172 research outputs found
Material Recognition CNNs and Hierarchical Planning for Biped Robot Locomotion on Slippery Terrain
In this paper we tackle the problem of visually predicting surface friction
for environments with diverse surfaces, and integrating this knowledge into
biped robot locomotion planning. The problem is essential for autonomous robot
locomotion since diverse surfaces with varying friction abound in the real
world, from wood to ceramic tiles, grass or ice, which may cause difficulties
or huge energy costs for robot locomotion if not considered. We propose to
estimate friction and its uncertainty from visual estimation of material
classes using convolutional neural networks, together with probability
distribution functions of friction associated with each material. We then
robustly integrate the friction predictions into a hierarchical (footstep and
full-body) planning method using chance constraints, and optimize the same
trajectory costs at both levels of the planning method for consistency. Our
solution achieves fully autonomous perception and locomotion on slippery
terrain, which considers not only friction and its uncertainty, but also
collision, stability and trajectory cost. We show promising friction prediction
results in real pictures of outdoor scenarios, and planning experiments on a
real robot facing surfaces with different friction
A framework for safe human-humanoid coexistence
This work is focused on the development of a safety framework for Human-Humanoid coexistence, with emphasis on humanoid locomotion. After a brief introduction to the fundamental concepts of humanoid locomotion, the two most common approaches for gait generation are presented, and are extended with the inclusion of a stability condition to guarantee the boundedness of the generated trajectories. Then the safety framework is presented, with the introduction of different safety behaviors. These behaviors are meant to enhance the overall level of safety during any robot operation. Proactive behaviors will enhance or adapt the current robot operations to reduce the risk of danger, while override behaviors will stop the current robot activity in order to take action against a particularly dangerous situation. A state
machine is defined to control the transitions between the behaviors. The behaviors that are strictly related to locomotion are subsequently detailed, and an implementation is proposed and validated. A possible implementation of the remaining behaviors is proposed through the review of related works that can be found in literature
Real-Time Navigation for Bipedal Robots in Dynamic Environments
The popularity of mobile robots has been steadily growing, with these robots
being increasingly utilized to execute tasks previously completed by human
workers. For bipedal robots to see this same success, robust autonomous
navigation systems need to be developed that can execute in real-time and
respond to dynamic environments. These systems can be divided into three
stages: perception, planning, and control. A holistic navigation framework for
bipedal robots must successfully integrate all three components of the
autonomous navigation problem to enable robust real-world navigation. In this
paper, we present a real-time navigation framework for bipedal robots in
dynamic environments. The proposed system addresses all components of the
navigation problem: We introduce a depth-based perception system for obstacle
detection, mapping, and localization. A two-stage planner is developed to
generate collision-free trajectories robust to unknown and dynamic
environments. And execute trajectories on the Digit bipedal robot's walking
gait controller. The navigation framework is validated through a series of
simulation and hardware experiments that contain unknown environments and
dynamic obstacles.Comment: Submitted to 2023 IEEE International Conference on Robotics and
Automation (ICRA). For associated experiment recordings see
https://www.youtube.com/watch?v=WzHejHx-Kz
Authoring and Operating Humanoid Behaviors On the Fly using Coactive Design Principles
Humanoid robots have the potential to perform useful tasks in a world built
for humans. However, communicating intention and teaming with a humanoid robot
is a multi-faceted and complex problem. In this paper, we tackle the problems
associated with quickly and interactively authoring new robot behavior that
works on real hardware. We bring the powerful concepts of Affordance Templates
and Coactive Design methodology to this problem to attempt to solve and explain
it. In our approach we use interactive stance and hand pose goals along with
other types of actions to author humanoid robot behavior on the fly. We then
describe how our operator interface works to author behaviors on the fly and
provide interdependence analysis charts for task approach and door opening. We
present timings from real robot performances for traversing a push door and
doing a pick and place task on our Nadia humanoid robot.Comment: 8 pages, 12 figures, for Humanoids 202
A Universal Footstep Planning Methodology for Continuous Walking in Challenging Terrain Applicable to Different Types of Legged Robots
In recent years, the capabilities of legged locomotion controllers have been significantly advanced enabling them to traverse basic types of uneven terrain without visual perception. However, safely and autonomously traversing longer distances over difficult uneven terrain requires appropriate motion planning using online collected environmental knowledge. In this paper, we present such a novel methodology for generic closed-loop preceding horizon footstep planning that enables legged robots equipped with capable locomotion controllers to autonomously traverse previously unknown terrain while continuously walking long distances. Hereby, our approach addresses the challenge of online terrain perception and soft real-time footstep planning. The proposed new formulation of the search-based planning problem makes no specific assumptions about the robot kinematics (e.g. number of legs) or the used locomotion control schemes. Therefore, it can be applied to a broad range of different types of legged robots. Unlike current methods, the proposed new framework can optionally consider the floating base as part of the state-space. It is possible to configure the complexity of the planner online, from efficiently solving tasks in flat terrain to using non-contiguous contacts in highly challenging terrain. Finally, the presented methodology is successfully applied and evaluated in virtual and real experiments on state of the art bipedal, quadrupedal, and a novel eight-legged robot
A behavior-based framework for safe deployment of humanoid robots
We present a complete framework for the safe deployment of humanoid robots in environments containing humans. Proceeding from some general guidelines, we propose several safety behaviors, classified in three categories, i.e., override, temporary override, and proactive. Activation and deactivation of these behaviors is triggered by information coming from the robot sensors and is handled by a state machine. The implementation of our safety framework is discussed with respect to a reference control architecture. In particular, it is shown that an MPC-based gait generator is ideal for realizing all behaviors related to locomotion. Simulation and experimental results on the HRP-4 and NAO humanoids, respectively, are presented to confirm the effectiveness of the proposed method
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