Inductive Proximity Sensor Interfaced with Arduino

Transcription

1 IJSTE - International Journal of Science Technology & Engineering Volume 2 Issue 09 March 2016 ISSN (online): X Inductive Proximity Sensor Interfaced with Arduino Anish A. Naik Shruti S. Naik Deeksha A. Naik Shubham D. Naik Rolan G. Pereira Abstract The present paper describes the analysis of an accurate Inductive Proximity Sensor that is interfaced to the Arduino and is used to detect metal. A graph of Distance v/s Current is plotted for different metallic materials. The Detection of various metallic materials can be done by using an accurate Inductive Proximity Sensor like the M18DPO. The Arduino interacts with software developed in the PC end through USB architecture and an attractive Graphical User Interface (GUI) based system is developed in the PC end to provide the user with real time, online display of the Inductive Sensor Output. Keywords: Inductive Proximity Sensor, Arduino, USB Architecture, Graphical User Interface I. INTRODUCTION The Inductive Proximity Sensor (IPS) is a solid state device that generates an output signal when metal objects are either inside or entering into its sensing area from any direction. IPS s work best with ferrous metals, however, they also work well with non - ferrous metals(aluminium, Brass, copper, etc.) at reduced sensing distances. Initially, IPS s were made with housing similar in size & dimension to the limit switch, but had short sensing distances. Following very good results with these new devices, market pressure led to the development of large sensors with increased sensing distances. Inductive Proximity Sensors have no moving parts, operate very fast, are extremely reliable, require no maintenance & operate under extreme environmental conditions. They typically interface with PLC (programmable Logic Controllers) process, & personal computers with appropriate hardware & software. They also can control relays, solenoids, valves, etc, up to their maximum output current.[1] II. TYPES Based on Shape Basically there are four Inductive Proximity Sensor families: Cylindrical Inductive Proximity Sensors They represent the most popular device, & are available in diameters from 4mm (159in.) to 30mm (1.18in.) & sensing distances up to 40mm (1.57in.). Typically, cylindrical models have low sensing distances & are used in applications requiring compact sizes that are easily mountable. Limit-style Inductive Proximity Sensors They are physically larger than Cylindrical IPS s and have sensing distances up to 40mm(1.59in.). These units feature a unique 17 position rotating sensing head with snap and lock construction (no screws). These are used to replace mechanical limit switches and for applications where adjustments of the sending head is desired. Block Inductive Proximity Sensors Feature models with adjustable sensing distances up to 70mm (2.78in.). Block sensors are used for applications where maximum sensing distances are required. All rights reserved by 245

2 Ring Inductive Proximity Sensors These are special devices that detect metal objects passing through the ring. The range of the ring diameters varies from 12mm (47in.) to 300mm (11.91in.). Typical application is in stamping operations and detection for unwanted metals. [2] Based on Housing Design Flush Mount Sensors These are sometimes called Shielded or Embedded sensors. A metal band surrounds the sensing head which contain a coil wound around a ferrite core as shown in figure 2. The resulting electromagnetic field is directed in front of the sensor face. Flush sensors have a narrow sensing field which is desirable in certain applications. Non Flush Mount Sensors In a Non-Flush sensor; There is no metal band and the resulting electromagnetic lines are much wider than the sensor face. These have a larger sensing distance than Flush Sensors.[2] III. METHODOLOGY An Inductive Proximity Sensor consists of an oscillator, a ferrite core with coil, a detector circuit, an output circuit, housing, and a cable or connector. The oscillator generates a sine wave of a fixed frequency. This signal is used to drive the coil. The coil in conjunction with ferrite core induces a electromagnetic field. When the field lines are interrupted by a metal object, the oscillator voltage is reduced, proportional to the size & distance of the object from the coil. The reduction in the oscillator voltage is caused by eddy currents induced in the metal interrupting the field lines. This reduction in voltage of the oscillator is detected by the detecting circuit. In standard sensors, when the oscillator voltage drops below a present level, an output signal is generated. Fig. (a): IV. BLOCK DIAGRAM Fig. (b): The block diagram of the Inductive Proximity Sensor interfaced with arduino is shown above. The Sensor comprises of 3 terminals i.e. Red, Green and Black. The Red terminal is the Vcc terminal of the sensor and is connected to a 9V Power Supply. The Black terminal depicts the ground of the sensor. It is connected to the the GND pin of the Arduino and simultaneously shorted with the All rights reserved by 246

