Pneumatic muscle analogs for exoskeletal robotic limbs and associated control mechanisms

An artificial muscle analog for mimicking an organic muscle, substantially disposed within a void or cavity, defined by an interior surface, within a first substantially rigid member or exoskeletal bone, comprising;

• a substantially flexible artificial tendon or cable of diameter substantially less than the dimensions of said cavity, having a first fixed end and a second free end, disposed substantially within said cavity;
• a plurality of cable constraint points for constraining the motion of said cable, each located on said interior surface, including a first fixed cable constraint point and a group of one or more second sliding cable constraint points;
• wherein said fixed end of said cable is affixed to said bone at said fixed constraint point;
• a group of one or more low-friction rollers, guides or cable positioning means, each disposed near a different one of said sliding cable constraint points, whereby said cable is constrained to pass near each said sliding point, each of said guides nevertheless allowing said cable to slide freely past the point near said guide with relatively little friction;
• whereby a shortest cable path is defined, it being the unobstructed path followed by said cable when taut, from said first point through each of said guides, thereby passing near each of said second points within said cavity;
• a group of one or more inflatable bladders, each affixed to said interior surface, each said bladder placed such that it forces said cable to deviate from said shortest cable path, when inflated;
• and
• a plurality of valves or connection means whereby one or more of said bladders may be selectively connected to ones of pressurized fluid reservoirs selected from a group of one or more pressurized fluid reservoirs.

A control means for controlling a first or primary pneumatic or hydraulic actuator and a second or opposed pneumatic or hydraulic actuator, said actuators being of arbitrary type, which actuators are arranged so as to act in opposition to one another to control the motion of an object, said actuators having a first port and a second port whereby pressurized fluids may be connected to said first and second opposing actuators, respectively, comprising:

• a first fluid reservoir having a first high pressure and a second fluid reservoir having a second low pressure, said high pressure being greater than said low pressure;
• a first or primary connection means whereby either reservoir may be selectively connected to said first port, which is controlled using a primary variable control signal which can be varied;
• such that when said control signal is greater than a first upper threshold value, said connection means connects said first port to said first reservoir;
• whereby said high pressure fluid attempts, through said first actuator, to move said object in a first direction;
• and
• such that when said control signal is less than a first lower threshold value, said connection means connects said first port to said second reservoir;
• whereby said low pressure fluid attempts, through said first actuator, to move said object in the opposite direction;
• a second or opposed connection means whereby either reservoir may be selectively connected to said second port, which is controlled using an opposed variable control signal which can be varied;
• such that when said control signal is greater than a second upper threshold value, said connection means connects said second port to said second reservoir;
• whereby said low pressure fluid attempts, through said second actuator, to move said object in said first direction;
• and
• such that when said control signal is less than a second lower threshold value, said connection means connects said second port to said first reservoir;
• whereby said high pressure fluid attempts, through said second actuator, to move said object in said opposite direction.