Heart Rate Variability Control Using a Biofeedback and Wearable System.

Heart rate variability is an important physiological parameter in medicine. This parameter is used as an indicator of physiological and psychological well-being and even of certain pathologies. Research on biofeedback integrates the fields of biological application (physiological behavior), system modeling, and automated control. This study proposes a new method for modeling and controlling heart rate variability as heart rate acceleration, a model expressed in the frequency domain. The model is obtained from excitation and response signals from heart rate variability, which through the instrumental variables method and the minimization of a cost function delivers a transfer function that represents the physiological phenomenon. This study also proposes the design of an adaptive controller using the reference model. The controller controls heart rate variability based on the light actuators designed here, generating a conditioned reflex that allows individuals to self-regulate their state through biofeedback, synchronizing this action to homeostasis. Modeling is conducted in a target population of middle-aged men who work as firefighters and forest firefighters. This study validates the proposed model, as well as the design of the controllers and actuators, through a simple experiment based on indoor cycling. This experiment has different segments, namely leaving inertia, non-controlled segment, and actively controlled segment.

Design and Testing of a Computer Security Layer for the LIN Bus.

Most modern vehicles are connected to the internet via cellular networks for navigation, assistance, etc. via their onboard computer, which can also provide onboard Wi-Fi and Bluetooth services. The main in-vehicle communication buses (CAN, LIN, FlexRay) converge at the vehicle's onboard computer and offer no computer security features to protect the communication between nodes, thus being highly vulnerable to local and remote cyberattacks which target the onboard computer and/or the vehicle's electronic control units through the aforementioned buses. To date, several computer security proposals for CAN and FlexRay buses have been published; a formal computer security proposal for the LIN bus communications has not been presented. So, we researched possible security mechanisms suitable for this bus's particularities, tested those mechanisms in microcontroller and PSoC hardware, and developed a prototype LIN network using PSoC nodes programmed with computer security features. This work presents a novel combination of encryption and a hash-based message authentication code (HMAC) scheme with replay attack rejection for the LIN communications. The obtained results are promising and show the feasibility of the implementation of an LIN network with real-time computer security protection.