Creating a mechanical prototype

 I'm very excited to return to the world of non-electric mechanical objects! As much as I want to learn more about the Arduino there is something about a viewer/user having to manually control an art piece that I am very into at the moment in time.

Right now I interested in the motions of camshafts, so when we had the opportunity in class to create a mockup that I wanted to make that first! As cute as v1 ended up being, I think I became too ambitious at too small of a scale with this attempt. I wanted to see what it would look like to have different cams shapes for each section but I also made them all eccentric. Problem one: it was difficult to make the shapes of the cams neatly, causing the flat followers that I made to get stuck on the rough edges. Problem two:  since they were all eccentric cams of differing shapes meant that the flat followers would move around erratically. As well as I didn't account for the long side of each of the shapes to fit very well in the box that held them. Problem 3: I made the slide holes too wide, which also caused the followers to flop around. I tried to fix this by adding so much hot glue into the cavities to make up for the missing material.

Over the reading week break, I created a larger four-section camshaft as a second prototype. At the larger size, cutting went much more smoothly as well as I learned from some of the mistakes from v1. Firstly even though I am very interested in the different motions that can be created by other shapes of cams I decided it was best to stick with a circular eccentric cam for all four sections just to get the movement and understanding of the build down. The flat followers run much more smoothly across the new cams.

I wanted each of the followers to rise and fall at different times so each cam is rotated about 45 degrees from the one in front of it. In this version of the prototype, I still had only one level of the slide and I found that the followers still would flop around even though the slide holes were only slightly larger than the shafts compared to v1.

So I created a second level slide! This fixed the issue handily. After thinking about it for a few days after this build I most likely didn't have to make the second level slide so tall, I probably could have laid it right on top of the first one.

Well, I will try that in the next prototype!

This working camshaft leads me into what I have been thinking about for the kinetic project.

I would like to create a similar box as my v2 prototype but be able to have fans pushed and pulled by the followers. I want to use the wave-like movement that is already being created by these eccentric cams in sequence and with the fans to bring about an ocean splashing effect.

I have been able to make a somewhat working proof of concept of this:

I was only able to make one of the camshafts into the concept as I realized with a bit of testing that there would need to be a counterweight for the flat follower in order to pull the fan back down the slide and I only had one coin-type piece of metal that was heavy enough to use for this experiment.

I am quite happy to see that it works okay right off the bat! I think that there will need to be some small amount of weight on each end of a fan to help pull it more open. I also think that making a V-shaped slide would help to ease the fans shut as they descended. I am not sure that is something I could do with the laser cutter? Some more experimenting is in order!

PS. I had forgotten that I already had some foam core at home and I picked up an approx 2x2 ft sheet at Dollarama and I think I like this cheaply made type much better for prototyping! 

You can see the regular foam core on the top and the paper is much thicker which takes more strokes to cut through. The Dollarama foam core the paper is much thinner so a new blade just cuts through it like butter. The center foam seems just strong enough to build without issue since I made all of v2 using it. And best of all it was $1.25 so I don't feel like I have to be as precious with it as I did with the foam core in class, which makes me feel better about larger-scale prototyping and general mistakes and rebuilding.

 

Kinetic Actuator Circuits

This was a big project! And thank goodness for last year's post of the week by Nicholas otherwise I would have been pretty lost. I used Tinkrcad to create my schematics, as they have a nice circuits section on their site. They are missing a few of the components such as a solenoid and the A4988 driver.

a) DC motor with a relay. This one had a tough time with and never got working. I am most surprised by this because I worked with motors last semester in Rita's class. A DC motor connected to a 555 and a TIP122 and had no problems at all. It's interesting to me that adding the Arduino made it so difficult for me.

I tried a few different setups for this. The top one is based on how the motor works with a relay and a 555 chip and the bottom is how Nicholas set up his circuit as far as I can tell. Unfortunately, I was not able to get this circuit to work. I also tried it with the solenoid which did not work either.

b & c) Solenoid/DC motor with TIP122. Second easiest set up of the bunch! I am putting these two together because their circuits are basically the same.

