Method for estimating the relative orientation between a tibia and a femur

Equipment for estimating the relative orientation between a tibia and a femur of a lower limb of a person during a working movement of said lower limb from an initial position, characterised in that it comprises a data processor configured to implement:

• receiving, during at least one reference movement of said lower limb from a reference position having a same relative orientation between the tibia and the femur as the initial position, a reference acceleration and a reference angular velocity of said tibia acquired by first inertial measuring means affixed to the tibia of said lower limb, and a reference acceleration and a reference angular velocity of said femur acquired by second inertial measuring means affixed to the femur;
• estimating a plurality of morphological parameters of said lower limb, as a function of said measured reference accelerations and reference angular velocities;
• determining a relative orientation in said initial position between said tibia and femur, as a function of said estimated morphological parameters of said lower limb;
• receiving, during said working movement of said lower limb from the initial position, a working angular velocity of said tibia acquired by the first inertial measuring means, and a working angular velocity of said femur acquired by the second inertial measuring means;
• estimating the relative orientation between said tibia and femur as a function of said measured working angular velocities, and of said relative orientation in said initial position between said tibia and femur.

A non-transitory computer-readable medium comprising instructions stored thereon for execution by a processor of a method for estimating the relative orientation between a tibia and a femur of a lower limb of a person, wherein the instructions configure the processor to perform acts comprising:

• During at least one reference movement of said lower limb from a reference position having a same relative orientation between the tibia and the femur as an initial position, acquiring by first inertial measuring means affixed to the tibia of said lower limb a reference acceleration and a reference angular velocity of said tibia, and acquiring by second inertial measuring means affixed to the femur a reference acceleration and a reference angular velocity of said femur;
• Estimating a plurality of morphological parameters of said lower limb, as a function of said measured reference accelerations and reference angular velocities;
• Determining a relative orientation in said initial position between said tibia and femur, as a function of said estimated morphological parameters of said lower limb;
• During said working movement of said lower limb from the initial position, acquiring by the first inertial measuring means a working angular velocity of said tibia, and acquiring by the second inertial measuring means a working angular velocity of said femur;
• Estimating the relative orientation between said tibia and femur as a function of said measured working angular velocities, and of said relative orientation in said initial position between said tibia and femur.