Since the 1980s, a wave of "sensor fever" has gradually swept across the world. All advanced industrial countries attach great importance to sensing technology and the research, development, and production of sensors. Sensing technology has become an important modern scientific and technological field, and the production of sensors and their systems has become an important emerging industry.
Sensors are devices or components that can sense the specified measured quantity and convert it into a usable output signal according to certain rules. They are mainly used to detect the state of the mechatronic system itself, the operating objects, and the working environment, providing necessary relevant information for effective control of the operation of the mechatronic system. With the expansion of human exploration fields and spaces, the types of electronic information are increasingly diverse, information transmission speeds are accelerating, and information processing capabilities are enhancing. Correspondingly, information collection—sensing technology will also develop increasingly, and sensors will become ubiquitous.
Sensors are one of the important technologies that determine the development of mechatronic systems (or products), and are widely used in various automation products:
1. Sensors for robots. Industrial robots can operate accurately because they can accurately perceive the state of themselves, the operating objects, and the working environment through various sensors. This includes: obtaining information about their own state through internal sensors (position, displacement, velocity, acceleration, etc.), and perceiving the operating objects and external environment through external sensors. This process is very important and sufficient to provide feedback information for robot control.
2. Sensing and detection technology in machining processes.
(1) Sensing technology for cutting processes and machine tool operation. The purpose of sensing and detection in cutting processes is to optimize productivity, manufacturing cost, or (metal) material removal rate during cutting. The targets of sensing and detection in cutting processes include cutting force and its changes, chatter during cutting, contact between tool and workpiece, chip state during cutting, and identification of the cutting process. The most important sensing parameters include cutting force, vibration during cutting, acoustic emission during cutting, and motor power during cutting. For machine tool operation, the main sensing and detection targets include the drive system, bearings and rotating systems, temperature monitoring and control, and safety. The sensing parameters include machine tool downtime due to faults, surface roughness and machining accuracy of the workpiece, power, machine tool status, and coolant flow rate.
(2) Workpiece process sensing. Compared with tool and machine tool process monitoring technology, workpiece process monitoring has been the earliest and most extensively researched and applied. Most of them aim at workpiece machining quality control. Since the 1980s, requirements for workpiece identification and workpiece installation pose monitoring have also been put on the agenda. Roughly speaking, process identification is to identify whether the machining process being executed is the process required for the workpiece (part) machining; workpiece identification is to identify whether the workpiece or blank sent to the machine tool for machining is the required workpiece or blank, and also to identify whether the installation pose of the workpiece meets the pose required by the process specification. In addition, workpiece identification and installation monitoring can also be used to sense the machining allowance and surface defects of the blank or workpiece to be machined. To accomplish these identifications and monitoring, many sensors will be used or developed, such as machine vision sensors based on TV or CCD, laser surface roughness sensing systems, etc.
(3) Tool (grinding wheel) detection sensing. Cutting and grinding processes are important material removal processes. When the tool and grinding wheel wear to a certain limit (judged according to the blunt standard) or suffer damage (collectively referred to as breakage, chipping, burning, plastic deformation, or edge rolling), causing them to lose cutting (grinding) ability or unable to guarantee machining accuracy and surface integrity, it is called tool/grinding wheel failure. Industrial statistics prove that tool failure is the primary factor causing machine tool downtime due to faults, and the downtime caused by it accounts for 1/5 to 1/3 of the total downtime of NC machine tools. In addition, it may also cause equipment or personal safety accidents, even major accidents.
