Category: Team Status Reports

This week, our team focused on finalizing our subsystems as well as starting integration. Not having the motor control board was a blow, but we still have our backup plan of direct connecting the battery to the launcher. Outside of directly connecting the battery to the launcher we experienced little to no design changes. During integration between the CV and the Motor Control, we found that we our robot wasn’t turning well either overrotating past the POI or rotating very slowly.  In order to counter this we decided to implement PID control. We also while testing found that running pose estimation when there were multiple people in the room caused a lot of latency. In order to counter this we implemented the temporary solution of capping the amount of people that we’d perform pose estimation on. We also realized that when actively targetting someone the latency that would come from running pose estimation on the target could interfere with our control, for that reason we decided to cut pose estimation once a target was found.

 

Our unit testing so far has been focused on making sure the CV is accurate by manually following our codes turning commands and seeing if our launcher is in line with our POI. The test we are currently running consists of the same except with the PID control fully controlling our launcher as the integration testing of our old linear turning algorithm failed.

This week, our team mostly worked on building our new structure. We drilled holes in our PVC sheet and attached the motors to it. Our robot also came in, so we worked on getting the motors attached to it as well with the PVC sheets. Our new motor board also arrived, so we have been working on integrating it. The most significant risk that could jeopardize the success of the project is still the launcher, but that will be revealed in the next few days as the new motor control board is integrated. We tested our launcher at 10% power and analyzed that it consistently reached around 1.5 feet. Assuming power and range are linear, this means that we can at least launch 15 feet. We are thinking of testing out different wheels with different frictions/compressions to see which one launches the tennis ball the best.

No changes were made to the existing design of the system from last week. There is also no change in schedule.

Over the new week we plan to refine our structure and get started on building the ball feeder/ramp as well. We also want to get the new motor board working and begin integrating it with everything else, like the CV and robot motors.

Here is our structure so far:

This week, our team spent most of our time preparing and doing the interim demos. We believe our biggest risk is still with our launch, as now we have to wait for our replacement motor board to arrive, but after our lower power tests this week we are more confident that it will launch our required distance of 20+ feet. This week we also have been considering a design change by the suggestion of Tamal. Since we have fallen slightly behind due to our parts breaking down, he made the suggestion to instead use a mobile robot for the turning of the base instead of our current turret design that we would have to build from scratch. This idea could both make implementing the turning easier and more reliable, but also opens up many more possibilities, such as actually moving towards a target who is out of range. We think this idea is promising and we have been researching what robot kit would be the best to use, so we can have it ordered hopefully by Monday. We would still likely use the PVC materials to place on top of the robot to give the launcher some height, but the actual lid would now be stationary with the robot doing the turning and moving instead.

Over the new week, once our new board and potentially our robot arrives, we want to focus much more on working with the motor control code and actually integrating all our subsystems now that we have tested them individually.

Over the next few weeks we will be continuing to run tests as we finish and integrate our subsystems. So far we have been able to test a low power version of the launch as well as the computer vision and physics calculations separately, all of which gave promising results. In the coming weeks as we integrate all these systems as well as implement the turning, we will also be running many tests on these. We will ensure that the range and physics calculations actually match up with the physical launch and tune them as necessary, and that our targeting actually properly tracks the target and our launcher faces them respectively. Based on the results of our tests, we will likely have to tune our targeting algorithms however much necessary to ensure the accuracy meets our requirements.

The most significant risks that could jeopardize the success of the project is still the actual launcher mechanism, but it is not as severe as last week since we are already building it. With the 3D printed wheel attachments, 45º angle connectors and screws, PVC pipe/sheet, and putty, we are able to attach the wheels to the axis of the bike motor and use putty for stabilization and strongly attach the motor base at a 45º angle. The PVC pipe is very sturdy, which makes us feel more confident about our structure compared to the 3D printed design. A small risk would be that we are currently using temporary solutions for some parts. The PVC sheet, which acts as our base lid, did not arrive in time this week so we are using a temporary solution to attach the motors and create a distance between them to launch a tennis ball. The motor control board we borrowed from the ECE department is also not working, so a temporary one that has an on and off switch and potentiometer speed control is being used. However, these are mainly used for interim demo and once we have better working parts come in, we are confident in having everything work and integrated as intended. Pictures of current setup are included below.

No changes were made to the existing design of the system. We have updated our new schedule/ghant chart below. We are back on track with our progress after the setback from last week.

 

Gannt Chart – Interim Demo

The most significant risk that could jeopardize the success of the project is still the launcher mechanism. We still cannot be entirely sure how well it will launch until a prototype is built. We are working on finalizing a base that will hold the DC motors and tilt it 45º and creating an attachment between the wheels and the motors for spinning. Once these are put together, we already found a library that works with C and Python for the motor control code to launch the tennis ball.

The main change we have made this week is how we plan to assemble the launcher. We realized that an entirely 3D printed design would not be feasible. It is too expensive at around 65 cents per gram, and it cannot print over 175g, which our base weight significantly surpassed.  Instead, we will only be printing the more precise components like the gear mechanisms and the attachment between the wheels and DC motors, and we will be using PVC pipes and sheets for the outer housing and base lid. This will confidently allow for a  stronger foundation at a cheaper price compared to PLA 3D printed material and a guaranteed (and wider if needed) diameter. Other than the material change, we still plan to use the same lid rotation for the actual design, just no longer fully 3D printed. As stated earlier, it is much cheaper to use PVC over PLA 3D printing, which gives us much more flexibility in purchasing other products in case situations similar to this occur down the road.

There are no changes in our schedule. We just need to try complete building the launcher mechanism as soon as possible for the interim demo and integrate other components in (draft CV and motor control code).

