In today's class, I followed the advice of my Nuvu coaches and made more extensive research on stepper motors. First, I searched for lighter versions of the stepper motors that could still provide me with enough power to move my robot. When I found out that a stepper motor (42x38cm) could lift up to 2.4 kg of weight (see video below) and could lock itself in place better than the servos, I was convinced that they would be well fitted for what I want to accomplish.  Among the stepper motors I found, I chose to use the NEMA 17 model that weight 285 grams.

Next, I enlarged the leg dimensions from 8.5cm to 10cm to create a bigger robot meant to accommodate the larger stepper motors. I also decided to change the building material for the legs from wood to acrylic. I found out that metal screws wore wood very quickly, which meant that screw holes that were meant to fit the screw would be expanded, hence creating space for the screws to wobble.

Next class, I plan on studying how to control stepper motors efficiently while I wait for the motors to arrive. I also plan on assembling more legs in advance to save time.

- About stepper motors and other types of propulsion: https://www.hackster.io/taifur/complete-motor-guide-for-robotics-05d998

- On the capabilities of the stepper motor:

https://www.youtube.com/watch?v=kFzrrzmT_LY

Today, I worked on finalizing the first phase of my project. First, I made simple adjustment in the code to correct mistakes I found during my testing yesterday. I also made a number of improvements, such as reducing the length of that the leg has to travel in order to complete one walking motion. In addition, I included a void_setup function that allows the leg to get into the walking position when it is first connected to power. 

Then I attempted to find ways to solve the power issue with the stepper motors. Due to the fact that I have not yet figure out how to more power to the motors, I decided to use a gearbox to improve their performance. However, the gearboxes proved to be very large and occupy most of the motor shaft length I need to mount the leg. As such I need to lengthen the motor shaft length, which would allow me to put the gearbox on the back of the motor and keep my current leg setup.

Overall, I believe that the core objectives of my project for this mod have been achieved. However, if time allows it, I would include a potentiometer into the arduino setup to control the different modes of the leg (ie. jumping, climbing stairs or normal walking)

During today's class, I made further improvements on the code for controlling the stepper motors. I tried to make each steps of the stepper motor smaller (i.e. 2 instead of 5) to create a smoother motion of the leg. Still, even with this method, the leg movement was still very fragmented and I fear that the choppiness of the movement may affect the effectiveness of the leg at walking (only one of the two motors move at any given time). My first response was to try to modify the "accel_multiStepper" code to fit my setup. However, my attempts to do so failed, and I decided to make more research on how to make the motors move simultaneously. While doing so, the new stepper drivers arrived. At the same time, I found a tutorial that could control the two motors to move in sync. In light of this new discovery, I decided to first setup the A4899 driver for testing. However, due to time constraint, I was unable to begin testing. 

Tomorrow, I plan on beginning testing with the A4899 drivers. If I manage to make them work, then the first phase of my project would be essentially completed.

Today, I started working on adjusting the code to create the movement of the leg. At first, I separated each leg motion into 4 lines of code. However, when I ran the code in the Arduino, I found that due to the block nature of the lines of code, the first motor had to complete its motion before the second one could move. This was not ideal for my leg setup, as it required a coordination of the two legs moving simultaneously. I tried to use another code where I could control the two motors at the same time, but due to time constraints (A-team meet), I deemed that I would not have enough time to figure it out. Instead, I decided to command the motors to move smaller steps one after another. This way, the motors would not come in conflict with one another and I managed to make the current code work. However, during my testing, I ran into another issue. Though the stepper motors worked fine while the is placed on the table, the leg upper leg refused to move when placed on the test rig. It seemed that the motor cannot handle the weight of the leg and it would get stuck whenever it tries to lift itself. 

Tomorrow, I plan on making further testing of the leg and attempt to use the new code as well. I also plan on making research on how to solve the power issue for the legs.

In today's class, I successfully overcame the issue with controlling the stepper motors. At first, I tried to figure the problem using the code Luis gave me. Despite my efforts, I made little progress. I tried to combine elements of the new coding with a simpler example I used earlier. However, my decision to do so backfired as the motors ceased to move completely and showed no signs of moving after I imported the allegedly improved code. 

