Dexterity and strength are essential for performing a variety of tasks in the unstructured environments of household services and craftsmanship. For these tasks, we have developed neoDavid, a robust humanoid robot with dexterous manipulation skills. neoDavid has joints with variable-stiffness actuators (VSAs), which have mechanically adjustable elasticity in the drive train, a continuum elastic neck, and a gravitationally compensated torso with overload couplings. We present our modular approach in the development, starting from system architecture over mechatronic components, communication, and control to higher-level software. We demonstrate how this modularity enables scalable enhancements, allowing us to evolve the system from a single arm and hand into a complete humanoid robot. Additionally, we highlight advancements in perception, manipulation, and motion planning, along with the implementation of offline task planning utilizing capability maps. The versatile character in terms of dexterity and robustness is demonstrated in challenging applications, e.g., handling a drill hammer, fine manipulation of a pipette, and emptying a dishwasher.

This paper presents an automated framework for designing and reconfiguring robotic workcells in high-mix, lowvolume manufacturing scenarios. The framework utilizes a modular workcell with various tools and a flexible grid system, the Variable Workstation (VWS), and uses an ontological representation of available robotic systems and assembly tasks. The major contribution is a tool for automatic layout planning and reconfiguration, and its integration into the overall pipeline. The tool optimizes component placements for efficient task execution with minimal path lengths and maximized manipulability. Constraints guarantee the reachability of each task and absence of collisions. The framework is evaluated in a real scenario using tasks from the assembly of an electric chainsaw. Overall, the proposed framework provides an efficient and complete system of designing and reconfiguring robotic workcells for high-mix, low-volume manufacturing.

Dieser Artikel gibt einen kurzen Uberblick uber die Arbeiten des Instituts am Safe Autonomous Robotic Assistant (SARA), den Airbag fur Roboter sowie das SwarmRail-System.

Physical human-robot interaction is known to be a crucial aspect in modern lightweight robotics. Herein, the estimation of external interactions is essential for the effective and safe collaboration. In this work, an extended momentum-based disturbance observer is presented which includes the sensing redundancy related to additional force-torque measurements. The observer eliminates the need for acceleration measurements/estimates and it is able to accurately reconstruct multiple simultaneous contact locations. Moreover, it provides uncoupled, configuration-independent, and singularity-free estimates of the external forces. The performance of the approach is experimentally validated on the SARA robot, the new generation of DLR lightweight robots, involving high resolution force-torque sensors in a redundant arrangement.

Lightweight robots are known to be intrinsically elastic in their joints. The established classical approaches to control such systems are mostly based on motor-side coordinates since the joints are comparatively stiff. However, that inevitably introduces errors in the coordinates that actually matter: the ones on the link side. Here we present a new joint-torque controller that uses feedback of the link-side positions. Passivity during interaction with the environment is formally shown as well as asymptotic stability of the desired equilibrium in the regulation case. The performance of the control approach is experimentally validated on DLR's new generation of lightweight robots, namely the SARA robot, which enables this step from motor-side-based to link-sided-based control due to sensors with higher resolution and improved sampling rate.

Variable stiffness actuators (VSAs) are complex mechatronic devices that are developed to build passively compliant, robust, and dexterous robots. Numerous different hardware designs have been developed in the past two decades to address various demands on their functionality. This review paper gives a guide to the design process from the analysis of the desired tasks identifying the relevant attributes and their influence on the selection of different components such as motors, sensors, and springs. The influence on the performance of different principles to generate the passive compliance and the variation of the stiffness are investigated. Furthermore, the design contradictions during the engineering process are explained in order to find the best suiting solution for the given purpose. With this in mind, the topics of output power, potential energy capacity, stiffness range, efficiency, and accuracy are discussed. Finally, the dependencies of control, models, sensor setup, and sensor quality are addressed.

This paper gives an overview of the advancements in humanoid robotics at the German Aerospace Center (DLR) over the last 10 years. The development started with focus on dexterous, bimanual manipulation with the wheel-based humanoid Rollin’ Justin and continued with legged locomotion on TORO. With Rollin’ Justin, the team aims to create a cognitive robotic system that can reason about compliant manipulation tasks, based on intelligent decisions according to the actual state of the environment. These humanoids are expected to can perform a multitude of complex tasks and hereby contributing to human welfare. Possible fields of use include service robotics, industrial co-workers, search and rescue, space applications, medical robotics, etc. The experts suggest that teleoperated scenarios are feasible in short term, developing in long term towards shared or even full autonomy. Still, advancements must be made in almost all areas, starting from mechatronic robustness, reliability and energy efficiency, over multimodal perception and control up to autonomous planning and Artificial Intelligence-based reasoning. Development of interaction interfaces and communication modalities to humans will play an increasingly key role in the future.

This paper gives an overview on the torque-controlled humanoid robot TORO, which has evolved from the former DLR Biped. In particular, we describe its mechanical design and dimensioning, its sensors, electronics and computer hardware. Additionally, we give a short introduction to the walking and multi-contact balancing strategies used for TORO.

Research on bipedal walking is driven by the vision of humanoid robotic servants for the society of the future. Besides the human form, bipedal locomotion offers the possibility to step over small obstacles and stairs and allows for a relatively small support area. Active control of the zero-moment-point (ZMP) [15] by measuring the contact forces at the feet and precisely controlling the motion of the robot has been shown to be an effective paradigm of stabilizing walking motions of bipedal robots [2] [6]. In the design of humanoid robots that utilize this control approach the precision of the position controllers plays an important role [7]~ [9] [12] [14]. Joint torque sensing and control allows sensitive compliance and impedance control [10], but requires additional instrumentation in the drive units. The humanoid robot CB [1] utilizes explicit joint torque sensing in a hydraulic actuation system. Serial elastic actuators also offer an indirect way of measuring the joint torque and were applied to bipedal walking in Ref. [13]. While these actuators allow for force control due to their low impedance characteristics, precise trajectory tracking becomes more difficult. In this paper we present the hardware and control concepts for an electrically driven bipedal robot with integrated joint torque sensors (Fig. 1). The robot was designed as an experimental system for research on control aspects, including comparisons between strategies based on joint position or joint torque control.

