PowerPoint

Yoshihiro NAKATA

Intelligent Robotics LaboratoryDep. of Systems Innovation Graduate School of Engineering Science Osaka UniversityTOWARD REALIZING HOPPING OF MONOPEDAL ROBOTBY COMPLIANCE CONTROL

--- Development and application of an electromagnetic linear actuator ---The 28th Brush-up School of GCOE:Cognitive Neuroscience RoboticsFeb. 17th , 2011IntroductionElectromagnetic Linear Actuator for Artificial MusclePlaner Biped RobotHow can robot realize dynamical motion in complicated environment?

Athlete RobotActuator is the key device:Robust for disturbanceImpact absorptionLow processing costImportant factors of actuators for robotsElectromagnetic Linear Actuator for Artificial MuscleLarge output forceSmall size Actuator + Controller + Power sourceChange spring and damper characteristicsQuick responseIt is difficult to realize variable viscoelastic characteristics in small system

xspringdumperactuatorVariable compliance actuatorElectromagnetic Linear Actuator for Artificial Muscle

This actuator can change spring and damper characteristicsQuick responseSmall system Electric powerInteraction with human180mm20Weight: 170gForce: 5.7N/A (Effective current 1A)The electromagnetic linear actuatorElectromagnetic Linear Actuator for Artificial Muscle

Basic structure The effective radial component of flux with an inward and outward direction from the magnetic core The structure of the mover can generate high magnetic flux High power

The mover is robust structure

StatorMoverThis actuator can control output force by controlling exciting current depending on the position of the mover.Hopping of Monopedal RobotElectromagnetic Linear Actuator for Artificial MuscleConcept of the monopedal robotElectromagnetic Linear Actuator for Artificial MuscleVariable compliance actuator Electromagnetic linear actuator In this research, we focus on controlling stiffness in hopping

xspringdumperactuatorImplement the actuator as bi-articular muscle to the monopedal robot Control the stiffness ellipse at foot of the robot Simple control method is proposedStructure of the human legElectromagnetic Linear Actuator for Artificial MusclePelvisFemurTibiaFibulaCalcaneus

HipKnee

HipKneePatellaStiffness ellipseElectromagnetic Linear Actuator for Artificial Muscle

HipKnee

Control the direction by adjusting axesThe stiffness of the leg is expressed as ellipse and its gradient of long axisStiffnessellipseHardSoftThe major axis of the stiffness ellipse is oriented along the direction of maximum stiffnessThe minor axis of the stiffness ellipse is oriented along the direction of minimum stiffnessRelationship between stiffness ellipse and stiffness of musclesElectromagnetic Linear Actuator for Artificial Muscle

The stiffness of f1 e1 become large

The stiffness ellipse rotates in the clockwise direction

The foot move backupward and the robot leans forwardHard

Stiffness ellipse at footMono-articular muscle

Relationship between stiffness ellipse and stiffness of musclesElectromagnetic Linear Actuator for Artificial Muscle

HardThe stiffness of f2 e2 become large

The stiffness ellipse dose not rotateStiffness ellipse at footMono-articular muscle

Relationship between stiffness ellipse and stiffness of musclesElectromagnetic Linear Actuator for Artificial Muscle

HardThe stiffness of f3 e3 become large

The stiffness ellipse rotates in the counter clockwise direction

The foot move foreupward and the robot leans backwardStiffness ellipse at foot

Bi-articular muscleControl of the bouncing direction (Simulation)Electromagnetic Linear Actuator for Artificial Muscle

Hopping direction []Stiffness (f3, e3) [N/m]Stiffness (f1, e1) [N/m]Evaluate the relationship between bouncing direction and stiffness

Stiffnessf3, e3 > f1, e1Stiffnessf1, e1 > f3, e3Monopedal robot with electromagnetic linear actuatorsElectromagnetic Linear Actuator for Artificial Muscle

We will do experimentusing this robot.BeamCounter weight >In the simulator, weight and inertia ofmonopedal robot are considered

A1(M1)A3(M3)A2,1(M2)HipKneeA2,2(M2)210mmWeight:1.2kg

Hopping of the robot (Simulation)Electromagnetic Linear Actuator for Artificial MuscleGroundkcTouch down130msStiffness[N/m]kmTime[s]Take offf1, e1f3, e3f2, e2Control the bouncing direction:

Distribute jumping energy:Actuator ( f1, e1) = 500 [N/m]Actuator ( f3, e3) = 340 [N/m]kc =310 [N/m]km =370 [N/m]Hopping of the robot (Simulation)Electromagnetic Linear Actuator for Artificial Muscle

0xyxyReturn mapHip positionConclusionsElectromagnetic Linear Actuator for Artificial MuscleDevelopment of the electromagnetic linear actuator as a variable compliance actuatorStiffness ellipse is controllableVariable stiffness reduces complexity of control rule

Experiment using the prototypeControl bouncing direction in hoppingEvaluate the effect of viscosity properties for stable hopping

Future works