Versatile and robust bipedal walking in unknown environments: real-time collision avoidance and disturbance rejection

Abstract

Autonomous navigation in complex environments featuring obstacles, varying ground compositions, and external disturbances requires real-time motion generation and stabilization simultaneously. In this paper, we present and evaluate a strategy for rejection of external disturbances and real-time motion generation in the presence of obstacles and non-flat ground. We propose different solutions for combining the associated algorithms and analyze them in simulations. The promising method is validated in experiments with our robot Lola. We found a hierarchical approach to be effective for solving these complex motion generation problems, because it allows us to decompose the problem into sub-problems that can be tackled separately at different levels. This makes the approach suitable for real-time applications and robust against perturbations and errors. Our results show that real-time motion planning and disturbance rejection can be combined to improve the autonomy of legged robots.

A force-control scheme for biped robots to walk over uneven terrain including partial footholds

“…The accelerations are limited to the vertical domain of the CoM for the following reasons: (1) Horizontal accelerations typically require the combination with a time-global step adaptation method to reach stable motions. 4 (2) Although angular accelerations do work, they are hard to apply due to the limited support area of the feet. Furthermore, this can lead to large foot angles with low reserves to actuator limitations.…”

“…Typically, the environment is perceived by cameras or similar sensors on the robot and safe footholds are computed based on a generated environment model. [1][2][3][4] Although most approaches require the terrain to be flat around the contemplated footholds, recent work exists on vision-based foothold planning for irregularly protruded terrain. 5 Vision-based planning, however, greatly depends on the quality of the sensor signals.…”

Real-time Collision Detection for Position-Controlled Humanoid Robots

“…Legged locomotion on humanoid robots like ASIMO and BIPER having superior means of walking and maintaining a balanced posture when combined with suitable walking pattern generation has shown to be suitable for preventing collisions [6]. As the aspect of collision avoidance based on the perceived information about the surrounding environment highly allows a safer walking, it's beneficial to target collision avoidance and step generating in cluttered environments [7][8]. To do so most humanoids employ vision system to examine the environment and prevent collisions.…”

“…It is a well-known fact that human beings can rely on their hands to protect themselves in case of falling and have a more balanced posture when compared to humanoids. Due to humanoids' close physical characteristics to humans they can also benefit from using their hands and other body parts besides their feet for balance enhancement [7][8][9][10][11]. With improved and comprehensive methodologies to maintain balanced, humanoids will reach safer close-proximity interactions with humans.…”

“…With improved and comprehensive methodologies to maintain balanced, humanoids will reach safer close-proximity interactions with humans. However, to fulfil this vision humanoids need to engage complementary technologies and methods to their current sensor and motion systems to assure effective handling of systematic errors/disturbances [7].…”