【VEX V5】How to connect your pneumatics?

Hello! Welcome back to IntroVex, your robotics guide to Vexcellence.

In this episode, we'll be talking about how you can connect pneumatic pieces to make the cylinder extend and retract. This time, we'll talk about the theory behind how the air flows in the system, while we'll talk about where these pieces can be placed on the robot next time.

Why use pneumatics?

The first question that might pop into your mind is: Why even bother using pneumatics on the robot? 

In Vex V5, even though we already got 88 Watts of motor power to use, meaning that at least 8 motors can be used to power mechanisms or subsystems, there are still some small-angle motions that are not used consistently, which would be a waste of using motors for those. Thus, pneumatic cylinders are basically an additional motion source to help you create some additional functions that support you throughout matches.

In the following cases, it is best to use pneumatic cylinders:

• There is a repetitive motion back and forth or up and down
• The mechanism is not used consistently, but is used only when needed
• The mechanism doesn't require rotational motion
• The range of motion is small (not exceeding 180 degrees)

On the other hand, if the motion is rotational, requiring consistent motion, and ranges widely, it should be assigned a motor.

Take our second-generation robot in this year's Push Back Season, for example, the chassis and the intake are all rotational motions that continue for a long period, which they use motors for. While the retracting mechanism here that allows the robot to go under the long goal is a up and down motion with around 90 degrees angle, and only used when needed, this here uses a pneumatic cylinder.

What are the components?

Now that you know when the pneumatics could be used, we can move on to discussing the individual components that make the system work.

Pneumatic cylinders

Starting with the most obvious component, you can see on the robot the pneumatic cylinders. These are the pieces that provide linear motion, that help extend and retract your structure. There is a built-in piston within the cylinder that can extend when air flows in from the back hole and retract when air flows in from the front hole.

That said, you can create a dual-acting mechanism and a single-acting mechanism using this characteristic. If you connect tubing to both holes, the cylinder retracts and extends with air/force; if you connect only one hole, leaving the other blank, one motion would not be done with air, but you can pull the cylinder with rubber bands. The advantage of this is that the structure is not fixed in place and can have some margin for moving freely, and it also saves air. The second-gen robot example used a single-acting system where the retraction is done by rubber bands and gravity.

There are three sizes of pneumatic cylinders: 25mm stroke, 50mm stroke, and 75mm stroke. This refers to the length of motion. Different lengths can be used in different settings based on your needs, but normally, as the angle of motion increases, the longer cylinders will be used.

Double-Acting Solenoids

Now it's time to control the cylinders with our V5 Brain and Cortex, and how do we do that? We can use the solenoids!

The solenoids have one end connected to the brain with cables and another end connected to the corresponding extend/retract hole on the cylinder. The two ports on the side of the solenoid are for connecting the solenoids together so that air flows through the system. Port A and B at the front each connect to the extending hole and retracting hole of the cylinder. The unused ports should be blocked with plugs so air doesn't leak. Connecting the A and B ports changes the initial state of the cylinder, so just switch them if, for example, the wing starts out open when it's supposed to be closed.

Fittings

These are used to connect to the holes for solenoids and cylinders, so tubes can be attached. The tee fitting is for separating one stream of air into two. The shut-off value fitting is to make pumping easier. You can switch out the golden value stem on the air tank to straight male fittings and connect it to the valve so you can pump air somewhere far from the tank. Or else, just imagine your air tank being at the middle of the robot, haha.

Air Tank

The air tank is where the air is getting pumped into, storing it for usage during a match. You can use up to two air tanks and pump up to 100 psi in V5. Each airtank powers a loop or system of air. You could also connect two airtanks together to use a larger amount of air for a single system.

Tubing

This is the pipe you are going to use to connect different components together. Air flows through the tubing.

How are they connected?

With all components introduced, it's now time to see how they are connected together to make the cylinder move!! Let's first start with an example of a double-acting single cylinder.

A whole system or cycle of air consists of the Air Tank, the double-acting solenoid, the tubing, the fittings, and the pneumatic cylinders. First, you have a structure that you have attached to the pneumatic cylinder, which moves under your control. Then, you can attach the straight male fittings or the elbow fittings to both holes of the cylinder. Next, you have to connect the double-acting solenoid A and B ports to either port on the cylinder.

To make the solenoid move, pull out your cable and attach the solenoid to the brain. Finally, let's attach the air tank! Pull out your air tank, attach a straight or elbow fitting on both ends. Connect one end to the shut-off valve fitting and the other to one side of the solenoid. Since this system only has one solenoid, you should block the empty port on the solenoid.

