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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
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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
Interrogating Laser Beam Laser Lens Mirror Mirrors Incoming Laser Communication Active Transmitter with Beam Steering Passive Transmitter with Corner-Cube Retroreflector Photodetector and Receiver Sensors Analog I/O, DSP, Control Power Capacitor Solar Cell Thick-Film Battery 1-2mm Smart Dust - Concept NEST Retreat, Spring 2002
TX Drivers 0-100kbps CCR or diode Power Power input ambient light sensor Photodiode Oscillator ADC Optical Receiver 13 state FSM controller Sensor input Smart Dust - Processes (CMOS) 330µm 1mm 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
CCR Solar Cells Accelerometer CMOS IC Smart Dust - Processes (MEMS) 2.8mm 2.1mm NEST Retreat, Spring 2002
Smart Dust - Integration Solar Cell Array CCR XL CMOS IC 16 mm3 total circumscribed volume ~4.8 mm3 total displaced volume NEST Retreat, Spring 2002
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 Smart Dust - Microcontroller • 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
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 Smart Dust - Instruction Set • 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 uW at 10 kS/s (180 pJ/sample 23 pJ/bit) • 8-bits, “information-on-demand” • Optical Receiver • Consumes 26 uW at 375 kbps (69 pJ/bit) • Receives 50 nW (-43 dBm) optical signals (visible through near IR) • 1 mrad transmit beam @ 50m req. 10 mW optical transmit power • CCR Passive Transmitter • Consumes 350 pW at 175 bps (2 pJ/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
Solar Cells, High Voltage Chip Motor and Linkages Chip CMOS Chip Microrobots - Concept • Autonomous • Articulated • Size ~ 1-10 mm • Speed ~ 1mm/s Goal: Make silicon walk. NEST Retreat, Spring 2002
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 TinyOS 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 of two motors, servos, and solenoids to a toy car platform • Sensor boards are currently being prototyped, including a whisker board for obstacle detection and a digital accelerometer (ADXL202) board for crude odometry • Low-level software components written to abstract hardware Motor-Servo Board (Top) Whisker-Accel Board (Bottom) NEST Retreat, Spring 2002
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 Macrorobots - TOS Components 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
Laser CCR RF Pout True Efficiency Slope Efficiency Poverhead Pin Aside - Optical Communications 2km • Large antenna gain (~1e6) • Small radiator (mm scale) • Spatial division multiple access (SDMA) • Received power ~1/d2 (vs. ~1/d27 for RF) • No FCC regulations/right-of-way constraints • Rx and Tx can be the same beam • Output efficiency • Optical • Laser slope efficiency • Poverhead = 1µW-100mW • RF • GMSK slope efficiency ~50% • Poverhead = 1-100mW 100nJ NEST Retreat, Spring 2002
Aside - Energy Comparisons • Bluetooth • Transmit 1mW for 1ms - 1nJ/bit fundamental Tx cost. • Actual Tx, Rx power drain ~100mW - 100nJ/bit, 10s of meters? • GSM • Rx power drain= ~200mW 2uJ/bit • Tx power drain= ~4W 40 uJ/bit, <10km • Optical (laser) • 10nJ/bit 1-10km • 20pJ/bit 0-50m NEST Retreat, Spring 2002