Boston Dynamics Inc Three-piston ankle mechanism of a legged

US9878751B1 · Boston Dynamics Inc

Patent number
US9878751B1
Applicant
Boston Dynamics Inc
Filing date
2015-10-08
CPC class
B62D57/032
Pillar
Brain

The patent discloses a three-actuator (piston) ankle mechanism for legged robots (quadruped or biped) that enables precise control of foot pitch and roll relative to the shin. A control system determines a desired center of pressure (COP) location on the foot and computes pitch/roll torques to maintain balance, orientation, and speed while the robot operates on a surface. Hydraulic actuation and torque control are detailed.

Claims

Independent claim 1 covers the robot with three actuators connecting the foot to the shin for independent roll (via two actuators) and pitch (via coordinated extension/retraction with the third). Claim 8 covers the method of determining desired COP and applying torques via the actuators. Dependent claims cover hydraulic systems, specific torque calculations, and non-transitory computer-readable media.

Technical analysis

The mechanism uses two anterior actuators for roll and one posterior for pitch, allowing zero-backlash torque application at the ankle. The controller uses sensor feedback (e.g., IMU, force sensors) to adjust COP within the foot support polygon for dynamic balance, enabling stance stability, gait adaptation, and recovery from disturbances. This directly addresses balance control challenges in high-DoF legged locomotion.

Commercial impact

Core IP for Boston Dynamics' Atlas and Spot robots, enabling robust dynamic balance and terrain adaptation critical to their commercial quadrupeds and humanoids. Strengthens BD's position in defense, inspection, and logistics markets; cited in litigation against competitors like Ghost Robotics.

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