Method of Operating A Robotic System Having One or More Tunable Actuator Joint Modules Comprising A Quasi-Passive Elastic Actuator

Abstract

A tunable actuator joint module of a robotic assembly comprises an output member and an input member, where the output member is rotatable about an axis of rotation. A primary actuator (e.g., a motor) is operable to apply a torque to rotate the output member about the axis of rotation. A quasi-passive elastic actuator (e.g., rotary or linear pneumatic actuator) comprising an elastic component is tunable to a joint stiffness value and is operable to selectively release stored energy to apply an augmented torque to assist rotation of the output member and to minimize power consumption of the primary actuator. The tunable actuator joint module comprises a control system having a valve assembly controllably operable to switch the quasi-passive elastic actuator between an elastic state and an inelastic state during respective portions of movement of the robotic assembly (e.g., a hip or knee joint of an exoskeleton). Associated systems and methods are provided.

What is claimed is: 
     
         1 . A method for operating a robotic system comprising at least one tunable joint module, the method comprising:
 causing a first rotation of a tunable actuator joint module of a robotic assembly;   engaging a quasi-passive elastic actuator of the tunable joint module during the first rotation to store energy; and   actuating a primary actuator to apply a primary torque and cause a second rotation of the tunable actuator joint module in a different direction from the first rotation, the quasi-passive actuator releasing the stored energy and applying an augmented torque to the primary torque during the second rotation, thereby reducing the power needed by the primary actuator to apply the primary torque to cause the second rotation.   
     
     
         2 . The method of  claim 1 , further comprising disengaging the quasi-passive elastic actuator, such that it enters an inelastic state and a free-swing mode. 
     
     
         3 . The method of  claim 2 , wherein disengaging the quasi-passive elastic actuator occurs during a third rotation of the tunable actuator joint module. 
     
     
         4 . The method of  claim 1 , wherein engaging the quasi-passive elastic actuator comprises causing the quasi-passive elastic actuator to enter an elastic state. 
     
     
         5 . The method of  claim 4 , further comprising, in the elastic state, compressing a gas within a compression chamber of a housing of the quasi-passive actuator to store the energy, and expanding the gas about an expansion chamber of the housing to release the energy. 
     
     
         6 . The method of  claim 1 , further comprising, prior to the first rotation, providing a pressure differential between the compression chamber and the expansion chamber. 
     
     
         7 . The method of  claim 1 , further comprising selectively operating a valve assembly to permit or restrict the flow of the gas, and thereby engage, partially engage, or disengage the quasi-passive elastic actuator. 
     
     
         8 . The method of  claim 1 , further comprising opening a shunt circuit to facilitate the flow of gas between the compression and expansion chambers of the quasi-passive elastic actuator and the valve assembly with the quasi-passive elastic actuator in the inelastic state, the opening of the shunt circuit facilitating free-swing of the tunable joint module. 
     
     
         9 . The method of  claim 1 , further comprising providing the quasi-passive elastic actuator with a desired gas pressure to define a predetermined joint stiffness value. 
     
     
         10 . The method of  claim 9 , further comprising modifying the gas pressure to modify the joint stiffness value. 
     
     
         11 . The method of  claim 1 , further comprising coordinating operation of a plurality of tunable joint modules of the robotic system, one of the plurality of tunable joint modules defining a hip joint of the robotic system, one of the tunable joint modules defining a knee joint of the robotic system, one of the plurality of tunable joint modules defining an ankle joint of the robotic system, or a combination of these. 
     
     
         12 . The method of  claim 1 , wherein causing a first rotation of a tunable actuator joint module comprises actuating a primary actuator of the tunable joint module to apply a primary torque with the quasi-passive elastic actuator in the elastic state. 
     
     
         13 . A method of making a tunable actuator joint module for use within a robotic system, the method comprising:
 configuring a primary actuator to apply a torque about an axis of rotation of a joint of a robotic system; and   configuring a quasi-passive elastic actuator to operate with the primary actuator, the quasi-passive elastic actuator comprising an elastic component dynamically tunable to a joint stiffness value, the quasi-passive elastic actuator operable to selectively store energy upon a first rotation of the joint, and operable to selectively release energy upon a second rotation of the joint to apply an augmented torque to the primary torque to assist rotation of the joint during the second rotation.   
     
     
         14 . The method of  claim 13 , further comprising equipping the quasi-passive elastic actuator with a valve assembly operable to switch the quasi-passive elastic actuator between the elastic state and the inelastic state. 
     
     
         15 . The method of  claim 13 , further comprising forming a shunt circuit in the quasi-passive elastic actuator that is engageable to facilitate the flow of gas between the valve assembly and a housing of the elastic component of the quasi-passive actuator, and that is disengageable to restrict the gas from flowing through the valve assembly. 
     
     
         16 . The method of  claim 15 , further comprising configuring the housing with a compression chamber and an expansion chamber. 
     
     
         17 . The method of  claim 16 , further comprising configuring the compression chamber and the expansion chamber to comprise different volumes. 
     
     
         18 . The method of  claim 13 , wherein coupling a quasi-passive elastic actuator to the primary actuator comprises coupling one of a quasi-passive rotary pneumatic actuator or a quasi-passive linear pneumatic actuator to the primary actuator.