High-Level Control

1. MURI Fabrication Guiding questions Low-Level Control High-Level Control 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? Structures with functionally graded material properties (Stanford) Effects of Compliance in simple running machine (Stanford, Berkeley ME)

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

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

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

5. MURI Fabrication Design-by-Composition Interface Library Components Merged by Designer Primitive A Primitive B Result Primitive Primitives Part Compacts Support Compacts

6. MURI Fabrication Design-by-Composition Interface Library Components Merged by Designer Manufacturing Plans Merged By Algorithm a3 b3 a2 b2 a1 b1 Compact List A Compact List B Primitive A Primitive B Result Primitive Result Compact List Primitives Part Compacts Support Compacts

7. MURI Fabrication Embedded Components • Pneumatically-actuated Linkage • Piston, Valve, Pressure Sensor, Fittings Design Interface Process Planning

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

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

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

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

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

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

14. 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

15. 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

16. 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

17. 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

18. 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

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

20. 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

21. Wrap up • Status • Programmatic issues • Plans • Feedback

22. Status -- one year ago: 9.10.98 • “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.

23. Status (today: 9.2.99) • 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

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