Self-collision avoidance and angular momentum compensation for a biped humanoid robot

Abstract

To simplify the development of new trajectories for a humanoid robot with many joints, the ability to check for potential collisions is crucial. More importantly, to enable online generation of general motions, such as whole-body-motion, collision avoidance must be employed, which is usually more challenging. In this paper, a model-based and efficient on-line distance calculation between links of the robot is proposed. To avoid collisions the results are projected into the nullspace term of the inverse-kinematics which is based on the redundancy resolution framework of LIÉGEOIS. Additionally, a novel method to reduce the vertical angular momentum for a walking biped robot which uses the arm motion is proposed. It reduces the vertical angular momentum of the walking robot especially for larger steps. Since the method also works in the null-space, it can easily be combined with the proposed collision avoidance scheme. Finally, results for the proposed methods from simulations and experiments with the robot Lola are shown.

Real-time 3D collision avoidance for biped robots

“…For Lola the vector y is a gradient to an optimization criterion H dedicated to self-collision-avoidance, joint-limit-avoidance and angularmomentum-compensation. For further information see [1]. Since y is only projected into null-space, it doesn't affect the reference trajectories given in task-space.…”

“…Schwienbacher et al [1] developed a framework to detect and prevent self-collisions based on distance calculations via swept-sphere-volumes (SSV). It is a computationally efficient method which additionally provides a way to accurately model geometries.…”

“…Note that the environment can be varied dynamically by adding or removing obstacles. According to [1], we define the collision environment C as follows:…”

“…In this paper we present a new method which combines a local potential field method with a heuristic based on height and width of an obstacle. We add obstacle avoidance in taskspace to our framework for self-collision avoidance [1]. This has several advantages: Our framework enables the robot to avoid precisely modeled obstacles.…”

The Biped Walking Robot Lola

“…6 Animation of the simplified geometry model for self-collision avoidance together with the CADgeometry. Lines indicate the shortest distances between two segments, the distance is indicated by the color of the corresponding SSVs [5] required for contact force control are determined from a physical model of the compliant contact, the multibody model of the robot and the forces currently acting on the system (see Ref.…”