Let's simulate how the air will go! It comes in from pumping, goes into the airtank, then the solenoid, and finally it reaches the two ends of the cylinder. When the solenoid switches between the open and closed states of ports A and B, the state of the cylinder will change.

That's it for connecting the pneumatic system. Next time, we'll talk about where to place the cylinders, the air tanks, solenoids, and many more onto your robot! Stay Tuned!

This is IntroVex, your robotics guide to VEXcellence. See you next time!!

【EP3】【VEXIQ】Build Your Chassis!! – Construction

Hello! Welcome back to IntroVex, your robotics guide to Vexcellence.

In the past two episodes, we talked about the gear ratios and the difference between sprockets and gears. This time, we are moving on to constructing a full chassis. I'll be introducing the parts you could use to construct your chassis based on your needs, and take you through important steps for building.

How many wheels to use?

First, we have to think about the wheels. There are many factors for us to consider: the amount, the type, and the position. It is important to plan before construction to avoid possible conflicts while building.

First, it is the number of wheels we use. In VEX IQ, we typically use 2 wheels on each side of the chassis. Since robots are light, 4 wheels are enough to support the chassis. If we used 6 wheels with the same motors, it would increase friction, making the robot harder to turn. In rare cases where a robot is so heavy that wheel axles start to bend, a 6-wheel chassis can help spread the load and reduce stress.

Next, it’s the type of wheels to use. In VEX IQ, there are two main types of wheels: traction wheels and omni wheels. The difference is that traction wheels have higher friction and grip, while omni wheels have rollers that allow them to slide sideways more easily.

In competitions, we typically use omni wheels on the chassis because they reduce turning friction and make the robot drive more smoothly. The trade-off is that omni wheels provide less traction than regular traction wheels, which can reduce pushing power and result in less precise movements, but the smoother movement usually makes them the better choice.

Finally, it’s the position of the wheels. The main goal is to keep the robot stable and balanced. By placing the wheels near the front and back edges of the chassis, the weight is evenly supported, and the robot is less likely to tip forward or backward. However, wider is not always better; finding the right balance between stability and maneuverability is more important.

How many motors to use?

Now it’s time to decide how many motors to use on the chassis. This depends largely on how many motors are needed for other subsystems. In VEX IQ, a robot can use up to 6 motors total. For example, if the intake uses 1, the scoring system uses 2, and the endgame system uses 1, then only 2 motors remain for the chassis. In some cases, using pneumatic pistons for certain functions can help save motors.

Since the setup varies by game, the most common and simple solution is a two-motor chassis, with one motor on each side powering two wheels.

Constructing a chassis

When constructing the chassis, we need to decide on many things: the length of the beams, the width of the chassis, the gears to use, and the motor position, etc. Let’s go through them step by step.

1. Beams and wheel support

On each side, we need beams on both sides of the wheels. This is because a shaft spins smoothly only when it is supported in parallel on the same horizontal level. If the wheels are left on the outside without proper support, they can be damaged or fall off, and the wheels and gears will rub against the frame, creating friction instead of spinning freely.

2. Wheels and gears

Always make sure gears are firmly secured so they don’t slide during practice. For example, locking a gear with a fixed beam is usually more reliable than only using a rubber shaft collar.

For the wheels, it is recommended to fill up the empty side of it. Adding a 2x2 beam can provide another hole for supporting the wheel in place. By doing so, even if one side of the hole was damaged, the wheel could still spin nicely. This could also reduce the amount of spacers used.

3. Chassis Length

As an example, let’s consider a common 1:2 gear ratio. Since the wheels are spaced apart, you usually need more than three gears to bridge the gap—about five is common. Once you line up the wheels and gears, you can decide on the best beam length, making sure it’s long enough to fit corner connectors while still leaving room for the wheels.

4. Chassis width

The width depends on how you connect the two sides. Most teams use corner connectors, which can be arranged in multiple ways. Moreover, using corner connectors also helps in connecting the two sides together. In general, you want the chassis as narrow as possible so it doesn’t waste space needed for subsystems on top.

The overall width depends on your robot design; you could always adjust it.

5. Motor placement

Motor position also depends on the robot’s design. If you need systems in the front, place the drive motors in the back to free up space, and vice versa. Motor shafts are recommended for motor connections, obviously. It can make sure the shaft won't fall outwards.

Remember, the example I showed is only one possible setup. It’s not the only or best option. Use these tips and experiment with different configurations to see what fits your design needs. To give you some ideas, there are many possible ways to build a 1:2 gear ratio chassis. Don’t be afraid to try out different versions yourself.

That's it for this episode. This is IntroVex, your robotics guide to VEXcellence. See you in the next article or video!!

