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Continuum manipulator Ville Rahikka Manipulator basics • Basic types of manipulators: o Discrete (arms) o Serpentine • more discrete joints, redundancy/maneuverability increase o Continuum • no discrete joints and rigid links • bends (trunks, tentacles) Continuum robot • Two main methods: o actuation by cable/tendon o pressurized systems • Bulk of the mechanisms used for actuation not located directly on the robot (manipulator) • “Backbone” structure o sufficient amount of bending stiffness for support and maneuverability Continuum basics • Conventional manipulator a): o A serial of actuated joints o Every joint is actuated and rigidly connected to the next joint (3 DOF) • Continuum manipulator b): o Torque at the tip, coupling e.g. springs transmits the torque to the other joints (1DOF) QuickTime™ and a decompressor are needed to see this picture. Elephant’s trunk manipulator: • Hybrid of three classes • Four sections with 2 DOF actuated with cable servo system = 8 actuable DOF QuickTime™ and a decompressor are needed to see this picture. Elephant’s • Each section is based on four links serial connected by four 2 DOF joints • Elastic connections between each joint thus coupling all the joints • Total 32 kinematic DOF QuickTime™ and a decompressor are needed to see this picture. Objection: • ”Cable-tendons must be tensioned or the cables become snarled or fall off drive pulleys limiting robot speed” OctArm Continuum manipulator • Air muscle actuators a.k.a McKibben actuators o maximum pressure 8,27 bar o Consturcted by covering latex tubing with double helical weave, plastic mesh sheath. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. OctArm Continuum manipulator QuickTime™ and a decompressor are needed to see this picture. • first 2 sections with 6 control channels and last two with 2 control channels • Six actuator design o located at large radius o higher stiffness and load capacity QuickTime™ and a decompressor are needed to see this picture. • Three actuators o closely-spaced actuators o high curvature References: o http://www.ces.clemson.edu/~ianw/ o OCRobotics