My favourite aspect of mechanical engineering is seeing solutions materialize into existence. The inherent challenge of creating novel solutions for complex problems provides me with fulfillment and satisfaction. Highlights of various mechanical projects are outlined below.
360° Photography Rotary Stage
Objective: Design, fabricate, and install a rotary stage for taking 360° video of items.
Outcome: Installed and working.
I was introduced to an opportunity to design and build a robot to rotate items being photographed, in order to efficiently generate marketing materials for products being sold online. The rotary stage needed to hang items, inverted compared to everything available off the shelf, and thus a build to order solution was required. Specifications including load capacity, speed range, mounting height, and controls interface were thoroughly generated and accepted to ensure the final product would meet the client’s needs.
The robot was designed in SolidWorks and components were machined on my CNC mill or 3D printer. The robot is driven by a stepper motor and Arduino, and has a hard wired safety circuit with an emergency stop switch. Quick-Change item holders and a dressing station allow for multiple products to be cued up and maximize studio up time, a key justification for the robot’s purchase.
Lead time on the robot was remarkably short, the robot was designed and fabricated in a week, and installed immediately after. It was important to ensure delivery would be on time as the client had a tight production schedule, which required the robot to make it feasible.
Virtual Reality Haptic Feedback Design Project
Objective: Design, prototype, and verify a product to enhance feedback in virtual reality.
Outcome: Currently in progress, undergoing needs analysis and developing concepts.
I’m currently working on a haptic feedback peripheral as a capstone project with Chris Choi, Wesley Chai, and Sean Stanlick. The project involves a genuine design task, from problem identification through to generating specifications, conceptualizing, prototyping a final solution and verification. After hours of experiencing VR, we identified a need for additional haptic feedback for picking up objects and collisions. Initial concepts are focused on hand based interactions for existing simulations and gaming.
Functionally, the solution will take user input in the form of hand and finger positions, process inputs in conjunction with the virtual environment, and output force or vibration through actuators.
Recycling Compactor Design Project
Objective: Design, prototype, and verify a product to reduce the volume of household recycling.
Outcome: Completed on time, under budget, and met all design specifications.
A recycling compactor was designed as part of a design course project with 5 other team members. In a 4 month period, the goal of the course was to identify a problem and create a solution. My team elected to solve the problem of regularly overflowing recycling bins. My roles involved fabrication, mechanical and electrical design. generating all necessary design documentation such as assembly documentation, simulation results, and a bill of materials.
Key specifications for the project included size, power, cost, and lifetime constraints as a household appliance. The primary function of the device was to plastically deform common recyclables such as 500mL water bottles and 355mL aluminum cans to less than 50% of their original volume.
The final design uses a rotating wedge driven by a stepper motor through a gear train. The wedge itself is part of the gear train, with a gear section along its outer radius, leading to a very high reduction ratio and maximum output force of 1500N. An opening through the bottom of the compaction mechanism allows for compacted recyclables to drop into a standard recycling bin when the wedge is fully retracted. Safety interlocks including an inductive proximity sensor for hopper lid presence detection and optical sensor for recycling bin presence detection ensure safe operation of the device. The recycling compactor is constructed from 16ga. 5052-H32 aluminum for formability and corrosion resistance.
Compared to common trash compactors, this solution doesn’t require proprietary bags and isn’t permanently installed in a kitchen cabinet space.
IBroomBot Broomba Sumo Robot
Objective: Design a sumo style robot for a HEBOCON competition.
Outcome: Completed on time, defeated all other robots.
HEBOCON is a competition which involves comical and technically poor robots. The goal of the competition is to avoid using too much technology and instead try ridiculous ideas in the spirit of learning. The Broomba was created along with Chris Choi and Nicholas Manna for the 4th Terrible Hack hackathon at the University of Waterloo.
The Broomba is a semi-autonomous dustpan with motors, ultrasonic sensors, and an Arduino, all powered by two 18650 lithium cells. My contribution to the project included modeling the dustpan in SolidWorks, laying out components, wiring components, designing and 3D printing mounting brackets.