【EP2】【VEXIQ】Build Your Chassis!! – The difference between sprockets, gears, and pulleys

Hello! Welcome back to IntroVex, your robotics guide to Vexcellence.

In our last episode of Build Your Chassis, we talked about the fundamentals of gear ratios and the common ones found in a competition. This time, we will explore ways to create ratios beyond solely relying on gears.

Overall, there are three common ways to create ratios between the input and output while transferring the power from one location to another: Gears, Sprockets, and Pulleys. Later on, we will discuss the PROS and CONS of each and when is best to use them.

Gears

First, let's talk about the gears. Gears in VEX IQ come in different sizes, starting from 12-tooth gears up to 60-tooth gears. All gears are multiples of the 12-tooth gear, including a 24-tooth, 36-tooth, 48-tooth, and 60-tooth gear. Among these, the odd multiples of a 12-tooth gear can line up in a straight line together, while it forms a diagonal slope when one odd multiple connects with an even multiple tooth gear.

When two gears are connected together, they spin in opposite directions. Similarly, when three gears are connected together, the first and the third gear spins in the same direction. Overall, if the number of gears connected is even, the first and last gear spin in opposite directions; vice versa.

Sprockets

Next, let's talk about sprockets. Sprockets are shaped similarly to gears but with the teeth wider apart, and are connected through linked chains instead of connecting them side by side. Sprockets are sized from the smallest 8-tooth sprocket to the largest 40-tooth sprocket. You may also notice, all the sprocket sizes are multiples of the 8-tooth sprocket, including 16-tooth, 24-tooth, 32-tooth, and 40-tooth.

Since sprockets are connected through chains, the motion of all connected sprockets in the same chain spins in the same direction as the input. Also, there is never a limit on how you connect the sprockets. All can be connected as long as the chains can reach both ends while being straight.

Pulleys

Finally, let's introduce pulleys. Pulleys have no teeth like the others, but rather, it is connected through rubber belts just like how it appears in physics textbooks. Additionally, there are only 4 sizes of the pulley: 10mm, 20mm, 30mm, and 40mm (in perimeter).

Similar to sprockets but different from gears, the connection of pulleys requires a belt, which results in all pulleys connected together spinning in the same direction.

Comparison between Gears, Sprockets, and Pulleys

After the brief introductions, let's talk about when you can use the three connection methods as well as their advantages and disadvantages.

Gears:

PROS:

• Powers can transfer flawlessly and directly from the input to the output
• Doesn't have to worry about belts or chains falling off

CONS:

• There are restrictions on possible connections. You might not be able to reach a certain gear ratio with the correct direction of spin with a fixed amount of distance between the input and output.

Sprockets:

PROS:

• Can connect from any location to another
• Can easily switch up the sprockets to reach other ratios
• Can connect multiple outputs to one input easily

CONS:

• Chains may break upon collision or aging
• Need to adjust the length and tension of the chain when connecting

Pulleys:

PROS:

• The sizes are relatively smaller than sprockets and gears

CONS:

• The pulleys may slip easily when rubber belts don't provide enough friction
• Rubber belts are fixed in length, may not find the perfect belt to connect a certain distance
• Cannot connect locations that are too far away

Simply saying, gears are really useful in places where you need precision in the turning, and the power transfer has to be consistent. One prominent example is the chassis. Even though sprockets can also do the job, gears can increase the actual motion transferred to the wheels and avoid the risk of repairing broken chains.

Sprockets, on the other hand, are great when connecting input and outputs that are far apart and not lining up straight. If you tried using gears to connect and found that you cannot possibly reach the destination with the preferred gear ratio and number of gears, it may be best to switch to sprockets and try again.

Pulleys, finally, are uhmm... not really good at anything. First of all, the rubber belts can really slip easily, especially when you want to turn something heavy and requires torque, pulleys may fail the job. One of the better and common usages of the pulleys is using them as side wheels that guide the mechanism or robot smoothly.

Possible Combinations and Applications

After all the explanations, you may think that gears are gears and sprockets are sprockets, which they are, just separate things to consider when constructing. However, this is not always true. Sometimes, you may need two things spinning in different directions, but the distance won't fit an even number of gears with the gear size you prefer. This is the time to combine the two.

Take an example of the side rollers we made in the current VEX V5 Push Back season. The space at the time was 7 holes in between the two rollers, but after simple attempts, we found that we could not find the perfect combination to get a 1:2 gear ratio with an EVEN number of gears. At last, we figured that we could use an even number of gears to power one roller while using sprockets and chains to power another, making the rollers spin in opposite directions.

Aside from this example, there will definitely be more cases, but I am just here to remind you that sometimes thinking outside the box and combining different things can help you find the solution.