3 ground terminal of the 9V power supply. The Green terminal is the signal pin which gives the output of the sensor to the digital pin of the arduino. When a metallic material intercepts the magnetic field of the sensor there is instantaneous change in the output of the sensor which is then relayed to the Arduino via the digital pin. V. SPECIFICATIONS Inductive Proximity Sensor The Inductive Proximity Sensor used in our project is the M18DPO manufactured by Advance Tech. This Inductive Proximity Sensor provides very good dimensional accuracy, durability and unmatched quality. Fig. (c): The specifications of the sensor are depicted in the table below: Table - 1 Sr. No. Specification Comments 1 Type Non-Flush 2 Sensing Distance(mm) 5mm 3 Logic PNP 4 Supply voltage 5 to 30 VDC 5 Voltage Drop 1.5 VDC 6 Frequency 1KHz 7 Contact NO 8 Max. Load Current 300Ma 9 Output Indication Through LED 10 Circuit protection Reverse Polarity Arduino Uno The arduino Uno is a microcontroller board based on the ATmega328(datasheet). It has 14digital input/output pins (of which 6 can be used as PWM outputs),6 analog inputs,a 16MHz crystal oscillator,a USB connection,a power jack,an ICSP header,and a reset button. [3] All rights reserved by 247

4 Fig. (d): The Specifications of Arduino Uno are as follows: Table - 2 Sr No. Specification Value 1) Microcontroller ATmega328P 2) Operating Voltage 5V 3) Input Voltage (recommended) 7-12V 4) Input Voltage (limit) 6-20V 5) Digital I/O Pins 14 (of which 6 provide PWM output) 6) PWM Digital I/O Pins 6 7) Analog Input Pins 6 8) DC Current per I/O Pin 20 ma 9) DC Current for 3.3V Pin 50 ma 10) Flash Memory 32 KB (ATmega328P) of which 0.5 KB used by bootloader 11) SRAM 2 KB (ATmega328P) 12) EEPROM 1 KB (ATmega328P) 13) Clock Speed 16 MHz 14) Length 68.6 mm 15) Width 53.4 mm 16) Weight 25 g VI. IMPLEMENTATION The Inductive Proximity Sensor is operated independently with a 9v power source. It is placed at the initial position of the Conveyor Belt System. The Inductive Proximity Sensor comprises of three terminals. Two terminals are connected to power supply, ground and V cc and third terminal is connected to Arduino. Inductive Sensor is used to sort out metal from other waste. When a piece of metal enters the zone defined by the boundaries of the electromagnetic field, some of the energy of oscillation is transferred into the metal of the target and hence the metal is detected. The threshold is set using a software program and accordingly metal is detected. VII. OBSERVATIONS MATERIALS 4mm 3mm 2mm 1mm Copper Cast Iron Gold Steel Stainless Steel Magnet All rights reserved by 248

5 VIII. GRAPH IX. CONCLUSION The Inductive Proximity Sensor can be used to separate various metallic materials on the basis of the amount of current produced due to the change in the magnetic field of the sensor. This variation in current is directly proportional to the distance of the metallic material from the sensor. For the M18DPO Inductive Proximity Sensor the maximum detection range is 5mm beyond which the All rights reserved by 249

6 material is not detected. As depicted in the observation table, current is maximum at the largest distance (4mm in this case) and decreases with reduction in distance and the type of metallic material. [1] [2] Types of Inductive Proximity Sensors, Altec Sensors. [3] [4] agronomy.emu.ee/vol123/2014_3_31_b5.pdf [5] [6] Electronic Devices and Circuits by J.B. Gupta REFERENCES All rights reserved by 250