We propose a self collision avoidance system that superposes trajectories in order not only to protect the robot's hardware but also to enable continuous motions. The system runs in real-time so that the robot can work in an uncertain environment. It is based on virtual forces between close segments of the robot. The avoidance movements are blended with a whole body motion control in order to change the priority between target reaching and collision avoidance. The blending is performed autonomously without the necessity of external switching. Our method works both while the robot is standing and walking. Reaching motions from the front to the side of the body without the arm colliding with the body are possible. Even if the target is inside the body, the arm stops at the closest point to the target outside of the body. Our method can be used for other applications: We apply it to realizing a "body schema" and for "occlusion avoidance."

/pdf/real-time-collision-avoidance-with-whole-body-motion-control-4apj81fb42.pdf

Real-time collision avoidance with whole body motion control for humanoid robots

In this study we investigate the use of a laser scanner/range-finder and inertial measurement units (IMUs) for the application of human-robot interaction in a dynamic environment with moving obstacles/humans. Humans and robots are represented by capsules, allowing to calculate the human-robot minimum distance on-the-fly. A major challenge is to capture the capsules pose. Data from a laser scanner and IMUs attached to the human body are fused to define the torso relative position and the upper body (arms and chest) configuration, respectively. Collision avoidance is achieved with a customized potential field’s method that allows to adjust the pre-defined robot paths established off-line while keeping the task target. The proposed framework is validated in real environment using a SICK laser scanner, IMUs and a KUKA iiwa robot. Experiments demonstrated the robustness of the proposed approach in capturing human motion, calculating the human-robot minimum distance and the robot behavior that smoothly avoids collisions with the human.

Minimum distance calculation using laser scanner and IMUs for safe human-robot interaction

Human-robot collaboration (HRC) in the manufacturing context aims to realise a shared workspace where humans can work side by side with robots in close proximity. In human-robot collaborative manufacturing, robots are required to adapt to human behaviours by dynamically changing their pre-planned tasks. However, the robots used today controlled by rigid native codes can no longer support effective human-robot collaboration. To address such challenges, programming-free and multimodal communication and control methods have been actively explored to facilitate the robust human-robot collaborative manufacturing. They can be applied as the solutions to the needs of the increased flexibility and adaptability, as well as higher effort on the conventional (re)programing of robots. These high-level multimodal commands include gesture and posture recognition, voice processing and sensorless haptic interaction for intuitive HRC in local and remote collaboration. Within the context, this paper presents an overview of HRC in manufacturing. Future research directions are also highlighted.

Overview of Human-Robot Collaboration in Manufacturing

Smooth continuous transition between tasks on a kinematic control level: Obstacle avoidance as a control problem

One of the fundamental demands on robotic systems is a safe interaction with their environment. For fulfilling that condition, both collisions with obstacles and the own structure have to be avoided. We address the problem of self-collisions and propose an algorithm for its avoidance which is based on artificial repulsion potential fields and applicable to both torque and position controlled manipulators. To this end, we design a damping that incorporates the configuration dependance of the robot. For a maximum level of safety, an additional emergency brake strategy based on kinetic energy considerations is introduced for situations in which self-collisions are not avoidable by the controller. Experiments are performed on DLR's humanoid Justin.

/pdf/extensions-to-reactive-self-collision-avoidance-for-torque-2jur3ipmxn.pdf

Extensions to reactive self-collision avoidance for torque and position controlled humanoids

We have proposed a real-time self-collision avoidance control method for the robot which is used for human-robot cooperation. In this method, we represent the body of the robot by using elastic elements referred to as "RoBE (representation of body by elastic elements)". The self-collision avoidance motion could be realized based on a reaction force generated by the contacts between the elastic elements before the actual self-collision of the robot. In this paper, especially, we consider task constraints and environmental constraints during the self-collision avoidance motion, and propose two priority functions for robots to realize the several kinds of tasks in an environment based on the force/moment applied by a human. By using this control algorithm, we could apply the proposed control algorithm to any robot systems used for human-robot cooperation. The proposed motion control algorithm is implemented in a human-friendly robot, referred to as "MR Helper", and experiments are done for illustrating the validity of the proposed self-collision avoidance motion.

Self-collision avoidance motion control for human robot cooperation system using RoBE

In this paper, we propose a real-time self-collision avoidance system for robots which cooperate with a human/humans. First, the robot is represented by elastic elements. The representation method is referred to as RoBE (Representation of Body by Elastic elements). Elastic balls and cylinders are used as the elements to simplify collision detection, although elements of any shape could be used for RoBE. When two elements collide with each other, a reaction force is generated between them, and self-collision avoidance motion is generated by the reaction force. Experiments using the mobile robot with dual manipulators, referred to as MR Helper, illustrate the validity of the proposed system.

Real-time Self-collision Avoidance System for Robots using RoBE

We have proposed a real-time self-collision avoidance motion generation method for the manipulator of the robot used for human-robot cooperation. In this method, we represent the robots' body by using elastic elements referred to as "RoBE (Representation of Body by Elastic elements)". The self-collision avoidance could be realized based on a virtual reaction force generated by the contacts between the elastic elements before the actual self-collision of the robot. In this paper, we expand this method to control not only robots' manipulator, but also its mobile base. Furthermore, we focus on the range of the joint movement of the robot, and propose the self-collision avoidance motion generation method considering it. Because of these, the self-collision motions which could deal with task/environmental constraints could be generated on the robot cooperating with a human. The proposed method is implemented in the planar 4-DOF mobile manipulator, and computer simulations are done for illustrating the validity of it.

Motion Generation for Human-Robot Cooperation considering Range of Joint Movement

We have proposed a real-time self-collision avoidance control method for the robot which is used for human-robot cooperation. In this method, we represent the body of the robot by using elastic elements referred to as “RoBE (Representation of Body by Elastic elements)”. In this paper, especially, we consider task constraints and environmental constraints during the self-collision avoidance motion, and propose two priority functions for robots to realize the several kinds of tasks in an environment based on the force/moment applied by a human. By using this control algorithm, we could apply the proposed control algorithm to any robot systems used for human-robot cooperation. The proposed motion control algorithm is implemented in a human-friendly robot, referred to as “MR Helper”, and experiments are done for illustrating the validity of the proposed self-collision avoidance motion.

Real-time self-collision avoidance using RoBE for human-friendly robot

We have proposed a real-time self-collision avoidance motion generation method for the mobile manipulator which is used for human-robot cooperation using ";RoBE (Representation of Body by Elastic elements)";. Furthermore, we have proposed the cooperating motion generation method which considers range of joint movement of the robot to deal with environmental/task constraints in human-robot cooperation. In this paper, we apply the proposed cooperative motion generation method to the real human-friendly robot referred to as ";Mr Helper";. Because of the consideration of range of joint movement, the cooperative motions which could deal with task/environmental constraints could be generated on Mr Helper while cooperating with a human. Some experiments are also done for illustrating the validity of the proposed cooperative motion generation method.

Fumi Seto

Papers

Self-collision avoidance motion control for human robot cooperation system using RoBE

Real-time Self-collision Avoidance System for Robots using RoBE

Motion Generation for Human-Robot Cooperation considering Range of Joint Movement

Real-time self-collision avoidance using RoBE for human-friendly robot

Motion generation method for human-robot cooperation to deal with environmental/task constraints