【EP1】【VEXIQ】Build Your Chassis!! – Comparing Common Competition Gear Ratios

Hello! Welcome back to IntroVex, your robotics guide to Vexcellence.

In our new series: Build Your Chassis!!, we will talk about key ideas that might help you build a sturdy and smooth chassis for your robot. A robot needs a chassis with wheels that spin smoothly and as frictionless as possible to run fast at its intended speed. We'll cover some simple yet handy tips for you to improve.

In this episode, we will first talk about the common gear ratios of competition robots. Gear ratio is a key factor you have to decide based on the characteristic you want your robot to have, commonly between high speed and high torque.

How to calculate Gear Ratio?

At first, when you built your first robot using the VEX IQ super kit, competition kit, and education kit, you will most likely connect the wheel's shaft directly to the motor's shaft. This either makes one of the wheels not connected to motor power, or it connects two wheels with gears to make the power transfer to both wheels.

In the two cases, the latter (connecting wheels with gears) performs better because there wouldn't be one wheel that only provides friction resistance and does not contribute to forward motion. Taking the first-generation starter kit clawbot for example, even though the shaft of the wheel is still connected directly to the motor, the 36-tooth gears bring rotational motion to the second wheel as well.

However, in both cases, they barely covered the gear ratio idea used in competition robots. In competition chassis, we often make the chassis longer. Additionally, we alter the size of gears connected to generate faster or slower speeds; this is called the Gear Ratio.

Gear Ratio is a "ratio", obviously, but between what two values? We have to take into account the "input gear" and the "output gear". The input gear is the one that is directly spun by the motor, and the output gear is the one being driven. Regarding the clawbot, the 36-tooth gear connected to the motor serves as the input gear, and the final gear at the end is the output gear. 

What does the middle one do? You may ask. The middle gear in this case is an idle gear that doesn't affect the final gear ratio, meaning we can change the middle gear into 84T, yet the two wheels still spin at the same rate.

Next, the Gear Ratio is calculated by dividing the output gear tooth by the input gear tooth. Please make sure you don't get it the opposite way because they can mean very different things. In the clawbot case, the gear ratio will be 36:36 = 1:1.

Looking at another case, why not try to identify the input, idle, and output gear, then calculate the gear ratio by yourself? The answer will be at the end of this blog.

Common Gear Ratio Used?

The common Gear Ratios in VEX IQ are normally used for increasing speed, in other words, a lower gear ratio. For example, the most common ones are 1:2, 1:1.5, and 1:1, and two of them are for increasing speed, while the other doesn't change speed.

In super kits, there are only three sizes of gears included: 60T, 36T, and 12T. If you do a little calculation, it is impossible to create the above 1:2 and 1:1.5 gear ratios using only the three sizes. Additionally, 60T cannot be used in a chassis as it has a greater diameter than most commonly used 200mm travel wheels (Note: 200mm is the perimeter, so the radius is about 3.183cm).

If you want to connect wheels and motors through gears, you will have to purchase the gear add-on pack containing 24T and 48T gears. You'll have to use sprockets or pullies, which we will talk about in our next episode. 

With 24:48 or 12:24, we can generate a 1:2 gear ratio, making the wheel spin twice as fast as the motor's rotation. However, 12:24 is not recommended in this case because both gears are too small, and you'll have to use additional gears to separate the wheels, like the picture indicates.

Moving on to 1:1.5 gear ratio, it can only be accomplished with 24:36. This might require some more complicated connection method since the wheel covers the center of the 36T gear when aligning both gears side by side with 24T attached to the wheel (shown above).

An example of a 1:1.5 gear ratio is my chassis during slapshot season. As you can see above.

A 1:1 gear ratio can be achieved by any type of gears if the output and input gears have the same number of teeth.

An additional gear ratio possibility is 1:1.3333, using 36:48 gears. This provides a little more speed while not altering the motor torque that much.

What's the difference between these Gear Ratios?

Now, I am here to answer the question of "What's the difference between the gear ratios?". Aside from changing the output speed, it also changes the output torque, which is inversely proportional to the change in the output speed.

Let's use the gear ratios we talked about as an example to calculate the speed and the torque of the chassis. Before calculating, we have to acknowledge that the VEX IQ smart motor spins at 120 RPM and has a stall-torque of 0.414Nm (Nm=Newton Meter), meaning the motor can resist 0.414 Newton of force at a distance of 1 meter. 

When we use a gear ratio less than one, the speed is multiplied by 1/gear ratio, which increases, but the output torque is multiplied by gear ratio, which decreases. An easier way to think about the relationship between speed and torque without calculation, the larger the motor gear is than the wheel gear, the higher the speed and the lower the torque. 

