G. Heppner

LAURON V: A versatile six-legged walking robot with advanced maneuverability

Adaptive multi-legged walking robots are predestined to be applied in rough and hazardous terrain. Their walking and climbing skills allow them to operate at places that are unreachable for most wheeled vehicles. In this paper, we present the design and development of the new six-legged walking robot LAURON V with its improved kinematics and robust mechanical structure. Each leg has four independent joints that enable LAURON to cope with steep inclines, large obstacles and makes it possible to manipulate objects with its front legs. Autonomy, robustness and a large payload capacity together with its impressive terrain adaptability make LAURONV highly suitable for all kinds of field applications.

Reactive posture behaviors for stable legged locomotion over steep inclines and large obstacles

Multi-legged walking robots often make use of sophisticated control architectures to play their strengths in rough and unknown environments. The adaptability of these robots is an essential skill to achieve the maneuverability and autonomy needed in their application fields. In this work we present a reactive control approach for the hexapod LAURONV, which enables it to overcome large obstacles and steep slopes without any knowledge about the environment. A key to this success can also be seen in the increased kinematic adaptability due to the fourth rotational joint in the bio-inspired leg kinematics. An extended experimental evaluation shows that the reactive posture behaviors are able to create an effective and efficient locomotion in challenging environments.

A multi-resolution 3-D environment model for autonomous planetary exploration

A key skill for autonomous exploration and inspection missions is the ability to find safe and traversable paths within previously unknown environments. We present an approach for mapping typical environments encountered by autonomous planetary exploration robots, a pre-interpreted multi-resolution 3-D environment model generated from point cloud data, and a hybrid planner for basically any kind of mobile robot. Our system builds upon and enhances freely available standard frameworks such as ROS and OMPL. We present results of our system applied to our six-legged walking robot LAURON V, showing the progression from individual 3-D point clouds to a rich environment model queried by an RRT*-based planner to find and adapt a feasible and optimal path.

KAIRO 3: A modular reconfigurable robot for search and rescue field missions

Search and rescue field missions, especially in environments which are dangerous for humans, increasingly requires the usage of robust and flexible robots. We describe the development of the modular reconfigurable robot KAIRO 3 focusing on applications in search and rescue, inspection and maintenance. After a short retrospect of previous generations of modular robots, the latest design of KAIRO 3 is presented. In particular, enhancements of the mechatronics and the control software are shown. Furthermore, the necessity to increase the flexibility of search and rescue robots will be demonstrated. To comply with this requirement, we utilized reconfiguration and adaptation of modular robots. Finally, the field results of applying KAIRO 3 at a civil protection field exercise are discussed.

Evaluation of physics engines for robotic simulations with a special focus on the dynamics of walking robots

Detailed simulations of robotic systems, including their components and dynamics, play an increasingly important role in the development of new robotic systems and their applications. There are many physics engines with a mature development stage, but all of them suffer from fundamental inaccuracies due to the approximative character of the internal calculations. This article provides an in-detail evaluation of the physics engines Bullet, ODE and PhysX with a focus on robotics and legged locomotion. We present a variety of run-time experiments which provide an insight into these engines, their strengths and weaknesses. Our findings offer valuable information for the application-specific selection of a physics engine for robotics simulations.

Fault diagnosis and system status monitoring for a six-legged walking robot

Rough, unstructured and hazardous areas are typical application scenarios for autonomous mobile robots. In the case of an error or fault, these robots cannot rely on a human to recover or repair them. Therefore, intelligent fault detection systems have to be developed that can autonomously detect faults and create a system status corresponding to the operability of the robot. After a fault has been detected, it might be possible to adapt the robot and still continue with its primary task. This paper presents a fault diagnosis and status monitoring system for a six-legged walking robot. Our developed system is based on expert knowledge and was implemented on the six-legged robot LAURON. It is able to detect seven different types of faults and errors, ranging from mechanical coupling problems to the total loss of leg controller units. The status monitoring part gives the operator a detailed, but still understandable status report about the most important components and their functionality.

Autonomy of Mobile Robots

What do we actually mean when we talk about “autonomous mobile robots”? This chapter gives an introduction into the technical side of autonomy of mobile robots in the current state of the art and provides the relevant technical background for discussions about autonomy in mobile robot systems. A short history of robotic development explains the origins of robotics and its development from industrial machines into autonomous agents. The term “autonomous robot” is looked at in more detail by presenting the way of decision-making with different categories of robots and by introducing the general model of a rational agent for decision making. Additionally a short outlook on the process of understanding the environment is discussed, giving an overview of the individual steps from sensing up to interpretation of a scene. Selected examples of modern robots present the current state of the art and its limitations within this field. Overall, this introduction provides the required technical insight for non robotic experts to get an understanding of the term autonomous mobile robots and the implications for regulations concerning it.

Pushing around a robot: Force-based manual control of the six-legged walking robot LAURON

Robots are built to assist people. Up to now the circle of people benefiting is still rather small because operating a robot is a very difficult task. To enable untrained people to operate a robot, an intuitive user interface has to be provided. Besides enlarging the number of people which are actually able to operate the robot, the operators are less burdened by controlling the robot and therefore are able to concentrate better on the task they actually have to perform. This paper presents a method of applying the maybe most intuitive modality of control: the operator can give commands to the six-legged walking robot LAURON by pushing or pulling its body. To achieve this the robots 18 joint torques are calculated based on the motor currents. These are then transformed and merged in a 6D force vector corresponding to LAURONs CoG. This vector is finally fed into a classifier which identifies the users intention out of a set of possible commands and triggers corresponding behaviors.

Service robots in the field: The BratWurst Bot

Service robotics has recently been a growing field as well in research as in industrial contexts. It offers adaptive robotic systems that allow direct human-robot interaction and cooperation. However these systems are often only used inside research labs. In this paper we present the BratWurst Bot, a service robotic system that demonstrates the combination of many different robotic skills to create a powerful application. With ROS as a software framework and standard robotic components this system also shows the short ramp-up time modern service robotics can provide. The BratWurst Bot offers an intuitive tablet interface and was extensively tested “in the field” on public events where it proved its reliability and effectiveness.

Bio-inspired optimization of kinematic models for multi-legged walking robots

Designing a walking robot for a specified task is a complex problem. It requires numerous calculations and evaluations to find the desired shape and topology to perform correctly. The abstraction of such a task is a multi-dimensional, multi-goal optimization problem. This paper proposes a bio-inspired solution to optimize such a kinematic model: A genetic algorithm aims to free the designer from the cumbersome procedure of calculating forces, evaluating models and selecting certain hardware components. Through a set of predefined preferences, it can be tasked to develop a light, stable or fast robot. It uses the classic evolutionary mechanisms of selection, recombination and mutation and adapts at runtime. The algorithm also allows the definition of a morphological type, a blueprint for walking robots, derived from common robot classes and calculates their dynamic model with a physics engine.