Device and method for decreasing energy consumption of a person by use of a lower extremity exoskeleton

A method of reducing the energy consumption of a person in motion along a trajectory in a direction of movement coupled to an exoskeleton device including at least one power unit, two leg supports for coupling to said person's lower limbs rotatably connected to an exoskeleton trunk, two hip actuators for creating torques between said leg supports and said exoskeleton trunk and at least one signal processor, said method comprising:

• supplying energy from said at least one power unit to said hip actuator of the leg support coupled to said person's lower limb in a stance phase and creating a torque profile in said hip actuator of said leg support in stance such that mechanical energy is transferred to said person from said lower extremity exoskeleton during said stance phase in the direction of movement, wherein said signal processor computes said torque profile and controls said hip actuator of said leg support in the stance phase to ensure said torque profile is larger than:
• (MTRUNKL2+I){umlaut over (β)}1−(LMTRUNK+RML)g Sin(β1+α)+TF
• wherein:
• M TRUNK is a mass of the exoskeleton trunk and any attached load;
• ML is a mass of the respective first and second leg support in the stance phase;
• I is moment of inertia of the respective first and second leg support in the stance phase;
• L is a length of the respective first and second leg support in the stance phase;
• R is a distance between a center of mass of the respective first and second leg support in the stance phase and a rotational point;
• g is force due to gravity;
• β1 is an angle between a support surface and the normal line of force on the exoskeleton trunk from the person's upper body;
• α is a ground slope defined by an angle between a support surface and a horizontal plane;
• and
• TF is a frictional torque opposing the motion of the leg support relative to the exoskeleton trunk.