Next, we can list out all the gear ratios and their input and output gears like above, then proceed to speed and torque calculation.

After filling in the calculated speed and torque, we can observe the fact that all speed*torque equals the original speed*torque, which is evident from the fact that both have an inversely proportional relationship.

"Speed difference can be observed, but what does torque do?" you may ask. Torque determines the maximum weight the chassis can handle before the motors stall. If your robot is too heavy or faces too much resistance, and your motor torque isn’t enough to handle it, the robot will slow down or may not move at all. We'll dive into the detailed calculation in the future, but for now, just remember: higher speed isn't always the best; you have to consider how much structure you'll put on the chassis.

Conclusion

If you know that you need to run around the field fast and don't have to carry a lot of game elements, you could try a lower gear ratio, like 1:2 first. However, if you need a complex structure like the full volume season robots, you might want to consider higher gear ratios than 1:2, or else you might carry weight heavier than intended and actually make your robot go slower than 1:1.5 gear ratio robots.

Feel free to experiment with different gear ratio combos and connection methods on your chassis!! Also, the answer to the gear ratio above is 4:1, with the 48T gear being the output gear and the 12T gear being the input!! Others are all idle gears.

In our next episode, we will talk more about sprockets and pulleys and how they differ from gears. Just a note, the two can also be used in chassis sometimes!! Also, we'll look at how they are used to connect chassis.

This is IntroVex, your robotics guide to VEXcellence. See you next time!!

【Interview】What 7 Years in VEX Taught Me – Andrew

Hello! Welcome back to IntroVex, your robotics guide to VEXcellence.

Every competitor in VEX has their own unique journey. Their experience in growth, learning, and failure is also irreplaceable. Have you ever wondered what the VEX players near you experienced that navigated them through competitions and made them what they are now?

In this interview, we are joined by someone who has participated in VEX competitions for 7 years. He is Andrew, a competitor from Taiwan. He participated in 5 years of VEX IQ and 2 years in VEX V5, while one of his greatest achievements was securing the teamwork world champion as well as the excellence award during the Live Remote World Championship in 2021-2022 Pitching In season. Let's hear what he has learned along the way!!

About Andrew

What roles have you taken on in your team, and which do you like best?

Andrew: "I’ve done everything, including driving, building, programming, and engineering notebooks. My favorite is driving because with every round of practice, I can feel myself improving, and reaching milestones gives me a real sense of accomplishment."

There are many kinds of roles that need people to complete and take on responsibility, but not everyone can determine their role when they first join VEX. It takes time for you to try different ones to find your favorite and to find the one you are good at. In the 7 years, Andrew tried everything and found that driving was his favorite. Aside from driving, we can also see from his achievements that he studied robot structures and programming deeply as well.

When did you first join VEX? Why did you start?

Andrew: "My first season was 2018–2019, Next Level. My parents bought a basic kit to let me try it out. I didn’t really feel much accomplishment at first, and kept going kind of half-heartedly. But over time, I found it more and more interesting, and I’ve been doing it ever since." 

Out of all VEX participants, there must be some who didn't start learning robotics to compete in VEX competitions but got attracted to it and continued to play. Indeed, I am one of them. I started going to robotics classes just to learn the new technology trend, but at last I got interested in competing and continued doing so until now. That is why I would suggest, instead of trying to make a decision in your head, trying a little at first to decide whether to compete or not would be the better option.

Learning Process

What kinds of difficulties did you encounter in your learning process?

Andrew: "When it came to learning programming and building, the resources felt limited and hard to find. Maybe they were out there, but most were in English, so I couldn’t understand much. And often they didn’t really get to the point."

Sometimes the online tutorials are made by experienced teachers or students, but they might accidentally miss some basic concepts that may seem obvious while actually being difficult for beginners to understand. It isn't easy to create tutorials that cover both difficult and fundamental concepts at once. IntroVex will work hard to cover the basic concepts and try to convey knowledge to everyone!!

What was the hardest problem you encountered? How did you solve it?

Andrew: "It was during the Skills Challenge. My robot’s autonomous program wasn’t moving steadily, so I looked up videos on PID control to learn how to fix it."

What kind of video or help would’ve made things easier at the time?

Andrew: "I only found one video from a foreign team explaining P control step-by-step. If there were more detailed tutorials, especially in Chinese, that would’ve helped a lot."

Since English-speaking teams are the majority of the teams that participate in VEX, many online tutorials are created in English. However, since Taiwanese teams often understand Mandarin better, IntroVex will try to cover some important or complex topics in both languages to reach out and help more teams. Also, subtitles can be found on YouTube and can be translated into many other languages as well.