The mobile humanoid Rollin'Justin is a versatile experimental platform for research in manipulation tasks. Previously, different state of the art control methods and first autonomous task execution scenarios have been demonstrated. In this video two new applications with challenging task requirements are presented. One is the catching of one or even two flying balls using all of Justin's degrees of freedom. The other is the autonomous preparation of coffee. Both applications need adequate sensors to support local referencing. The required precision in position and timing is realized in software, using the sensor information, taking the varying precision of Justin's kinematic sub-chains into account and handling all timings in sub-millisecond range.

The paper gives an overview on the developments at the German Aerospace Center DLR towards anthropomorphic robots which not only try to approach the force and velocity performance of humans, but also have similar safety and robustness features based on a compliant behaviour.We achieve this compliance either by joint torque sensing and impedance control, or, in our newest systems, by compliant mechanisms (so called VIA - variable impedance actuators), whose intrinsic compliance can be adjusted by an additional actuator. Both approaches required highly integrated mechatronic design and advanced, nonlinear control and planning strategies, which are presented in this paper.

An anthropomorphic hand arm system using variable stiffness actuation has been developed at DLR. It is aimed to reach its human archetype regarding size, weight and performance. The main focus of our development is put on robustness, dynamic performance and dexterity. Therefore, a paradigm change from impedance controlled, but mechanically stiff joints to robots using intrinsic variable compliance joints is carried out. Collisions of the rigid joint robot at high speeds with stiff objects induce the energy too fast for an active controller to prevent damages. In contrast, passively compliant robots are able to temporarily store energy. In this case the resulting internal forces applied to the robot structure and the drive trains are reduced. Furthermore, the energy storage allows to outperform the dynamics of stiff robots. The hand drives and the electronics are completely integrated within the forearm. Extremely miniaturized electronics have been developed to drive the 52 motors of the system and interface their sensors. Several variable stiffness actuation principles used in the arm joints and the hand are presented. The paper highlights the different requirements that they have to fulfill. A first test of the systems robustness and dynamics has been performed by driving nails with a grasped hammer and is demonstrated in the attached video.

Bringing mechanically compliant joints to robots is in the focus of interest world wide, especially in the humanoid robotics community. Variable Stiffness Joints (VSJ) promise to gain a high performing and robust robotic system. The presented DLR Floating Spring Joint (FSJ) is a VSJ module designed for the first 4 axes of the anthropomorphic DLR Hand Arm System. The DLR Hand Arm System aims to match the skills of its natural archetype. For this purpose, the joints have to be extremely compact to fit into the arm. At the same time they require a high power density in order to approximate the human arm skills. The new DLR FSJ is designed completely from an energy based point of view. This addresses not only energy efficient components and low friction design, but also that the potential energy of the spring is used as good as possible. A demonstration of robustness is given by the investigation of a blunt impact to the tip of the arm.

In this paper we present various new insights on the effect intrinsic joint elasticity has on safety in pHRI. We address the fact that the intrinsic safety of elastic mechanisms has been discussed rather one sided in favor of this new designs and intend to give a more differentiated view on the problem. An important result is that intrinsic joint elasticity does not reduce the Head Injury Criterion or impact forces compared to conventional actuation with some considerable elastic behavior in the joint, if considering full scale robots. We also elaborate conditions under which intrinsically compliant actuation is potentially more dangerous than rigid one. Furthermore, we present collision detection and reaction schemes for such mechanisms and verify their effectiveness experimentally.

Zusammenfassung Mit dem mobilen humanoiden Roboter Justin stellt das DLR eine für die feinfühlige Manipulation von Alltagsgegenständen ausgelegte Hardware-Plattform vor. Die Überlegungen und wesentlichen Designentscheidungen für den mechatronischen Entwurf des Systems werden vorgestellt. Weiterhin wird beschrieben wie die vorhandene Sensorik des Systems zur passivitätsbasierten Regelung genutzt werden kann und so dem Roboter eine einstellbare Nachgiebigkeit im Aufgabenraum gegeben werden kann. Dies ermöglicht die feinfühlige Anpassung an unbekannte Umgebungen. Einige beispielhafte Anwendungen und Experimente zeigen, wie diese Eigenschaften die Programmierung solcher komplexer Robotersysteme vereinfachen und sicherer machen können.

In this paper we introduce a classification of intrinsically compliant joint mechanisms. Furthermore, we outline design considerations for realizing such devices in order to match the requirements for robust and performant actuation. Based on this elaboration, a new design concept is presented, the DLR QA-Joint. Its performance is investigated by various experiments, covering velocity increase using the elastic energy, joint protection capabilities, and control performance.

With the mobile humanoid robot Justin DLR presents a platform capable of sensitive manipulation of everyday objects The considerations and fundamental design decisions for the mechatronic development of the system are presented Furthermore it is shown how the sensory information can be used for passivity based control In this way a compliant behavior of the robot in task space can be achieved This allows for sensitive adjustments to unknown environments Some exemplary applications and experiments demonstrate how these proper ties can simplify the programming of such complex robotic systems