Week 16 - Applications and Implications

This section discusses the final project that I will work on. We start with this overview, and will then discuss the motivation, related work, the design, the parts, components and systems, the processes, and the questions that need to be answered.

The project will be a race track for 1:64 scale model cars that my son cannot stop to play with. With all the spirals implemented, there will be a place to enter the cars that will be immediately picked up by a mechanism that pushes the car to a height of about 60 cm, much like a rollercoaster. From there gravity will take over and the car will drive down the track in a u-turn where it meets a ramp from which it will jump to the rest of the track. It will meet a platform there where the car is halted.

The platform can turn itself and can hold about four cars. The track can turn such that it can launch the car into the track being picked up by the lifting mechanism again. There will be buttons for selecting which cars to launch.

Finally, when the car jumps, a camera will move with the car taking a picture while the car is in flight. Please note that this is with all the spirals in mind.

Motivation

I changed my final project from a device for my eyes to the project I described above, because this program has been very intensive for me but also for my family. As such, in the spirit of the slide I created in the CNC week, I preferred to do something back for my family.

Spirals

The base development is a 3D-designed track where we can drive a model car onto the track that is picked up by a lift mechanism, raising the car about 60 cm. Then gravity will take over and the car will drive down in a u-turn to make a jump.

Ideally, the u-turn is created with flexures but the modeling may be difficult, so we can revert back to a 3D-printed u-turn and make the u-turn the first spiral.

The second spiral is the platform for the car. The platform should rotate and point the car to the beginning of the track to launch it again onto the track, operated by buttons with which you can select one out of about four cars.

A third spiral is moving a camera with the jumping car and take a photo while the car is in the air. We can make pillars with LEDs to make the photo from the camera module look good.

Beyond the existing commercial ones, there are various students that worked on race tracks. Most close to my plans are these from Nick Anastasia . He bent wood as I'm planning as well and needs to detect cars as well. It is a great project that I will study closely.

Alberto Porri made a race track for marbles. Although this is not as directly related, I can still take a look at how he handled cornering.

Although less related in terms of usefulness, this race track was also designed for a nephew in this case. It is a similar goal as my own construction set in the laser cutting week.

Also not so related, but very interesting and mentioned by Neil was this final project by Alberto Gonzalez that was all about making the model cars themselves as a final project. Finally, Dimitris Papanikolaou has also experimented with model cars. This project was also meant as a toy.

The race track itself will be fully designed in 3D and laser cut from wood. Specialized parts will be 3D printed and designed as well. There will be various controller boards that can mostly operate autonomously and these boards will be designed as well.

For documentation purposes, I intend to design almost everything. Additionally, I would like to make it a construction set, such that the track is easy to extend or adjust, given access to a laser cutter.

The project can be subdivided into several parts. First, there is the track itself, made of plywood. The track will be elevated by parametric pillars also from plywood. For specialized connections, 3D-printed parts may be used. We can also distinguish the rotary platform as a part, and the camera system as a part.

I intend to make the race track out of 3 mm plywood that will be laser cut, that are available at our lab. There will be a more solid wooden board that will hold the race track, also sourced from our lab.

Other significant components are three standard NEMA 17 stepper motors, a solenoid or a servo for launching the cars, an aliminium profile to let the camera "ride", based on the beehive project, a belt, and sensors for detecting the cars.

For details the Bill of Materials for several parts:

The Track

The Lift Mechanism

The Infrared Sensors

The infrared sensors are small boards and there are two of them:

The Electronics for the Lift and Sensors

The Source of the Components

Although the project seems to be very expensive, most components I already had available or were available in the Fab Lab. The plywood sheets come from the attic of Waag. They were old and curved, but they have a nice color and texture and seem to be hardwood.

The stepper motor happens to be an expensive one, but I retrieved this from an old 3D printer. Cheaper versions will most likely do as well. The flanged wheel bearings came from the same old printer as well together with the stepper driver.

There were two components that I bought myself, namely the 1 m M6 threaded beams and the wing nuts. All the other parts were available at the Fab Lab.

The Components for the Other Spirals

The components for the other spirals are less clear, but it will require two similar stepper motors and drivers, similar electronics, an aluminium profile for moving the camera, an ESP32 Camera board, and a servo or a solenoid to launch the cars. Let's see how far I will get in the project...

One subsystem is elevating the cars. The car and its speed will be detected by two sensors that will adjust the speed of the stepper motor to "pick up the car". A belt that is clipped together at both ends with a 3D-printed part will act as the "scoop" that pushes the car up the lift.

Another system is the camera on the axis that will move with the driving car. Based on two sensors that detect the speed of the car, the camera will move on the axis driven by a stepper motor, taking a picture of the car in flight. The picture will be uploaded to a website.

Finally, the third subsystem is the rotary platform that will hold four cars. A car entering the platform will cross the middle point and come to a stop. The platform can turn such to line up a car to be injected into the track as well. The rotary platform is driven by a stepper. Cars will be detected to be on the platform. A servo or solenoid will push up a part of the platform to launch the car into the lift again. This will be operated by buttons.

A large part of the process will be laser cutting and making it such that it is a press fit model. Another process is using flexures for the curves, both going up or down, and curving to make a turn.

Other processes are 3D printing parts and calibrating the sensors and the pickup of the lift and the camera. This all needs to be programmed as well.

There are several important questions to be answered that I have no clear answer for yet: Firstly, for a height of 60 cm, the length of the belt is quite large, requiring quite some tension in the belt. However, the position to tension the belt is at the other side of the motor, but this will give a force that potentially pulls down the pillar.

Another question is how to best detect the cars, but I assume Anastasia has already solved this. Finally, a question is how to apply flexures to bend the wood best, such that a car can drive over it.

I will consider the project to be successful if at least the lift mechanism works activated by a car on the track that is picked up by the sensors. This requires a tight enough belt, a track with elevation with proper integration of the lift mechanism.

The other spirals are nice to have and essentially use similar mechanisms: the rotaty platform will require cars to be detected with infrared sensors and will turn with a stepper motor. The camera activation will also happen with the same sensors and there is the question mark if a stepper motor will have a high enough speed to follow the speed of the car.

Fab Academy

• Propose a final project.
• Explain what it will do.
• Analyze prior work.
• Discuss the materials and components that will be used, where they come from, and how much they cost.
• Discuss the parts and systems to be made.
• Describe the processes to use.
• Discuss unanswered questions at this stage.
• Discuss how the project will be evaluated.