Revell VEXplorer Kit Build Review

By Michael Benolkin

Introduction

A few months ago, I happened across a web page that listed a new radio-controlled robot from Revell. I figured that someone had been mistaken because we all know that Revell and robotics are mutually exclusive, right? I continued on with my information quest and didn't give this another thought.

At the recent iHobbyExpo, the 'new' Revell was in full swing after their purchase by Hobbico earlier this year. In addition to a new round of kits coming from this well-known hobby company, there was that very same robot on display in their pavilion. Meet VEXplorer.

VEXplorer

Revell, along with many other hobby companies, has struggled with how to attract younger customers away from their video games and to (re)discover the hobby workbench. To get there, they formed an interesting alliance.

Vex Labs is the maker of robot kits. If you go to their website ( www.vexlabs.com), you'll discover a whole universe of parts that will drive you deep into the world of robotics. The engineer in me felt like I'd died and gone to robot heaven as I scrolled through the possibilities, but the analyst in me could see where many folks might be intimidated by a huge box of parts and a programmer's manual. Working with Revell, they've hit on a solution for both of their challenges. VEXplorer is the their first 'consumer' robot kit.

What is the difference between a consumer robot kit and one of Vex Lab's usual robot kits? Well, the Vex Lab's starter kit consists of 500 parts and costs around $300 USD. The Revel VEXplorer is 300 parts and costs around $200 USD. The Lex Lab's kit really is a box of parts. The VEXplorer comes with many of the subsystems pre-assembled, though they can be dismantled and reconfigured once you are ready to 'play'. In other words, you have some work ahead of you to get an operating robot from the Vex Lab's kit (which is great for students and hobbyists who are ready for that step), whereas the VEXplorer requires about an hour to assemble the modules and you're off on your first adventure.

At the iHobbyExpo, I had a good look at this interesting machine and the features that might interest hobbyists (and potential hobbyists) everywhere.

The Kit

The VEXplorer comes in a huge well-protected package with a carrying handle. You won't miss this box on the shelf or under the Christmas tree! Inside the box is a huge styrofoam tray that has each of the pre-assembled modules as well as the compulsory bag of parts needed to finish the assembly.

The foundation of this project is the lower hull that consists of pre-formed and pre-holed aluminum C-channels. The workmanship is excellent. Two of the C-channels are pre-installed on the drive systems (actually serving as the mounts for the axles, motor and drive gears.

The main modules included in the box are:

• Twin drive systems, each with three powered wheels
• Powered robot arm assembly that moves up and down
• Powered claw
• Six-channel radio control (RC) transmitter (powered by one 9 volt battery)
• Six-channel RC receiver
• Wireless camera/microphone unit with 2.4 GHz transmitter
• Receiver module that connects to your TV to display the robot video/audio (powered by four AA batteries or optional AC adapter)
• Robot battery pack (powered by six AA batteries)

In addition, a bag of screws, bolts and aluminum parts that make up the main robot chassis is also included with tools. The kit comes with everything you need except batteries.

Construction

Assembly comes rather quickly, so I didn't bother to photograph each step, but I do include some notes from my experience.

Step 1 simply gets you acquainted with all of the various parts in the kit. The first thing I noted was that all of the screws are neither standard nor Phillips head, they're Allen. I happened to have an Allen driver of the right size to make assembly a little easier, but an Allen wrench is also included.

Step 2 is also another orientation step, but this one is crucial or your project with get complex fairly quickly. Take the two powered wheel assemblies and get them oriented with the wide part of the frame up top and the motor modules on the same end.

Step 3 is the first assembly step and we add the front and rear crossmembers to form the robot chassis. This is the step where you get acquainted with working in confined spaces as you need to get nuts placed into semi-blind spots between the frame and motors. Once you get your technique for manipulating these parts and not dropping them on the carpet, the rest of the assembly moves along faster.

Step 4 adds a bottom plate to the chassis and here you begin to appreciate the nice illustrations in these instructions.

Step 5 intends for the camera to be mounted onto the rear of the robot arm assembly. The way this arm was packed in my example, the arm was deflected full-up which didn't allow access to insert screws from under the arm. Don't force the arm into position as you'll damage the stepper motors and/or gear drive system. I just set this step aside until I could power up and move the arm.

Step 6 installs the arm assembly onto the chassis. This step did require a little patience and dexterity. Take your time.

Step 7 installs the robot's battery pack. This was where I encountered my first error in the instructions. The text correctly says to use the longer screws provided, but the illustration shows the shorter screws. It didn't take me long to 'read' the instructions. The diagram was also unclear which direction the battery pack should be oriented to get the power connecter where it needs to go. It can only go in two directions, I got it wrong and simply reversed it (it should face away from drive motors as shown in the photo below).

Step 8 installs the six-channel receiver module.

Step 9 runs the antenna wire into a rigid nylon tube and onto a mount that fastens to the frame.

Step 10 adds the claw to the end of the robot arm. We're just about done!

Step 11 where we route the cabling from each of the motor modules and into the receiver module. I simply plugged each cable into the channel shown in the instructions, added a battery to the transmitter, and did a simple power-on check of the robot. I ran the arm up and down to see where wires might get into trouble, the moved the arm to the full-down position and installed the wireless camera that I had to skip in Step 5.

