Rotary actuator

An actuator system comprising:

• a controlled element configured for rotary movement about a first axis relative to a reference structure;
• a linkage system connected to said element and said reference structure;
• a first actuator configured and arranged to power a first degree of freedom of said linkage system;
• a hold device configured and arranged to selectively lock a second degree of freedom of said linkage system, said first degree of freedom and said second degree of freedom being independent degrees of freedom;
• said linkage system having a first link configured for rotary movement about a second axis relative to said reference structure;
• said first axis and said second axis not being coincident;
• said linkage system having a second link configured for rotary movement about a third axis relative to said reference structure;
• said first link and said second link coupled such that rotation of said first link about said second axis in a first direction causes rotation of said second link about said third axis in a second direction;
• said linkage system configured and arranged such that a first angle of rotation between said element and said reference structure may be driven independently of a second angle of rotation between said first link and said reference structure;
• wherein said hold device is configured and arranged to lock said second degree of freedom when said first actuator is operational and to unlock said second degree of freedom when said first actuator is operatively locked.

An actuator system comprising:

• a controlled element configured for rotary movement about a first axis relative to a reference structure;
• a plurality of actuator units, each of said actuator units comprising:
• a linkage system connected to said element and said reference structure;
• a first actuator configured and arranged to power a first degree of freedom of said linkage system;
• a second actuator configured and arranged to power a second degree of freedom of said linkage system, said first degree of freedom and said second degree of freedom being independent degrees of freedom;
• said linkage system having a first link configured for rotary movement about a second axis relative to said reference structure;
• said first axis and said second axis not being coincident;
• said linkage system having a second link configured for rotary movement about a third axis relative to said reference structure;
• said first link and said second link coupled such that rotation of said first link about said second axis in a first direction causes rotation of said second link about said third axis in a second direction;
• said linkage system configured and arranged such that a first angle of rotation between said element and said reference structure may be driven independently of a second angle of rotation between said first link and said reference structure;
• wherein one of said first or second actuators is configured and arranged to drive rotation of said element about said first axis when said other of said first or second actuator is operatively locked.

An actuator system comprising:

• a controlled element configured for rotary movement about a first axis relative to a reference structure;
• a plurality of actuator units, each of said actuator units comprising:
• a first actuator configured and arranged to power a first degree of freedom of said linkage system;
• a hold device configured and arranged to selectively lock a second degree of freedom of said linkage system, said first degree of freedom and said second degree of freedom being independent degrees of freedom;
• said linkage system having a first link configured for rotary movement about a second axis relative to said reference structure;
• said first axis and said second axis not being coincident;
• said linkage system having a second link configured for rotary movement about a third axis relative to said reference structure;
• said first link and said second link coupled such that rotation of said first link about said second axis in a first direction causes rotation of said second link about said third axis in a second direction;
• said linkage system configured and arranged such that a first angle of rotation between said element and said reference structure may be driven independently of a second angle of rotation between said first link and said reference structure;
• wherein said hold device is configured and arranged to lock said second degree of freedom when said first actuator is operational and to unlock said second degree of freedom when said first actuator is operatively locked.

An actuator system comprising:

• a reference structure;
• an output member rotatably coupled to the reference structure for rotation about a first axis;
• a first actuator having a first member and a second member, the second member configured to rotate relative to the reference structure, the first member configured to rotate relative to the reference structure about a second axis, the first member configured to rotate relative to the reference structure independent of the rotation of the second member relative to the reference structure;
• a second actuator having a first member and a second member, the second member configured to rotate relative to the reference structure, the first member configured to rotate relative to the reference structure about a third axis, the first member configured to rotate relative to the reference structure independent of the rotation of the second member relative to the reference structure;
• a first link pivotally connected between the first member of the first actuator and the first member of the second actuator, the first member of the first actuator and the first member of the second actuator coupled such that rotation of the first member of the first actuator in a first direction causes rotation of the first member of the second actuator in a second direction;
• a second link pivotally connected between the second member of the first actuator and the output member.

An actuator system, comprising:

• a reference structure;
• an output member rotatably coupled to the reference structure for rotation about a first axis;
• a first actuator having a first member and a second member, the second member configured to rotate relative to the reference structure, the first member configured to rotate relative to the reference structure about a second axis, the first member configured to rotate relative to the reference structure independent of the rotation of the second member relative to the reference structure;
• a holding device having a first member and a second member, the second member configured to rotate relative to the reference structure, the holding device configured to alternate between a first configuration where the rotational position of the first member relative to the second member is locked and a second position where the first and second members are free to rotate relative to each other;
• a first link pivotally connected between the first member of the first actuator and the first member of the holding device, the first member of the first actuator and the first member of the holding device coupled such that rotation of the first member of the first actuator in a first direction causes rotation of the first member of the holding device in a second direction;
• a second link pivotally connected between the second member of the first actuator and the output member;
• wherein the holding device moves from the first configuration to the second configuration when the first actuator is operatively locked.

A method of controlling an actuator system comprising the steps of:

• providing an actuator system comprising:
• a controlled element configured for rotary movement about a first axis relative to a reference structure;
• a linkage system connected to said element and said reference structure;
• a first actuator configured and arranged to power a first degree of freedom of said linkage system;
• a second actuator configured and arranged to power a second degree of freedom of said linkage system, said first degree of freedom and said second degree of freedom being independent degrees of freedom;
• said linkage system having a first link configured for rotary movement about a second axis relative to said reference structure;
• said first axis and said second axis not being coincident;
• said linkage system having a second link configured for rotary movement about a third axis relative to said reference structure;
• said first link and said second link coupled such that rotation of said first link about said second axis in a first direction causes rotation of said second link about said third axis in a second direction;
• said linkage system configured and arranged such that a first angle of rotation between said element and said reference structure may be driven independently of a second angle of rotation between said first link and said reference structure;
• wherein one of said first or second actuators is configured and arranged to drive rotation of said element about said first axis when said other of said first or second actuator is operatively locked;
• and
• providing power to said first actuator and said second actuator simultaneously such that said controlled element is rotated about said second axis and an angular position of said first link is held constant about said first axis.

A method of controlling an actuator system comprising the steps of:

• providing an actuator system comprising:
• a controlled element configured for rotary movement about a first axis relative to a reference structure;
• a linkage system connected to said element and said reference structure;
• a first actuator configured and arranged to power a first degree of freedom of said linkage system;
• a hold device configured and arranged to selectively lock a second degree of freedom of said linkage system, said first degree of freedom and said second degree of freedom being independent degrees of freedom;
• said linkage system having a first link configured for rotary movement about a second axis relative to said reference structure;
• said first axis and said second axis not being coincident;
• said linkage system having a second link configured for rotary movement about a third axis relative to said reference structure;
• said first link and said second link coupled such that rotation of said first link about said second axis in a first direction causes rotation of said second link about said third axis in a second direction;
• said linkage system configured and arranged such that a first angle of rotation between said element and said reference structure may be driven independently of a second angle of rotation between said first link and said reference structure;
• wherein said hold device is configured and arranged to lock said second degree of freedom when said first actuator is operational and to unlock said second degree of freedom when said first actuator is operatively locked;
• and
• providing power to said first actuator and said hold device simultaneously such that said hold device link locks said second degree of freedom of said linkage system, and said first actuator applies a desired torque to said controlled element.