The Cassie bipedal robot designed by Agility Robotics is providing academics a common platform for sharing and comparing algorithms for locomotion, perception, and navigation. This paper focuses on feedback control for standing and walking using the methods of virtual constraints and gait libraries. The designed controller was implemented six weeks after the robot arrived at the University of Michigan and allowed it to stand in place as well as walk over sidewalks, grass, snow, sand, and burning brush. The controller for standing also enables the robot to ride a Segway. A model of the Cassie robot has been placed on GitHub and the controller will also be made open source if the paper is accepted.

Analysis and controller design methods abound in the literature for planar (also known as 2-D) bipedal models. This paper takes one of them developed for underactuated bipeds and documents the process of designing a family of controllers on the basis of a planar model and achieving stable walking on a physical 3-D robot, both indoors and outdoors, with walking speed varying smoothly from 0 to 0.8 m/s. The longest walk in a single experiment is 260 m over terrain with ±7 • of slope variation. Advantages and disadvantages of the design approach are discussed.INDEX TERMS 3D walking, underactuated bipedal robot, optimal control.

No abstract

This paper presents the first experimental results of crutch-less dynamic walking with paraplegics on a lowerbody exoskeleton: ATALANTE, designed by the French start-up company Wandercraft. The methodology used to achieve these results is based on the partial hybrid zero dynamics (PHZD) framework for formally generating stable walking gaits. A direct collocation optimization formulation is used to provide fast and efficient generation of gaits tailored to each patient. These gaits are then implemented on the exoskeleton for three paraplegics. The end result is dynamically stable walking in an exoskeleton without the need for crutches. After a short period of tuning by the engineers and practice by the subjects, each subject was able to dynamically walk across a room of about 10 m up to a speed of 0.15 m/s (0.5 km/h) without the need for crutches or any other kind of assistance. *This work has been conducted under IRB No. 16-0693.

No abstract