Stair ascent and descent control for powered lower limb devices
First Claim
1. A lower limb device comprising:
- a powered knee joint with a motor for providing an output torque at the powered knee joint;
a powered ankle joint with a motor for providing an output torque at the powered ankle joint;
a plurality of sensors for generating real-time sensor information for the lower limb device, wherein at least one of the plurality of sensors comprises an inertial measurement unit and a position sensor for angle measurements of the powered knee joint;
at least one processor communicatively coupled to the plurality of sensors, the powered knee joint and the powered ankle joint; and
a computer-readable medium comprising stored instructions for causing the at least one processor to perform the steps comprising;
selecting one of a plurality of phases of a finite state model defining a stair ascent controller to yield a current phase;
operating the motor of the powered knee joint and the motor of the powered ankle joint according to the current phase,based on the real-time sensor information for the lower limb device and a transition trigger for the current phase, transitioning from a current phase to a subsequent phase in the finite state model,computing an estimate of an orientation with respect to gravity of a thigh associated with the powered knee joint based on the real-time sensor information from the at least one inertial measurement unit, andrepeating the operating, the transitioning, and the computing until a criteria for exiting the stair ascent controller is met, wherein the criteria is met when the estimate indicates a presence of thigh flexion for a period of time.
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Abstract
Systems and methods of operating a lower limb device having at least a powered joint are provided. A method includes configuring the device to a first state in a finite state model for a current activity mode including a stair ascent mode or a stair descent mode. The method also includes, based on real-time sensor information, transitioning the device between different states in the finite state model when pre-defined criteria for transitioning among the different states are met. In the method, the finite state model for stair ascent includes lifting and swing phases, where the lifting phase includes a powered knee extension and a powered ankle push-off. The finite state model for stair descent includes yielding and swing states, where the swing states include providing a powered plantarflexion of the powered ankle joint and the yielding states include providing a resistive and passive plantarflexion of the powered ankle joint.
20 Citations
10 Claims
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1. A lower limb device comprising:
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a powered knee joint with a motor for providing an output torque at the powered knee joint; a powered ankle joint with a motor for providing an output torque at the powered ankle joint; a plurality of sensors for generating real-time sensor information for the lower limb device, wherein at least one of the plurality of sensors comprises an inertial measurement unit and a position sensor for angle measurements of the powered knee joint; at least one processor communicatively coupled to the plurality of sensors, the powered knee joint and the powered ankle joint; and a computer-readable medium comprising stored instructions for causing the at least one processor to perform the steps comprising; selecting one of a plurality of phases of a finite state model defining a stair ascent controller to yield a current phase; operating the motor of the powered knee joint and the motor of the powered ankle joint according to the current phase, based on the real-time sensor information for the lower limb device and a transition trigger for the current phase, transitioning from a current phase to a subsequent phase in the finite state model, computing an estimate of an orientation with respect to gravity of a thigh associated with the powered knee joint based on the real-time sensor information from the at least one inertial measurement unit, and repeating the operating, the transitioning, and the computing until a criteria for exiting the stair ascent controller is met, wherein the criteria is met when the estimate indicates a presence of thigh flexion for a period of time. - View Dependent Claims (2, 3, 4, 5)
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6. A lower limb device comprising:
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a powered knee joint with a motor for providing an output torque at the powered knee joint; a powered ankle joint with a motor for providing an output torque at the powered ankle joint; a plurality of sensors for generating real-time sensor information for the lower limb device, wherein at least one of the plurality of sensors comprises an inertial measurement unit and a position sensor for angle measurements of the powered knee joint; at least one processor communicatively coupled to the plurality of sensors, the powered knee joint and the powered ankle joint; and a computer-readable medium comprising stored instructions for causing the at least one processor to perform the steps comprising; selecting one of a plurality of states of a finite state model defining a stair descent controller to yield a current state; operating the motor of the powered knee joint and the motor of the powered ankle joint according to the current state, based on the real-time sensor information for the lower limb device and a transition trigger for the current state, transitioning from a current state to a subsequent state in the finite state model, computing an estimate of an orientation with respect to gravity of a thigh associated with the powered knee joint based on the real-time sensor information from the at least one inertial measurement unit, and repeating the operating, the transitioning, and the computing until a criteria for exiting the stair descent controller is met, wherein the criteria is met when the estimate indicates an absence of thigh flexion for a period of time. - View Dependent Claims (7, 8, 9, 10)
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Specification