Step 12 is where we secure the wires with cable ties, and these guys provide a nice big bag of them! The instructions only call out for four, but I used more than that to safely route the wires under the robot as well as the wires in the arm assembly.

Step 13 checks you out on the controls of the RC transmitter.

Step 14 shows you how to set up the wireless TV receiver. Unless something doesn't work right, we're done.

Test Drive

I powered everything up and proceeded to drive the robot around. The camera works better under certain lighting conditions, but the colors are a little skewed under fluorescents (we have those light bulbs that are mini-fluorescents that replace standard incandescent bulbs in the house). Never mind, this is like operating a robot on a remote world, why not a color shift? Driving the robot upstairs (where I was) wasn't much of a challenge. I took it downstairs and resumed my place upstairs in front of the TV.

Whoever added the wireless microphone was a genius. While this sounds like a gimmick or spy option, you can hear the motors of your robot and that provides you with better feedback when you're not with the machine. Not to mention the sound of the 'thump' when you run into something. So with this test drive, I discovered several things:

1. I need to clean my floors
2. The robot has all six wheels powered. For those of us with four-wheel drive and limited slip differentials, you know this means that the robot won't steer well when the wheels are slipping
3. The robot handles VERY well on hard floors. It operates okay on carpet, but you can hear in the motors that it takes more power on carpet, which translates to shorter battery life
4. The camera is ineffective in low light/no light conditions
5. The robot arm works well even when controlled remotely. Remember that there is no depth perception via camera
6. My cats love this thing

Adding Some Attitude

The whole point of this product is to get your creative juices flowing and to have some fun. Given the lessons learned above, I decided to add a few quick improvements:

I used a pair of cable ties to strap a common laser pointer to one side of the frame. I wanted to add this to the arm, but I'll need a bracket to do this later. I used a third cable tie to slide over the 'on' button to power the laser on/off. Meet Locutus of VEX. Those of you who have previously mixed cats and laser pointers know that I now have a remotely controlled cat 'bot.

I used another pair of cable ties to strap on a small flashlight. Now the robot can 'see' in the dark. Combine the circle of light from the flashlight with the laser spot and you can now judge distance from objects (with practice).

The third and most demented attitude adjustment was the installation of a 'Cylon' eye to the arm assembly base. I couldn't help myself. I had spotted an interesting electronic project on Evil Mad Scientist Laboratories' website

to create an LED-based Cylon eye. I ended up ordering enough parts for two eyes, and after my VEXplorer test drive, I sat back down at my workbench with my soldering iron and built my Cylon eye. The circuit card is simply held in place inside the frame with cable ties.

I think the modifications look great, though perhaps a little too subtle in these pictures. In the dark, Locutus of VEX has a life of his own and I can watch the cats chasing the laser spot from my TV. Cat TV...

Batteries

I haven't yet exhausted this first battery pack, though I read online that the batch of AA batteries in the robot will last 30-40 minutes (your mileage may vary). VEX offers a similar rechargeable battery pack to that used by radio control car (and tank) users. I learned several years ago that I'd be broke with all of the AA and AAA batteries we go through around here, so we went rechargeable. A company called Maha

produces the Powerex line of rechargeable batteries that have 2700mAh of capacity, and they recharge fairly quickly as well. This robot, the flashlight, and even the laser are powered by rechargeables, so battery consumption is not a problem.

Moving Forward

So where do go from here? Once you've played with the robot as it is designed out of the box, you can simply disassemble it and create variants of your own design. Revell has provided a copy of SolidWorks in this kit which allows you to build your next robot first on your PC, then for real. SolidWorks, for those that don't know, is an amazing three-dimensional CAD tool that modern kit manufacturers (as well as many other industries) use to create their projects before every cutting any tooling. This package comes with a student version with a 150 day free trial, then a nominal fee to continue using the tool. Nice touch!

Conclusions

As you can see in this short video, the VEXplorer has lots of fun potential. The big beverage can that the robot is lifting is full, so the arm and claw have lots of torque - you can do some serious things with this device. The only drawback I see so far is that while this robot can fetch you your favorite adult beverage, the arm doesn't rotate, so it can't pour.

If you're thinking that this is simply a remote control gadget, you're technically correct. The electronics modules in this version have no autonomous capabilities, but the modules in this kit are compatible and interchangeable with the VEX Labs modules, and they also offer both remote control and autonomous controllers. If you want your robot to operate on its own, that is indeed possible.

Don't look now, but we've been overtaken by robotics for some time. Your radio controlled car, my latest Tamiya RC tank project, even many of your appliances, all have degrees of intelligence and robotics in each one. That tank project for instance - the computer in the model does interpret my commands, but it matches those commands up with sound and certain motion to provide realism. Even model railroaders have smart controllers now that provide newer engines with more realistic sound and motion.

So here is your first robot kit. Whether this appeals to you or seems to go over your head, put one of these in front of your game-addicted kids, and you might be surprised by their re-entry into the real world again. Revell may have hit on just the thing to bring kids back from cyberspace.

My sincere thanks to Revell for this review sample!