I/O: Conveyor Belt Prototype

For my I/O device, I prototyped a conveyor belt. I was inspired by an art installation I saw at the Havana Bienal in 2019.

The conveyor belt could be decorated with images that create a moving image effect when inched along, or perhaps, at the slow speed of my servomotors, a more stop-motion, flip book effect, but regardless a storytelling device that shows images in succession. The artwork that inspired me was more of a horizontally moving collage, but I thought I could adapt the idea so that the images along the belt have a different kind of visual continuity.

I just got the servomotor lab working last night so I set my expectations within reach. I expanded upon this lab by adding a second servomotor, to be controlled by the same force resisting sensor (FSR). When I printed the FSR readings in the Serial Monitor, it had a sensitivity range of about 0 to 1000. I mapped this range from 0° to 180° for the servomotor controlled by pin 9 and from 180° to 0° for the servomotor controlled by pin 8.

Code for two servo motors to turn at the same time but in opposite directions:

#include “Servo.h”

Servo servoMotor; // creates an instance of the servo object to control a servo

int servo1 = 9;

int servo2 = 8;

// int fsrPin = (A0, INPUT);

long lastMoveTime = 0;

void setup() {

Serial.begin(9600);

servoMotor.attach(servo1); // attaches the servo on pin 9 to the servo object

servoMotor2.attach(servo2); // attaches the servo on pin 8 to the servo object

}

void loop() {

int analogSensorValue = analogRead(A0);

// Serial.println(analogSensorValue);

int servo1Angle = map(analogSensorValue, 0, 1000, 0, 180);

int servo2Angle = map(analogSensorValue, 0, 1000, 180, 0);

if(millis() – lastMoveTime > 20){

servoMotor.write(servo1Angle);

servoMotor2.write(servo2Angle);

lastMoveTime = millis();

}

Since the servomotors I have don’t turn 360°, but rather only 180°, I couldn’t just attach them to the spools and rotate the cylindrical objects to which the belt clings. I would have to let the servomotors move the belt in an “inching along,” pushing-and-resetting, pushing the next thing then resetting manner.

I started calling the white things along one side of the belt the teeth. They have to be stiff and rigid enough for the servomotor blade to make contact with them and, in its motion, inch along the belt. They also have to be sticking out of the belt at an angle and slightly flimsy so that when the servomotor resets back to its 0° position, the blade can glide over the next tooth and then secure itself to the back of it for the next push. All that to say, a lot of particularities with how these teeth might actually function.

Lisha taught me how to use the sewing machine.

I found some fabric with a grippy underside, to cling to the spools, and a belt-like toughness on the overside. I measured it to fit onto the two Ultimaker spools that Maryse pointed me to in the junk shelf.

Cut for a a generous seam allowance, sewed the edges to look neater with a sort of digital stitching pattern.

Broke the needle on the last stitch.

To mount the conveyor belt, I decided to have the spools sit upon a wooden surface. I needed to create tension in the belt in order for the servomotor blades to have an impact on the belt’s changing position. I found two Wifi router antennae that could firmly hold the spools on the board. In order for them not to collapse from the inwards tension, I decided to sand little pits/holes into the board to mark the antennae’s places.

Then I hot-glued the antennae into place.

I realized the contact between the servomotors and the teeth wouldn’t have to be so firm and the push of the blade wouldn’t have to be so forceful if there were less resistance from the belt to inch along. My initial solution to this was to reduce friction for the spools’ rotation by putting acrylic plastic between the spools and the wooden surface.

For the teeth, I first tried to sew the tough fabric onto the underside of the belt in three different ways to test if any of them produced motion in the belt.

Very minimal motion, so I fortified their stiffness with white gaffer tape and cardboard.

Came up with a new cardboard configuration for shallow/short teeth with good staying power/structure:

Figuring out where to put the servomotor. It worked better when it could act on the spool rather than on the belt itself, but I thought it would be harder to mount there, but perhaps not.

IMG_5748

I inverted the belt to face outwards to more easily hold the servomotor in the optimal position to push the teeth.

IMG_5751

Attached the second servomotor.