Additionally, I developed a LabVIEW virtual instrument and interface for controlling the Broomba over a Bluetooth serial connection. The user interface would allow for manual control of the Broomba’s drive system and reading back distance measurements from the ultrasonic sensors. Audible feedback in the form WWE quotes were also incorporated to indicate when the Broomba found a target. To fit the spirit of the competition, the interface is purposely terrible with a visually confusing colour scheme, illogical data presentation in both graphs and meters, and generally cluttered.
Although the robot was supposed to be terrible overall, it’s build quality and overall design made it undefeatable.
Arm-O Virtual Reality Force Feedback Device
Objective: Design a force feedback device for VR applications.
Outcome: Final design met all design specifications, functioned as intended.
The Arm-O is a device intended to apply braking force about a human elbow to provide force feedback in virtual reality. This is a Systems Design Engineering project in which I consulted on the mechanical design with Chris Choi, Wesley Chai, Duy Huynh, and David Derooy. Primarily, I was consulted on the design of the braking mechanism and elbow joint.
The brake is actuated when the user’s hand collides with virtual objects at various distances and corresponding elbow angles to provide force feedback. The brake mechanism consists of a sloping brake disk bonded to a rubber-like material which interfaces with a wiper arm attached to the servo motor. Braking torque is generated when the wiper arm is driven into the brake disk. The sloping feature on the brake disk allows for self-locking action as the user extends their arm towards objects, and quick releasing as the user retracts their arm.
The elbow joint consists of plain bearings to allow for a low profile construction. This minimizes the distance between the elbow and braking mechanism, reducing the moment generated the weight of Arm-O which would otherwise cause the device to slip around the user’s arm and bind.
CNC Milling Machine Conversion
Objective: Design a retrofit CNC motion system for a 3 axis manual milling machine.
Outcome: Design completed, in process of machining and procuring new components.
To fulfill various goals and to continue learning about CNC machining, I justified the the purchase of a manual milling machine which was converted to CNC in a matter of weeks. My justification for a personal milling machine was being able to have access to a machine outside of normal student machine shop hours at the University of Waterloo.
The first phase of the conversion involved simply replacing the hand wheels with timing pulleys and adding stepper motors to drive each axis with the original lead screws. The current status of my mill is documented here.
To further improve the accuracy of the machine, ball screws are being retrofitted to all 3 axis. With the current CNC capability, necessary parts with circular and complex pockets can be easily machined.
Quick change tool holders were also designed to maximize machining time. Similar to the Tormach Tooling System, the holders adapt weldon set screw shanks to a 3/4″ straight section accepted by an R8 collet. Unlike the Tormach system, the holders are comprised of a shank, made from ground steel shaft stock, press fitted into a steel collar. The shank is drilled and reamed to accept 3/8 Weldon shanks, common on small end mills. A raised shoulder on the collar locates against the spindle for repeatable height positioning. Compared to the existing R8 tool holders, the quick change holders should be on the order of 3-4 times faster and significantly lower cost.
Electric Formula SAE Drivetrain
Objective: Design a dual motor drivetrain for an electric FSAE car.
Outcome: Design completed, vehicle final assembly did not occur and project was a failure.
The former UW Electric Motorsports team was set to compete in FSAE Lincoln in 2015. Unfortunately, the team never finished the car, didn’t make it to competition and disbanded for various reasons. My role was initially to design a motor mounting system and briefly holding the role of drivetrain lead. Tasks included modeling a drop-in drive unit, housing 2 motors and a single stage of chain reduction.
The motors used are similar to brushless “outrunners”, where the outer case of the motor rotates instead of am output shaft. The motors inherently have higher stall and continuous torque output compared to conventional “inrunner” motors due to the increased moment arm of the rotor. As a result, less chain reduction is necessary, and the overall system weight can be reduced. FEA simulations were run in order to minimize component weight wherever necessary.
Electric Formula SAE Battery
Objective: Design a battery pack for an electric FSAE car.
Outcome: Design completed, vehicle final assembly did not occur and project was a failure.