My unsuccessful attempt compelled me to look for other solutions. Looking into the studio's electronics inventory, I discovered the only TB6600 driver available to me. After finding a reliable tutorial on Youtube on how to use it to control stepper motors, I decided to attempt to discard the motor shield temporarily and incorporate the driver into my Arduino setup. Though I followed all of the instructions, I was still unable to control the stepper motors.  However, just as I was about to discard the driver, I remembered that there was always the possibility that I had wired up the motor incorrectly. As such, I swapped the position of the wires from the negative port to the positive port. In doing so, I corrected the problem of conflicting current direction within the stepper motor and I was able to control the motors to create a back and forth swinging motion. 

Using this progress, I moved on to create a code that could control the stepper motor using the motor shield. When this attempt was successful, I decided to try to control 2 motors at the same time. After some experimentation and research, I was able to control two stepper motors simultaneously. Unfortunately, due to a lack of time, I was unable to make further progress today. 

Tomorrow, I plan on creating a code that would control the motion of the leg, which I plan on completing this week. 

Today, I built the test rig used to experiment with the different motions of the leg. At first, I wanted to build a structure with four support beams. However, I wanted to keep it as simple as possible, so I decided to go with a three leg support platform. Next, I had to figure out the height at which the leg would be hung. While I wanted to allow the leg to walk, I decided to place it higher because I needed to create the walking motion first. I could then make the ground level taller or driller another whole at a lower point. 

After completing the test rig, I tried to reinforce the structure holding the motors. I wanted a material that would be strong enough to not crack but thin enough to fit and light enough to not increase the weight. I found that the thin transparent plastic sheet fitted many of the qualities that I had been looking for. However, when I cut out the pieces and fitted it to the motors, I found that the material was too soft and flimsy. In the end, I deemed that this addition was not absolutely necessary and I scrapped the idea.

At the end of the day, I looked at what Luis sent me about the Arduino code used to control the motor. Due to time constraint, I did not have time to complete the analysis. I intend to complete it during the weekend. Next week, I plan on working on the code and the movement of the legs. I hope to finish the coding part of my project before pencils down.

Today, I worked on constructing the complete prototype leg of my robot. I began by trying to figure out a way to extend the motor shaft long enough to reach the supporting structure placed on the opposite side of the stepper motors. My first idea was to buy a motor shaft adaptor, but this option was expensive and I would have to wait until the order arrived. Furthermore, I would need to re print one of the linkages to adjust to the increased diameter of the shaft adapter. 

My next idea was to screw a second motor handle wheels to the one already used to drive the upper leg and link it to the supporting sturcture with a short screw. While this option would increase the weight of the leg, I decided to use it because the materials used were abundant and I did not have to wait for new orders. Once the decision was made, I put myself to work on extending the shafts of both stepper motors.

During the process, I faced a number of challenges. For instance, i had to widen the screw holes to fit the screws that were used to link the two hand wheels together. In another’s case, I had to change the height of the lock nut in order for the screw to fit into the hand wheel. After a whole period dedicated to this task, I managed to solve all the issues and I succeeded in extending the motor shaft.

I also worked on reinforcing the support structure. While I initially tried to use a 3D printed piece to link the support structure to the main body of the robot, I decided to use acrylic instead, as it was simpler and took much less time to make. 

Next class, I plan on studying what Mr. Luis has sent me. I also plan on working on a testing rig, which I will be using on exhibition day.

Today, I continued my work on trying to figure out the Arduino Code used to control the stepper motors. I decided to focus on making the motors move to a certain specific angle first before proceeding to making them repeat a swinging motion. After some research online, I found a code on the Adafruit forum that could in theory work with stepper motors. However, I soon found out that it was incompatible with motor shields, and I was forced to look for alternatives.

In the meantime, I decided to work on the feet for my robot. I refined the design I made before Thanksgiving break and printed it out for testing. Experimentation on the prototype foot proved that it would work in the leg setup. The question remains, however, about whether I should put 1 spring instead of two, as the foot seems to be very stiff when I tried to displace it when attached to the springs. In my opinion, the setup is fine as it is right now, as the weight of my robot, estimated at 2kg, would be enough to put the foot on a horizontal position, which would maximize the surface in contact with the ground.

Tomorrow, I plan on consulting Asli about controlling the stepper motor and while also making progress on testing the foot.