System and method for providing biomechanically suitable running gait in powered lower limb devices
Inventors
Goldfarb, Michael • Shultz, Amanda • Lawson, Brian
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Publication Number
US-12558237-B2
Publication Date
2026-02-24
Expiration Date
Abstract
Systems and methods for a running controller for a lower limb device including at least a powered knee joint are provided. The method includes collecting real-time sensor information for the lower limb device and configuring the lower limb device to a first state in a finite state model for an activity mode including the running mode. The method further includes, based on the sensor information, transitioning the lower limb device from a current state to a subsequent state in the finite state model for the detected mode when a pre-defined criteria for transitioning to the subsequent state is met, and repeating the transitioning until the activity mode changes. In the system and method, the finite state model includes at least one stance state and at least one swing state, where the at least one stance state includes at least one absorption state and at least one propulsion state.
Core Innovation
A powered lower limb device for running is controlled using a finite state model for an activity mode comprising a running mode. The model includes an absorption phase, a propulsion phase, a swing flexion phase, and a swing extension phase, with transitions configured in a sequence between these phases. The controller collects real-time sensor information and transitions the device from a current state to a subsequent state in the finite state model when pre-defined criteria for transitioning to the subsequent state is met, repeating the transitions until the activity mode changes from the running mode.
In the absorption phase, the powered knee joint and the powered ankle joint are each configured to behave as a combined stiffness and damping, with stiffness and damping components configured such that the powered knee and ankles absorb energy associated with decelerating a vertical motion of a body center of mass. Transitioning into the propulsion phase occurs when the powered knee joint has absorbed the load on the lower limb device. In the propulsion phase, the powered knee and ankle joints are configured such that the powered knee and ankles generate energy associated with accelerating the vertical motion of the body center of mass.
The controller continues through swing flexion and swing extension phases by using pre-defined criteria based on real-time sensor information. Transitioning into the absorption phase occurs when a load on the lower limb device increased above a first threshold, and the phase transitions are repeatedly generated as additional control signals while the activity mode remains the running mode. The finite state model is used to configure how the powered joints generate, absorb, or emulate energy during decelerating and accelerating vertical motion across the running phases.
Claims Coverage
The provided excerpt includes two independent claims that share the same core finite-state running control structure. The excerpted dependent claims refine running-mode selection and define additional phase transition triggers and propulsion and swing sub-mode behaviors, yielding a total of eight inventive-feature refinements across the independent claims and their dependents.
Finite-state running activity model with phase transitions
Configuring the lower limb device to a current state in a finite state model for an activity mode comprising a running mode; collecting real-time sensor information; transitioning from the current state to a subsequent state when a pre-defined criteria for transitioning to the subsequent state is met; and repeating until the activity mode changes from the running mode, wherein the finite state model comprises an absorption phase, a propulsion phase, a swing flexion phase, and a swing extension phase.
Absorption energy absorption via combined stiffness and damping in powered knee and ankle joints
Configuring the powered knee and ankle joints in the absorption phase to behave as a combined stiffness and damping, the stiffness and damping components configured such that the powered knee and ankles joints absorb energy associated with decelerating a vertical motion of a body center of mass.
Propulsion energy generation for accelerating vertical motion in powered knee and ankle joints
Transitioning into the propulsion phase occurs when the powered knee joint has absorbed the load on the lower limb device, and the first and second motors of the powered knee and ankle joints are each controlled configured in the propulsion phase such that the powered knee and ankles joints generate energy associated with accelerating the vertical motion of the body's center of mass.
Load-threshold entry into absorption phase and repeated running-mode control signals
Transitioning into the absorption phase occurs when a load on the lower limb device increased above a first threshold, and repeating generating control signals for transitioning until the activity mode changes from the running mode in the finite state model.
Running-mode selection from walking using real-time sensor information
Selecting the running mode for the lower limb device based on real-time sensor information during a walking mode prior to operating the powered knee joint and powered ankle joint, where the switch from walking to running is determined by measuring at least one of a load or acceleration at foot strike, stance time, swing time, or stride time.
Propulsion phase split into two sub-modes of coordinated knee/ankle actions
Defining the propulsion phase as having a first sub-mode involving active extension and plantarflexion of both the powered knee joint and the powered ankle joint, and a second sub-mode involving knee flexing while the powered ankle joint continues to plantarflex to assist knee flexing.
Swing flexion transition by decreased load threshold and dorsiflexed ankle state
Entering the swing flexion phase by detecting a decreased load on a lower-limb device below a second threshold, then flexing a powered knee joint and configuring a powered ankle joint to a dorsiflexed state.
Swing extension transition by knee velocity threshold and load-above-threshold completion
Entering the swing extension phase when detecting that the powered knee joint velocity reaches a threshold, further extending the powered knee joint, detecting that the load on the lower limb device rises above a first threshold, and then completing the swing extension mode.
Across the independent claims, the invention is directed to a controller or system that repeatedly transitions a lower limb device through absorption, propulsion, swing flexion, and swing extension states within a finite state model for a running activity mode, using real-time sensor information and pre-defined transition criteria. The powered knee and ankle joints in absorption are configured to behave as combined stiffness and damping to absorb energy associated with decelerating vertical center-of-mass motion, while in propulsion they generate energy associated with accelerating vertical center-of-mass motion. The dependent claims further specify running-mode selection from walking and refine propulsion and swing transitions with additional threshold-based triggers and joint-state sub-mode behaviors.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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