Force and/or motion measurement system having inertial compensation and method thereof

• US 8,315,823 B2
• Filed: 06/30/2011
• Issued: 11/20/2012
• Est. Priority Date: 04/20/2011
• Status: Active Grant

• Current Assignee: Bertec Corporation
• Original Assignee: Bertec Corporation
• Inventors: Berme, Necip, Guler, Hasan Cenk
• Primary Examiner(s): West, Jeffrey R
• Application Number:
  US13/173,084
• Publication Number:
  US 20120266648A1
• Time in Patent Office: 509 Days
• Field of Search: 702/41, 702/42, 702/87, 702/101, 702/102, 702/174, 702/173, 600/592
• US Class Current: 702/41
• CPC Class Codes: A61B 5/1036 Measuring load distribution, e.g. podologic studies
• CPC Class Codes: A61B 5/1112 Global tracking of patients, e.g. by using GPS
• CPC Class Codes: A63B 22/0235 driven by a motor
• CPC Class Codes: A63B 2220/51 Force
• CPC Class Codes: A63B 2220/806 Video cameras
• CPC Class Codes: A63B 2225/50 Wireless data transmission, e.g. by radio transmitters or telemetry
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• CPC Class Codes: G01L 5/1627 of strain gauges using piezoresistors G01L5/162

Abstract

According to one aspect of the invention, a force measurement system includes a force measurement assembly, a motion base configured to displace the force measurement assembly, and an inertial compensation system configured to determine the inertial forces and/or moments resulting from the displacement of the force measurement assembly by the motion base. According to another aspect of the invention, a method for accurately determining the forces and/or moments applied to a surface of a force measurement device by a subject disposed thereon is disclosed, which includes the step of determining, by using an inertial compensation system, the inertial forces and/or moments resulting from the displacement of a force measurement assembly by a motion base. According to still another aspect of the invention, a force and/or motion measurement system having inertial compensation includes a motion acquisition system having a plurality of motion sensing devices configured to capture a subject'"'"'s movement.

Claims

1. A force measurement system having inertial compensation, the force measurement system comprising:

a force measurement assembly configured to receive a subject, the force measurement assembly including;

a surface for receiving at least one portion of the body of the subject;

at least one force transducer, the at least one force transducer configured to sense one or more measured quantities and output one or more signals that are representative of forces and/or moments being applied to the surface of the force measurement assembly by the subject;

a motion base, which includes at least one actuator and a movable surface, the movable surface of the motion base attached to the force measurement assembly, the motion base configured to selectively displace and rotate its movable surface and the force measurement assembly attached thereto in multiple dimensions;

an inertial compensation system operatively coupled to the force measurement assembly, the inertial compensation system configured to determine both multi-dimensional inertial forces and moments resulting from the displacement and rotation of the force measurement assembly by the motion base in multiple dimensions, wherein the inertial compensation system utilizes a plurality of inertial parameters, which include the mass of the force measurement assembly, for determining the multi-dimensional inertial forces and moments resulting from the displacement and rotation of the force measurement assembly in multiple dimensions by the motion base, and wherein the motion base is used for determining the plurality of inertial parameters of the force measurement assembly during a calibration procedure, the mass of the force measurement assembly being computed as a function of measured forces determined using the at least one force transducer and an acceleration of the force measurement assembly measured by at least one accelerometer of the inertial compensation system; and

a data manipulation means configured to convert the one or more signals that are representative of the forces and/or moments being applied to the surface of the force measurement assembly by the subject into output forces and/or moments, the data manipulation means being further configured to correct the output forces and/or moments by utilizing the multi-dimensional inertial forces and/or moments determined by the inertial compensation system so as to improve the measurement accuracy of the forces and/or moments being applied to the surface of the force measurement assembly by the subject.

2. The force measurement system according to claim 1, wherein the inertial parameters further include the rotational inertia parameters of the force measurement assembly and the position of the center of gravity of the force measurement assembly.

3. The force measurement system according to claim 1, wherein the inertial compensation system comprises at least one angular velocity sensor, and wherein a multi-component angular velocity of the force measurement assembly, as measured by the at least one angular velocity sensor, is used for computing the multi-dimensional inertial moments about at least two orthogonal axes.

4. The force measurement system according to claim 1, wherein the motion base applies linear and/or rotational motion profiles to the force measurement assembly during the calibration procedure.

5. The force measurement system according to claim 1, wherein the force measurement assembly is in the form of a force plate or platform.

6. The force measurement system according to claim 1, wherein the force measurement assembly is in the form of an instrumented treadmill.

