Monday, 30 January 2012

Lab 2: Basic Actuation - Converting Rotatory to Linear Motion

This lab has been completed by 'Aidin Mirsaeidi' and 'Li Huan'.

In this lab, we were assigned to formulate three hardware sketches/designs to acheive 1, 10 and 100 mm movements actuated by simple dc motors using the Arduino kit. Below are descriptions of the three respective sketches:

Sketch #1:

For this sketch, we used the Circuit
#3 in the Arduino booklet to drive the dc motor. We have a styrofoam box with two pins on either side to produce a linear motion of the box. We secure a ring with small hole drilled close to the edge of the ring. We attach one end of a stiff wire to the box and the other end to the ring. As we make the motor turn, there will be an oscillatory linear movement of the box. The diameter of the ring is carefully chosen as to produce a forward/backward movement of 10mm. This can be demonstrated by the follwoing video:


Using the same electronic setup as in sketch
#1 but slightly changing the physical setup. We still have the stiff wire connected to the ring but this time, we use a piece of string in between the box and the wire, shown in the figure below. As we start rotating the motor, the wire will pull the string and hence pull the box. By using the string, we will prevent the box to go backward since the wire push will just relax the tension in the wire. After setting the output pin to digital HIGH, we will cause some dealy and then set the pin to digital LOW and hence stop the motor. We have chose a sufficient amount of delay as to produce a 100mm movement. This can be demonstrated by the following video:

Sketch #3:

For this sketch, we used the circuit
#4 outlined in the Arduino booklet with the servo as the actuator. We simply program the microcontroller to cause a 30 degrees turn of the servo and attache an object to the servo through a string. This will produce approximately a 1mm up and down movement of the box. This can be demonstrated in the following video: