Walking+Robots+2018-03++concep conceptsconceptsts.pdf
- 2. Outline l Boston Dynamics l BigDog l Bio-inspired Legged Locomotion
- 3. Boston Dynamics - Robots
- 4. Outline
- 5. 5 Boston Dynamics - BigDog
- 6. 6 Boston Dynamics - BigDog
- 7. 7 Boston Dynamics - BigDog
- 8. 8 Boston Dynamics - BigDog
- 9. 9 Boston Dynamics - BigDog
- 10. 10 Boston Dynamics - BigDog Engine Hydraulic System
- 11. 11 Boston Dynamics - BigDog Multi-jointed Legs
- 12. 12 Boston Dynamics - BigDog Component Layout
- 13. 13 Boston Dynamics - BigDog Sensors
- 14. 14 Boston Dynamics - BigDog BigDog Sensors
- 15. 15 Boston Dynamics - BigDog 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
- 16. 16 Boston Dynamics - BigDog Software Architecture
- 17. 17 Boston Dynamics - BigDog Software Processes
- 18. 18 Boston Dynamics - BigDog Vest Operator Control Unit (OCU)
- 19. 19 Boston Dynamics - BigDog Control Principles
- 20. 20 Boston Dynamics - BigDog Control – BigDog
- 21. 21 Boston Dynamics - BigDog Control – BigDog
- 22. 22 Boston Dynamics - BigDog Control – BigDog
- 23. 23 Boston Dynamics - BigDog Additional Controls l Estimate ground plane using history of leg kinematic data and odometry l Adjust posture to optimize leg strength while maintaining reach on terrain l Use traction control to avoid, detect and recover from foot slips l Move legs to avoid leg collisions l Determine ego-motion using kinematic, inertial and visual odometry
- 24. 24 Boston Dynamics - BigDog Trot Control Features l Engine Power Control. Ø Engine RPM regulated in response to actual and predicted load. Ø Ground steepness, ground roughness, and lateral body velocity predict demand. l Leg Collision Avoidance. Ø Adjacent legs have overlapping workspace. Ø Swing leg trajectories avoid hitting adjacent stance legs.
- 25. 25 Boston Dynamics - BigDog Trot Control l X – Closed loop. Speed error corrected by x direction foot forces. l Y – Lateral foot position chosen to offset unwanted lateral body velocity. l Z l Roll l Pitch l Yaw Coupled Controller. Corrections for height and Euler errors map to y and z direction foot forces.
- 26. 26 Boston Dynamics - BigDog LIDAR Leader Tracking
- 27. Main locomotion subfunctions: (1) axial stance leg function, (2) rotational swing leg function (an additional axial leg function of the swing leg is used for ground clearance), and (3) balance for maintaining posture. • the concepts behind the design and control of legged systems. • the insight obtained from biology that can be adapted to engineered systems. Bio-inspired legged locomotion
- 28. What is bio-inspired legged locomotion Bio-inspired legged locomotion
- 29. Bio-inspired legged locomotion What is bio-inspired legged locomotion
- 30. How animals move? Michael H. Dickinson et al. Science 2000;288:100-106 1. Forces exerted by moving animals vary in space and time How animals move: an integrative view
- 31. How animals move? 1. Forces exerted by moving animals vary in space and time Ground reaction force vectors (shown in red) for a running human and trotting dog are plotted at equal time intervals throughout the stance phase. At each instant, the resultant vector points through the hip or shoulder of each leg, minimizing the torque at each joint. An initial braking phase is followed by a propulsive phase. Michael H. Dickinson et al. Science 2000;288:100-106 How animals move: an integrative view
- 32. How animals move? 1. Forces exerted by moving animals vary in space and time Two basic models for legged locomotion. In a walking animal, the center of mass vaults over a rigid leg, analogous to an inverted pendulum. At mid stance, the center of mass reaches its highest point. Like a pendulum, the kinetic and gravitational potential energies of the body are exchanged cyclically. In a running animal, the leg acts as a spring, compressing during the braking phase and recoiling during the propulsive phase. At mid stance, the center of mass reaches its lowest point. Like a simple spring-mass system, the kinetic and gravitational potential energies are stored as elastic energy during the braking phase and recovered during the propulsive phase. Michael H. Dickinson et al. Science 2000;288:100-106 How animals move: an integrative view
- 33. How animals move? 1. Forces exerted by moving animals vary in space and time In a running cockroach, hind-leg ground reaction forces propel the animal forward, whereas each foreleg ground reaction force pushes backward, counter to the animal's movement. The middle-leg ground reaction force begins by pushing backward but then pushes forward at the end of the stance phase. In addition to these fluctuating fore-aft forces, all legs act to push the body toward the midline. Black (stance phase) and blue (swing phase) dotted lines indicate the path of the distal end of each leg relative to the whole-body center of mass. Michael H. Dickinson et al. Science 2000;288:100-106 How animals move: an integrative view
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