Design of the berkeley lower extremity exoskeleton (bleex)

摘要

Many places in the world are too rugged or enclosed for vehicles to access. Even today, material transport to such areas is limited to manual labor and beasts of burden. Modern advancements in wearable robotics may make those methods obsolete. Attempts to navigate difficult terrain via purely autonomous robotics have been only moderately successful as highly unstructured environments have proved too unpredictable for pre-programmed robotics with limited sensory inputs. Lower extremity exoskeletons seek to circumvent these challenges by combining the innate intelligence, dexterity and sensory capabilities of a human with the significant strength and endurance of a pair of wearable robotic legs capable of supporting a payload. This dissertation outlines the development of one such system - the Berkeley Lower Extremity Exoskeleton (BLEEX). Previous lower extremity exoskeletons have been limited by difficulties in sensing the human operator and power supply limitations. The BLEEX however utilizes a novel control architecture that estimates the forces exerted on the human by the exoskeleton structure via measurements of only the exoskeleton itself. The BLEEX also utilizes a simplified kinematical architecture with powered joints only in the sagittal plane to minimize power demands. The wearer connects to the BLEEX at a pair of foot bindings and a shoulder harness. Extensive mock-up testing was used to develop the flexible anthropomorphic architecture. The BLEEX wearer can squat, bend, swing from side to side, twist, walk on slopes, and traverse obstacles while carrying significant payloads with ease. Clinical Gait Analysis (CGA) data was used to provide the framework for the design of the hydraulic BLEEX actuation system. Six double-acting hydraulic cylinders actuate the BLEEX ankles, knees and hips in the sagittal plane. Applying CGA motion data to the actuation design yielded hydraulic flow and prime mover requirements. A suitable self-contained hydraulic power supply was designed and built, making the BLEEX one of the first energetically autonomous lower extremity exoskeletons in the world. The BLEEX prototype has been walked, un-tethered on a treadmill at speeds of up to 1.3 m/s. The prototype has been tested in both indoor and outdoor environments and demonstrated short duration (∼30 min) energetic autonomy.