Apparatus and Method of Controlling Lower-Limb Joint Moments through Real-Time Feedback Training

• US 20120277063A1
• Filed: 04/26/2012
• Published: 11/01/2012
• Est. Priority Date: 04/26/2011
• Status: Active Grant

• Current Assignee: Rehabtek
• Original Assignee: Rehabtek
• Inventors: Zhang, Li-Qun, Kang, Sang Hoon
• Granted Patent: US 8,840,527 B2
• Time in Patent Office: Days
• US Class Current: 482/8
• CPC Class Codes: A61B 2562/0252 Load cells
• CPC Class Codes: A61B 5/112 Gait analysis
• CPC Class Codes: A61B 5/22 Ergometry; Measuring muscular strength or the force of a muscular blow exercising apparatus A63B21/00 ; measuring of work or force in general G01L
• CPC Class Codes: A61B 5/4585 Evaluating the knee
• CPC Class Codes: A61B 5/4595 Evaluating the ankle

Abstract

A real-time estimation of 3D moments of lower-limb joints using a robotic multi-axis training system with a 6-axis force/torque (F/T) sensors and a 6-DOF goniometer is described. A joint moment such as the knee abduction moment (KAM) can be determined in real-time without using sophisticated optoelectronic motion tracking system. The system also does not require computation of the COP location. The knee adduction moment or any other lower-limb 3D joint moments can be determined conveniently during stepping movement on the training system for real-time biofeedback training on controlling the targeted joint moment(s). The 6-DOF goniometer is convenient to use with other analog signals including the 6-axis F/T and locomotion variables. As an example application, combined with the frontal plane movement on the robotic multi-axis elliptical trainer, it provides a useful tool suitable for clinical setting to help patients with knee OA to reduce potentially damaging peak knee adduction moment through real-time feedback training.

Claims

1. In a coordinate system of an exercise apparatus 100 wherein a generally up and down Z-axis defines an axial rotation axis, a generally front to back Y-axis defines a coronal axis and a generally left to right X-axis defines a sagittal axis, the lower-limb joint moment real-time feedback training apparatus and system comprising:

A multi-axis force sensor 1;

said force sensor 1 is mounted on the moving arm of said exercise device 100 and moves together with the moving arm in the said sagittal plane,

A footplate 2;

it is attached to the said force sensor 1 and supports the human foot/shoe,

A compact real-time lower-limb motion measurement unit 3G and 3I;

said motion measurement unit 3G and 3I can be attached to the lower limb segments and measures lower-limb joint motion in multiple degrees of freedom (DOF),

A central processor 4;

said processor 4 incorporates the multi-axis force sensor 1, motion measurement unit 3G and 3I and limb geometry information and calculates lower-limb joint moments in real time,

A feedback device 5;

said device 5 displays the lower-limb joint moments and/or generates sound or haptic feedback based on the amplitude and/or timing of the joint moments in real-time.

2. The apparatus of claim 1 wherein said lower-limb real-time motion measurement unit 3G and 3I can be one or more multi-DOF goniometer 3G or multi-DOF inertial measurement units (IMU) 3I.

3. The apparatus of claim 2 wherein said multi-DOF goniometer 3G;

the one end of said goniometer sensor 3G is attached to the said footplate 2, and the other end is attached to the leg;

said multi-DOF goniometer 3G is used to measure ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle in real-time.

4. The apparatus of claim 2 wherein said IMUs are attached to the foot and leg;

said IMUs are used to measure ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle in real-time.

5. The apparatus of claim 2 wherein said IMUs is attached to the leg and thigh;

said IMUs are used to measure knee flexion/extension, abduction/adduction (valgus/varus) angle and shank internal/external rotation angle in real-time.

6. The apparatus of claim 1 wherein said footplate 2 further comprising a foot bootstrap 6, which straps the foot to the footplate and prevents motion of the foot relative to the footplate.

7. The apparatus of claim 1 wherein said exercise apparatus 100 comprises a pivoting and/or a sliding 8 mechanisms so as to induce or apply a pivoting and/or sliding movement to the footplate 2, said pivoting movement being substantially about an axis parallel to the said Z axis or about an axis parallel to the Y axis;

and said sliding movement being along the said X and Y axes.

8. The apparatus of claim 1 wherein the force sensor 1 further includes a multi-axis force sensor, said multi-axis force sensor measures at least one of said three ground-reaction forces along said X, Y and Z axes and at least one of said three moments about said X, Y and Z axes.

