Design and construction of a mechanical tail for quadrupedal robots

Este trabajo ha recibido el primer premio en el concurso de prototipos de FGULEM Universidad de León 2022-2023.[ES] Este proyecto surge como un intento en el campo de la biomimética de robots cuadrúpedos, con el objetivo de lograr una interacción emocional con perros mascotas mediante la instalación de una cola mecánica en el robot Unitree A1.El proyecto es un sistema integrado que consta de dos módulos principales: diseño mecánico y control. El módulo de diseño mecánico consiste en la cola física y su mecanismo de transmisión. El cuerpo principal de la cola está compuesto por múltiples articulaciones universales conectadas en serie, impulsadas por dos pares de cables de acero: un par se conecta a una polea colocada horizontalmente, lo que permite que la cola oscile lateralmente; mientras que el otro par se conecta a una polea colocada verticalmente, permitiendo que la cola oscile verticalmente. Ambas poleas están conectadas a sus respectivos motores. El módulo de control se encarga de controlar la velocidad, dirección y número de ciclos de los dos motores, lo que permite que la cola oscile de diversas formas. Este módulo está compuesto por una caja de suministro de energía, una placa de desarrollo Arduino Nano con la placa de expansión CNC V4 y el entorno de desarrollo integrado Arduino IDE. El Arduino IDE se instala en una computadora y se utiliza para escribir el código de control, el cual se compila en un archivo ejecutable binario. Posteriormente, este archivo se envía al Arduino Nano a través de una interfaz USB y un cable. El microprocesador en el Arduino Nano ejecuta el código binario para controlar el funcionamiento de los motores.[EN] This project arises as an attempt in the field of biomimetics of quadruped robots, aiming to achieve emotional interaction with pet dogs by installing a mechanical tail on the Unitree A1 robot. The project is an integrated system consisting of two main modules: mechanical design and control. The mechanical design module consists of the physical tail and its transmission mechanism. The main body of the tail is composed of multiple universal joints connected in series, driven by two pairs of steel cables: one pair is connected to a horizontally placed pulley, allowing the tail to swing laterally; while the other pair is connected to a vertically placed pulley, allowing the tail to swing vertically. Both pulleys are connected to their respective motors. The control module is responsible for controlling the speed, direction, and number of cycles of the two motors, allowing the tail to swing in various ways. This module consists of a power supply box, an Arduino Nano development board with the CNC V4 expansion board, and the Arduino IDE integrated development environment. The Arduino IDE is installed on a computer and is used to write the control code, which is then compiled into a binary executable file. This file is then sent to the Arduino Nano via a USB interface and cable. The microprocessor on the Arduino Nano executes the binary code to control the operation of the motors

A Bubble Model for the Gating of Kv Channels

Voltage-gated Kv channels play fundamental roles in many biological processes, such as the generation of the action potential. The gating mechanism of Kv channels is characterized experimentally by single-channel recordings and ensemble properties of the channel currents. In this work, we propose a bubble model coupled with a Poisson-Nernst-Planck (PNP) system to capture the key characteristics, particularly the delay in the opening of channels. The coupled PNP system is solved numerically by a finite-difference method and the solution is compared with an analytical approximation. We hypothesize that the stochastic behaviour of the gating phenomenon is due to randomness of the bubble and channel sizes. The predicted ensemble average of the currents under various applied voltages across the channels is consistent with experimental observations, and the Cole-Moore delay is captured by varying the holding potential