The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-1 Skyworker Preliminary Design Review Field Robotics Center September 10, 1999 William “Red” Whittaker Peter Staritz Chris Urmson

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-2 Constellation of SSP satellites in GEO 1GW of energy to the ground via a microwave transmission antenna 1 km in diameter 150m wide and 10 to 15 kilometers in length Mass of 4800 MT (10X as massive as ISS) Assembled over 1 year, maintained for 30 years Need for robotic systems capable of Assembly, Inspection, and Maintenance (AIM) tasks Space Solar Power (SSP) Facilities

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-3 SSP Facility AIM Solar array –Assembled through automated docking and deployment Microwave antenna –Requires completion of complicated assembly tasks Joining of deployable truss sections Attaching transmitter elements Coupling Power Management and Distribution (PMAD) system Entire facility will benefit from automated inspection and maintenance capabilities

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-4 Space Solar Power Automated Technology Roadmap < 2000 Electrodynamic Propulsion Systems FY99FY00FY01FY02FY03FY04FY05FY06FY07FY08FY09FY10FY11FY12FY13FY14FY15FY16FY17FY18FY19FY20 LEGEND R&D Result-Driven Decision Point Major R&D Prm Milestone Strategic Program Objective Tether and Antenna Front Plane Maneuvering Demonstration single axis ED thruster in uwave field Autonomous Rendevous and Dock Air-bearing precision maneuvering 80% Reliable Fly-to-grapple and Robust Abort Demo terminal guidance sensing system Trajectory planning and optimization Robust control w/ attached robot interaction Force and Redundancy Control Strategies for Cooperative Systems Learning/adapta- tion for unknown payloads&failure 90% Reliable Fly-to- grapple and Robust Abort Sensing/Perception Stable Posture and gait control w/ 4 cooperating truss walkers Perform mating tasks w/ 4 cooperating truss walkers & flex. structure Payload balancing w/ 6 cooperating truss walkers Force-controlled free flyer payload exchange Joint failure compensation and increased structural disturbance Robust locomotion and free flyer interaction in dynamic environment Locate standard grabrail fixture under nominal conditions Identify feducial mark scheme to simplify vision Integrate high- bandwidth optical flow, range, and force to improve grasp reliability Develop compact flight hardware implementation of high-rate vision algorithms Demonstrate strategies to mitigate lighting effects Borrowed from Automated Assembly, Maintenance, and Operations of a Space Solar Power System

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-5 Space Solar Power Automated Technology Roadmap < 2000 FY99FY00FY01FY02FY03FY04FY05FY06FY07FY08FY09FY10FY11FY12FY13FY14FY15FY16FY17FY18FY19FY20 LEGEND R&D Result-Driven Decision Point Major R&D Pgm Milestone Strategic Program Objective Integrated Technology Demos On-orbit walker/free flyer antenna assembly and repair demo Autonomous grasp and locomotion of antenna element Multi. walker automated antenna assembly in neutral buoyancy Multi. walker/free-flyer antenna repair in neutral buoyancy Prototype neutral buoyancy truss walker On-orbit multi. walker antenna assembly demonstration FY05 Decision on first flight demo Assembly and Maintenance Planning Assembly activity planning for 4 cooperating truss walkers Assembly activity planning for 4 cooperating truss walkers + free flyer Simulation and visualization of assembly activity Demo automated Ground Segment operations inc. power sales Demo automated Space Segment operations inc. maintenance flights Demonstrate 100% automation of space and ground segment operations Borrowed from Automated Assembly, Maintenance, and Operations of a Space Solar Power System

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-6 ObjectivesObjectives Demonstrate the viability of using robots for orbital construction Prove the validity of using structure walkers for orbital AIM Demonstrate SSP AIM relevant tasks using robotics Simulate prospective SSP AIM robots and tasks

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-7 Representative Tasks Walk, turn, and transition across planes on a truss structure Pick up and place a payload at arbitrary locations and orientations in space Carry a payload while walking, turning, and transitioning Conduct calibration and inspection tasks Connect power and communications cables Cooperatively carry massive or large payloads Perform tasks that require multiple robot collaboration

