180 likes | 578 Views
Comparing the Locomotion Dynamics of a Cockroach and a Shape Deposition Manufactured Biomimetic Robot Sean A. Bailey, Jorge G. Cham, Mark R. Cutkosky Biomimetic Robotics Lab Stanford University Robert J. Full PolyPedal Laboratory University of California at Berkeley December 12, 2000
E N D
Comparing the Locomotion Dynamics of a Cockroach and a Shape Deposition Manufactured Biomimetic Robot Sean A. Bailey, Jorge G. Cham, Mark R. Cutkosky Biomimetic Robotics Lab Stanford University Robert J. Full PolyPedal Laboratory University of California at Berkeley December 12, 2000
Overview Intro Design SDM Dynamics Conclusions • Introduction • Shape Deposition Manufacturing • Robot Design • Locomotion Dynamics • Conclusions
Introduction Intro Design SDM Dynamics Conclusions • Motivation • Small • Fast • Robust • Integrated approach • Biomimetic structures • Biologically-inspired control De-mining in an unstructured environment
Shape Deposition Manufacturing (SDM) Piston Fitting Inlet Valve Pressure Sensor Exhaust Valve Leaf-spring Intro Design SDM Dynamics Conclusions Manufacturing Prototype Limb with Embedded Pneumatic Actuator, Sensor, Leaf Spring and Valves
Shape Deposition Manufacturing (SDM) Multi-material part w/ embedded components Intro Design SDM Dynamics Conclusions • Arbitrary geometries • Embedded components • No fasteners • Multi-materials • Tailored compliance Graded, multi-material 5-bar
Biological Example Intro Design SDM Dynamics Conclusions • Death-head cockroach Blaberus discoidalis • Fast • Speeds of up to 10 body/s • Rough terrain • Can easily traverse fractal terrain of obstacles 3X hip height Blaberus discoidalis running over fractal terrain
Biological Inspiration Intro Design SDM Dynamics Conclusions • Control heirarchy • Passive component • Active component Neural System (CPG) Feedforward Motor Pattern Sensory Feedback (Reflexes) Mechanical System (muscles, limbs) Mechanical Feedback (Preflexes) Environment Passive Dynamic Self-Stabilization Locomotion Full and Koditschek, 1999
Robot Design Intro Design SDM Dynamics Conclusions Cockroach Geometry Functional Biomimesis Robot Implementation • Passive Compliant Hip Joint • Effective Thrusting Force • Damped, Compliant Hip Flexure • Embedded Air Piston • Rotary Joint • Prismatic Joint Cham et al., 2000, Clark et al., 2001
Sprawlita Intro Design SDM Dynamics Conclusions Actuators and wiring embedded inside structure • Mass - .27 kg • Dimensions - 16x10x9 cm • Leg length - 4.5 cm • Max. Speed - 55 cm/s 3+ body/sec • Hip height obstacle traversal Legs with Compliant Flexures 2.5 cm
Movie Intro Design SDM Dynamics Conclusions • Superficially insect-like • Stable running • Obstacle traversal
Whole Body Dynamics 15 filtered vertical force unfiltered horizontal force 10 Force (N) 5 0 High speed video markers High speed video markers -5 450 550 650 750 Time (ms) Force plate Locomotion Direction Intro Design SDM Dynamics Conclusions • Force plate • High speed video Force Plate Data High-speed Footage with Markers
Animal Running - the SLIP model Intro Design SDM Dynamics Conclusions SIX- Legged EIGHT- Legged Cockroach Crab B o d y V e r t i c a l TWO- Legged W e i g h t F o r c e FOUR- Legged Fore-aft F o r c e T i m e Spring-Loaded Inverted Pendulum SLIP Blickhan 1989 Human Dog Cavagna et al., 1975
Whole Body Ground Reaction Forces Intro Design SDM Dynamics Conclusions Spring-Loaded Inverted Pendulum (SLIP) Blaberus discoidalis Sprawlita 6 0.025 4 Vertical Force 0.02 2 0.015 .004 2 0 Fore-aft Force 0 -.004 -2 0 50 100 20 40 60 80 Time Time (ms) Time (ms) Dragging Accelerate Accelerate Decelerate Decelerate Decelerate Accelerate
Individual leg forces Intro Design SDM Dynamics Conclusions • Sprawlita drags middle and rear foot • Individual legs have functions dissimilar from cockroach legs • More questions • Relative contact time Front Leg Middle Leg Hind Leg 10 12 10 0 0 0 mN ms -6 -6 -6 0 140 0 60 140 0 140 4 4 4 0 0 0 N ms -2 -2 -2 0 20 50 0 50 0 50 filtered vertical force filtered horizontal force Dragging
Summary and Conclusions Intro Design SDM Dynamics Conclusions • Sprawlita • Physically robust • Operationally robust • Open loop • Comparing locomotion dynamics suggests design improvements • Foot drag - longer stroke • If more SLIP-like... • faster? • more efficient? • more robust?
Future Work Valve Cylinder Prototype with close proximity valve and cylinder Double piston extension SDM linkage extension Intro Design SDM Dynamics Conclusions • Sprawley Davidson • Leg extensions • The Sprawlettes • High level, not real-time sensor-based control
Acknowledgements Intro Design SDM Dynamics Conclusions • Stanford • Center for Design Research • Dexterous Manipulation Lab • Rapid Prototyping Lab • Berkeley • PolyPedal Lab • Sponsors • Office of Naval Research • National Science Foundation