10%

What could have been...

Continuous iteration works - sometimes

By Sohaib Nadeem

April 13^th, 2019

Lows and Highs

This robot, at the end of the season, reached it's peak performance. Unfortunately, that was a little too late. There was a major mechanism change at every event with this robot. The main "ball" handling mechanism was tweaked to maximize performance and minimize failures, though we were never really 100% confident in it.

"Disk" mechanism

The "disk" handling mechanism was completely different at each event we competed at. The first mechanism would grab the disk on the outside and inside, constraining it by essentially clipping it in place. The idea was, with this mechanism, driving up against the disk would pick it up, with no need to have the operator time a button press to secure the disk, reducing variables, and improving cycle time.

That was the theory anyways. It turned out to be quite poor. At times, it was brilliant, and at others barely usable. Inconsistent, but with a day until we can no longer build, surely it will be good enough for our first competition, right?

That's after 6.5 weeks of meetings, 5 days every week. After bagging the robot and arriving at the competition, we quickly realized how poor the mechanism was. The worst part, good acquisitions were impossible to distinguish from bad ones - and bad acquisitions meant we dropped the "disk" into a position that we could not retrieve it from.

Velcro Mechanism

After a disappointing knockout in the quarter-finals of our first competition, we knew we had to improve our "disk" handling to have any chance of doing well. With a limited six hour window during which we could build, many little repairs to perform, and funds stretched thin, we built a mechanism that would interface with the velcro on the "disk". The disk would be released with pneumatic pistons pushing it off.

The stats at our next competition were better, we scored three times the amount of disks we did at our first competition!

That actually means we scored only nine disks at our second competition. An improvement no doubt, but still nothing to write home about. We did better at this competition, captaining our alliance to the semi-finals to lose to the eventual winners.

We had all but qualified for the Provincial Championship, but in order to secure a spot at the world championship, we would have to do better.

There was also a time in the semi-finals where a "ball" got jammed in our "ball" mechanism for a quarter of the match. This lead to us dancing around the field, hitting things, trying to dislodge it.

Afterwards, we realized that after some quick repairs, we forgot to put some spacers in. This off-set of spacing led to a situation where the ball jammed in the mechanism, something we had not seen in our prototyping, or throughout our first event.

That was quickly fixed, and then we made the new "disk" mechanism.

Wheeled Mechanism

This was the final creation. It used powered soft compliant wheels to both grab, and eject the "disk." It showed promise in the shop, but there was no more time to work on the robot, and it had to be put on at the competition.

Establishing a comprehensive plan of what we needed to complete and assigning tasks, we did manage to attach it during the practice day at the provincial championships.

It worked really well. However, we did burn some motors due to stalling them. Sensor positioning, and logic (things we didn't test before hand - notice a trend here?) resulted in the motors running when they should not have and they burned out. By the end of the competition we got it down pat, but we essentially spent our matches at the Provincial Championship prototyping our "disk" mechanism.

The Importance of Prototyping

Prototyping is important, we know that but we still did not prototype enough. 6.5 weeks to make a robot from scratch is a bit of a strict time frame...

Prototyping with the intention of making it fail in my opinion is even more important. Asking the prototype to handle unexpected situations is even more important. "That will never happen," - until it does, and Murphy rolls in his grave: "If something can go wrong, it will go wrong!"

The result of the season was disappointing. But seeing the students come together, take initiative and build arguably our most complex robot yet (certainly one that could do the most) was heart warming. Lots of lessons were learned, and it was a very fun season!

We had a very simple, self centering "ball" intake that allowed the driver to effectively intake anywhere from the front side of the robot. We needed to go from a wide acquisition zone to a narrow, predictable release point. We did so by centering the ball using mecanum wheels which vector the ball inwards. (They're also used on omni-directional mobility bases in industry) Using a series of sensors, the ball would always sit in the same position in the conveyor, until the driver chose to release it. Additional little bits of automation made the sequence more efficient. For example, when a ball was detected, the intake automatically stopped running, and the intake arms folded in to prevent collision damage.

Little things add up to make processes more efficient. In industry today, everyone is looking for efficiencies to essentially make more money, while spending less money. Being able to optimize this ratio is key for not only to stay competitive at robotic competitions, but also for major players in the industry.

Ideas I brought up like the green light turning on when a "disk" was successful acquired might sound like a purely aesthetic decision. But the reality is, it simplifies a complex decision for the driver into a binary one. (Do I have a "disk" ? If yes, I can drive away, If not, continue to try and acquire) The driver does not have to take time to process whether or not the "disk" is properly acquired by the robot - and immediately upon acquisition, a signal is given that tells the driver they can go. There are valuable seconds saved here that add up in the course of a two minute and fifteen second match.

Here is our first match of the season: (5036 in blue)

At the end, there were some moments of absolute brilliance, but they were not enough to outweigh the average and sub-par moments. It will always be a thought in my mind of "what could have been" but it just motivates everyone to work harder, and its a good lesson in humility and the importance of expect-able (consistent) outcomes of any engineered product. Here is one of our last matches in the season, that will always remind us to prototype harder, to put a finished product on the field, and what could have been: (5036 in blue)

Button Label

Rapid Prototyping

Quickly Manufacturing Information-Generating Prototypes

Read

Autonomous Rickshaw Pulling Biped

CAD | 3D Printing | Programming | Teamwork

Read

Story Told With

Start publishing stories like this