Determination of thumb position using measurements of abduction and rotation
First Claim
1. A method employing sensors, a data processor and a memory for measuring the position of an anatomical model of at least a portion of a thumb relative to a reference coordinate system, wherein said anatomical model comprises joints and links, wherein each joint is a revolute joint and the axis of each joint represents the center of rotation between two articulated bone segments and each bone segment is represented by a link, said measuring using said anatomical model employing at least some of the following components:
- (1) a thumb rotation axis (TR axis) and the angle about said axis, θ
TR ;
(2) a trapeziometacarpal joint, TMJ, comprising a pitch axis (TMJP) and a roll axis (TMJR);
(3) a thumb metacarpal;
(4) a thumb proximal phalanx;
(5) a thumb distal phalanx;
(6) a thumb metacarpophalangeal joint (thumb MPJ);
(7) an interphalangeal joint (IJ);
(8) a thumb abduction axis (TA axis) and the angle about said TA axis, θ
TA , said TA axis normal to the plane defined by (a) the thumb metacarpal and (b) the TR axis;
(9) an index metacarpophalangeal joint (index MPJ), wherein each of said components has a known initial value for an initial thumb position;
said method comprising;
transmitting signals to said data processor from said sensors mounted in juxataposition to said thumb, wherein said signals indicate the change in values, Δ
θ
TR and Δ
θ
TA, for θ
TR and θ
TA from said initial values defining the movement of the thumb from said initial position;
processing said signals in said memory relating to said Δ
θ
TR and Δ
θ
TA, by first rotating said initial position of said thumb MPJ about the initial TA axis by an amount Δ
θ
TA to determine a first rotated thumb MPJ; and
further rotating said first rotated thumb MPJ about the TR axis by an amount Δ
θ
TR to produce a signal related to a second rotated thumb MPJ;
processing said signal related to a second rotated thumb MPJ in conjunction with said thumb TMJ to define the position of said thumb metacarpal;
relating the position of said TMJP axis as being normal to the plane defined by said thumb metacarpal and said TMJR axis to specify the orientation of said thumb metacarpal;
whereby the position and orientation of said thumb metacarpal relative to a reference coordinate system is determined.
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Abstract
Methods and systems are provided for calculating the position of a thumb in a model of links and joints representing the physical thumb. The thumb position and orientation are calculated using the change in values of the angle of the thumb rotation and the thumb abduction from selected initial values, which change is detected by means of sensors mounted in juxtaposition to said thumb. Various joint axes are predefined, while others are calculated.
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Citations
11 Claims
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1. A method employing sensors, a data processor and a memory for measuring the position of an anatomical model of at least a portion of a thumb relative to a reference coordinate system, wherein said anatomical model comprises joints and links, wherein each joint is a revolute joint and the axis of each joint represents the center of rotation between two articulated bone segments and each bone segment is represented by a link, said measuring using said anatomical model employing at least some of the following components:
- (1) a thumb rotation axis (TR axis) and the angle about said axis, θ
TR ;
(2) a trapeziometacarpal joint, TMJ, comprising a pitch axis (TMJP) and a roll axis (TMJR);
(3) a thumb metacarpal;
(4) a thumb proximal phalanx;
(5) a thumb distal phalanx;
(6) a thumb metacarpophalangeal joint (thumb MPJ);
(7) an interphalangeal joint (IJ);
(8) a thumb abduction axis (TA axis) and the angle about said TA axis, θ
TA , said TA axis normal to the plane defined by (a) the thumb metacarpal and (b) the TR axis;
(9) an index metacarpophalangeal joint (index MPJ), wherein each of said components has a known initial value for an initial thumb position;
said method comprising;transmitting signals to said data processor from said sensors mounted in juxataposition to said thumb, wherein said signals indicate the change in values, Δ
θ
TR and Δ
θ
TA, for θ
TR and θ
TA from said initial values defining the movement of the thumb from said initial position;processing said signals in said memory relating to said Δ
θ
TR and Δ
θ
TA, by first rotating said initial position of said thumb MPJ about the initial TA axis by an amount Δ
θ
TA to determine a first rotated thumb MPJ; and
further rotating said first rotated thumb MPJ about the TR axis by an amount Δ
θ
TR to produce a signal related to a second rotated thumb MPJ;processing said signal related to a second rotated thumb MPJ in conjunction with said thumb TMJ to define the position of said thumb metacarpal; relating the position of said TMJP axis as being normal to the plane defined by said thumb metacarpal and said TMJR axis to specify the orientation of said thumb metacarpal; whereby the position and orientation of said thumb metacarpal relative to a reference coordinate system is determined. - View Dependent Claims (2, 3, 4, 5, 6)
- (1) a thumb rotation axis (TR axis) and the angle about said axis, θ
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7. A system for measuring the position of at least a portion of a thumb, using an anatomical model employing:
- (1) a thumb rotation axis (TR axis) and the angle about said axis, θ
TR ;
(2) a trapeziometacarpal joint, TMJ, comprising a pitch axis (TMJP) and a roll axis (TMJR);
(3) a thumb metacarpal;
(4) a thumb proximal phalanx;
(5) a thumb distal phalanx;
(6) a thumb metacarpophalangeal joint (thumb MPJ);
(7) an interphalangeal joint (IJ);
(8) a thumb abduction axis (TA axis) and the angle about said TA axis, θ
TA, said TA axis normal to the plane defined by (a) the thumb metacarpal and (b) the TR axis;
(9) an index metacarpophalangeal joint (index MPJ); and
(10) an index metacarpal, wherein the change in angles of θ
TR and θ
TA from known initial values for an initial thumb position as a result of movement of said thumb are Δ
θ
TR and Δ
θ
TA, respectively, said system comprising;a first goniometer in juxtaposition to the soft tissue between said thumb metacarpal and said TR axis to provide a signal for θ
TA indicating said Δ
θ
TA value;a second goniometer in juxtaposition to said TR axis to provide a signal for θ
TR indicating said Δ
θ
TR value;means for supporting said goniometers in position in relation to the thumb; a data processor for receiving said signals and processing said signals to provide a value for the position of said thumb metacarpal from said Δ
θ
TA and Δ
θ
TR values; anda data processor for receiving said value for the position of said thumb metacarpal for determining the orientation of said thumb metacarpal from said value of the position of said thumb metacarpal and the position of said TMJP axis as being normal to the plane defined by said thumb metacarpal and said TMJR axis. - View Dependent Claims (8, 9, 10, 11)
- (1) a thumb rotation axis (TR axis) and the angle about said axis, θ
Specification