Exploration on the Teaching of Sensor and Detection Technology
Sensor and detection technology is a basic technical course of automation, electrical engineering and automation, process equipment and control, which plays a key role in the comprehensive application of students' professional knowledge. According to the characteristics and existing problems of this course, the adjustment of teaching content and the improvement of teaching methods are discussed in order to obtain better teaching quality and effect.
Key words: sensor and detection technology; Teaching reform; teaching method
China Library Classification Number: G7 1 Document Identification Number: A
Article number:1009-0118 (2012) 05-0132-02.
Sensor and detection technology is a basic technical course for automation, electrical engineering and automation, process equipment and control. It is an applied technology course, which mainly studies the theory and technology of information extraction, information conversion and information processing in automatic detection system. Sensing technology is not only an automatic detection system, but also an outpost of control system. It is widely used in various fields and plays an important role in promoting the development of production and the progress of modern science and technology. Learning this course well can not only lay a good foundation for subsequent courses, but also play a key role in students' comprehensive application of their professional knowledge. Since the adjustment of curriculum outline in 2005, some new problems have appeared in teaching, and it is difficult for the original traditional teaching mode to obtain good teaching quality and effect.
First, the problems in curriculum teaching
Since 2005, our school has re-established the teaching syllabus of automation specialty, in which the course of sensor and detection technology has been adjusted from examination to assessment, and the class hours have been changed from 64 hours to 32 hours. Through several years of teaching, some difficulties in the teaching of this course are summarized:
(A) the teaching content is numerous and scattered
The content of the course is numerous and scattered, covering a wide range of knowledge, including physics, chemistry, electronics, mechanics and so on. It is a multi-disciplinary course, which is difficult for students to learn, especially some students with poor foundation.
(2) Typical applicability
Sensor and detection technology is a typical application course. If we want to learn the principles of various sensors and master their usage methods, and on this basis, master the method of building a detection system, there must be a gap only by theoretical learning. However, the experimental hours are insufficient and the experimental conditions are limited.
(c) Time is running out.
What is the current orientation of the school for students? Cultivate outstanding engineering applied talents? In order to increase practicality, the curriculum and class hours have been adjusted, and the class hours of this course have been reduced to 32 hours.
(D) Students' learning initiative is poor
Because this course is designated as an examination course, a considerable number of students do not attach much importance to their learning attitude, do not invest the necessary energy and time, and have poor learning initiative, which directly affects the teaching effect.
Second, the exploration of teaching content and teaching methods
(A) the adjustment of teaching content
At present, most of the teaching materials of sensor and detection technology focus on the working principle of sensor, measuring circuit and information processing, and less on the specific application. In view of too much course content and too few class hours, it is impossible to cover everything in teaching, so the teaching content must be adjusted appropriately. According to the school's positioning of engineering application-oriented talents for engineering undergraduates, the adjustment of teaching content follows the following principles:
1, to avoid the tedious theoretical derivation process, and explain the working principle of the sensor to students in simple terms. For example, the slide shows that the two ends of a thermocouple are ignited by an alcohol lamp. When there is a temperature difference between the two ends, there is a potential difference between the two electrodes, and when there is no temperature difference, the potential difference disappears. Through this example, we can use a simple formula that everyone can understand to explain the reason for the existence of potential difference, instead of focusing on the formula derivation of thermoelectric potential and contact electromotive force that constitute thermocouple.
2. Pay attention to the physical application of sensors. Increase practical cases, so that students have a more emotional understanding of the application of sensors.
3. Appropriate auxiliary methods for interconnection between sensors and systems. In the early application of several sensors, the introduction of sensor access controller made them think about the relationship between the courses they studied, got a deeper understanding of the relationship between the courses they studied, and established the concept of the system.
(B) the reform of teaching methods
In order to overcome the objective difficulties in course teaching and achieve good teaching results, a variety of teaching methods and means are used in classroom teaching to explain the teaching content more vividly and concretely.
1, adopt multimedia technology and modern teaching methods to improve teaching effect and quality.
