right arrow over (a)}₁,

b) of the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, from the absolute acceleration vector {right arrow over (a)}₁ and the measurement (M₁) representing the orientation vector ({right arrow over (Θ

)}₁) of the segment of rank 1;

c) of an acceleration vector {right arrow over (a)}_n (n≧

2) of the articulation point p_n in the reference frame, from the equation;

${\stackrel{\to <br><br>}{a}}_n={\stackrel{\to <br><br>}{a}}_{n-1}+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}}{<br><br>t}\right)<br><br>\mathrm{\Lambda <br><br>}<br><br><br><br>\stackrel{\to <br><br>}{L_{n-1}}+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br><br><br>\stackrel{\to <br><br>}{L_{n-1}}\right)$

where {right arrow over (ω

)}_n=d({right arrow over (Θ

)}_n)/dt, {right arrow over (L)}_n being a vector oriented from the articulation point p<sub>n−

1</sub>, towards the articulation point p_n and whose modulus has as its value the distance that separates the articulation point p_n from the articulation point p<sub>n−

1</sub>, the supplementary measurement representing the orientation vector {right arrow over (Θ

)}_n being delivered by fixed measuring means, on the segment of rank n, substantially at the articulation point p_n; and

d) of an orientation vector {right arrow over (Θ

)}_n (n≧

2) of the segment of rank n from the acceleration vector {right arrow over (a)}_n and the measurement (M_n) representing the orientation of the segment of rank n.

40. Method for reproducing motion of a structure consisting of N successive solid segments articulated with respect to one another from a segment of rank 1 as far as a segment of rank N, N being an integer number greater or equal to 2, segment of rank n (n=2, . . . , N) being articulated with the segment of rang n−

1 at an articulation point p_n, characterised in that it comprises;

a motion capture method according to claim 35; and

a calculation, at each time t_k;

a) of the absolute acceleration vector {right arrow over (a)}₁ in the reference frame, from the information delivered by the first means,

b) of the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1 in the reference frame, from the absolute acceleration vector {right arrow over (a)}₁ and the measurement (M₁) representing the orientation vector {right arrow over (Θ

)}₁ of the segment of rank 1;

c) of an acceleration vector {right arrow over (a)}_n (n≧

2) of the articulation p_n in the reference frame, from the equation;

${\stackrel{\to <br><br>}{a}}_n={\stackrel{\to <br><br>}{a}}_{n-1}+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}}{<br><br>t}\right)<br><br>\mathrm{\Lambda <br><br>}<br><br>\stackrel{\to <br><br>}{L_{n-1}}+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_{n-1}<br><br>\mathrm{\Lambda <br><br>}<br><br><br><br>\stackrel{\to <br><br>}{L_{n-1}}\right)$

where {right arrow over (ω

)}_n=d({right arrow over (Θ

)}_n)/dt, {right arrow over (L)}_n being a vector oriented from the articulation point p<sub>n−

1</sub> to the articulation point p_n and whose modulus has as its value the distance that separates the articulation point p_n from the articulation point p<sub>n−

1</sub>; and

d) the orientation vector {right arrow over (Θ

)}_n (n≧

2) and an acceleration vector {right arrow over (b)}_n of the measuring point of the supplementary measuring means fixed on the segment of rank n from the acceleration vector {right arrow over (a)}_n, the measurement (M_n) representing the orientation of the segment of rank n, and orientation vectors of the segment of rank n at least two times that precede the time t_k, with {right arrow over (b)}_n such that;

${\stackrel{\to <br><br>}{b}}_n={\stackrel{\to <br><br>}{a}}_n+\left(\frac{<br><br><br><br>{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n}{<br><br>t}\right)\bigwedge <br><br>{\stackrel{\to <br><br>}{D}}_n+{\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n\bigwedge <br><br>\left({\stackrel{\to <br><br>}{\mathrm{\omega <br><br>}}}_n\bigwedge <br><br>{\stackrel{\to <br><br>}{D}}_n\right)$

where {right arrow over (D)}_n is a vector oriented from the articulation point p_n to the supplementary measuring means of the segment of rank n and whose modulus is substantially equal to the distance that separates the articulation point p_n from the supplementary measuring means of the segment of rank n.