BigDog Overview



                        November 22, 2008




©2008 Boston Dynamics
BigDog Architecture
                      Heat Exchanger
Gyro/IMU
                        Engine/Pump
Hip
                ...
Engine


         •   Leopard go-kart engine
         •   One cylinder
         •   Two stroke
         •   Water cooled
 ...
Hydraulic System
  • Variable displacement hydraulic pump (3,000 psi)
  • Custom actuator package (x16)
     –   Low-frict...
Hydraulic System   Engine
Multi-jointed Legs
  Animal                                   BigDog


            Actuation                          Actu...
Component Layout




   Component                Weight
   Heat Exchanger           9.62 lbs
   Engine / Drive / Pump:   2...
Sensors
GPS               LIDAR

Battery Voltage

Ring Laser        Stereo Vision
Gyro & Linear
Accelerometers

Engine Tem...
BigDog Sensors
                   Measurement
  Type                                       Location    N
                 ...
Onboard Computer
•   PC104 stack
•   Pentium CPU
•   QNX real-time OS
•   Code: C++
•   Custom I/O interface boards
•   Fu...
Software Architecture
HUMAN FOLLOWING                     10Hz   PLANNING                              2Hz          DATA L...
Software Processes

Function:      Control          Servo             Logging
Description:   Main process.    Joint contro...
Vest Operator
Control Unit (OCU)
               Head Mounted
                  Display

                 900 Mhz
         ...
Control Principles

                     Support - Bounce on
                     springy legs




                     Ba...
Control – BigDog
                            Net force
Maintain Body Posture       & moment
• Control of body posture
  th...
Control – BigDog
                            Net force
Maintain Body Posture       & moment
• Control of body posture
  th...
Control – BigDog

Maintain Body Posture
• Control of body posture
  through force control
Maintain Ground Contact         ...
Additional Controls
  • Estimate ground plane using history of
    leg kinematic data and odometry
  • Adjust posture to o...
Trot Control Features
• Engine Power Control.
     • Engine RPM regulated in response to actual
       and predicted load....
Trot Control
• X – Closed loop. Speed error corrected
  by x direction foot forces.
• Y – Lateral foot position chosen to ...
LIDAR Leader Tracking
• Follow leader without direct driving and without GPS:
   – Leader wears retro-reflective marker
  ...
End
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Big Dog - американский военный робот

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Big Dog - американский военный робот