Similar to above, the former UW Electric Motorsports team was set to compete in FSAE Lincoln in 2015. Unfortunately, the team never finished the car, didn’t make it to competition and disbanded for various reasons. After being the drivetrain lead, I became the battery lead. Tasks included picking cells and designing the entire battery system to be in compliance with strict FSAE specifications.
Lithium polymer pouch cells were eventually chosen for the final design. They were 3.7V, 12Ah cells, capable of 60C discharge and 30C charge. These were the highest power density cells available, which were also capable of accepting high charge currents for regenerative braking. High power density desirable as the courses the car would be competing in would involve constant braking and acceleration.
The cells are packaged into modules, 24s1p each. Each of the modules is comprised of waterjet cut FR4/G10 sheets, nylon cylindrical spacers, aluminum end compression plates, and threaded rod. Cells are retained by friction resulting from the compression force provided by the end plates and threaded rod. Nylon spacers limit compression and ensure cells are not over compressed. Connections between cell tabs are similarly made by aluminum blocks compressed in a similar manner to the cells.
The cell container is mostly sheet metal and was subject to strict guidelines from FSAE. Modules had to be separated in order to minimize the chances of the entire pack catching on fire. A simple lumped capacitance thermal calculation, considering the cell’s internal resistance, indicated cooling would be unnecessary over the course of the longest event. The container is a combination of aluminum and steel sheet metal, using the minimum allowable material to minimize weight while still meeting structural requirements.
Electric 1997 Audi A4 Conversion
Objective: Retrofit an electric drivetrain to a gasoline vehicle.
Outcome: Currently drivable, ongoing project.
Growing up around cars has lead me to have a fascination with cars, leading to a career in Mechanical Engineering. As an ambitious teenage, I wanted to build my own electric car. With hundreds of hours researching, I eventually bought an Audi A4 and converted it to electric drive.
The process itself is simple enough for a 16 year old to figure out.
- Remove the engine, exhaust, and gas tank
- Add batteries and a motor controller
- Design a coupler and adapter plate to mate with the original transmission and clutch
- Reinstall electric motor mated with transmission
- Design and build brackets to mate with original mounting points
- Wire everything up
At a high level, that’s it. The car is exactly what I intended to build and as a result I love electric cars. The project is documented here.
FIRST Robotics Competition 2012
Objective: Design and build a basketball-playing competition robot.
Outcome: Overly complex, poorly designed, and untested robot.
After designing a very competitive robot in 2011, I took it upon myself to design, in theory, a far superior robot. I mostly contributed to the drive system; a system with 4 steerable modules with 2 speed transmissions and a power takeoff system. A steerable drive system was intended to offer very good mobility, and the ability to balance on a bridge sideways.
To minimize the weight of the system, a vertical shaft both transmits power and allows the modules to pivot. Power is transmitted through a set of miter gears, through to a 1:1 chain drive, down to the wheels. The gearboxes were mounted vertically, concentric with the vertical drive shaft on one side. Unfortunately, this system inherently had “torque steer”, due to the reaction torque of the drive system overcoming the torque available in the steering system.
On one end of the robot, a second output shaft was used to actuate an appendage for tipping balanced bridges. In operation, a series of clutches would decouple the drive system on one end of the robot and route it to the appendage. Drive power would be provided with the opposite side of the robot when the appendage was in operation. This solution allowed for the use of much more powerful motors, and lower weight than a comparable system with an independent drive system.
More details about the robot are available here.
FIRST Robotics Competition 2011
Objective: Design and build a, inner tube hanging competition robot.
Outcome: Well designed, 2nd, 3rd and 4th place robot at 3 different official season competitions. 1st place at an off-season competition.
In contrast to 2012, 2011 was much more successful. Again, my contribution was the design and manufacture of steerable drive units, and design of the overall robot. The basic operation of the robot would involve no turning while scoring the most points, compared to skid-steer style robots.
Each drive unit had an individually driven wheel, going through 2 stages of gear reduction. The modules steer about vertical shafts, actuated by a motor through chain reduction.
The arm of the robot pivots and telescopes to reach 10′ high goals with inner tubes. The claw mechanism features 2 sets of belts to actively grab and manipulate inner tube angle.
More details about the robot are available here.