Teeny-Weeny Hardware Platforms That Get Up and Walk

Teeny-Weeny Hardware Platforms That Get Up and Walk Around: Smart Dust, Microrobots, and Macrorobots Michael Scott, Brett Warneke, Brian Leibowitz, Seth Hollar, Anita Flynn, Sarah Bergbreiter, and Kris Pister UC Berkeley NEST Retreat, Spring 2002

Overview • Smart Dust – Concept – Where we are now • Microrobots – Concept – Where we are now • Macrorobots – Concept – Where we are now • Conclusions NEST Retreat, Spring 2002

Overview • Smart Dust – Concept – Where we are now • Microrobots – Concept – Where we are now • Macrorobots – Concept – Where we are now • Conclusions NEST Retreat, Spring 2002

Smart Dust - Concept Interrogating Laser Beam Laser Lens Mirrors Passive Transmitter with Corner-Cube Retroreflector Active Transmitter with Beam Steering Sensors Incoming Laser Communication Photodetector and Receiver Analog I/O, DSP, Control Power Capacitor Solar Cell Thick-Film Battery 1 -2 mm NEST Retreat, Spring 2002

330µm Smart Dust - Processes (CMOS) ambient light sensor Photodiode Sensor input Power input ADC TX Drivers 0 -100 kbps CCR or diode Power Oscillator 13 state FSM Optical Receiver controller 1 mm What’s working – Oscillator, FSM, ADC, photosensor, TX drivers What’s kind of working – Optical receiver (stability problems lead to occasional false packets) NEST Retreat, Spring 2002

Smart Dust - Processes (MEMS) 2. 8 mm 2. 1 mm Solar Cells CCR Accelerometer CMOS IC NEST Retreat, Spring 2002

Smart Dust - Integration Solar Cell Array CCR XL CMOS IC 16 mm 3 total circumscribed volume ~4. 8 mm 3 total displaced volume NEST Retreat, Spring 2002

Smart Dust - Microcontroller • • 8 -bit datapath, 12 -bit addressing • Dual program and data memories Load-store RISC-style 32 registers, but most are for special hardware interfacing – Five general purpose – Two autoincrementing – 16 -bit RTC – Five timers – Four config/status Laser reprogrammable System sleeps most of the time, but woken up by various timers Software support – Assembler – Cycle-accurate simulator w/power estimation – Compiler Common sensor node tasks are automated by the hardware – Receiver decodes packets • Stores new code or data in memory • Executes immediate instructions • Allows message packets to be interpreted by the datapath – Transmitter • Synchronous or asynchronous • Can stream a block of memory – ADC interface has several modes ranging from automatically taking a sample, thresholding it, and storing it to memory to allowing full program control NEST Retreat, Spring 2002

Smart Dust - Instruction Set • • • • Move, Move Immediate Load Store Add, add w/carry Sub, sub w/carry AND, OR, XOR, complement Compare, signed and unsigned Shift – one bit Bit set/clear/xor/test Branch, Always, zero, carry, no carry Call – direct and function pointers Software Interrupt Halt • 1 cpi for all, but no pipelining • Addressing modes – Direct – Register indexed • Timers – Transmit – Receive – power up, check for signal – Sample sensor 1, 2 – Software wake-up NEST Retreat, Spring 2002

Smart Dust - Peripheral Specs • ADC – Consumes 1. 8 u. W at 10 k. S/s (180 p. J/sample 23 p. J/bit) – 8 -bits, “information-on-demand” • Optical Receiver – Consumes 26 u. W at 375 kbps (69 p. J/bit) – Receives 50 n. W (-43 d. Bm) optical signals (visible through near IR) – 1 mrad transmit beam @ 50 m req. 10 m. W optical transmit power • CCR Passive Transmitter – Consumes 350 p. W at 175 bps (2 p. J/bit) – Requires laser interrogation beam which acts as the downlink beam as well • Photosensor and 1 -axis accelerometer integrated NEST Retreat, Spring 2002