Advice for New Competitors

What advice would you give to someone new to VEX?

Andrew: "Choosing teammates is really important. Instead of just picking close friends, it’s better to find people who are passionate about VEX and willing to work hard. If you're just doing it for fun, that’s fine, but if you want to be serious about competing, choose wisely." 

That's right!! Team composition is a very important factor to consider!! If every team member has similar goals and is willing to cooperate with each other on different aspects, naturally, a good team could be formed. This is why taking your time to find teammates is an important step before the season starts!!

What’s something you wish you knew in your first year?

Andrew: "I wish I had divided the work better and trusted my teammates more. Of course, I could still keep learning myself, but I didn’t need to do everything alone. If you do too much on your own, your teammates don’t improve, and then later, you won’t feel comfortable letting them take over. It becomes a cycle, and in the end, you’re competing alone."

This experience delivers the importance of allocating roles within a team. If someone in your team takes on the role of allocating jobs for each person, with correct cooperation and trust, the team would be able to grow and learn together from successes and failures. However, it isn't an easy task if you just joined the competition recently. This year, I am also trying to accomplish this by understanding more about my teammates and trusting them in the process of trying.

What’s the biggest thing VEX has taught you over the past 7 years?

Andrew: "It’s definitely expanded my perspective. If I hadn’t done robotics, I probably would’ve only known people from Yilan. But because of VEX, I’ve met all kinds of people. One time at a tournament in Taipei American School, I got to connect with students from different regions — it was a great experience."

I agree with Andrew's response. Participating in VEX allows you to meet people from different backgrounds, different cities, and with different ideas, and this is the biggest thing VEX can bring you. It doesn't matter if you are an introvert or an extrovert; you will definitely make friends along the way. You might start by connecting with people from your lab, club, or city, but eventually you'll meet other teams during competitions. I would definitely recommend you to devout time to make connections with people during competitions aside from competing. 

That's it for this interview. I really hope this helps you on your VEX journey by understanding what VEX can bring to you. I am really thankful to Andrew for partaking in this interview and sharing his experience over the years. 

This is IntroVex, your robotics guide to VEXcellence. See you in the next article or video!!

【訪問】七年的 VEX 經驗教會我什麼？一 資深選手 Andrew

歡迎回到 IntroVex，陪你邁向 VEXcellence 的機器人指南！

每一位 VEX 選手的旅程皆不一樣，每一位選手在比賽過程中的體會、成長、挫折等等的經歷都是獨一無二的，每一位選手的參賽時長更是不相同。你是否曾經好奇身邊的選手們經歷過怎麼樣的學習才造就現在的他們呢？

這次的訪問，我尋找到一位參加 VEX 比賽總共 7 年的選手一Andrew。這位來自宜蘭的選手，從 2018 至 2019 的 Next Level 賽季開始參賽，至今累積了許多參賽經驗，而他最亮眼的成績是在 2021-2022 Pitching In 賽季的線上 LRT 世界賽當中獲得團隊挑戰賽冠軍以及全能總冠軍。讓我們透過訪問，了解他對於 VEX 的想法以及在 7 年經驗中的收穫吧！

關於 Andrew

在你所參加過的賽季當中，有負責過哪些工作？最喜歡的是？為什麼？

「全部都有，遙控、組裝、程式、工程筆記都有。這些當中最喜歡的是遙控，因為可以在一遍又一遍的練習中不斷成長，當達到一個段落後會有很大的成就感」 Andrew 說。

其實比賽當中有很多不同種類的工作需要有人負責，但剛開始加入的時候，並不是每個人都能夠迅速地尋找到適合自己的工作。在這 7 年的時間，他透過嘗試每一種工作找到了自己最喜歡的「遙控」。不過他也在其他工作中掌握到訣竅並持續鑽研，這幾年的比賽中都能夠看到他在結構和程式上努力的足跡。

你所參加的第一個賽季是？為什麼會想接觸 VEX 呢？

「2018-2019 Next Level」Andrew 說，「當時父母準備一套基本款讓我嘗試，第一次打比賽沒什麼成就感，之後有點半推半就的打下去，結果越打越有興趣就打到現在了 。」

在所有參賽選手當中，必定會有些人剛開始接觸時其實並沒有明確的目標或目的，但開始嘗試後卻被 VEX 有趣的地方吸引並持續下去。其實我也是這樣的，剛開始只是去上課並嘗試新的活動，但實際上我卻發掘了自己的好勝心，並繼續持續參賽。若你正在苦惱是否要參賽，可以考慮先嘗試一段時間後再做出決定喔！