 I had to make the image of the solenoid in PS

Here the Arduino is running the Blink tutorial code to control each circuit. The Arduino is the connection to the input, left most pin, on the 122 through a 220-ohm resistor The middle pin is what outputs the signal/stored energy to the motor/solenoid and the rightmost pin receives the charge from the 9v to then start storing up energy.

d) DC motor with L293D chip. Another DC motor fail for me. I can't remember if we when over this one in class but I tried following the schematic from Nicholas' posts. I think I need more time to familiarize myself with this chip as it seems pretty complicated or at least the wires make it look that way. Unfortunately, I don't understand how this setup actually works, I cannot go into detail on how it is all set up.

 e) Bipolar stepper motor with a A4988 chip. This circuit was a mixed success. I was able to get the motor to make a buzzing noise but it was not getting enough power (my hypothesis) to actually move. Once again I used Nicholas' schematic as the basis of my own circuit. I had to fudge this one a bit since Tinkrcad does not have most of the required parts.

 One thing I was not sure of is whether it matters which wires on the stepper motor plug into the chip? I tried different configurations and as far as I could tell it did not.

In this video, you can hear that the motor is getting something but not enough to actually move it.
I used the code that was supplied by Nicholas which he got from this site: https://howtomechatronics.com/tutorials/arduino/how-to-control-stepper-motor-with-a4988-driver-and-arduino/

const int stepPin = 3; const int dirPin = 4; void setup() { // Sets the two pins as Outputs pinMode(stepPin,OUTPUT); pinMode(dirPin,OUTPUT); } void loop() { digitalWrite(dirPin,HIGH); // Enables the motor to move in a particular direction // Makes 200 pulses for making one full cycle rotation for(int x = 0; x < 200; x++) { digitalWrite(stepPin,HIGH); delayMicroseconds(500); digitalWrite(stepPin,LOW); delayMicroseconds(500); } delay(1000); // One second delay digitalWrite(dirPin,LOW); //Changes the rotations direction // Makes 400 pulses for making two full cycle rotation for(int x = 0; x < 400; x++) { digitalWrite(stepPin,HIGH); delayMicroseconds(500); digitalWrite(stepPin,LOW); delayMicroseconds(500); } delay(1000); }
f) Last but not least the servo motor controlled by the Arduino. The easiest of the bunch!! We don't even need an external power supply as the servo works with the 5v & ground from the Arduino. Just add an output pin for the code and you are ready to go.

I used the Sweep code from the tutorial to control the servo. It's loud but it works!

Milestone Project 1 - Update 2

This week was a lot of work! I had to get my final circuit made and soldered. I got it all working well but there are a few hiccups. The main one being that we ran out of female ends to make our cables over the weekend meaning that I would not be able to solder more male ends to my board and I did not want to solder the LEDs directly to the board just in case one of the LED burnt out or did not work for some other reason and be stuck. The solution I came up with is to do a half and half Frankenstein's monster with the circuit board for the LED signal and the breadboard for ground connections.

 Here are the top and bottom of my soldered board. The 90-degree male end was originally going to be for the 5v connection but is now not in use due to the running out of female connectors. I connected the bottom pins that connect to the Arduino to the top pins by created soldered bridges. This was tough! And I'm honestly surprised there are no short circuits!!


 The issue with the female ends also meant that I will have to keep the sensor connected to the breadboard, which is an issue because originally I wanted to have that mounted outside and below the base. This means I will have to do extra modifications to the base today!!

