To detect the work objects and environment, or the robot's relationship with them, tactile sensors, visual sensors, force sensors, proximity sensors, ultrasonic sensors, and auditory sensors are installed on robots. These sensors greatly improve the robot's working conditions, enabling it to complete complex tasks more effectively. Because external sensors are products integrating multiple disciplines, some aspects are still under exploration. As external sensors are further improved, the functions of robots will become increasingly powerful, making greater contributions to humanity in many fields.
Sensors can be categorized into internal sensors and external sensors based on the type of object being detected.
1. Internal Sensors: Sensors used to detect the robot's own state (such as the angle between its arms). These are mostly sensors that detect position and angle.
II. External Sensors: Sensors used to detect the robot's environment (such as what the objects are, how far away they are, etc.) and its condition (such as whether the grasped object has slipped). These include object recognition sensors, object flaw detection sensors, proximity sensors, distance sensors, force sensors, and auditory sensors.
III. Main Sensors
(I) Vision Sensor
Emerging in the late 1950s, it has developed rapidly and is one of the most important sensors in robots.
Machine vision began in the 1960s by processing the world of building blocks, and later evolved to process the real world outdoors. After the 1970s, practical vision systems emerged.
Vision generally involves three processes: image acquisition, image processing, and image understanding. Relatively speaking, image understanding technology is still quite underdeveloped.
(II) Force Sensor
In terms of installation location, robot force sensors can be divided into joint force sensors, wrist force sensors, and finger force sensors.
International research on wrist force sensors began in the 1970s, with major research institutions including DRAPER Laboratories, SRI Research Institute, IB+M in the United States, and Hitachi and the University of Tokyo in Japan.
(III) Tactile Sensor
As a complement to vision, touch can perceive the surface properties and physical characteristics of a target object: softness, hardness, elasticity, roughness, and thermal conductivity, etc.
Tactile research began in the early 1980s and yielded significant results by the early 1990s.
(iv) Proximity sensor
The purpose of this research is to enable robots to know the proximity of targets (obstacles) during movement or operation. Mobile robots can avoid obstacles, and manipulating robots can avoid the impact of the gripper on the target due to excessive approach speed.
(V) Hearing Sensor
1. Personal speech recognition system
Speaker-specific speech recognition methods store the feature matrix of each syllable in the voice of a pre-designated person, forming a standard template, and then perform matching. It first memorizes one or several speech features, and the content of the designated person's speech must be a limited set of pre-defined sentences. A speaker-specific speech recognition system can then identify whether the speaker is the pre-designated person and which sentence they are speaking.
2. Person-independent speech recognition system
Speaker-independent speech recognition systems can be broadly categorized into language recognition systems, word recognition systems, and digit sound (0-9) recognition systems. Speaker-independent speech recognition methods require training on a representative group of speakers to identify commonalities in the sounds of the same words. This training is often open-ended, allowing for continuous system refinement. During system operation, the feature matrices of received sound signals are calculated using the same method and then compared with standard patterns. The system identifies which template it matches or is similar to, thereby determining the meaning of the signal.
Security robots, with their close-range reconnaissance and proactive intervention capabilities, will bring new development opportunities to the security industry and promote the construction of an intelligent security service system that combines static and dynamic elements. A number of security and robotics companies both domestically and internationally have already begun research and development and application of security robots. Currently, the market is still in the cultivation stage, but the market potential is enormous. Navigation and positioning, image transmission, intelligent recognition, and management software are key core technologies that security robots need to address. Overcoming these technical challenges will clear the way for the industrialization of security robots.
