Despite the development of a large number of mobile manipulation robots, very few platforms can demonstrate the required strength and mechanical sturdiness to accommodate the needs of real-world applications with high payload and moderate/harsh physical interaction demands, e.g. in disaster-response scenarios or heavy logistics/collaborative tasks. In this work we introduce the design of a wheeled-legged mobile manipulation platform capable of executing demanding manipulation tasks, and demonstrating significant physical resilience while possessing a body size (height/width) and weight compatible to that of human. The achieved performance is the result of a combining a number of design and implementation principles related to the actuation system, the integration of body structure and actuation, and the wheeled-legged mobility concept. These design principles are discussed, and the solutions adopted for various robot components are detailed. Finally, the robot performance is demonstrated in a set of experiments validating its power and strength capability when manipulating heavy payload and executing tasks involving high impact physical interactions.

Despite enhancements in the development of robotic systems, the energy economy of today's robots lags far behind that of biological systems. This is in particular critical for untethered legged robot locomotion. To elucidate the current stage of energy efficiency in legged robotic systems, this paper provides an overview on recent advancements in development of such platforms. The covered different perspectives include actuation, leg structure, control and locomotion principles. We review various robotic actuators exploiting compliance in series and in parallel with the drive-train to permit energy recycling during locomotion. We discuss the importance of limb segmentation under efficiency aspects and with respect to design, dynamics analysis and control of legged robots. This paper also reviews a number of control approaches allowing for energy efficient locomotion of robots by exploiting the natural dynamics of the system, and by utilizing optimal control approaches targeting locomotion expenditure. To this end, a set of locomotion principles elaborating on models for energetics, dynamics, and of the systems is studied.

Joint torque sensing represents one of the foundations and vital components of modern robotic systems that target to match closely the physical interaction performance of biological systems through the realization of torque controlled actuators. However, despite decades of studies on the development of different torque sensors, the design of accurate and reliable torque sensors still remains challenging for the majority of the robotics community preventing the use of the technology. This letter proposes and evaluates two joint torque sensing elements based on strain gauge and deflection-encoder principles. The two designs are elaborated and their performance from different perspectives and practical factors are evaluated including resolution, nonaxial moments load crosstalk, torque ripple rejection, bandwidth, noise/residual offset level, and thermal/time dependent signal drift. The letter reveals the practical details and the pros and cons of each sensor principle providing valuable contributions into the field toward the realization of higher fidelity joint torque sensing performance.

The ongoing trend from mass-produced to mass-customized products with batch sizes as small as a single unit has highlighted the need for highly adaptable robotic systems with lower downtime for maintenance. To address these demands, this article proposes the development of a novel reconfigurable collaborative robot (cobot), which has the potential to open up many new scenarios within the rapidly emerging flexible manufacturing environments. As the technological contribution, we present a complete hard- and software architecture for a quickly reconfigurable EtherCAT-based robot. This novel approach allows to automatically reconstruct the topology of different robot structures, composed of a set of body modules, each of which represents an EtherCAT slave. As the theoretical contribution, we propose a method to obtain in an automatic way the kinematic and dynamic model of the robot and store it in universal robot description format (URDF) as soon as the physical robot is assembled or reconfigured. The method also automatically reshapes a generic optimization-based controller to be instantly used after reconfiguration. While this article focuses on reconfigurable manipulators, the proposed concept can support arbitrary serial kinematic tree-like configurations. We demonstrate the contributions with examples of the following: how the topology of the robot is reconstructed and the URDF model is generated, and a Cartesian task application for a cobot built with the basic modules, demonstrating the quick reconfigurabilty of the system from a 4-degrees-of-freedom (DOF) robot to a 5-DOF robot, in order to satisfy new workspace requirements.