9. The apparatus of claim 1 further comprising a real-time central processor 4, said central processor implements a real-time calculation method 9 of interested lower-limb joint moments based on said multi-axis force sensor and lower-limb motion measurement unit.

10. The central processor 4 of claim 9 further implements a real-time calculation method 9 requiring real-time measurement of one or more components of said three ground-reaction forces along said X, Y and Z axes and three moments about said X, Y and Z axes when the said foot strap is used:

Computing one direction ankle force requires only the same direction component of the said ground-reaction forces;

Computing one direction ankle moment requires two components of said ground-reaction forces, direction of which are orthogonal to the direction of the said one direction ankle moment, and one moment measured from the said multi-axis force sensor 1, direction of which are the same as said one direction ankle moment;

Computing one direction knee force requires the said all three ground-reaction forces along said X, Y and Z axes;

Computing one direction knee moment requires the said all three ground-reaction forces along the said X, Y and Z axes, and the said three moments about the said X, Y and Z axes.

11. The central processor 4 of claim 9 further implements a real-time calculation method 9 requiring real-time measurement of one or more components of the said three ground-reaction forces along the said X, Y and Z axes and three moments about the said X, Y and Z axes when the said foot bootstrap 6 is not used:

Computing one direction ankle force requires only the same direction component of the said ground-reaction forces;

Computing one direction ankle moment requires two components of the said ground-reaction forces, direction of which are orthogonal to the direction of the said one direction ankle moment, and the said axial axis moment measured from the said multi-axis load sensor;

Computing one direction knee force requires the said all three ground-reaction forces along the said X, Y and Z axes;

Computing one direction knee moment requires the said all three ground-reaction forces and the said axial axis moment measured from the said multi-axis load sensor.

12. The central processor of claim 9 further implements a real-time calculation method 9 requiring real-time measurement of lower-limb kinematic variables when the foot strap 6 is used:

Computing the said sagittal axis direction ankle force requires the said sagittal axis direction translational acceleration of the ankle joint;

Computing the said coronal or axial direction ankle force requires the said coronal and axial direction translational acceleration of ankle joint and the said sagittal axis angle, angular velocity, and angular acceleration of foot;

Computing the said sagittal direction ankle moment requires the said coronal and axial direction translational accelerations of ankle joint and the said sagittal axis angle and angular acceleration of foot;

Computing the said coronal or axial direction ankle moment requires all three direction translational accelerations of ankle joint and the said sagittal axis angle, angular velocity, and angular acceleration of foot;

Computing the said sagittal or coronal direction knee force requires the said all three X, Y and Z direction translational accelerations of ankle joint, the said sagittal axis angle, angular velocity and angular acceleration of foot, and the said ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle and the 1^st and 2^nd time derivatives of the said ankle dorsiflexion/planar-flexion and inversion/eversion angles;

Computing the said axial direction knee force requires the said all three X, Y and Z direction translational accelerations of ankle joint, the said sagittal axis angle, angular velocity and angular acceleration of foot, and the said ankle dorsiflexion/planar-flexion and inversion/eversion angles and 1^st time derivatives of the said ankle dorsiflexion/planar-flexion and inversion/eversion angles;

Computing the said sagittal and coronal direction knee moments requires the said all three X, Y and Z direction translational accelerations of ankle joint, the said sagittal axis angle, angular velocity and angular acceleration of foot, and the said ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle, the 1^st time derivatives of the said ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle, and the 2^nd time derivatives of the said ankle dorsiflexion/planar-flexion and inversion/eversion angles;

Computing the said axial direction knee moment requires the said all three X, Y and Z direction translational accelerations of ankle joint, the said sagittal axis angle, angular velocity and angular acceleration of foot, and the said ankle dorsiflexion/planar-flexion and inversion/eversion angles and shank internal/external rotation angle, the 1^st time derivatives of the said ankle dorsiflexion/planar-flexion and inversion/eversion angles, and the 2^nd time derivatives of the said ankle dorsiflexion/planar-flexion angle and the said shank internal/external rotation angle;

13. The apparatus of claim 1 wherein said apparatus can be configured as a pair of joint moment measuring assemblies and attached on each footplate on said exercise device.

14. The apparatus of claim 7 further comprising a motor 10, said motor 10 being operatively engaged with at least one of said pivoting 7 or said sliding motion 8 to drive the pivoting and/or sliding movements, wherein said motor 10 is configured to exert a preconfigured force to change knee loading moments.

15. The apparatus of claim 7 further comprising position sensor 11, said position sensor 11 operatively measures the internal/external pivoting motion of foot.