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Vex Robotics Kit Design System Review

January 1, 2006

in All Articles,Robotics

What is the Vex Robotics Kit?

The Vex Robotics Design System, available from, is a build-it-yourself robot creation kit. Like an electric erector set, you need some batteries, some imagination, and a desire to build. The results will be a functional robot you can control with a wireless radio transmitter (like a remote-controlled car). With upgrades to the basic kit, you can add more features, parts, abilities, and even the ability to program the robot, allowing it to interact with the world on its own.

The excellent Vex manual provides you with instructions on how to build a basic robot, capable of movement and collision detection. The three shots below are a slightly-modified version of that robot.

Examining the components: The battery pack is the blue box on top of the unit. The radio receiver is the smaller yellow box beside the battery pack. The red and gray buttons on the front and back ends are collision detectors: If the robot bumps into something, it stops the wheels from turning (preventing your from stripping the gears or wearing out the axle mounts or motors). The large gray unit below the battery pack and radio receiver is the brain of your robot: The Vex Micro Controller. Plugging motors, sensors and other things into this unit allows your robot to move and interact with the world.

What do you get?

From Lincoln Logs to Erector Sets, I played with similar building kits as a child. I remember being frustrated at always running out of pieces. While still possible, this is harder to accomplish with Vex, as just Vex Robotics Starter Kit comes with over 500 parts! This gives you everything you need to build and control robots. The number of different robots you can create is limited only by your time and imagination. If you do happen to run out of parts, no problem: Parts are available, either in kits or individually, for fairly low prices.

The Vex Robotics Starter Kit gives you everything you see below (and more):

How does the Vex Robotics Design System work?

Design a robot (you can start with the Vex robot designs provided in the manual or get ideas and samples from Vexlabs. As you build, you’ll put together the chassis, and eventually the moving parts, consisting of motors, wheels, levers, and various sensors. After it’s built, you control the robot with a six-channel radio transmitter (it’s the big thing in the center of the picture above).

The transmitter takes 8 AA batteries. The robot you create takes 6 AA batteries. That’s a lot, and you’ll go through batteries quickly. Be sure to purchase NiMH rechargeable batteries – they work fine with Vex equipment.

The Vex is intended for use by children and adults able to not only understand basic mechanics, but those able to work with small parts (like screws and motor components) and understand basic electronics concepts (you’ll need to do a bit of tweaking to adjust trim levels on the radio transmitter, and motors and batteries and radio receivers need to be connected correctly for everything to function. The manuals do an excellent job of describing how everything works, but you still need the patience and delicate handing such components require. (If you are looking for a fun, educational robot, but not so complex, check out the Scribbler Robot.)

For those interested in advanced Vex designs, excellent upgrades are available. These include sensors for light detection and range finding, additional motor gearing for high speed or high torque applications, tank treads and specialized wheels, and a programming kit, allowing the Vex robot to be programmed and move autonomously. You’ll need a Windows-based computer with an available USB port.

A quick sampling of additional modules and parts used to expand the capabilities of your Vex robot include modules for movement and sensing. Below we have an Omni-Directional Wheel kit, used when the robot’s terrain demands a wheel that can easily move side-to-side, in addition to forwards and backwards:

For rough terrain or specialized climbing applications, give your robot tank treads, or use the Sprocket and Chain Kit:

The sensing capabilities are impressive. One of the slick upgrades available is the Ultrasonic Range Finder Kit.

Vex problems

Radio transmitter and rechargeable batteries: I only had one problem with the Vex Robotics Starter Kit itself. This involved the battery pack for the radio transmitter. Here’s what it looks like:

When I charged up my batteries and plugged everything in, the Vex radio transmitter didn’t turn on! Was it broken? Well, no, but it wasn’t designed properly for rechargeable batteries. Examine the picture below, which is a closeup of the radio transmitter battery pack:

The red arrows are pointing to the contacts in the battery pack that should touch the positive terminal on a AA battery. In this case, the contacts weren’t doing their job: There was a space between the contact and the battery’s positive terminal! (This is a known issue with rechargeable batteries – the positive terminal tabs are shorter than their non-rechargeable equivalents). The symptom was that my Vex radio transmitter wouldn’t turn on. It had no power.

The fix was easy. I just took a small blade, wedged it behind the positive terminal connector in the battery pack, and pried the connector out a bit. Be careful not to break them, you just need them to extend out just a little bit to make the proper connection. Do this for every positive terminal in the battery pack. When all batteries are making connections, you should be getting around 11-12 volts pumping into the transmitter (but if just one battery isn’t connected properly, the transmitter has no power).

Ordering replacement parts was difficult: Say you’ve lost a part from your Vex kit. Or you’ve broken something and need a replacement. In my case, I somehow lost “Bag 28”, Radio Shack catalog number 12430518, titled “JUMPER CLIPS 5 PCS”. It wasn’t available on the VexLabs site, where you can go to order replacement parts. Calling Radio Shack’s support number, I was told I was out of luck. But then, luckily, I found the right way to do this. When all else fails, try the following to find replacement parts for your Vex Robotics Design System:

Try VexLabs to order your Vex parts. They have replacements for most of the components from the Vex Robotics Starter Kit as well as expansion modules. At this point, I see they have just about everything you could possibly want – their inventory has risen from being good, to almost all-inclusive.

Try Radio Shack’s Vex Robotics site, and click on “Buy Accessories”.

No luck? You need Vex replacement parts? You may think you can get them online. This isn’t always the case. At the time I had my problem, VexLabs didn’t have the pieces I needed. If you’ve tried them and Radio Shack, and still can’t find your replacement part, do the following:

1) Find the Radio Shack catalog number. You need to do a little research in order to find this information. Find your missing part by looking at the inventory of all the parts contained in the Vex Robotics Basic kit.

2) With the catalog number, call your local Radio Shack, and verify this is something they can order. Ask them to use the “store system support line”, Radio Shack stores’ link to the mother ship. Stop in to order the part (yes, Radio Shack’s policy is that you must order parts in person – you can’t do it over the phone). Note that local Radio Shacks are different than calling the main Radio Shack catalog order line. The local outlets can order things via the “store system support line”, including things you can’t get from the main catalog center, and this is why you have to go local.

Vex Resources

The main Radio Shack site for ordering the Vex Robotics Design System and accessories.

More Vex parts and accessories from VexLabs.

Get more information on how to program the Vex Robotics Design System, including sample programs, Vex programming manuals for the Vex Micro Controller, and Vex firmware downloads.

The FIRST Vex Challenge is an annual robotics competition. Utilizing the Vex Design System, student teams design robots to complete certain goals.

Check out this article for an advanced design and test of the Vex system.

Vex Robotics community site. Includes general and detailed discussion forums for everything Vex, from competitions to programmng to design to information about all the Vex subsystems.

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