The Latest in Hobby, Science and Consumer Robotics
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The Latest in Hobby, Science and Consumer Robotics
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A Robust Educational Robot Kit with Remote Video Cam and Bundled Design Software
by Grant ImaharaYou may remember way back in the premiere issue of Robot magazine, my fellow Mythbusters and I reviewed the VEX Robotics Design System. Needless to say, I couldn’t wait to get my hands on the VEXplorer, the latest addition to the VEX family from industry giants Revell Monogram and Innovation First. The VEXplorer kit has inherited the engineering excellence of the original VEX system but has been revamped for more mass-market appeal than its predecessor. The intent is clear: to expand the VEX product and make it more attractive to younger people. How do you do this? Well, here’s the formula: Step 1. Start by making it look cooler. You know that feeling that you get when your friend or neighbor drives up in a newer, flashier car? That’s the feeling this kit will inspire. To appeal to a younger target market, they’ve incorporated more aggressive styling and bolder colors. How much more hip is the new VEXplorer? Let’s compare. With the original VEX starter kit, you build the “Squarebot,” which is, well … square. It has generic green wheels, green gears and plain steel rails. Not to knock it, but functionality definitely won out over aesthetics. On the other hand, the VEXplorer comes with chrome mag wheels that look like they’ve been snatched from a Hummer and matte black rails with burgundy gears and custom-molded plastic fairings. It’s like they took a VEX kit and gave it an “Extreme Bot Makeover." Step 2. Give it revolutionary accessories–the kind that haven’t been seen in the VEX lineup before. How about a gripper claw or a video camera? The VEXplorer has both. Now, we’re not talking about some wimpy claw that can only pick up pencils or foam blocks. We’re talking about a custom-designed grasper that can pick up a can of soda–a full can of soda. And the video camera is a 2.4GHz wireless full-color “spycam” that’s mounted on the robot. This isn’t just video that you record and play back on your computer later. It’s a live video feed, so you can see what you’re doing in real time and navigate remotely. A separate receiver has video and audio outputs that you can plug directly into a TV so you can also hear the environment you’re exploring.  Step 3. Make it easier to put the kit together. What this means is minimum work for maximum return. When you’re looking to sustain the attention of younger minds, getting the system up and running quickly is extremely helpful. When using the original VEX system, even experienced students take awhile to get to the “fun stuff,” which is the actual driving around and picking things up. Younger students tend to “tune out” or grow impatient until the robot is finished, and then they perk up. The VEXplorer slingshots you out of the complicated building phase and into the fun phase. Several hours with the original VEX starter kit shrink to around an hour with the VEXplorer–well within the attention span of the target 14-year-old age bracket. This is accomplished by having several of the parts already built in modules before the product is packaged. Of course, you can eventually disassemble the robot completely to make something else of your own design. In total, the kit has over 300 parts, including six wheels, four motors, 24 gears, a bunch of hardware, and many custom metal and plastic pieces. The great news is that all of the mechanical parts in the VEXplorer system are 100-percent compatible with original VEX hardware, including frame pieces, gears, tracks and wheels. In fact, the back page of the VEXplorer assembly manual lists numerous VEX expansion kits that are readily available online. Step 4. Drop the price and put it on the shelves of major retailers. The VEXplorer kit has a lower price than the original VEX starter kit by $100, with a suggested retail price of $199.99, and Revell has managed to get it on the shelves of Toys R Us, Hammacher Schlemmer and Fred Meyer, as well as in the online stores of Amazon.com, Target.com, Walmart.com and CompUSA.com just to name just some. ASSEMBLY AND OPERATIONSo, now that you have the overview, let’s talk more about how the VEXplorer kit performs. How easy is it to assemble? For example, could you build this kit on Christmas morning, or perhaps late on Christmas Eve? Well, if you can assemble a bike, you certainly have the skills to assemble this kit or to help a young person to assemble it, but it won’t exactly be a walk in the park. I assembled the kit using the stock tools and completed it in well under the recommended hour. But I experienced a little frustration during the process. While it’s super-helpful to have the parts built into big chunks, it seems as if the nuts that connect these chunks always seem to be in the wrong place–blocked by a motor or a bracket–and require that you hold nuts at an odd angles. Carefully inspect the parts as you remove them from the packaging. You may find that one or two screws have shaken loose during shipping. This is fine and is nothing to worry about. