Laboratory: Introduction to Mechatronics. Instructor TA: Edgar Martinez Soberanes Lab 1.

Transcription

1 Labratry: Intrductin t Mechatrnics Instructr TA: Edgar Martinez Sberanes (eem370@mail.usask.ca) Lab 1. Intrductin

2 Lab Sessins Lab 1. Intrductin Read manual and becme familiar with the peratin and cmpnents f the car. Lab 2. Assemble the Mechanical and Electrical cmpnents f the car. Lab 3. Install the Sftware, debug the electrnics and run the tutrial prgram. Lab 4. Prgram and run the sample prgrams fr each mdule. Lab 5. Prgram the run the main sftware mdule t run the car and fine tune the car. Lab 6. Write up reprt and run the car n the test track and determine its perfrmance. 2

3 Lab 1. Outline Objective. Lecture Prject kit (Mechatrnics Prject Kit Feedback) Review f basic knwledge abut the circuits invlved in the prject. Read the manual and get familiar with the cmpnents f the car. Time fr the experimental questin in assignment 1 3

4 Objective T design and build a self-guided vehicle (buggy) frm a set f mdules, including tw drive mdules, tw steering and ne jckey wheel slutins and a micrcntrller (PIC). When cmpleted, the autnmus buggy is able t fllw a track using infra red sensrs. 4

5 Mechatrnics Prject Kit Mdules: Micrcntrller. Drive mdules (Single DC mtr) Steering mdule (Ackermann Steering) Unassembled fr cnstructin: Different slutins. 5

6 Micrcntrller (PIC) PIC 16F877 Running at 10MHz, with bytes f data memry, bytes f EEPROM data memry and 8k 14 bytes f FLASH prgram memry. Prgram language Machine Cde Prgraming using MPLAB (Micrchip Resurces) Data Sheet is available in the manual (Appendix A) 6

7 Drive (Single mtr) Single DC mtr arrangement with ptical speed sensrs t drive the buggy The ptical speed sensr is ptinal. Withut speed sensr, an pen lp structure is als acceptable. 7

8 Steering (Ackermann steering) Tw wheels, linked tgether by tw arms that are cnnected t a plate attached t a stepper shaft (steeper mtr). Stepper mtrs are DC mtrs that mve in discrete steps. They have multiple cils that are rganized in grups called "phases". By energizing each phase in sequence, the mtr will rtate, ne step at a time. Inside wheel has a greater turning angle fr a tighter radius f the crner, thus allwing the wheels t have a differential crnering speed. This allws fr a lt f grip but the turning circle is the smallest. 8

9 9

10 Optical Sensr. Use ptical sensrs t fllw the track Infrared reflective sensrs available Optimize the sensing cnfiguratins fr fllwing a 19mm tape 10

11 Chassis Three types available t chse frm Shrt rectangle Lng rectangle Lng rectangle chassis tapered at ne end 11

12 Battery Rechargeable Ni-MH Battery Charging time abut 10 minutes 7.2v, 2000mAH 12

13 Circuitry- DC Mtr Three signals are required frm the micrcntrller t drive the mtr circuit. PWM Bi/Uni (bidirectinal, unidirectinal) Directin (Frward/Reverse) 13

14 PWM (Pulse With Mdulatin) Cntrls the average value f the DC vltage t the mtr. Square wave at a certain frequency t cntrl the MOSFET. Basically yu are telling yur cntrller t turn n and ff the mtr at very high rates. S thrugh inductance the mtr is neither fully n r fully ff, but smewhere in between. Mtr trque, under PWM, remains the same whether fully n r nly a percentage n. With PWM yu have maximum trque yet slwer speeds 14

15 PWM 15

16 Bi/Uni Directin Bi/Uni (Bidirectinal/Unidirectinal) cntrls whether the mtr can turn in bth directins nly r ne directin nly. Directin Fwd/Rv (Frward/Reverse) cntrl determines whether the mtr turns frward r reverse. Take effect nly when the Bi/Uni cntrl is set t Bi. 16

17 GAL (Generic Array Lgic) These three signals are injected int a GAL (Generic Array Lgic) with the fllwing circuit prgramed. 17

18 Lgic Gates 18

19 Lgic Gates 19

20 Lgic Gates 20

21 Lgic Gates 21

22 Lgic Gates 22

23 Lgic Gates 23

24 DC Mtr Circuitry 24

25 H-Bridge Enables a vltage t be applied acrss a lad in either directin. Allw DC mtrs t run frwards and backwards. 25

26 MOSFET Shrt fr metal xide semicnductr field-effect transistr A field-effect transistr used fr amplifying r switching electrnic signals. 26

27 Circuitry Optical Rtatin Sensr fr Speed It senses the white and black grid n the circumference f the disk. Black gives 0 vlts and white gives 5 vlts Mnitred by the micrcntrller t determine speed 27

28 Optical Sensr Switches the transistr n when the ptical sensr utput passes the transistr threshld. Adjusting the variable resistr RV5 mdifies the threshld. 28

29 Optical Sensr Opt-electrnic sub circuit Threshld determined by RV5 Output f sensr pass the threshld Switch n the transistr. Secnd sub-circuit cnsists f a dual transistr arrangement allw higher vltage switching at the utput and high current thrugh R52 Dide D10 is used as a prtective measure fr transistr TR9. The third sub-circuit cnsists f the capacitr C22 in cnjunctin with R52 and they effectively create a lw pass filter fr the utput, and subject t the sizing f the capacitr, culd cnvert the switched utput signal t an analg equivalent. 29

30 Circuitry- Steeper Mtr 30

31 Steeper Mtr Drive Bard Infrmatin frm the micrprcessr Prduce sequential pulses t 4 lines f a stepper mtr, in rder t prvide the pwer fr mtr The driving signals fr the stepper mtr are buffered int MOSFETS (TR1 4) that prvide the switching fr the cils in the mtr. 31

32 Hexadecimal Binary Hexadecimal Decimal A B C D E F 15 32

33 Machine Cde Machine cde r machine language is a set f instructins executed directly by a cmputer's central prcessing unit (CPU). Each instructin perfrms a very specific task, such as a lad, a jump, r an arithmetic peratin n a unit f data in a CPU register r memry. 33

34 Resistr Clr Cde 34

35 Thanks 35