CETDP Surface Systems Review 7/99 Participants and Facilities Objectives Schedule and Funding Personnel: MIT - Salisbury/Anthony JPL - Schenker/Wilcox ARC - ARC - Thomas, Shirley, Costa Facilities: MIT AI WAM Lab MIT AI Rover Lab MIT AI Haptic Lab Acquisition of Buried Samples via enhanced arm mechanics adaptive digging and sampling Compact/Compliant Arm Design for digging SSX “Imaging” Technology via technology assessment single and multiple down-hole sensors data interpretation Sample Acquisition surface/vis. sub-surface -x-----x------x- impacting -----x least resistance path x-- efficient digging -----x------x--- efficient arm x------x- excavation-----x------x- (soil properties while dig.) (sub-surface) Compact Compliant Arm Design for Digging 1-DOF Technology Study --x x--- 5-DOF Arm Design ---x---x-- Fabrication ---x--- SSX Technology imaging assessment ---x x x- single down-hole sensors --x- multi down hole sensors --x-----x----x- (constellation reconfiguration) (sensors in cable) Funding (incl. JPL OH) ?? ?? SAGE; CADD; and SSX Technology - MIT/AI Lab

CETDP Surface Systems Review 7/99 Task history and accomplishments prior to FY 99 Adaptive Digging –Cartesian impedance based digging method –Path of least resistance for yanking of constrained objects. –Obstacle Avoidance and Detection –Experiments to gain insight into the primary challenges in robotic digging and buried object retrieval. –Buried Rock Removal Strategies –FEM/BEM Soil-Tool Interaction Modeling Compliant Arm Design –Linear Compliant Elements Series Elastic Actuator Haptic Geology Proof-of-Concept –Sensing and simulation for planar, rigid textures based on a stick slip friction model and a simple representation of surface micro- geometry –Modeling, Sensing, and Display –Grows into MarsScape project. SSX Technology –Ultrasonic Material Properties Sensor (UMPS) Identify: Rock Crystal Size, Density, Speed of Sound –Soil, Water Content Characterization Radar, Acoustic –Simple TOF Tomographic Inversion, Constellation of Acoustic Receivers –Scale model experiments / verification. –Preliminary Sensor Package for deployed arrays.

CETDP Surface Systems Review 7/99 Evaluate and develop soil-tool interaction models. Demonstrate robust techniques designed to follow the contour of buried obstacles. Select and develop appropriate force control techniques for interacting with deforming compliant media (soils). Use knowledge of soil properties and soil-tool interaction modeling to locally improve trenching efficiency. Development of control methodology which can do basic online adaptation to the varying soil mediums. Identify planetary science tasks that can be made possible, or greatly improved by our unique combination of non-linear (exponential) mechanical compliance and adaptive force control algorithms. Implement path of least resistance algorithm and other algorithms on a compliance added JPL arm Level-1 milestone and level-2 milestones for FY 99 Develop 1-DOF prototypes to verify and refine the "compliance element" models Characterize performance of prototypes for simple contact tasks and positioning tasks. Develop design specification of a "ruggedized" arm mechanism capable of withstanding the shocks and harshness of scraping and digging tasks. Evaluate the design tradeoffs associated with cable driven actuators for planetary robotics Arm design and fabrication. Report on a comparative/metric basis for the work. Performance of identified tasks with/without the compliance enhancement. Continue to develop 3D tomographic inversion routines using a surface distributed constellation of receivers. Work with Brian Wilcox over the summer to experimentally determine acoustic-radiation pattern for the SSX. Incorporate experimentally acquired acoustic radiation pattern in to the tomographic inversion models. Report on performance benchmarks, as measured by resolution at depth, and error in identified obstacle location. Adaptive Sample Acquisition Compliant Arm Design SSX Technology

CETDP Surface Systems Review 7/99 Goal: Bring new technologies for remote information gathering and presentation to the NASA planetary exploration effort. Our activities are linked to the following specific NASA projects: Long Range Science Rover, Microlander Dexterous Manipulator, Lightweight Survivable Rover Sample Acquisition Project and the Rover Design and Integration program (Schenker - JPL) MVACS Arm (Bonitz - JPL) Demonstration and evaluation of sample and information acquisition with a compliant arm versus a similar (kinematics) non-compliant arm. Develop adaptive sample excavation, digging, and manipulation algorithms for intelligent sample acquisition. Sub-Surface explorer (SSX) program at (Wilcox - JPL) Provide “vision” and sensory feedback to the SSX. Relevance to NASA This and the following slides…..