Overview • Smart Dust – Concept – Where we are now • Microrobots – Concept – Where we are now • Macrorobots – Concept – Where we are now • Conclusions NEST Retreat, Spring 2002

Microrobots - Concept Goal: Make silicon walk. Motor and Linkages Chip Solar Cells, High Voltage Chip NEST Retreat, Spring 2002 • Autonomous • Articulated • Size ~ 1 -10 mm • Speed ~ 1 mm/s CMOS Chip

Microrobots - Processes • • • CMOS Process • National’s 0. 25 micron 5 metal layer process High Voltage Electronics and Solar Cell process • Fabricated in-house • Demonstrated Solar Cells ~ 30 Volts Mechanical Linkages and Actuators Process – Glass Reflow Process NEST Retreat, Spring 2002

Microrobots - Integration Thinned Solar Cell/High Voltage Chip Thinned CMOS Chip Inchworm Motors Leg Solar Cells/ High Voltage CMOS Assembly Legs and Motors Substrate Wire Bonds NEST Retreat, Spring 2002

Microrobots - Test Results NEST Retreat, Spring 2002

Overview • Smart Dust – Concept – Where we are now • Microrobots – Concept – Where we are now • Macrorobots – Concept – Where we are now • Conclusions NEST Retreat, Spring 2002

Macrorobots - Concept Objectives: • Use off-the-shelf components to build inexpensive and modular autonomous robots • Take advantage of Rene motes and Tiny. OS for wireless networking and modularity Goals: • Build 50 robots to test various distributed algorithms NEST Retreat, Spring 2002

Macrorobots - Hardware • Motor-Servo board interfaces any combination Motor-Servo Board of two motors, servos, and solenoids to a toy car platform • Sensor boards are currently being prototyped, including a whisker board for (Top) obstacle detection and a digital accelerometer Whisker-Accel (ADXL 202) board for crude Board odometry • Low-level software components written to (Bottom) abstract hardware NEST Retreat, Spring 2002

Macrorobots - TOS Components • Abstract the hardware from the application (Ping -Pong) • Allows use of separate platforms or sensors without having to change code (whisker v. accel, tank v. car) • Simple applications written without worrying about hardware NEST Retreat, Spring 2002

Overview • Smart Dust – Concept – Where we are now • Microrobots – Concept – Where we are now • Macrorobots – Concept – Where we are now • Conclusions NEST Retreat, Spring 2002

Conclusions Projected milestones: • Smart Dust – Microcontroller (10 -bit addressing) – late March 2002 – 12 -bit addressing version to follow • Microrobots – Integrated with dust mote – December 2002 • Macrorobots – Several mobile motes – March 2002 – 50 “intelligent” mobile motes – May 2002 NEST Retreat, Spring 2002

Aside - Optical Communications • Large antenna gain (~1 e 6) • Small radiator (mm scale) • Spatial division multiple access (SDMA) • Received power ~1/d 2 (vs. ~1/d 2 7 for RF) • No FCC regulations/right-of-way constraints • Rx and Tx can be the same beam • Output efficiency 2 km – Optical • Laser slope efficiency • Poverhead = 1µW-100 m. W Laser CCR RF True Efficiency Slope Efficiency – RF • GMSK slope efficiency ~50% • Poverhead = 1 -100 m. W NEST Retreat, Spring 2002 100 n. J Pout Poverhead Pin

Aside - Energy Comparisons • Bluetooth – Transmit 1 m. W for 1 ms - 1 n. J/bit fundamental Tx cost. – Actual Tx, Rx power drain ~100 m. W - 100 n. J/bit, 10 s of meters? • GSM – Rx power drain= ~200 m. W 2 u. J/bit – Tx power drain= ~4 W 40 u. J/bit, <10 km • Optical (laser) – 10 n. J/bit 1 -10 km – 20 p. J/bit 0 -50 m NEST Retreat, Spring 2002