  1. 1. BigDog Overview November 22, 2008 ©2008 Boston Dynamics
  2. 2. BigDog Architecture Heat Exchanger Gyro/IMU Engine/Pump Hip Computer Knee Actuators Ankle Leg Spring Foot Force Sensor
  3. 3. Engine • Leopard go-kart engine • One cylinder • Two stroke • Water cooled • 9,000 rpm • ~15 hp • Electric starter
  4. 4. Hydraulic System • Variable displacement hydraulic pump (3,000 psi) • Custom actuator package (x16) – Low-friction hydrodynamic seals – 2-stage electro-hydraulic servovalve – Position sensor – Force sensor • Heat exchanger • Various filters, manifolds, accumulators, and valves Hydraulic Actuator Package
  5. 5. Hydraulic System Engine
  6. 6. Multi-jointed Legs Animal BigDog Actuation Actuation More compliance Less actuation Compliance Compliance + + Actuation Actuation Compliance + Dissipation Dissipation
  7. 7. Component Layout Component Weight Heat Exchanger 9.62 lbs Engine / Drive / Pump: 26 lbs / 1.42 lbs / 6.5 lbs Fuel tank / Fuel: 2.1 lbs / 10.4 lbs Oil tank: 3.6 lbs
  8. 8. Sensors GPS LIDAR Battery Voltage Ring Laser Stereo Vision Gyro & Linear Accelerometers Engine Temp Joint angles & Speed & forces Hydraulic Pressure, Flow & Temp
  9. 9. BigDog Sensors Measurement Type Location N Quantity Knee, Linear Pot Joint displacements Hip (2), 16 Ankle Load Cell Actuator, ankle force Legs 16 Current Sensor Servo valve current eBox 16 Proprioception Stereo Vision Obstacles, Optic Flow Body 3 Ground Slope LIDAR Human Tracking Body 1 Gyro 3 angular rates 3 linear accelerations Body 6 Exteroception Temperature Engine, Oil temperature Body 3 Flow Oil flow Body 4 Pressure Oil pressure Body 2 Homeostasis Engine RPM Governor Body 2 Battery voltage Total 69
  10. 10. Onboard Computer • PC104 stack • Pentium CPU • QNX real-time OS • Code: C++ • Custom I/O interface boards • Functions Performed: – Control – Sensing – Data Collection – Communications – Electric Power Distribution
  11. 11. Software Architecture HUMAN FOLLOWING 10Hz PLANNING 2Hz DATA LOGGING 200Hz LIDAR Position Terrain Map Laser Data Object Tracking Long Term 30 Sec Data Log Cost Map Fault Log Terrain Map 5k vars Planned Path Visual Odometry Smoothed Path POSE ESTIMATION 200Hz IMU Visual Leg CONTROL 200Hz Odometry Kinematics 802.11 GPS IMU Smoothed Path Joint Data World Position, Orientation Engineering Interface Steering Command IK Gait Control TDLO DEVICE DRIVERS 1kHz Actuation Commands 900 MHz RF IMU Joint Data LIDAR GPS ACTUATION 1kHz Operator Interface Position Servos Force Servos
  12. 12. Software Processes Function: Control Servo Logging Description: Main process. Joint control, Log engineering Balances and read sensors, data for steers robot, command performance odometry, actuators, development communicates engine control. and failure with operator. analysis. Update 200 Hz 1,000 Hz 200 Hz Frequency:
  13. 13. Vest Operator Control Unit (OCU) Head Mounted Display 900 Mhz Antenna HMD Electronics Steering controller OCU Computer Battery 900 Mhz Radio
  14. 14. Control Principles Support - Bounce on springy legs Balance - Move legs with symmetry to achieve balance Posture - Keep body level using stance legs
  15. 15. Control – BigDog Net force Maintain Body Posture & moment • Control of body posture through force control Hip torque control
  16. 16. Control – BigDog Net force Maintain Body Posture & moment • Control of body posture through force control Hip torque control Maintain Ground Contact • Force control through compliant leg shock Position control
  17. 17. Control – BigDog Maintain Body Posture • Control of body posture through force control Maintain Ground Contact Lateral • Force control through velocity compliant leg shock Maintain Lateral Balance • Place feet to control body lateral velocity Stance leg motion predicts lateral veloc. and accel. for New stance swing leg placement legs
  18. 18. Additional Controls • Estimate ground plane using history of leg kinematic data and odometry • Adjust posture to optimize leg strength while maintaining reach on terrain • Use traction control to avoid, detect and recover from foot slips • Move legs to avoid leg collisions • Determine ego-motion using kinematic, inertial and visual odometry
  19. 19. Trot Control Features • Engine Power Control. • Engine RPM regulated in response to actual and predicted load. • Ground steepness, ground roughness, and lateral body velocity predict demand. • Leg Collision Avoidance. • Adjacent legs have overlapping workspace. • Swing leg trajectories avoid hitting adjacent stance legs.
  20. 20. Trot Control • X – Closed loop. Speed error corrected by x direction foot forces. • Y – Lateral foot position chosen to offset unwanted lateral body velocity. • Z • Roll Coupled Controller. Corrections for height and • Pitch Euler errors map to y and z • Yaw direction foot forces.
  21. 21. LIDAR Leader Tracking • Follow leader without direct driving and without GPS: – Leader wears retro-reflective marker – SICK LIDAR used to locate leader and generate steering signals – BigDog follows at approximate fixed distance
  22. 22. End

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