Digital Twins of Building Physics Experimental Laboratory Setups for Effective E-learning

Hands-on experiments in laboratories are fundamental educational tools for technical sciences. However, laboratories are expensive and not always accessible to students: lockdown and in-person meeting restrictions due to the ongoing Covid-19 pandemic, distant location of teachers and students, facilities used for higher-priority purposes. Moreover, creating specific experimental setups for teaching only can be costly. In that context, digitalizing laboratory setups provides an attractive teaching alternative for remote e-learning. Digital twins are not meant to replace real-world experiments but should enable flexible teaching and effective learning at a lower cost. They complement physical setups and can be virtual extensions, allowing for larger and more complex study cases. e-learning is now popular and many educational institutions provide open-access videos of entire courses. However, the digitalization of practical exercises for engineering is yet limited. The e-learning effort presented in this paper aims to establish a series of digital twins of experimental setups for teaching building physics, energy in buildings and indoor environment. The development of the two first digital twins is detailed here. They are designed for teaching operation and balancing hydronic heating systems. Their numerical models and graphical user interfaces are created with the LabVIEW programming environment.

Cooperative Control of Manipulator and Human Operator for Direct Teaching

A cooperative control of a manipulator and a human operator has been proposed for an efficient direct teaching operation in this research. The main goal is making the operator be convenient and relaxed when he is operating the manipulator for a direct teaching. The proposed control strategy has two layers: In the first layer, human motion estimator (HME) has been designed to estimate a human intention. The recursive least square method has been utilized for the HME to simultaneously estimate the interaction force and the human arm admittance model. In the second layer, human motion reactor has been designed to keep the human motion intention precisely by a proportional derivative and gravity compensation in real time. Real experiments with a 3-degree of freedom robotic manipulator guided by the human operator have been conducted to draw a diamond shape on a panel. The experimental results demonstrate the effectiveness of the proposed cooperative control strategy.

Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.