Method for moving an exoskeleton
The present invention relates to a method for moving an exoskeleton ( 1 ) receiving a human operator, said exoskeleton ( 1 ) having a plurality of degrees of freedom including at least one degree of freedom actuated and at least one non-actuated degree of freedom, the method being characterised in that it comprises the implementation of steps of: (a) when a start request is received, generating and emitting a command to at least one of said actuators so as to put the exoskeleton ( 1 ) in a tipping state; (b) in a database stored in data storage means ( 12 ) of triplets of: a set of virtual requirements on said actuated degrees of freedom, a controller for said exoskeleton ( 1 ) capable of generating commands of said actuators so as to fulfil said virtual requirements by implementing at least one attracting stable trajectory, a stability pool formed by all the points from which the execution of said controller allows a convergence to said attracting stable trajectory; identifying a set of virtual requirements such that said tipping state is included in said stability pool associated with this set of virtual requirements; (c) executing the controller associated with the set of virtual requirements identified such that the exoskeleton ( 1 ) walks.
1. A method for moving an exoskeleton receiving a human operator, said exoskeleton having a plurality of degrees of freedom including at least one actuated degree of freedom actuated by an actuator controlled by a data processor and at least one non-actuated degree of freedom, the method comprising executing by the data processor the steps of:
(a) when a start request is received, generating and emitting a command to said actuator so as to put the exoskeleton in a tipping state;
(b) in a database stored in a data storage unit of triplets of:
a set of virtual constraints on each actuated degree of freedom, the virtual constraints being parameterised by a phase variable,
a controller for said exoskeleton generating commands of said actuator so as to fulfill the virtual constraints by implementing at least one attracting stable trajectory in a topological manifold formed by all n-tuples of the possible values for each non-actuated degree of freedom and the phase variable,
a stability pool formed by all the points of a hyperplane of said topological manifold for a given value of the phase variable, from which the execution of said generated commands of said controller allows a convergence to said attracting stable trajectory;
identifying a set of virtual constraints such that said tipping state is included in said stability pool associated with said set of virtual constraints;
(c) executing said generated commands of the controller associated with the set of virtual constraints identified such that the exoskeleton walks.
2. The method according to claim 1 , wherein step (a) comprises determining a walking speed and/or direction set point as a function of which said command to said actuator is generated, step (c) comprising checking that said walking speed and/or direction set point is fulfilled by a current walk in said database.
3. The method according to claim 2 , comprising, if said walking speed and/or direction set point is not fulfilled by the current walk, a step (d) of identifying in said database a new set of virtual constraints such that the current state of the exoskeleton is included in said stability pool associated with said new set of virtual constraints; and repeating step (c).
4. The method according to claim 2 , wherein said walking speed and/or direction set point is determined as a function of a posture of said human operator.
5. The method according to claim 4 , wherein the operator's chest is equipped with a plurality of posture sensors, said walking speed and/or direction set point being determined as a function of the posture of said operator's chest measured by the plurality of sensors.
6. The method according to claim 1 , wherein the tipping state is a state in which a Zero Moment Point, ZMP, is not inside a lift surface for the exoskeleton.
7. The method according to claim 1 , wherein step (c) comprises stopping the exoskeleton if no acceptable set of virtual constraints is identified.
8. An exoskeleton for receiving a human operator, comprising a data processor and having a plurality of degrees of freedom including at least one actuated degree of freedom actuated by an actuator controlled by the data processor and at least one non-actuated degree of freedom, wherein it comprises a data storage unit storing a database of triplets of:
a set of virtual constraints on each actuated degree of freedom, the virtual constraints being parameterised by a phase variable,
a controller for said exoskeleton generating commands of said actuator so as to fulfill said virtual constraints by implementing at least one attracting stable trajectory in a topological manifold formed by all the n-tuples of the possible values of each non-actuated degree of freedom and the phase variable,
a stability pool formed by all the points of a hyperplane of said topological manifold by a given value of the phase variable, from which the execution of said generated commands of said controller allows a convergence to said attracting stable trajectory;
and in that the data processor is configured to implement:
a module for generating and emitting a command to said actuator so as to put the exoskeleton in a tipping state when a start request is received;
a module for identifying in said database of the storage unit a set of virtual constraints such that said tipping state is included in said stability pool associated with this set of virtual constraints;
an execution module of the controller associated with the set of virtual constraints identified such that the exoskeleton walks.
9. A non-transitory storage means on which a computer program product comprises code instructions for the execution of a method according to claim 1 for moving the exoskeleton.