High-Level Control MURI Low-Level Control Fabrication How do we build robust biomimetic structures and systems? Shape deposition manufacturing of integrated parts, with embedded actuators and sensors (Stanford) How do we build-in tailored compliance and damping? Effects of Compliance in simple running machine (Stanford, Berkeley ME) Structures with functionally graded material properties (Stanford) Guiding questions

MURI Fabrication Biomimetic Structures Increase Robustness Integrated Sensing and Actuation Tailored Structural Properties Boadicea Leg Design (MIT 1995) Contoured Multi-material Prototype

MURI Fabrication Shape Deposition Manufacturing Cycle of Material Deposition and Removal Complex 3D Geometry, Multi-materials Part Support Deposit (part) Shape

MURI Fabrication Shape Deposition Manufacturing Embed Components in mid-process Critical Geometry, Properties Embedded Component Part Support

MURI Fabrication Design-by-Composition Interface Part CompactsSupport CompactsPrimitives Primitive APrimitive B Result Primitive Library Components Merged by Designer

MURI Fabrication Design-by-Composition Interface Part CompactsSupport CompactsPrimitives Primitive APrimitive B Result Primitive Compact List A Compact List B Result Compact List Manufacturing Plans Merged By Algorithm a3 a2 a1 b3 b2 b1 Library Components Merged by Designer

MURI Fabrication Embedded Components Pneumatically-actuated Linkage Piston, Valve, Pressure Sensor, Fittings Design InterfaceProcess Planning

MURI Fabrication Embedded Components Issues in Embedded Components (Cham et. al.) –Fixturing, Retaining Functionality, Tolerances

MURI Fabrication Electrical Connectors Air Connector Embedded Components Reduction of Transport Volumes - Higher Bandwidth SDM moved us to new Control Regime 4 inches

MURI Fabrication Biomimetic Structures Multi-Materials Parts with different properties Arbitrary Geometry, Graded Materials Biological Inspiration Contoured-Shaped Multi-Material Prototype

MURI Fabrication Graded Materials Graded Materials Very Common Nature Few Examples of Functionally Graded Materials in Man-Made Assemblies

MURI Fabrication Graded Materials SDM Allows Variability in Compliance and Damping throughout a Candidate Design

MURI Fabrication Process Plan Graded Materials SDM Allows Control of Material Location and Property in a 3D space Fabrication Cycle

MURI Fabrication Graded Materials Un-Actuated Five-Bar Leg Mechanism Illustrates Benefits of Heterogeneous Material Properties Flexure Joints Replace Pin-Joints to Add Compliance and Damping

MURI Fabrication Graded Materials Desired Performance of Structural and Flexural Regions Very Different Fabricating With Single Material Would Result In Compliant Structural Regions or Brittle, Failure Prone Flexures Ideal Solution Requires Varying Material Properties Between Different Regions of the Part

MURI Fabrication Graded Materials Graded Interface Increases Surface Area, Resulting in Increased Bonding Mixing in Arbitrary Ratios Not Possible Function Needs to Be Applied To Discretize the Graded Regions Based Upon a Specified Tolerance Parameter

MURI Fabrication Compliance for 1 DOF Machine Berkeley 1 DOF Walking Machine Four-Bar Linkages Represent Practical Application Well Suited to Use of Graded Materials

MURI Fabrication Compliance for 1 DOF Machine Reduce Assembly Complexity, Increase Robustness Four-Bar Mechanism Utilizes Two Rotary Joints and Two Rocker Joints Original Design (Berkeley) SDM Re-Design

MURI Fabrication Compliance for 1 DOF Machine Original DesignSDM Re-Design Rocker Pin Joints Replaced With Flexural Regions to Introduce Compliance and Damping

MURI Fabrication Compliance for 1 DOF Machine New Design Features With SDM Geometry: Constant Ground Contact Replaced Pin Joints With Flexural Region: Introduced Compliance & Damping Leg Preflexes Defines by Build Orientation Future Analysis and Experiments to Tune Compliance to Locomotion

Wrap up Status Programmatic issues Plans Feedback

Status -- one year ago: “Building block” design/fabrication environment being tested and first components with embedded sensors, electronics fabricated Meetings among SU, SRI, UCB to determine biomimetic actuators for fabrication and testing at each site Designed and built apparatus for leg stiffness and perturbation experiments Test-bed for compliance manipulation control set up. Experimental results on human adaptive control suggest a specific design for manipulation Modeling and system I.D. applied to capture human walking on hills. The results have been used to develop two-legged machines. Comparison with biological models is underway.

Status (today: ) Detailed characterization of passive (fixed) and active components (adjustable) of preflexes in cockroach. Gecko foot adhesion characterized using new micromachined sensors. Sensors for insect leg forces being designed. SDM* environment used to create small robot limbs with embedded sensing and actuation and functionally graded material properties. SDM robot limbs and compliant non-SDM robot undergoing testing and comparison with results from insect legs. Compliant whole-arm-manipulator test-bed and minimum impedance control strategies demonstrated. Human impedance testing in progress. Model of human motor control learning tested and validated. Fast walker with biomimetic foot trajectory designed and tested; SDM compliant limb retrofit underway. *Shape Deposition Manufacturing

Plans (see project structure chart) Low-Level Control High-Level Control MURI Biomimetic Robots 2nd generation SDM robots with sensing and preflexes