On the one hand, the use of multimedia courseware can save a lot of time for teachers to write on the blackboard and overcome the problem of reduced class hours; On the other hand, the working principle of the sensor is vividly displayed in the form of animation, and various photos of the sensor and the schematic diagram or circuit diagram of the complex detection system are displayed, so that students can intuitively understand the sensor and understand the working principle and application of the sensor more easily. For example, when learning grating sensors, it is difficult for students to understand the formation and movement of moire fringes by traditional teaching methods. Using the media courseware, students can visually see what Moire fringes with alternating light and dark look like in the form of animation, and can also move the indicator grating at different speeds on the ruler grating, thus clearly seeing the relationship between the moving direction of the fringe and the included angle of the grating and the moving direction of the indicator grating. When learning incremental photoelectric encoder, it is difficult for many students to understand the direction discrimination of encoder. By showing the internal structure of the encoder with slides, students can directly understand the position relationship between the notch on the diaphragm, the code wheel and the photoelectric element, so that students can more easily understand the phase relationship between the pulses formed by the direction-finding code track, the incremental code track and the zero code track. With the help of simple direction-finding circuit, students can learn the working principle and usage method of the sensor more efficiently.
In a word, the use of multimedia technology can make students get more information and enhance their interest and vividness in learning.
2. Pay attention to lead-in and improve students' learning initiative.
The introduction of many textbooks is relatively simple, but I personally think this does not mean that it is not important, especially in the face of students' subjective neglect of the course, we should make great efforts to teach the introduction for the first time, attract students' attention, stimulate their interest in learning and make them realize the practical value of this course. The position and function of sensors and detection technology in the national economy are demonstrated by slides, so that students can understand the application of sensors and detection technology from daily life to aerospace and ocean forecasting and the key role of automatic control theory in the realization process according to the physical quantities that need to be detected in various industrial backgrounds, so that students can understand the importance of this course. On the other hand, our school has been developing undergraduate research and training programs for many years. At the time of offering this course, students have successfully applied for training topics. Generally, students of this major still apply for topics around professional application fields, and most of them will involve the contents of sensors and detection technology. Therefore, we will use sensors to discuss the specific problems they are solving in their ongoing projects, and realize the key role of this course more directly, so as to improve students' interest in learning, enhance their initiative and overcome some shadows brought by the examination course.
3. Increase the proportion of case teaching and pay attention to application.
According to the goal of cultivating engineering application-oriented talents, the primary purpose of this course teaching is to make students choose sensors reasonably, have certain analysis and processing ability on sensor technical problems, and understand the engineering design method and experimental research method of sensors. Therefore, in teaching, we should pay attention to analyze the differences and connections of various sensors, and use a large number of specific cases to analyze the application characteristics of sensors.
For example, the introduction of the resistance strain sensor in the teaching material is mainly from the structure, working principle and measuring circuit of the sensor, and there are few practical application cases. In teaching, slides are used to show physical drawings of different applications, such as spoke weighing sensor of ground scale, cantilever electronic scale, weighing scale, torque wrench and other common physical objects in daily life. Vivid animation is used to show the response of sensors in different applications. For example, when learning common sensor thermocouples, show pictures of various types of thermocouples to supplement the installation methods of thermocouples. Taking the control system of heat exchange station as an example, the application of thermocouple in temperature measurement is analyzed, and the output signal of sensor and its interconnection with control system are emphatically introduced. When introducing the photoelectric cell sensor, the application cases of hand dryer for control, photoelectric digital tachometer for detection and illuminance meter are added. Through the case, students have a deeper understanding of the application of sensors.
4. Make use of the school's scientific research and training to improve students' interest in learning and strengthen their practical ability.
Students in our school can apply for scientific research and training programs from the second grade, with the guidance of teachers and the responsibility of students. This course is offered in the first semester of grade three. Before that, some students had already participated in scientific research and training programs. In these projects, such as smart car project and the implementation of data acquisition system, the application of sensors and detection technology is included. Before class, teachers can ask questions about practical problems, so that students can learn with questions and enhance their interest in learning. In addition, it can also inspire students to brainstorm, contact the teachers in the experimental center, design and manufacture sensors in conjunction with second-year students, or enter professional laboratories to carry out practical experiments on sensor applications, encourage students to declare scientific research and practical projects, and improve their practical ability.
Three. Concluding remarks
Through several years of teaching and summary, the teaching contents and methods are analyzed and studied, and the corresponding reforms are carried out. The adjusted teaching content pays more attention to application, supplements rich cases and stimulates students' interest in learning. Multimedia teaching method enhances the vividness of teaching, and combines with scientific research and training to expand classroom teaching, strengthen learning initiative and enhance practical ability. Judging from the results of online teaching evaluation in recent years, the teaching adjustment and reform have been welcomed and praised by students, and good teaching results have been achieved.
References:
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