The rise of collaborative robotics has offered new opportunities for integrating automation into the factories, allowing robots and humans to work side-by-side. However, this close physical coexistence inevitably brings new constraints for ensuring safe human-robot cooperation. The current paramount challenge is integrating human safety constraints without compromising the robotic performance goals, which require minimization of the task execution time alongside ensuring its accomplishment. This letter proposes a novel robot trajectory planning algorithm to produce minimum-time yet safe motion plans along specified paths in shared workspaces with humans. To this end, a safety module was used to evaluate the safety of a time-optimal trajectory iteratively. A safe replanning module was developed to optimally adapt the generated trajectory online whenever the optimal plan violates dynamically provided safety limits. In order to preserve performance, a recovery trajectory planning algorithm was included such that the robot is allowed to restore higher speed motions as soon as the safety concern has been resolved. The proposed solution's effectiveness was evaluated both in simulations and real experiments with two robotic manipulators.

Adaptive cable-driven parallel robots are a special subclass of cable-driven systems in which the locations of the pulley blocks are modified as a function of the end-effector pose to obtain optimal values of given performance indices within a target workspace. Due to their augmented kinematic redundancy, such systems enable larger workspace volume and higher performance compared to traditional designs featuring the same number of cables. Previous studies have introduced a systematic method to optimize design and trajectory planning of the moving pulley-blocks for a given performance index. In this paper, we study the motions of the pulley blocks that optimize two performance indices simultaneously: stiffness and dexterity. Specifically, we present a method to determine the pulley blocks motions that guarantee ideal dexterity with the best feasible elastic stiffness, as well as those that guarantee isotropic elastic stiffness with the best feasible dexterity. We demonstrate the proposed approach on some practical cases of planar adaptive cable-driven parallel robots.

In robotics, many control and planning schemes have been developed that ensure the human physical safety in human-robot interaction. The human psychological state and expectation towards the robot, however, are typically neglected. Even if the robot behaviour is regarded as biomechanically safe, humans may still react with rapid involuntary motion (IM) caused by startle or surprise. Obviously, such sudden, uncontrolled motions can jeopardize safety and should be preventedby any means. In this paper, we propose the Expectable Motion Unit (EMU) concept which ensures that a certain probability of IM occurrence is not exceeded in a typical HRI setting. Based on a model of IM occurrence that we generate through an experiment with 29 participants, the mapping between robot velocity, robot-human distance, and the relative frequency of IM occurrence is established. This mapping is processed towards a real-time capable robot motion generator, which limits the robot velocity during task execution if necessary. The EMU is combined with the well-established Safe Motion Unit in order to integrate both physical and psychological safety knowledge and data into a holistic safety framework. In a validation experiment, it was shown that the EMU successfully avoids human IM in five out of six cases.

Limited resources and resulting energy crises occurring all over the world highlight the importance of energy efficiency in technological developments such as robotic manipulators. Efficient energy consumption of manipulators is necessary to make them affordable and spread their application in the future industry. Previously, the power consumption of the robot motion was the main factor considered in the evaluation of energy efficiency. Lately, the paradigm in industrial robotics shifted towards lightweight robot manipulators which require a new investigation on the disaggregation of robot energy consumption. In this paper, we propose a novel pipeline to identify and disaggregate the energy use of mechatronic devices and apply it to lightweight industrial robots. The proposed method allows the identification of the electronic components consumption, mechanical losses, electrical losses, and required mechanical energy for robot motion. We evaluate the pipeline and understand the distribution of energy consumption using four different manipulators, namely, Universal Robot's UR5e, UR10e, Franka Emika's FR3, and Kinova Gen3. The experimental results show that most of the energy (60–90%) is consumed by the electronic components of the robot control box. Using this knowledge, the approaches to further optimize their energy consumption need to shift towards efficient robot electronic design instead of efficient robot mass distribution or motion control. Finally, our disaggregation pipeline allows an understanding of the power consumption of any mechatronic device and thus enables deliberate optimization of energy consumption.

Flexible and versatile mobile robotic coworkers are becoming an indispensable commodity for helping humans with repetitive or physically demanding work. A key challenge with these systems is respecting the strict safety requirements in shared and collaborative workspaces. This inevitably requires solving their whole-body dynamics to obtain the necessary inertial impact properties. In this article, we present an integrated impact dynamics and safe precollision control framework to address the discussed challenge. We propose a novel modular dynamics approach that provides efficient formulations for reusing the uncoupled subsystem dynamics when evaluating the coupled system. Our approach is generalized for deriving the whole-body impact dynamics of any articulated floating-base robot. Furthermore, it outperforms classical monolithic approaches for computing the dynamics, making it favorable for systems with more than two dynamic subsystems while allowing decentralized computations. Finally, based on the proposed modular and generalized impact dynamics and extending our previous work, we introduce the generalized safe motion unit as a unified safety scheme for floating-base robotic structures with branched manipulation extremities. The proposed concepts are evaluated on an exemplary wheeled mobile manipulator, considering realistic use cases in simulation and real-world experiments. The obtained results validated the efficacy of our framework and developed methods.