This work describes a layout to carry out a demonstrative assembly task, during which a collaborative robot performs pick-and-place tasks to supply an operator the parts that he/she has to assemble. In this scenario, the robot and operator share the workspace and a real time collision avoidance algorithm is implemented to modify the planned trajectories of the robot avoiding any collision with the human worker. The movements of the operator are tracked by two Microsoft Kinect v2 sensors to overcome problems related with occlusions and poor perception of a single camera. The data obtained by the two Kinect sensors are combined and then given as input to the collision avoidance algorithm. The experimental results show the effectiveness of the collision avoidance algorithm and the significant gain in terms of task times that the highest level of human-robot collaboration can bring.
The rising interest in soft robotics, combined to the increasing applications in the space industry, leads to the development of novel lightweight and deployable robotic systems, that could be easily contained in a relatively small package to be deployed when required. The main challenges for soft robotic systems are the low force exertion and the control complexity. In this manuscript, a soft manipulator concept, having inflatable links, is introduced to face these issues. A prototype of the inflatable link is manufactured and statically characterized using a pseudo-rigid body model on varying inflation pressure. Moreover, the full robot model and algorithms for the load and pose estimation are presented. Finally, a control strategy, using inverse kinematics and an elastostatic approach, is developed. Experimental results provide input data for the control algorithm, and its validity domain is discussed on the basis of a simulation model. This preliminary analysis puts the basis of future advancements in building the robot prototype and developing dynamic models and robust control.
Summary: Underground gas storage (UGS) wells are essential components in energy security. However, UGS wells present a complicated and delicate combination of elements where ensuring safe and secure functionality over long periods is paramount. This paper showcases how a digital twin is used to evaluate and forecast the link between leaks and temperature and pressure trends in a UGS well, allowing the identification and quantification of defects and, subsequently, well barrier integrity. The digital twin used for this application presents advantages compared with other solutions present on the market with regard to the simplified configuration; that is, with minimal input data, the system can produce an accurate and useful output, which is then used in the well integrity decision-making process. UGS wells present additional criticalities with respect to normal production wells due to their longer life span and the repetitive production and injection cycles. This makes early and accurate leak detection essential for the safe management of the well barriers. The proposed digital twin simulates the trends of pressure and temperature within each annulus and compares results with data from the field, allowing the identification of the position and size of leaks. A genetic algorithm is applied to optimize the placement of leaks on their specific barriers. Once a leak is identified, a risk assessment is conducted to evaluate the overall integrity of the well. If the status of the well is found to be critical enough, an intervention may be planned. The studies presented show how the digital twin has been used on two wells with similar problems. At first, it has confirmed the necessity to put the well out of service as opposed to planning maintenance, thereby saving both time and cost. In the second case, it allowed the validation of a solution that led to a 60% reduction in failure consequence, allowing the well to continue operating without major costs or risks. The errors of the resulting simulations were always confined within the 0.5 bar limit highlighting its accuracy. The system has been in use for over a year and has shown great potential in accurate and efficient identification of leaks. This has accelerated the process of well integrity evaluation and allowed timely interventions on wells that required it. On the other hand, the process has highlighted cases where previous assumptions about leak location and size were corrected using the digital twin, therefore reducing the costs of interventions. Finally, the model showcases a clear readiness for predictive capabilities aimed to select, plan, and design fit for purpose mitigating actions.
This paper describes the latest application of the inflatable robotic manipulator called POPUP. It consists of two inflatable links, made of fibers with high elastic module, electric motors and a gripper. This architecture allows volume and weight reduction, still maintaining the same payload compared to traditional solutions if the internal pressure is set properly. This robot, specifically designed for space application, here goes into action for debris mitigation by means of a vision system. First, some of the aspects related to the physical modelling are discussed to point out the working ranges of such a system, mainly defined by wrinkling effects. Then, a debris capture procedure is simulated to investigate the possibility to catch the target despite the soft nature of the robot. The multibody model takes into account robot dynamics and contact forces with the target. A control strategy based on closed loop inverse kinematics and visual servoing is proposed. The strategy relies on joint velocity command, computed starting from signals of two camera systems, one observing from the robot base, another moving with the end-effector. This ensures the correct tracking of the target and allows to overcome potential errors deriving from a flexible kinematic chain. Results show the POPUP successfully reaching the target and dictate the next steps for a real-world application.
The spherical shape is an interesting approach to develop exploration robots, or rovers, thanks to its capability of ensuring omnidirectional motion and of being basically unsensitive to possible rollovers. This works intends to propose a novel detailed design for such a kind of robot and to discuss the performance that can be reached by adopting this solution. The work hence introduces the requirements assumed for the design of the robot and discloses the general layout that was selected, which includes a pendulum for motion transmission and two coupled gyroscopes to overcome high, steep obstacles, such as steps. The paper then summarizes the functional design computation carried out to size and selects the components of the system. Eventually, a control algorithm is described and tested on a complete multibody model of the robot. The results in the execution of standard maneuvers such as motion on a horizontal plane, as well as in the overcome of a step, are shown. The energetic balance of the rover is described, and some preliminary consideration about mission planning are reported in the final discussion.