When and Where to Step: Terrain-Aware Real-Time Footstep Location and Timing Optimization for Bipedal Robots

Online footstep planning is essential for bipedal walking robots, allowing them to walk in the presence of disturbances and sensory noise. Most of the literature on the topic has focused on optimizing the footstep placement while keeping the step timing constant. In this work, we introduce a footstep planner capable of optimizing footstep placement and step time online. The proposed planner, consisting of an Interior Point Optimizer (IPOPT) and an optimizer based on Augmented Lagrangian (AL) method with analytical gradient descent, solves the full dynamics of the Linear Inverted Pendulum (LIP) model in real time to optimize for footstep location as well as step timing at the rate of 200~Hz. We show that such asynchronous real-time optimization with the AL method (ARTO-AL) provides the required robustness and speed for successful online footstep planning. Furthermore, ARTO-AL can be extended to plan footsteps in 3D, allowing terrain-aware footstep planning on uneven terrains. Compared to an algorithm with no footstep time adaptation, our proposed ARTO-AL demonstrates increased stability in simulated walking experiments as it can resist pushes on flat ground and on a $10^{\circ}$ ramp up to 120 N and 100 N respectively. For the video, see https://youtu.be/ABdnvPqCUu4. For code, see https://github.com/WangKeAlchemist/ARTO-AL/tree/master.Comment: 32 pages, 15 figures. Submitted to Robotics and Autonomous System

Bio-Inspired Soft Robot for Locomotion and Navigation in Restricted Spaces

Soft robotics have been shown to be particularly versatile for accessing restricted and hazardous environments, such as nuclear and chemical processing plants, and pipelines. This paper presents a bio-inspired soft robot capable of propelling itself inside a cylindrical space. The continuum soft robot consists of three main sections, which, with coordinated inflation and deflation, enable a controlled locomotion of the robot. The sections are composed of two types of soft actuator: Radially-expandable cylindrical modules (RECMs) and vacuum-actuated muscle-inspired pneumatic structures (VAMPs). In this paper, the details of the soft actuators’ design and support structures are described. Tests conducted on the actuators verify their suitability for performing a number of specific motion tasks, including bending and navigation in restricted vertical and horizontal environments. The preliminary experimental results indicate that the bio-inspired design approach enables the soft components to move dexterously inside the restricted environment, perform longitudinal shifts of 28% its original length in one motion cycle, and lift loads up to 150 g per VAMP. These observations were confirmed using finite element analysis. The robot can also be safely and remotely operated to enable an efficient control of the robots’ soft actuators. The possibility of moving with infinite degrees of freedom and safely interact with humans provide the robot with the potential of being employed in wide ranging application in industry and research