Device and Method for Decreasing Energy Consumption of a Person by Use of a Lower Extremity Exoskeleton

Abstract

A lower extremity exoskeleton, configurable to be coupled to a person, includes: leg supports configurable to be coupled to the person's lower limbs and designed to rest on the ground during stance phases, with each leg support having a thigh link and a shank link; two knee joints, each configured to allow flexion and extension between respective shank and thigh links; an exoskeleton trunk configurable to be coupled to the person's upper body, rotatably connectable to the thigh links of the leg supports, allowing for the flexion and extension between the leg supports and the exoskeleton trunk; two hip actuators configured to create torques between the exoskeleton trunk and the leg supports; and at least one power unit capable of providing power to the hip actuators. In use, power is supplied to the hip actuators in an amount to reduce the energy consumed by a user during a walking cycle.

We claim: 
     
         1 . A method of reducing energy consumption of a person in motion along a trajectory in a forward 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, and two hip actuators for creating torques between said leg supports and said exoskeleton trunk, 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 wherein said energy is determined based on a force between said exoskeleton trunk and the person's upper body along the person's forward velocity direction and established to be larger than an amount of energy required to move said exoskeleton trunk and said leg support in the stance phase through the same trajectory in the forward direction of movement when not worn by said person. 
     
     
         2 . The method of  claim 1 , further comprising: determining said energy to establish a torque profile for controlling said hip actuator of said leg support in the stance phase to ensure said torque profile is larger than:
   ( M   TRUNK   L   2   +I ){umlaut over (β)} 1 −( LM   TRUNK   +RM   L ) g  Sin(β 1 +α)+ T   F  
   wherein:
 M TRUNK  is a mass of the exoskeleton trunk and any attached load; 
 M L  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; 
 β 1  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 
 T F  is a frictional torque opposing the motion of the leg support relative to the exoskeleton trunk. 
   
     
     
         3 . The method of  claim 1 , wherein 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 the stance phase includes creating a torque profile in said hip actuator of said leg support in the stance to provide torque at least equal to an amount of torque required to move said exoskeleton trunk and said leg support in the stance phase through the same trajectory in the forward direction of movement when not worn by said person. 
     
     
         4 . The method of  claim 3 , wherein each said leg support further comprises a thigh link, a shank link, and a knee joint configured to allow flexion and extension between said shank link and said thigh link, said method further comprising: allowing flexion and extension of a respective said knee joint during a swing phase and resisting flexion of the respective said knee joint during the stance phase to allow a transfer of force to the ground. 
     
     
         5 . The method of  claim 1 , wherein 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 the stance phase includes creating a force from said exoskeleton trunk onto the person's upper body by use of said hip actuator of said leg support in the stance phase, wherein said force from said exoskeleton trunk onto the person's upper body is along the person's forward velocity. 
     
     
         6 . The method of  claim 5  further comprising:
 measuring the force between said exoskeleton trunk and the person's upper body; and 
 ensuring that the force from said exoskeleton trunk onto the person's upper body is always along the person's forward velocity. 
 
     
     
         7 . The method of  claim 1 , further comprising: transferring weight of a load to said exoskeleton trunk through a connecting bracket. 
     
     
         8 . The method of  claim 7 , further comprising: holding the load in front of the person through an extension frame when said exoskeleton trunk is coupled to said person's upper body. 
     
     
         9 . The method of  claim 1 , further comprising: producing a stance signal utilizing at least one stance sensor for each said leg support, with the stance signal indicating whether a respective said leg support is in the stance phase. 
     
     
         10 . The method of  claim 9 , wherein said at least one stance sensor is located inside or connected to a bottom of a human shoe. 
     
     
         11 . The method of  claim 1 , wherein each said leg support includes a foot configured to rest on the ground and each said foot includes at least one stance sensor, said method further comprising: producing a stance signal utilizing the at least one stance sensor indicating whether a respective said leg support is in the stance phase. 
     
     
         12 . A method of reducing energy consumption of a person in motion along a trajectory in a forward direction of movement coupled to an exoskeleton device including at least one power unit, two leg supports rotatably connected to an exoskeleton trunk for attachment to the person's legs, and two hip actuators for creating torques between said leg supports and said exoskeleton trunk, the 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 to create a force from said exoskeleton trunk onto the person's upper body by use of said hip actuator of said leg support in the stance phase, wherein said force from said exoskeleton trunk onto the person's upper body is along the person's forward velocity and larger than an amount of energy required to move said exoskeleton trunk and said leg support in the stance phase through the same trajectory in the forward direction of movement when the exoskeleton is not worn by said person. 
     
     
         13 . The method of  claim 12 , further comprising: measuring a force between said exoskeleton trunk and the person's upper body and ensuring that the force from said exoskeleton trunk onto the person's upper body is always along the person's forward velocity. 
     
     
         14 . The method of  claim 12 , further comprising: transferring weight of a load to said exoskeleton trunk through a connecting bracket. 
     
     
         15 . The method of  claim 14 , further comprising: holding the load in front of the person through an extension frame when said exoskeleton trunk is coupled to said person's upper body. 
     
     
         16 . The method of  claim 12 , further comprising: producing a stance signal utilizing at least one stance sensor for each said leg support, with the stance signal indicating whether a respective said leg support is in the stance phase. 
     
     
         17 . The method of  claim 16 , wherein each said leg support includes a foot configured to rest on the ground, and each said foot includes the at least one stance sensor producing the stance signal. 
     
     
         18 . The method of  claim 12 , further comprising: determining said energy to establish a torque profile for controlling said hip actuator of said leg support in the stance phase to ensure said torque profile is larger than:
   ( M   TRUNK   L   2   +I ){umlaut over (β)} 1 −( LM   TRUNK   +RM   L ) g  Sin(β 1 +α)+ T   F  
   wherein:
 M TRUNK  is a mass of the exoskeleton trunk and any attached load; 
 M L  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; 
 β 1  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 
 T F  is a frictional torque opposing the motion of the leg support relative to the exoskeleton trunk. 
   
     
     
         19 . The method of  claim 12 , wherein 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 the stance phase includes creating a torque profile in said hip actuator of said leg support in the stance to provide torque at least equal to an amount of torque required to move said exoskeleton trunk and said leg support in the stance phase through the same trajectory in the forward direction of movement when not worn by said person. 
     
     
         20 . The method of  claim 19 , wherein each said leg support further comprises a thigh link, a shank link, and a knee joint configured to allow flexion and extension between said shank link and said thigh link, said method further comprising: allowing flexion and extension of a respective said knee joint during a swing phase and resisting flexion of the respective said knee joint during the stance phase to allow a transfer of force to the ground. 
     
     
         21 . A method of reducing the energy consumption of a person in motion along 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 for said hip actuator of said leg support in the stance phase 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 the sum of inertial, gravitation and frictional torques on said leg support in the stance phase.   
     
     
         22 . A method of reducing energy consumption of a person in motion along a trajectory in a direction of movement coupled to an exoskeleton device including 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, at least one power unit for providing power to said hip actuators, and at least one processor wherein, when said lower extremity exoskeleton is worn by the person, one of the two leg supports is in a stance phase and another of the two leg supports is in a swing phase, said method comprises:
 creating a torque profile which is larger than a required torque or energy needed to move said exoskeleton trunk and said one of the two leg supports in the stance phase through the same trajectory when not worn by said person; and   causing the hip actuator for said one of the two leg supports which in the stance phase to follow the torque profile.