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

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.

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.