This week, the main thing we did as a team was place our first set of orders. We ordered all the parts necessary for the main launch mechanism , which we plan to have done by the interim demo. We already started building it this weekend and so far it is going smoothly. On top of that, we all individually worked on our sections of the project and the Ethics Assignment.

As usual, we still believe that the launcher mechanism is the biggest risk of our project, but we are doing our best to get that part done as soon as possible to mitigate this risk. If we are confident in this by/before the interim demo, we will have confidence that everything else can come together as well.

The only changes made to the existing design of the system is that the CV, depth AI, and target coordination will all be done on the Oak-D Pro camera’s processor rather than the Raspberry Pi, which is just as capable and there will be less back and forth between the components. However, there is no change in costs and the overall project design is still the same as before.

The most significant risk that could jeopardize the success of the project is still the same, which is having the launching mechanism work. With the Design Report and all the physics calculations done, now we have to build the launching mechanism to see if the math follows following fall break. To mitigate the risk, we have purchased have a bike motor that significantly overshoots all of our finalized specifications to ensure we have room to make adjustments in case there were unexpected physical constraints. Furthermore, the Design Report has a section on Design Trade Studies, where there are other approaches to the launching mechanism discussed. If the spinning wheels do not work as intended no matter what we adjust, our contingency plan is to use a spring system that contains guaranteed energy.

No changes were made to the existing design of the system. We are also currently on schedule, so there are no updates to report. Following fall break, we will have our focus entirely on building the launching mechanism, figuring out CV, and working with our motor control board, so we are confident in our current progress.

Part A was written by Miles: Our project can affect many people outside of Pittsburgh and across the world, as throwing and catching a ball is one of the most universal pastimes. Furthermore, many sports (like soccer for example) are very popular in many countries and tennis balls are most commonly used to enhance training and hand-eye coordination. Anyone across the globe who regularly catches, whether for fun or training for a sport, can gain value from our product. Since our product automatically targets a person and shoots the tennis ball when ready, this launcher is feasible to use for those who are familiar or not used to technology. As a result, anyone who wants to catch a ball on their own can have a need for this product, regardless of where they are from.

Part B was written by Andrew: Our project could affect the culture surrounding sports and how people practice them. Typically, practice always involves multiple people and even some personnel used, like coaches or teammates, for menial actions such as throwing a ball, but our project could potentially change this norm. Entire franchises and organizations could potentially switch their traditional practice methods to using our product, allowing coaches to be put in more critical roles such as analyzing player performance. Additionally, our launcher allows all athletes on a team to receive proper training instead of being stuck on passing duty or having inconsistent balls thrown at them. This could also majorly change the traditions of a variety of groups, like sports teams or even recreational leagues, who may not have enough players.

Part C was written by John: From our perspective, our project does not have an appreciable environmental impact. The original problem itself had little to no effect on any environment or surrounding ecosystems, and our solution will also have no additional environmental consequences. As a result, we do not anticipate any positive or negative environmental effects from our project. Perhaps there is an off chance that by having the machine take up the duties of a ball thrower, like a quarterback, more people could practice sports outdoors anytime without needing to coordinate with a large group. To elaborate, normally if a dedicated ball thrower is not available, practice as a group would be difficult, but our product removes this barrier. This would mean greater physical activity instead of having people remaining indoors using electricity. However, since the launcher itself requires power, the overall environmental difference is small.

 

As a team earlier this week, we mainly worked on the design presentation. Since there was a lot of material to cover about Passing Partner, going through the slides together helped John prepare what to say within the time limit. After we went through our design change last week by having the vertical tilt function static at 45º, our biggest risk that could jeopardize our success is still likely the wheel launching mechanism. We have been mitigating this risk as much as we can by thoroughly outlining calculations and selecting parts that overshoot our quantitative specifications to have room for flexibility.

We are currently on schedule, so there are no updates to report. Besides the change made last week to implement a 45º vertical angle instead, we have not had any other significant changes to the existing design of the system. We have shifted our focus entirely to the design report for next week, which is our main deliverable.

As a team we have spent a lot of this week collaborating on the Design Review Presentation and searching for essential components (Oak-D Camera, motor board, Raspberry Pi) for our launcher. Our biggest risk we think this week after more design is the tilt adjustment. We realized that adjusting the vertical angles ties to our stretch goals of launching different curves/launches. To mitigate this, the vertical tilting is now a stretch goal and the launcher will stay at a constant 45 degree angle for now. To adjust distance we will instead adjust the power, RPM, and torque of the motor. Because 45º is the optimal angle, at max motor power, it will get us our max distance, and if we want to shoot closer we can decrease the parameters of the motors. This overall is a minimal design change, and if anything it simplifies our design. If we in the future want to add the tilt back in, it will not be a major change: just implementing a rack and pinion mechanism.

We are still on track with our schedule, so no changes have occurred.

Below is a still WIP but more complete CAD diagram of what our launcher is now like. Some of the parts are to scale placeholders for our actual parts(motors, rollers, etc.)

Our biggest risk for the project going forward will be the main ball launch mechanism. We are confident in the design itself, but we are just not sure of exactly how far we will be able to launch the tennis ball. We are mitigating this risk by trying to overestimate the launch force, energy, power, and exit speed needed from the spinning wheels so that we will have some wiggle room, while also having backup plans in case it fails (spring load mechanism for guaranteed energy).

No changes in design nor schedule have been made thus far. Our main goal as a team for next week is to complete the design presentation for 9/28 and get a more complete Bill of Materials.

Very Rough Draft of CAD Modeling(WIP) of the launcher base (x-axis rotation):