Joey Zhu

During this week, I was able to get a lot more of the test rig finished. However, I am starting to have problems with the steering aspect of the bogie. When introducing the magnet to the hall-effect sensor, and going through the expected logic of the entire path, the interrupt activates and the code works fine, when having the right side switches be the ones that are initially pressed. When the left side switches are the ones that are initially pressed, the steering motion occurs regardless of having a magnet be introduced even though the latter is a specifically required condition to introduce steering. Despite this, one way that we have allowed the bogie to differentiate the direction to turn is by introducing a counter that begins every time the hall-effect sensor gets activated. This variable is then taken through a modulo two operation (% 2 ), which allows us to differentiate the turn to take due to the introduction of two new conditions, when the new variable is one, and when the...

During this week, I had to begin creating a test rig and getting parts machined to improve the bogie. Parts such as shafts, jackets, spacers, and gears were sent out to both the central machine shop and the ENGR 123 in the engineering building. The jackets and spacers had a quick turnaround time and I was able to retrieve them quickly. However, there will be a long wait on the shafts and the gears, due to the amount of orders that the central machine shop machinist has. As for the mechatronics portion of the robot, I was able to begin building a test rig to emulate the half-scale bogie. First, I began by utilizing the hall effect sensor, and two DC motors. This will emulate the propulsion of the half-scale bogie. When the hall effect sensor encounters a magnet, both of the DC motors stop moving. Afterwards, I used a different Arduino to emulate the steering of the half-scale bogie. When the limit switch is pressed, the stepper motor starts rotating. Combining the two proves to ...

During this week, I made a lot more progress towards redesigning the mechanical portion of the steering on the half-scale bogie. The 0.5" diameter 4140 steel rod and other parts arrived this week, and my team was able to utilize the miter saw to cut portions of the steel off. Although not all of us have access to ENGR 123, we plan to finish fabrication as soon as the door codes are sent to us. As we wait for door codes, I have been looking into implementing regenerative braking for the half-scale bogie. This would yield at least a ten percent efficiency in regeneration (back to the battery) due to the nature of the brushed DC motor. I am considering replacing the H-bridge in favor of a full bridge rectifier and MOSFET combination that utilizes N-AND logic gates to act as switches. I do not believe that we would require a PWM generator because the duty cycle is either at 0% or at 100% (most likely because it is a two phase DC motor). This configuration allows for a more compact s...

During this week, I was given the opportunity to learn about the half-scale bogie and take one of the two bogies apart. The steering shaft on one of the bogies was twisted and buckled due to fatigue failure. I plan to machine a new steering shaft from a 0.50" diameter 4130 cold-rolled steel rod. Another fix that we wanted to implement was to change the amount of slop that the bevel gears experience when in motion. To do so, we plan to place a spacer or bearing between the bevel gear and the surface of the shaft, so the bevel gear does not move around when in contact with the other bevel gear. The team believes that sprocket and chain will prove to be a better and more reliable option as opposed to timing chain and pulley. However, I think that this will not be utilized within the half-scale bogie, as the tolerances are already very tight, and the bogie is not designed for a sprocket and chain drive train. The information that I have learned from disassembling one o the half-sca...