So you’ve spent the last week frantically trying to get your bot ready for this next event, and now you’re sleep deprived and trying to get everything packed. You end up spending precious time trying to remember what you need to bring rather than sleeping. Here’s how to reduce how much time you spend searching for tools. Print the list I linked below and check it off as you load your vehicle.
Servos are a great way to add an active weapon to your basic wedge robot. They are extremely easy to integrate and can really help tip the judges decisions in your favor. You can use them for lifters, clamps, and even hammers. The only (kinda) challenge with using servos is powering them and even that isn’t that difficult.
Most of the ESCs or speed controllers used in combat robots contain a BEC or battery eliminator circuit. This circuit takes the power from the main battery and feeds it back to the receiver. This saves the weight of an additional battery just to power the receiver. Most receivers run on 5v, but some can operate on higher voltages. These BECs are great for powering the electronics in the receiver, but often times they struggle to provide the current the servos need to power hungry motors.
The easiest thing to do is power those suckers straight off the main battery. This works great, except when it doesn’t. You may be thinking “Huh?” Well you see servos are designed to run on 5v like we mentioned earlier and often times our drive motors are being run on a 2s (2 cells or 7.4v), 3s (3 cells or 11.v), or even a 4s (4 cells or 14.8v) lithium battery. Now there are lot’s of different servo options out there. Nearly all servos are designed to work on 4.8-6 volts. Some servos will work fine on 7.4v. Some may even work on 11.1v, but most will smoke. Smoking is bad. It’s bad for humans, but it’s really bad for servos. I have been using some Hitec HSR-8498HB servos in our lifter ant Mucho Destructo. As you can see by the performance data on the linked page, these servos are rated for 7.4v, so we want to run them as high as possible. (I’m working on a Motor primer in a future post that will explain why higher voltage is gooder). In the last event I plugged in the wrong battery pack (a 3s 11.1v pack) and after just a few cycles of the arm, the arm went up and stayed up and the magic smoke came out. This was clearly too high.
As I previously mentioned receivers are designed to run on 5v and some can tolerate higher voltages, but if you don’t want to risk over-volting your receiver then you can wire the servo to the battery very easily. First, you should probably know what each wire means in your servo. The wires are typically colored black/brown, red, and white/yellow/orange (depending on the manufacturer). The black or brown wire is the ground wire. This is common is low-voltage dc (direct current) circuits. The red wire is the power wire. The power to drive the motors and the circuits is carried on this wire. The white, yellow, or orange wire is the signal wire. This wire is the command wire that tells the servo which direction to go and how far it should go. There’s a lot more to cover on servos and esc signals, but that’s for a future post. See all the pretty colors.
In this case we want to remove the red (power) wire from the servo plug. This can be accomplished by using an exacto knife or other small instrument to lift the tab at the servo. There is a small catch that retains the pin at the end of the wire. Simply lift that tab and pull out the wire. See even I can do it and I didn’t even get any blood on the picture.
Now you can cut off that pin and strip back a small length of wire. Solder that wire to the plug that will connect to your battery. Boom you now are feeding your servo off main battery pack. If you are using a separate battery for the lifter then you will need to solder the ground wire from your battery to the ground wire of the drive ESCs. This will tie all the grounds in your system together. A picture is worth a thousand words, so check out my sweet MS Paint schematic and it will all make sense.
That should just about cover how to get your servo wired up and ready to run. I have a list of future posts to work on, but the very next one will be on some tricks I learned about lifters.
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Or you at least want to. The BattleBots that you see flying around the arena are purpose built machines by builders with years, sometimes decades, of experience building combat robots. You may be thinking that there is no way you could get involved, but you’d be surprised how truly easy it is to get started. BattleBots is one of those things that you can learn in a week, but take a lifetime to master. That’s why nearly every veteran builder will encourage you to start with a smaller bot and here’s why:
- Events for small bots occur more frequently and in more locations
- The cost to compete is lower (parts and event entry fees are usually much cheaper)
- Hand/Garage tools are usually all you need to build a small bot
- Small bots take less time to build
- Moving/Storing a 250 pound machine between events is not awesome
The really cool thing is the concepts you learned to build a 1 or 3 pound death machine are very very similar to building a 250 pound death machine. At the bottom of this post is a high-level description of our 1 pound bot named “Chainsaw”. The basic parts of most combat robots are similar. Our 220 pound robot uses the same transmitter/receiver as our one pound bots. It just has bigger speed controllers, gear motors, and batteries.
CE Robots is gearing up for Clash of the Bots (COB) in Gastonia, NC. This is one of our favorite events (okay the next event is always our favorite). But this is the only event on the East coast with Bot Hockey. We will be attending with 2 ants, 1 beetle, and a 12 pound hockey bot built of wood.
Also, we’ve been frantically working on our design for BattleBots season 3. The first preview episode hits the air on May 10th with subsequent episodes on Thursdays at 8 PM starting in mid-June.
Lastly, and perhaps most exciting is we will be hosting Mini Bot Hockey at the Orlando Maker Faire. Check out our rules page for the official Mini Bot Hockey Ruleset. This is a fast-paced game with 6 bots (3 on each team) all trying to put a small puck into a goal. It’s all the hard-hitting action of real hockey, but with a slightly easier to follow the puck.
A lot of exciting stuff has happened over the past quarter at CE Robots. I started a new job working for NASA in Florida, which required a move. Unfortunately we had to cancel the robot fighting at Jekyll*Con this year, which was a major bummer, but there are new projects in the works. Coming this spring we’ll be working on or new robot lab (pictures to follow) and we’ll be gearing up to run the first Mini Bot Hockey event. The plastic is in to start machining the pucks, so it’s youtime to get excited.
BattleBots 2016 is complete. What a great season. Congratulations to…wait you’ve seen the finale, right?…If not head on over to http://www.abc.com/shows/BattleBots where you can check out all the fights including the finals. I won’t spoil the ending, but Bite Force totally wins. Congrats Paul.
Welcome to CE Robotics. We’re glad you joined us, and we’re even more glad to be here. Stay tuned to this site for exciting news on the latest Combat Robotics adventures, and be sure to tune it to BattleBots on ABC at 9EST to check out some of our amazing friends battle to the death for your enjoyment.