Optical System And Timing Ranging Method For Pulse Laser Ranging

In recent years,laser ranging technology has been widely used in autonomous vehicle,unmanned aerial vehicles,robots and other equipments.Obstacle detection and navigation can be realized by using laser ranging system,which has promoted the development of transportation and industrial manufacturing in China.However,the current laser ranging system still has a problem that it is difficult to take into account the manufacturing costs,system weight and volume,and measurement accuracy.Therefore,this paper focuses on the research of timing ranging methods and optical systems for the problem.The main research contents of this article are as follows:1)In order to achieve high-precision measurement of the system,in terms of timing and ranging methods,a timing and measurement platform of the system was designed based on TDC-GP22 and STM32F103-ZET6 microcontroller.Firstly,the communication and mode configuration between STM32 and TDC were completed through SPI protocol;Secondly,a built-in platform was designed to achieve TDC analog measurement;Finally,through the test,the timing and ranging of TDC in pulse laser ranging system were realized,which can achieve high precision with 1.1 mm in 0.21 m.The designed system has the advantages of low power consumption and low cost,providing an important expperimental basis for the subsequent improvement of the range of the system.2)In order to achieve low cost and miniaturization of the system,while improving the range,optical systems at the transmitter and receiver have been designed respectively.ⅰ)Designing the transmitting optical system,including single point system and multiline collimation system.The single point system uses the cylindrical lens to compress the half-divergence angles of the LD from 20.6° and 7.6° to 6.73 mrad and 5.57 mrad;The multi-line system uses a combination of cylindrical lens and standard lenses to achieve 4 x 4 LD array to collimate the beam,and the half-divergence angles after collimation are 11.85 mrad and 6.65 mrad.Through the test,the actual half-divergence angles of the single point system are 7.79 mrad and 6.54 mrad.In summary,both systems have a simple structure,and all components have standard circular curvature,which can effectively reduce system costs while holding the high performance.ii)Designing the receiving optical system,including single point system and multi-line receiving system.Firstly,a Galileo type receiving system was designed,with an aperture of 50 mm and invariant of 125 mrad·mm.It has the advantages of low cost,light weight,and small size,while ensuring sufficient light intake;Secondly,a multi-line receiving system was designed.The result shows that the received ratio of each unit in the APD array is 6%,and it can achieve detection in 16 units;Finally,a stray light suppression structure for single point system was designed by using a combination of shield and barrier in the lens barrel,which can effectively suppress stray light at an off-axis angle of 20° to 85°(RPST≤1.04 ×103),and the length of the shield is short,which reduces the impact of stray light while achieving lightweight and miniaturization of the system.Further,indoor and outdoor tests were completed on the receiving system.The result of indoor test shows that the single point system can comprehensively increase the range of the system by 21.8 times.And outdoor vehicles were targeted,the range of the system is improved to 102 m.The results show that the receiving optical system has high performance,achieves the ranging target of 100 m,and has advantages such as low manufacturing cost,light weight,and small size,so it has a great application prospect.