A Two-dimensional Area-Scanning Protection Device Design Based On Laser Ranging

Along with the rapid development of industrial automation and the continuous expansion of the mechanical processing industry, the number and severity of all kinds of mechanical injury to processing staff caused by mechanical moving parts is constantly increasing. The problem is especially serious in China which is full building industrial society, causes significant physical and mental harm to production workers, bring great economic losses to the enterprise and the country, causes serious adverse effects to the society. Machinery safety has become an important factor affecting the happiness index of the majority of industrial workers. With the development of China’s industrialization process and continuous improvement of the national economy, the personal security is increasingly attracting universal attention of the country and society. A variety of personal safety protection products are introducing and promoting, including safety light curtains, hands button, safety carpets, laser safety scanners(two-dimensional area scanning protection devices), etc, which are widely applied to various industrial sites for personal safety protection. As domestic security products research started late and the application of functional safety technology is immature and technical difficulty is relatively high, there has been no domestic company which can indepently produce two-dimensional regional scanning protection device. The price of the imported similar products need tens of thousands of RMB yuans, the application costs are high. Two-dimensional area scanning protection device is widely used, in addition to being used in the industrial field for regional intrusion detection within the plane scope, can also be installed vertically for large-area、non-contact security isolation, also the product can be applied to the surrounding environment detection of the automatic feeding vehicles and guide the car to run in default route. Given the current foreign products are expensive (tens of thousands of RMB yuans frequently) and there are no mature products, the paper studied the two-dimensional area scanning protection device based on the principle of laser ranging.The protection device core of this study is accurate laser ranging and the safety integrity of control functions. Systems include high precision ranging system (including pulsed laser emission system, signal reception system, precision timing system), the optical scanning system and overall control system and the development and design of man-machine interface.Pulse laser system mainly adopt the avalanche transistor as switch device, cooperate the semiconductor laser diode to produce high power、narrow pulse width、 short rising detecting pulse laser beam.The signal receiving system adopts the high sensitive APD receiving tube for receiving the reflected signal, and designs high-bandwidth、wide dynamic-range amplifier circuit to amplify the received signal.Precise timing system based on precise timing chip TDC-GP2records the time difference between the transmitting and receiving signals.The optical scanning system takes use of the mirror driven by a DC brushless motor to make the laser beam deflected and scan in the two-dimensional space within the scanning angle ranges according the system requirements, and receives the reflected laser signals in all directions.The overall control system with the DSP chip as the core components, adopts dual-loop architecture which focuses on improving the functional safety integrity level, realizing the basic functions of the system at the same time. The system safety level meets the requirements of Type3in standard IEC61496-1/-3, the safety integrity level meets SIL2.The main task of the human-machine interface design includes designing PC interface, providing a communication channel between operators and protection devices, being convenient to set the functions the protection and alarm region of the protection devices.In addition, the design process also fully considers the electromagnetic compatibility to ensure that the system can work stably and reliably in a variety of complex electromagnetic environment.The main innovations of the paper include:1. The research on the protection device will fill the gaps in the fields of two-dimensional area scanning protection.2. The laser transmitter circuit using avalanche transistor effectively improves the transmission power and the output velocity of the semiconductor laser diode. 3. The application of imbedded controllers in industrial personal safety protection devices.4. The innovative optical system can effectively reduce the loss of the reflected light energy.