學習過程

在學習和資源方面，有沒有遇到找不到方向或資訊不足的情況呢？

「學習程式以及組裝上的資源其實都感覺很少，不好找，應該說可能有但大多是英文，所以也看不太懂」Andrew 說。他也強調「時常有些地方感覺沒有講到點上 」。

有時網路上的教學影片是由經驗豐富的選手或老師所製作，而時常會漏掉一些看似理所當然但其實剛加入的選手在理解上會有困難的知識。要如何製作第一年參賽的選手也能輕鬆看懂的教學影片並不容易，IntroVex 也會努力將基礎的概念都完整傳達給各位的！

你遇到過困擾你最久的問題是什麼？那時是怎麼處理的？

 「技能挑戰賽的自動，當初為了解決移動不穩的問題上網找了 PID 控制相關的影片學習」

承上，你覺得怎麼樣的資源(或影片內容)能夠幫助當時的你？

「當初我上網找可以手把手教學的只有一部外國賽隊的 P 控制的影片而已，如果可以有中文或是更詳細的教學就會更好」Andrew 說。

由於外國隊伍比例上較多，網路上較多教學影片是使用英文介紹。在 IntroVex，即便大多的影片內容為英文，每一支影片都會提供中文字幕的選項。在接收到 Andrew 的建議後，IntroVex 之後在介紹較複雜的概念時也會出兩個語言的影片的！

給予新同學的建議

如果要給剛開始參加 VEX 的同學一個(或多個)建議，你會說什麼？

「隊友的選擇很重要。」Andrew 說。他也強調：「比起找熟人，找對 VEX 有熱情並願意付出努力的隊員可能更好。除非是休閒打，如果想要認真打比賽還是要謹慎思考隊友。」

隊伍的組成是非常重要的考量！若每一位隊員都有相同的目標，而且在工作分配上都能互相配合、努力，自然就能夠組成一支不錯的隊伍。在賽季開始之前，尋找適合的隊員也是非常重要的呢！

經歷過 7 年的 VEX 比賽，有沒有什麼是你現在已經學會、但希望當初第一年就懂的事情？

「希望當初我可以分配不同工作給隊友，當然我還是可以學習，只是不要放不下心就都自己來。」Andrew 說。他也進一步說明：「如果可以的話盡量讓隊友可以跟你一起成長，如果當下你選擇自己多努力一點，當然你自身能力會更強，不過相對你的隊友也就無法進步。這會導致之後你很有可能會放不下心讓隊友去做，如此反覆循環下的結果就是最後就變你一個人在打比賽了。」

這樣的經驗也告訴我們團隊中工作分配的重要性。隊伍中若有一位隊長能夠發掘各隊員的長處並妥善分配工作，配合團隊默契和隊友間彼此的信任，才能促使團隊一起成長、一起學習。不過在自己也不完全了解比賽內容時，要做出這樣的決定不容易。今年我在團隊當中也希望能夠分配更多工作給每一位隊員嘗試，也會在 IntroVex 當中將自己的知識傳達給大家！

你覺得這 7 年的 VEX 旅程當中，收穫最多的是什麼呢？

「我覺得對我來說最大的收穫應該是擴大我的視野。」Andrew 說。他也分享：「如果不是有打機器人，我認識的人應該都侷限在宜蘭而已。但因為有打機器人，我可以認識各式各樣的人。之前有一次在台北美國學校參加比賽時，有認識一些人，可以跟不同地區的人交流很不錯。」

我也同意 Andrew 的說法，參加 VEX 最大的收穫之一就是認識不同背景、不同城市、不同想法的人。不管是較內向或外向的人，在 VEX 的旅程當中，一定會結交不同的朋友，可能從相同教室或隊伍的成員開始，但慢慢的也會在比賽中認識不同縣市的隊伍成員。希望大家在比賽當中，除了專注於取勝之外，也可以多去和不同隊伍聊聊天！

希望大家透過這次的訪問能夠更了解 VEX 帶給選手的影響，也許能夠幫助正在了解此賽事的人在決定上更果斷！真的很感謝 Andrew 選手願意接受簡短的訪問，也希望他的經歷能夠幫助到正在經歷 VEX 各種時期的選手們。

這是 IntroVex，陪你邁向 VEXcellence 的機器人指南！我們下一篇文章見！

The subsystems of a robot - Robot Design Introduction

Hello! Welcome back to IntroVex, your robotics guide to VEXcellence.

We compared the differences between VEX IQ and V5 competition designs and overviews in previous episodes. Starting from now, we will start including some "robotics" ideas for the competition, such as constructing a robot and programming. If you are someone who struggled during robot preparation, maybe this is the kind of article you're looking for!