7. The force measurement system according to claim 6, wherein a force plate is disposed underneath a treadmill belt.

8. A method for accurately determining the forces and/or moments applied to a surface of a force measurement device by a subject disposed thereon, the method comprising the steps of:

providing a force measurement assembly configured to receive a subject thereon, the force measurement assembly including;

a surface for receiving at least one portion of the body of the subject;

at least one force transducer, the at least one force transducer configured to sense one or more measured quantities and output one or more signals that are representative of forces and/or moments being applied to the surface of the force measurement assembly by the subject;

providing a motion base, which includes at least one actuator, operatively coupled to the force measurement assembly, the motion base configured to selectively displace and rotate the force measurement assembly in multiple dimensions;

providing an inertial compensation system operatively coupled to the force measurement assembly, the inertial compensation system configured to determine multi-dimensional inertial forces and/or moments resulting from the displacement and rotation of the force measurement assembly in multiple dimensions;

determining a plurality of inertial parameters for the force measurement assembly during a calibration procedure, the plurality of inertial parameters including the mass of the force measurement assembly, the mass of the force measurement assembly being computed as a function of measured forces determined using the at least one force transducer and an acceleration of the force measurement assembly measured by at least one accelerometer of the inertial compensation system;

positioning the subject on the surface of the force measurement assembly;

selectively displacing and rotating the force measurement assembly and the subject disposed thereon in multiple dimensions using the motion base;

determining, by using the inertial compensation system, both the multi-dimensional inertial forces and moments resulting from the multi-dimensional displacement and rotation of the force measurement assembly by the motion base;

utilizing the plurality of inertial parameters in determining the multi-dimensional inertial forces and moments resulting from the displacement and rotation of the force measurement assembly in multiple dimensions by the motion base;

sensing, by utilizing the at least one force transducer, one or more measured quantities that are representative of forces and/or moments being applied to the surface of the force measurement assembly by the subject and outputting one or more signals representative thereof;

converting, by using a data manipulation device, the one or more signals that are representative of the forces and/or moments being applied to the surface of the force measurement assembly by the subject into output forces and/or moments; and

correcting the output forces and/or moments by mathematically combining the output forces and/or moments with the multi-dimensional inertial forces and/or moments determined by the inertial compensation system so as to improve the measurement accuracy of the forces and/or moments being applied to the surface of the force measurement assembly by the subject.

9. The method according to claim 8, wherein the inertial parameters further include the rotational inertia parameters of the force measurement assembly and the position of the center of gravity of the force measurement assembly.

10. The method according to claim 8, further comprising the step of:

using the motion base to determine the plurality of inertial parameters of the force measurement assembly during the calibration procedure.

11. The method according to claim 10, further comprising the step of:

applying linear and/or rotational motion profiles to the force measurement assembly during the calibration procedure by using the motion base.

12. A force and/or motion measurement system with inertial compensation, comprising:

a motion acquisition system having a plurality of motion sensing devices configured to capture the movement of a plurality of limbs on a subject, the motion sensing devices generating a plurality of first measured quantities;

a force measurement assembly configured to receive the subject, the force measurement assembly including;

a surface for receiving at least one portion of the body of the subject;

at least one force transducer, the at least one force transducer configured to sense one or more second measured quantities and output one or more signals that are representative of forces and/or moments being applied to the surface of the force measurement assembly by the subject;

a motion base, which includes at least one actuator, operatively coupled to the force measurement assembly, the motion base configured to selectively displace and rotate the force measurement assembly in multiple dimensions;

an inertial compensation system operatively coupled to the force measurement assembly, the inertial compensation system configured to determine both multi-dimensional inertial forces and moments resulting from the displacement and rotation of the force measurement assembly by the motion base in multiple dimensions, wherein the inertial compensation system utilizes a plurality of inertial parameters, which include the mass of the force measurement assembly, for determining the multi-dimensional inertial forces and moments resulting from the displacement and rotation of the force measurement assembly in multiple dimensions by the motion base, and wherein the motion base is used for determining the plurality of inertial parameters of the force measurement assembly during a calibration procedure, the mass of the force measurement assembly being computed as a function of measured forces determined using the at least one force transducer and an acceleration of the force measurement assembly measured by at least one accelerometer of the inertial compensation system; and

a data manipulation means being configured to convert the one or more signals that are representative of the forces and/or moments being applied to the surface of the force measurement assembly by the subject into output forces and/or moments, the data manipulation means being further configured to correct the output forces and/or moments by utilizing the multi-dimensional inertial forces and/or moments determined by the inertial compensation system, and the data manipulation means being additionally configured to determine forces and/or moments at one or more joints of the subject by using the corrected output forces and/or moments in combination with force and/or moment data generated from the plurality of first measured quantities.

13. The force and/or motion measurement system according to claim 12, wherein the inertial parameters further include the rotational inertia parameters of the force measurement assembly and the position of the center of gravity of the force measurement assembly.

14. The force and/or motion measurement system according to claim 12, wherein the inertial compensation system comprises at least one angular velocity sensor, and wherein a multi-component angular velocity of the force measurement assembly, as measured by the at least one angular velocity sensor, is used for computing the multi-dimensional inertial moments about at least two orthogonal axes.

15. The force and/or motion measurement system according to claim 12, wherein the motion base applies linear and/or rotational motion profiles to the force measurement assembly during the calibration procedure.

16. The force and/or motion measurement system according to claim 12, wherein the force measurement assembly is in the form of a force plate or platform.

17. The force and/or motion measurement system according to claim 12, wherein the force measurement assembly is in the form of an instrumented treadmill.

18. The force and/or motion measurement system according to claim 17, wherein a force plate is disposed underneath a treadmill belt.