Robots with intrinsic joint elasticity can perform highly dynamic manoeuvres by leveraging energy storage and release, enabling explosive motions such as throwing. By augmenting elastic robots with clutch mechanisms, link decoupling can be used to fully exploit inertial coupling effects and gravitational acceleration in motion while effectively circumventing spring deflection limits. However, braking such systems in a decoupled state presents a challenge, as re-engaging the link risks damaging the joint. While optimal control strategies could be applied, they are not inherently safe due to model uncertainties. To address this, we propose a feedback-based two-stage method that coordinates the transition through the hybrid modes of the system. These modes are characterized by underactuated and actuated dynamics. First, a decoupled link is braked via inertial coupling until a safe velocity for clutching is reached, after which the link is re-coupled and actively braked. We demonstrate the effectiveness of this method through simulations comparing it with optimal control and validate it experimentally using a physical prototype.

Robotic system development must adopt a holistic approach for tactile and dynamic tasks, shifting from the decoupled design of end-effectors and robot manipulators for traditional sequential tasks. Although established metrics exist for traditional tasks, such as pick-and-place, they lack the nuanced evaluation required for dynamic and tactile operations. Accordingly, this paper introduces an integrated framework that defines and unifies decoupled and coupled gripper metrics into a single perspective. We categorise gripper metrics based on their interaction with the robot manipulator, which can be entirely decoupled, coupled by time-sequence, or coupled. Using this classification, we propose 16 metrics to evaluate force control, force reaction, and efficiency. We introduce three new experimental setups and describe the corresponding procedures to quantify these metrics. Results from three commercial finger grippers demonstrate the efficacy of the proposed metrics, revealing each gripper’s strengths and limitations when integrated into different manipulator systems. Incorporating these metrics into performance reviews provides a comprehensive evaluation of robotic system fitness, considering dynamic, real-time challenges. This supports informed design choices and enhances tactile manipulation tasks.

Intrinsically elastic robots surpass their rigid counterparts in a range of different characteristics. By temporarily storing potential energy and subsequently converting it to kinetic energy, elastic robots are capable of highly dynamic motions even with limited motor power. However, the time-dependency of this energy storage and release mechanism remains one of the major challenges in controlling elastic robots. A possible remedy is the introduction of locking elements (i.e. clutches and brakes) in the drive train. This gives rise to a new class of robots, so-called clutched-elastic robots (CER), with which it is possible to precisely control the energy-transfer timing. A prevalent challenge in the realm of CERs is the automatic discovery of clutch sequences. Due to complexity, many methods still rely on pre-defined modes. In this paper, we introduce a novel contact-implicit scheme designed to optimize both control input and clutch sequence simultaneously. A penalty in the objective function ensures the prevention of unnecessary clutch transitions. We empirically demonstrate the effectiveness of our proposed method on a double pendulum equipped with two of our newly proposed clutch-based Bi-Stiffness Actuators (BSA).

Mobile manipulators (MM) have proven valuable in assisting humans in industrial settings. However, their strict separation from humans in controlled environments limits their effectiveness. Efforts have been made to bridge this gap for physical human-robot interaction (pHRI), leading to the development of collaborative mobile manipulators (CMM). Nonetheless, unpredictable environments continue to present challenges. This paper introduces an innovative suspension design for mobile bases (MBs) to enhance the safety and autonomy of CMMs. We propose an electromechanical approach leveraging variable stiffness and combining passive springs with adaptive transmission mechanisms. Through simulation, physical prototype development, and experimental validation, we demonstrate the effectiveness of our approach in stabilizing the MB against external disturbances. Our findings provide valuable insights for the development of CMMs in dynamic environments.

Nowadays, wheeled mobile robots constitute a considerable portion of robots in industrial applications. Generally, regardless of their purpose, these systems are not designed to physically interact with humans, other robots, or the environment. In this study, we present a novel safe autonomous mobile - SAM - robot, which is a torque-controlled compliant robot that is conceived for safe human-robot interaction. This work provides an overview of the development philosophy of the system, its mechanical and mechatronics structure along with control and navigation architecture. Preliminary results show the advantages of the proposed mobile robot while interacting with its surroundings. We believe that this study will bring the wheeled mobile robots one step closer to the proactive interaction with their environment and humans surrounding them.

Compliance in actuation has been exploited to generate highly dynamic maneuvers such as throwing that take advantage of the potential energy stored in joint springs. However, the energy storage and release could not be well-timed yet. On the contrary, for multi-link systems, the natural system dynamics might even work against the actual goal. With the introduction of variable stiffness actuators, this problem has been partially addressed. With a suitable optimal control strategy, the approximate decoupling of the motor from the link can be achieved to maximize the energy transfer into the distal link prior to launch. However, such continuous stiffness variation is complex and typically leads to oscillatory swing-up motions instead of clear launch sequences. To circumvent this issue, we investigate decoupling for speed maximization with a dedicated novel actuator concept denoted Bi-Stiffness Actuation. With this, it is possible to fully decouple the link from the joint mechanism by a switch-and-hold clutch and simultaneously keep the elastic energy stored. We show that with this novel paradigm, it is not only possible to reach the same optimal performance as with power-equivalent variable stiffness actuation, but even directly control the energy transfer timing. This is a major step forward compared to previous optimal control approaches, which rely on optimizing the full time-series control input.

Necessity of precise positioning in percutaneous needle operations enables robotic systems to take part in medical procedures. Researches that have been done until today showed robotic systems increase the accuracy of medical interventions. This paper presents the design and modeling of a 5DOF parallel robot that will be used in Ultrasound image guided percutaneous needle interventions. In order to design the robot, workspace and torque analysis were conducted. System identification was performed on robot to understand the system dynamics. System calibration was performed with optical tracking system to increase the accuracy of the system. Gravity compensation and friction modeling were conducted on the robot. Using gravity compensation and friction models, a torque computed controller was implemented to system.