Otherwise, the circuit is running well!
//I still was not able to get the pins 2 & 3 to work so I decided to stick with that I know works pins 6 & 7 for the sensor #define trigPin 6 #define echoPin 7 int distance; int duration; void setup() { //initializing the pins for the LED signals. I did this in 2 parts because of the 6 & 7 pin interuption for the sensor. There may be a better way to //do this? for(int i = 8 ; i<=13;i++) { pinMode(i,OUTPUT); } for(int i = 2 ; i<=5;i++) { pinMode(i,OUTPUT); } Serial.begin(9600); //don't for get to still add the sensor pins into the setup! pinMode(trigPin, OUTPUT); pinMode(echoPin, INPUT); } void loop() { //the time setup for the sensor to send and receive its signal digitalWrite(trigPin, LOW); delayMicroseconds(2); digitalWrite(trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW); duration = pulseIn(echoPin, HIGH); distance = (duration/2) / 29.1; //the many if/else statements to determine which lights turn on depending on viewers' physical distance, many a better way to write this? if (distance <= 1) { digitalWrite(13, HIGH); digitalWrite(12, HIGH); }else{ digitalWrite(13, LOW); digitalWrite(12, LOW); } if (distance <= 25) { digitalWrite(11, HIGH); digitalWrite(10, HIGH); }else{ digitalWrite(11, LOW); digitalWrite(10, LOW); } if (distance <= 50) { digitalWrite(9, HIGH); digitalWrite(8, HIGH); }else{ digitalWrite(9, LOW); digitalWrite(8, LOW); } if (distance <= 75) { digitalWrite(4, HIGH); digitalWrite(5, HIGH); }else{ digitalWrite(4, LOW); digitalWrite(5, LOW); } if (distance <= 100) { digitalWrite(2, HIGH); }else{ digitalWrite(2, LOW); } }
I still may add a delay at the end of the void loop so that the viewer will have time to look at the piece from different angles without the light immediately shutting off.

It looks like a real mess but once it is inside the base no one will be the wiser! It's not all daisies yet.
Things I still have to get done today:
-Pick up the transparency from the printer
-Modify the base at the woodshop
-Modify plexiglass to sit on top of the base
-Cut the trapezoid out of a plastic sheet
All doable but still stressful!!
But for the moment I will enjoy that I got the circuit running!

Milestone 1 - Late Post

Just a quick update on what I did last week for the upcoming Milestone 1. The LED project that I came up with is a Pepper's Ghost optical illusion. Using this website as a jumping-off point: https://maker.pro/custom/projects/diy-hologram

The concept of the project is to create a display for an animal, chosen by me, that went extinct in 2019. I want the display unit to have a holographic feel to this as if the viewer is only getting the chance to see the animal in a futuristic museum setting. The LED will be embedded into the base which, will be the light source for the projection. The LEDs will be controlled by an ultrasonic sensor that will slowly light up as the viewer walks up to the piece.
 Here is a quick mock-up I made in Tinkrcad:

During this week I worked on the basic code for the LED lights which I converted from this site:
https://www.mousa-simple-projects.com/2015/09/distance-meter-with-6-leds-using.html

#define trigPin 2 #define echoPin 3 int distance; int duration; void setup() { for(int i = 8 ; i<=13;i++) { pinMode(i,OUTPUT); } Serial.begin(9600); } void loop() { digitalWrite(trigPin, LOW); delayMicroseconds(2); digitalWrite(trigPin, HIGH); delayMicroseconds(10); digitalWrite(trigPin, LOW); duration = pulseIn(echoPin, HIGH); distance = (duration/2) / 29.1; if (distance <= 1) { digitalWrite(13, HIGH); }else{ digitalWrite(13, LOW); } }

I was having issues getting it to work and it looks like there were two problems at hand.
1) Pins 2 & 3 did not seem to register with the sensor (this may be because my pin 3 is not working on the Arduino but I will have to test that after this project is done) so switching those to pins 6 & 7 was the first solution.
2) I had not added the 6 & 7 pinModes into the void setup as input and output so they were not being read from anyway.
After changing all that the LED would light with no issue!

Now on to this week!...