CETDP Surface Systems Review 7/99 Compliant Arm Design for Digging Surface Systems PRODUCT DESCRIPTION : Arm designs containing non-linear (exponential) mechanical compliance. Control algorithms for using said arms for efficient excavation and digging. PRODUCT FUNCTION : Provide a robust arm design for interacting with unknown obstacles and environments. A naturally compliant arm can be used as a force sensor to enable force control. UNDERLYING TECHNOLOGIES : Exponentially stiffening compliance to provide constant force measurement resolution over the entire dynamic range. Metrics: Improved force measurement over entire dynamic range. Improved response to the complex dynamics of active digging and trenching. Current TRL TRL 2 (99) PRODUCT DEVELOPERS J.K. Salisbury/ Andrew Curtis / Arrin Katz / 5899 / 8966 CUSTOMERS Paul Schenker Exponential Compliant Coupling Springs

CETDP Surface Systems Review 7/99 Sample Acquisition, Grasping, and Excavation Surface Systems PRODUCT DESCRIPTION : Control algorithms and sensor specifications to provide for power/energy efficient surface and near surface sample acquisition PRODUCT FUNCTION : Robotic Technology for Buried Sample Acquisition. UNDERLYING TECHNOLOGIES : Force controlled arm/surface interaction. Compliant arm control. Metrics: Soil displaced/removed vs. power. Rock surface exposed vs. time & power. Current TRL TRL 3 (99) PRODUCT DEVELOPERS J.K. Salisbury / W. Jesse Hong / / CUSTOMERS Paul Schenker Bonitz

CETDP Surface Systems Review 7/99 PRODUCT DESCRIPTION : Algorithms and sensor specifications to provide “Vision” to the Subsurface Explorer PRODUCT FUNCTION : Provide “Vision” to the Subsurface Explorer for obstacle avoidance and navigation. UNDERLYING TECHNOLOGIES : SSX acts as acoustic source. Constellation of receivers on surface. 3D Tomographic inversion to provide a map of subsurface features and obstacles. Current TRL TRL 2 (99) PRODUCT DEVELOPERS Brian Anthony / CUSTOMERS Brian Wilcox - Subsurface Explorer Potential Customers: Rover based systems to provide underground map/image of an area local to a rover. Ex: Ben Dolgin for underground drilling. SSX Technology - Underground “Vision” Surface Systems - Subsurface Explorer

CETDP Surface Systems Review 7/99 Progress….

CETDP Surface Systems Review 7/99 Obstacle Negotiation in Robotic Excavation Wrote and submitted a conference paper documenting our previously developed techniques for obstacle negotiation and contour following in robotic excavation. –Hong, WJ and Salisbury, JK. “Obstacle Negotiation in Robotic Excavation”, IASTED Robotics and Applications 1999 Soil-Tool Interaction Modeling Wrote basic simulation code to study existing soil-tool interaction theories for predicting draft forces during excavation. This is a necessary stepping stone to improving digging effectiveness and for developing techniques for extracting soil characteristics from interaction data. Determination of the path of least resistance is used to trace the contour of the object, technique was verified experimentally. Three dimensional model of soil failure zones. Factors contributing to net resistance force are shown in green. Sample Acquisition, Grasping, and Excavation (SAGE)

CETDP Surface Systems Review 7/99 Non-linear (exponential) force- displacement curve successfully obtained. Will provide for a constant dynamic range force measurement. 1-DOF Test Mechanism of a Compliant Element Cable Transmission 1-DOF Test-Mechanism of “Wrapping-Spring” Compliant Joint Designed a prototype rover scale YPPR arm for the evaluation of integrated compliant element performance during digging tasks. Beginning construction now. 14 in 12 in Compliant Arm Design for Digging - CADD –Prototype exhibits desirable nonlinear behavior over  30° range for  800 mNm force range -- working on increasing the force range without sacrificing sensitivity or range of motion. –Dynamic range of 100 demonstrated (Max force exerted / Min force detected) -- limited by sensor resolution (encoder) -- working on better resolution in a smaller package using a potentiometer.

CETDP Surface Systems Review 7/99 SSX Imaging Technology Constellation of Receivers Surface SSX Obstacle Sound Path Developed theory, and algorithms to image subsurface obstacle using a buried source (the SSX) and a Constellation of Receivers. Demonstrated need for re- configurable Constellation as depth of SSX is increased. The code for a travelling SSX and the algorithm for redeployment of Receivers is being developed. If the constellation of receivers is stationary as the SSX goes deeper, it becomes difficult to pinpoint the location of the obstacle. Obstacle LocationImaged Location SSX Distance From Surface: 0 m 700 m 1500 m Note: SSX not drawn to scale. 100 m 200 m