A sensor is a device that converts a physical parameter or an environmental characteristic (e.g., temperature, distance, speed, etc.) into a signal that can be digitally measured and processed to perform specific tasks. Mobile robots need sensors to measure properties of their environment, thus allowing for safe navigation, complex perception and corresponding actions, and effective interactions with other agents that populate it. Sensors used by mobile robots range from simple tactile sensors, such as bumpers, to complex vision-based sensors such as structured light RGB-D cameras. All of them provide a digital output (e.g., a string, a set of values, a matrix, etc.) that can be processed by the robot's computer. Such output is typically obtained by discretizing one or more analog electrical signals by using an Analog to Digital Converter (ADC) included in the sensor. In this chapter we present the most common sensors used in mobile robotics, providing an introduction to their taxonomy, basic features, and specifications. The description of the functionalities and the types of applications follows a bottom-up approach: the basic principles and components on which the sensors are based are presented before describing real-world sensors, which are generally based on multiple technologies and basic devices.

翻译：传感器是一种将物理参数或环境特征（如温度、距离、速度等）转换为可被数字测量和处理信号的设备，以执行特定任务。移动机器人需借助传感器测量环境属性，从而实现安全导航、复杂感知与相应动作，以及与环境中其他智能体的有效交互。移动机器人使用的传感器范围广泛，从简单的触觉传感器（如保险杠）到基于视觉的复杂传感器（如结构光RGB-D相机）。所有传感器均提供数字输出（如字符串、数值集、矩阵等），可由机器人计算机处理。此类输出通常通过传感器内置的模数转换器（ADC）对模拟电信号进行离散化获得。本章介绍移动机器人领域最常用的传感器，阐述其分类体系、基本特性及技术规格。功能描述与应用类型分析采用自下而上的方式：在描述基于多种技术与基础器件的实际传感器之前，先行介绍传感器的基础原理与构成组件。