Presentation Slides - Mechatronics

By Clay DavisandRichard BalsamelThis work was supported by the National Science Foundation under an RET Site Grant 0227479

Mechatronics is an integration of mechanical engineering,electrical engineering, control theory, and computer engineering.PhototransistorCircuit(photogate)V ddTo BS2 IC4.7 K ohmresistorV ssThis Project shows an application of mechatronic priciples toanalysis and control of cars on roadway

MotionINVOLVES:Average speed = displacement /time or v= d / tAcceleration = ∆ velocity/ ∆ time or a= ∆ v /∆ tAcceleration = ∆ velocity/ ∆time or a= ∆ v /∆ tD=v o t +1/2at 2

ComponentsThe parts used include IR LEDs, phototransistors, a rotarypotentiometer, a servo motor, and resistors and the Board ofEducation.IR LED Phototransistor Rotary PotentiometerServo Motor Resistor Board of Education and BS2 IC

Servo MotorA servo motor was connected to the shaft of a rotatrypotentiometer and the BS2 IC. The PULSOUT command wasthen used to adjust the position of the potentiometer and thecar’s speed.

Electric Circuit SchematicsFour photogates were constructed using IR LED’s andphototransistors. The photogates were then connected thethe BS2 IC as inputs and the servo motor was controlledusing a BS2 IC pin as an output.V ddPhototransistorCircuit(photogate)ServomotorGate 1Gate 2220 ohmresistor V ddP0 P1 P2V ddBasic Stamp 2 ICTo BS2 IC4.7 K ohmresistorIR LED CircuitV ssV ssP3 P4Gate 4Gate 3V ss

Program LogicUsing PBasic commands and routines, the car’s motion throughthe photogates was detected and timed. The velocity wass thencalculated and displayed.The data was also sent to a subroutinethat compared the speed of the car to a selected speed limit. Ifthe speed was above the limit the servo motor then changed theposition of the potentiometer to lower the speed.Start: ' Check Gate 1 for carLOOP :Gate1:Detect1 = IN5IF Detect1 = 0 THEN Count1 'WAITS FOR CAR TO ENTER GATE 1PAUSE 20GOTO LOOP'Timing loopCOUNT1: ' TIME BETWEEN GATES 1 AND 2FOR y = 1 TO 65000 ' COUNTS TIME BETWEEN GATESDetect2 = IN8IF Detect2 = 0 THEN Count2PAUSE 10y= y+1NEXTCalcSpeed: ' Calculates the speed using the “modulus”Command to get three decimal places.vel = 19*145/yr4 = 19*145//yv2 = 10*r3/yvel2 = 19* 145/br5 = 19*145//bv22 = 10*r5/bvel3 = 16* 145/cr6 = 16*145//cv32 = 10*r6/c

ResultsA slot car roadway was set up with four photo-gates and detectors aligned along the railings. Thesewere able to detect the motion of the passing toy car. The time between detectors for the car’smotion was then determined from the intervals between the gate blockings and then used to calculatethe speed of the car between photo-gates. A program to control the speed of the car was made basedon a set speed limit for the car’s motion. This was able to reduce the speed of the car at apredetermine rate for a set duration of time. A program to calculate the velocity and acceleration ofthe car as is passed through the four photogates was. However, because the Basic Stamp 2 IC canonly do integer math, the acceleration could not be accurately, and thus the acceleration portion hasnot be implemented at this time. The students must calculate the acceleration based on the computedvelocities.ConclusionsThis racetrack apparatus can be used to demonstrate to student’s changes in velocity andacceleration at various distances. Students can input various input speed and see how the systemreacts based on these inputs. This demonstrates several aspects of mechatronics. A DC motor ismodified to include a mechanical component (gears) and electronic components. Its speed is thencontrolled by a microcontroller connected to sensors that monitor the environment. A computer isinterfaced with the mircocontroller to both program the microcontroller and to display systemoutputs and monitor system performance.

The Final Product