This paper presents the conceptual and functional design of a novel hybrid leg-wheel-track ground mobile robot for surveillance and inspection, named WheTLHLoc (Wheel-Track-Leg Hybrid Locomotion). The aim of the work is the development of a general-purpose platform capable of combining tracked locomotion on irregular and yielding terrains, wheeled locomotion with high energy efficiency on flat and compact grounds, and stair climbing/descent ability. The architecture of the hybrid locomotion system is firstly outlined, then the validation of its stair climbing maneuver capabilities by means of multibody simulation is presented. The embodiment design and the internal mechanical layout are then discussed.

This article presents a new design for a two-degrees-of-freedom compliant robotic wrist for upper limb prostheses that matches the maximum range of motion of a human wrist by utilizing cross axis flexural pivot (CAFP) as compliant joints. The wrist design is manufactured using additive manufacturing technology as a single, monolithic component. An optimization routine that utilizes the bi-beam constraint model technique to synthesize compliant joints in the wrist design is presented and verified using finite element analysis (FEA). This optimization routine includes the computation of passive contact profiles through the centroid approach to prevent buckling in the CAFP compliant beams caused by external forces. Furthermore, an accurate analysis of various tendon routing paths for the actuation of the wrist is conducted, providing a flexible and reliable solution to avoid unnecessary power consumption. The proposed wrist is lightweight, cost-effective, easy to maintain, and thanks to the utilization of CAFP joints, it is frictionless and immune to backlash. Experimental tests are conducted to verify the FEA results and confirm the range of motion achieved by the joint (i.e., $\pm 80^{\circ }$ of flexion/extension, $\pm 40^{\circ }$ of ulnar/radial deviation). Overall, this article demonstrates the development of a novel compliant robotic wrist that offers several advantages over traditional prostheses, including a wider range of motion, increased flexibility, and reduced maintenance costs.

New technological advances are changing the way robotics are designed for safe and dependable physical human–robot interaction and human-like prosthesis. Outstanding examples are the adoption of soft covers, compliant transmission elements, and motion control laws that allow compliant behavior in the event of collisions while preserving accuracy and performance during motion in free space. In this scenario, there is growing interest in variable stiffness actuators (VSAs). Herein, we present a new design of an anthropomorphic elbow VSA based on an architecture we developed previously. A robust dynamic feedback linearization algorithm is used to achieve simultaneous control of the output link position and stiffness. This actuation system makes use of two compliant transmission elements, characterized by a nonlinear relation between deflection and applied torque. Static feedback control algorithms have been proposed in literature considering purely elastic transmission; however, viscoelasticity is often observed in practice. This phenomenon may harm the performance of static feedback linearization algorithms, particularly in the case of trajectory tracking. To overcome this limitation, we propose a dynamic feedback linearization algorithm that explicitly considers the viscoelasticity of the transmission elements, and validate it through simulations and experimental studies. The results are compared with the static feedback case to showcase the improvement in trajectory tracking, even in the case of parameter uncertainty.

In this article, we describe the design, fabrication, and validation of a push-latch gripper produced via additive manufacturing, which is capable of performing planar grasps of objects with two opposite parallel surfaces. In particular, the gripper modes of operation are presented, along with an efficient virtual prototype of the system based on a pseudo-rigid body approximation. Such model is proven to be considerably more computationally efficient as compared to the corresponding finite element simulation, while still accurately capturing the fundamental behaviors of the mechanism. Finally, quantitative performance assessments are reported to practically show how fused filament fabrication of Nylon components can be an excellent approach for creating monolithic robotic mechanisms with embodied intelligence that can be effectively employed for pick and place operations. Furthermore, this work represents one further example of an alternative approach to mechanisms development that combines part minimization, faster design iterations, and high repeatability.