Sistem Instrumentasi

Transkripsi

1 Sistem Instrumentasi Sensor Gerakan (posisi dan kecepatan) Ir. Jos Pramudijanto, M.Eng. Jurusan Teknik Elektro FTI ITS Telp Fax Instrumentasi Sistem Pengaturan

2 Pengantar Objektif: Macam sensor posisi dan sensor kecepatan Metode pengukuran dengan sensor posisi dan kecepatan Definisi: Suatu sensor yang mengkonversikan perubahan gerakan suatu objek menjadi energi listrik Suatu perubahan kecepatan bisa didapatkan dari perubahan posisi Instrumentasi Sistem Pengaturan

3 Resistive Potentiometers Inductive Sensor Posisi Linear Variable Differential Transformers (LVDTs) Synchros, Resolvers, and Inductosyn Electro-optical Optical encoders Capacitive, piezo-electric, ultrasonic, magnetostrictive, etc. Instrumentasi Sistem Pengaturan

4 Potensiometer Sensor analog yang bekerja seperti divider Instrumentasi Sistem Pengaturan

5 Potensiometer dan Proximity Potensiometer (rotary and linear) Proximity switch (mechanical) Instrumentasi Sistem Pengaturan

6 Potensiometer untuk posisi Instrumentasi Sistem Pengaturan

7 LVDT Linear-Variable Differential Transformer Instrumentasi Sistem Pengaturan

8 Konstruksi LVDT LVDT terdiri dari magnetic core yang bergerak dalam silinder. Instrumentasi Sistem Pengaturan

9 Prinsip Kerja LVDT Inti berada di tengah-tengah maka : Flux S1 = S2 Tegangan induksi E1 = E2 Enetto = 0 Inti bergerak ke arah S1 maka : Flux S1 > S2 tegangan induksi E1 > E2, Enetto = E1 - E2 Inti bergerak ke arah S2 maka : Flux S1 < S2 Tegangan induksi E1 < E2 Enetto = E2 E1 Instrumentasi Sistem Pengaturan - 06

10 Synchro Instrumentasi Sistem Pengaturan

11 Rangkaian Synchro Instrumentasi Sistem Pengaturan

12 Synchro to Digital Converter Instrumentasi Sistem Pengaturan

13 Resolver Uses an AC signal to excite the rotor winding. Stator has two windings at 90 degrees to each other. As the rotor turns the coupling to the two windings will change Cosine Reference Sin Instrumentasi Sistem Pengaturan

14 Rangkaian Resolver Instrumentasi Sistem Pengaturan

15 Inductosyn Similar to a resolver but made in two planes. The Inductosyn has many pole pairs, +50 The output will repeat ones for each pole pair. Each cycle can be decoded to +14 bits Require very precise alignment, and high quality amplifiers. Analog Encoders offer similar solution at a lower cost. Instrumentasi Sistem Pengaturan

16 Konstruksi Inductosyn Instrumentasi Sistem Pengaturan

17 Optical Encoder Instrumentasi Sistem Pengaturan

18 Sinyal Output Optical Encoder Instrumentasi Sistem Pengaturan

19 Increment Encoder Generally Have two picks up that are 90 degrees out of Phase (A and B) This allows you to determine the direction of rotation and thus count up or down By using the rising and falling edges of both A and B we can get 4 times the number of slots. May have one or more index marks for homing. Instrumentasi Sistem Pengaturan

20 Absolute Encoder Gray Code Vs Binary Gray Code only changes by one bit per transition. At least one sensor per track Instrumentasi Sistem Pengaturan

21 Pengukuran dg Encoder Absolute! Shaft Encoder convert position into binary equivalent. This system use 8 bit shaft encoder. So, the resolution of shaft encoder is : 360 resolution = = 1, ! The linear displacement is : o angle linear displaceme nt = Χ 2π 360 o r Instrumentasi Sistem Pengaturan

22 Konstruksi Encoder Increment Instrumentasi Sistem Pengaturan

23 Konstruksi Encoder Increment Instrumentasi Sistem Pengaturan

24 Konstruksi Encoder Absolut Instrumentasi Sistem Pengaturan

25 Perbandingan Sensor Posisi Incremental Encoder dan Resolver paling populer Type Encoder Incremental Encoder Absolute Sinusoidal Encoders Resolver Inductosyn Capacitive Inductive Resolution Bits Incremental or Absolute Signal Type 12 Incremental Digital Signals A, B, Index 16 Absolute Digital Binary 22 Absolute Analog 14 Absolute 24 Incremental 24 Either 24 Either Analog Volts RMS Analog millivolts Analog millivolts Analog millivolts Sin, Cos, Index Electrical Imunity Very Good Very Good Number of Wires Electrical Interface 4-8 None 20+ None Fair 6-10 Interpolator Sin,Cos Good 6 R/D Converter Sin, Cos Fair 6 Amp +Converter Sin, Cos Fair 6-10 Converter Sin, Cos Fair 6-10 Converter Instrumentasi Sistem Pengaturan

26 Inductive tachogenerators linear sensors Sensor Kecepatan Gyroscopes Differentiation of position analog digital Integration of acceleration Instrumentasi Sistem Pengaturan

27 Tachogenerator Sensor ini konstruksinya mirip motor DC magnet permanen. Tegangan keluaran yang dihasilkan berupa tegangan DC. Instrumentasi Sistem Pengaturan

28 Increment Encoder Encoder yang digunakan untuk pengukuran kecepatan menggunakan encoder dengan output A, B, dan Z Output A dan B berbeda phase sebesar 90 derajat. Sedang output Z untuk zero index (untuk kecepatan tinggi). Instrumentasi Sistem Pengaturan

29 Accelerometer Accelerometer bahan piezo-electric. Pengukuran kecepatan dengan membuat rangkaian integrator. Instrumentasi Sistem Pengaturan

30 Capacitive and Inductive Sensors Operate similar to analog encoders. Patterns are placed on the rotor and stator. Rotor and stator can be made of low cost materials Technology similar to printed circuit board fabrication. Capable of very low power operation. This would allow for battery baked operation. Resolution similar to analog encoders and Inductosyns Electronics utilize Digital to Analog converters and DSPs or PLDs. Instrumentasi Sistem Pengaturan