This time we'll be discussing what makes up a robot and talk about common aspects of a robot. You may often see a robot as one big system/structure, but they are often constructed of different subsystems. Knowing the types of subsystems often incorporated in robots can benefit you during both the brainstorming and construction stages, meaning you don't have to think and build the whole robot in one go. Rather, you can think about each subsystem one by one, and then finally combine them into a robot.

The common subsystems include the following: Chassis(Drivetrain), Intake, Scorer, End Game Mechanism, and other subsystems based on the year's game.

Chassis / Drivetrain

The chassis, also known as the drivetrain, is the base of a robot. This subsystem is usually the one you start with because the structure of your base will decide how to cooperate with other subsystems.

One of the most important aspects of deciding on the drivetrain is the gear ratio. Gear ratio is the ratio between the gear driven by your motors to the gears driving your wheels. If you have a higher gear ratio, meaning you use a larger gear on your motor than the wheels, your robot will have a faster speed. Oppositely, if you have a smaller gear ratio, your chassis will run slower but have more torque.

Simply put, use a higher gear ratio when the game requires fast movement speed, but use a lower gear ratio when your robot is heavy and big, as a fast drivetrain with a heavy top will make the overall speed even slower.

Another important aspect to consider is the number of motors and wheels you use. Motor usage may have to be considered alongside other subsystems. If there are many missions to complete on the field, you might have little motor usage available left.

For VEX IQ, the number of motors used on the chassis usually goes around 2-4, since the motor limit is 6. For VEX V5, the number of motors used is usually 4-8. The VEX V5 game gives you more space for creativity, so there might be a robot using all 8 motors on the chassis, and using PTO or pneumatics for other functions.

Intake

The intake is the subsystem used for picking up the game object, for example, balls or blocks. Usually, intakes are constructed with wheels or rubberband rollers, but some intake designs can also be plowers or claws that also show the ability to hold onto the game object.

If the game object is a round object like a ball or the triball in over under season, using a wheel or rubberband roller is common and simpler. Some special intakes include the hero bot for this year's VEX V5 game, High Stakes. It uses a passive ring grabber to hold onto the ring and pushes it out with a motorized mechanism. A More detailed explanation can be found in VEX's official YouTube introduction above.

Scorer

Next, a scorer is often the subsystem used to score the game object. For example, for shooting a ball into the goal, or putting rings onto a game element. The scorer doesn't have to be a shooting structure, it can be a conveyor belt like this year's High Stakes V5 game, or the elevator used in VEX IQ Full Volume.

Depending on the game, scorers can have tons of designs, and they usually keep evolving as the season progresses. One of the most common scorers is shooting mechanisms, exemplified in Pitching-In, Slap Shot, Over Under, and this year's VEX IQ game, Rapid Relay.

Common types of shooters include flywheel, puncher, and catapult. Flywheel uses one or two wheels and shoots out the game object straight by sliding it between the wheels that spin super fast. Puncher uses a linear moving stick to hit out objects through a straight line, like how I designed the shooter during Slap Shot. A catapult is a mechanism that first drops to the lowest point, and then shoots out the object by sudden release, creating a parabola when the object is sent flying.

Sometimes, scorers are combined with intakes, like the Rise-Above season where we use claws to stake game objects, so don't limit yourself to these categories. Finding the most creative and useful solution is most important when designing your robot.

End Game Mechanism

Some games include end games like elevation or touching something, and the end game mechanism is for this. Since how the end-game scoring is done varies in every game, it is hard to state what one will look like, but you may get a sense of it by some examples.

During the Pitching In season, we had to elevate from the ground. The low elevation is often done with passive mechanisms by running the robot onto the stick for elevation, same with Over Under's low elevation. High elevation requires some creativity, and it depends on the stick for you to climb. In Pitching In, we had a wall to support our robot and a horizontal stick to grab onto, so we used a 4 bar lift structure to climb. However, elevations in this year's High Stake provide only horizontal sticks and not a wall, so the hanging structure will be more complicated.

Other mechanisms

Some other mechanisms may include supporting hooks or hands to push away game elements and stuff, it can be moved using a motor or pneumatics.

An example is the wing used to push triballs during Over Under, which functioned through pneumatics. Another example is the robot guide used to touch both sides of the walls in Rapid Relay, it doesn't have motors nor pneumatics for movement, but it is an important subsystem to have for particular strategies.

These are more game-specific, and teams often develop their own, so it is not much for generalization.

This is about all for the subsystems of a robot. I will continue to introduce different subsystems in detail in the future. If you like this type of content, please let me know!

This is IntroVex, your robotics guide to VEXcellence, see you next time! Bye~!!