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-8 DemonstrationDemonstration Prototype Robot –Pick up and carry a model transmitting element the length of the truss, turn while carrying, couple the element to the structure –Connect Power Management and Distribution (PMAD) to the element –Perform a mock calibration Simulation –Large scale construction utilizing multiple robots –Coordinated installation of full scale transmitting elements –Demonstrate extended lifetime operations

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-9 Program Philosophies Design for Earth based demonstration, but always maintain a path to orbital application Accept a baseline environment (structure, tasks, etc..) Leverage heritage technologies when available Design and manufacture in house whenever possible Consider physical scalability of design Ensure robust software operation through incremental testing of components Maintain software scalability through Object Oriented Principles

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-10 Configuration - Key Metrics Control Complexity –The number of joints that must be actuated in synchrony Continuous Motion –System supports a gait in which the payload can maintain a constant velocity –How difficult it is to control that gait Cost –DOF, links, grippers, sensors, control complexity, gravity compensation Compatibility with gravity compensation –Possible to compensate with available resources, new system or recycled heritage system Forces exerted / Forces experienced –Maximum forces and torques experience/exerted by the robot

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-11 Configuration - Key Metrics (Cont.) Workspace –Effective working volume with one gripper attached to the structure Energy Consumption –The energy consumed by the machine to move a specified distance and speed with a given payload DOF –Total number of joints –Number of different joint types Mass –DOF, links, grippers, sensors, constants Layout of available volume –Sufficient room for onboard components

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-12 ContendersContenders

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-13 N-typeN-type Key Features –Walking posture –Manipulating posture –Sufficient internal volume to allow tetherless operation – Fine motion / Transition Joint Inchworm Gait Cable Mating

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-14 Configuration N-type Control Complexity –At most 4 joints must operate in synchrony for standard gait Continuous Motion –System supports a continuous gait –Simplified gait, uncertainties in only one dimension Cost –Lowest number of total components affecting cost Compatibility with GC –Compatible with heritage system, only minor modifications needed Forces Exerted / Forces Experienced –Normal stride exerts/experiences minimal torques

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-15 Configuration N-type Workspace –N-type “unfolds” to become a 3 link manipulator Energy Consumption –Continuous gait and fewer motors needed for standard stride result in lower consumption DOF –11 joints, 3 grippers Mass –~35 kilograms Layout of available volume –Sufficient room for onboard components

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-16 Gripper Design Issues Skyworker will move its own mass in addition to a payload –Increased possibility of truss failure due to point loads –Gripper faces will be extended and shaped to match the structure (reducing point loads) Rotation about the longeron is a possibility –High coefficient of friction coatings Simple structure detection is necessary –Proximity sensors (capaciflectors)

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-17 JointsJoints 3 Joint types –3 Axial revolute joints –2 Offset revolute joint –6 Inline revolute joints

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-18 Force Analysis Forces: -Payload Inertia -Arm’s Inertia Given: -Payload Velocity -Payload acceleration Concept of “Walking lightly” Largest forces occur during a standard stride as opposed to during acceleration 2 forms of force analysis –Further analysis will minimize the torque generated by the base joints

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-19 Maximum Torques A C D B

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-20 Gravity Compensation Allows for maneuvers not possible in normal gravity Passive compensation –Counterweight system –Transmission 10:1 ratio –Active X-Y table –Heritage system

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-21 Power Electronics Tetherless operations 20 minute demonstration Less than 40 watt-hours of energy at a peak rate of 120W +/- 30% Mass Constraint –  3kg (batteries/charger/converters) Volume Constraint

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-22 Battery Recharging Onboard Charging Solution –Power obtained through special gripper –Contact with electrified terminal on demonstration structure –Inductively Coupled Charging a future possibility –All charging electronics/distribution onboard Battery Monitoring System –Automatically detects when charge is necessary –Returns to ‘Charging Station’ when needed –Disconnects and returns to work when fully recharged

The Next Step SPACE ROBOTICS INITIATIVE Skyworker PDR 9/10/99-23 Battery Technologies Batteries we considered: NiCd batteries selected for prototype, different battery technology may be used in space applications.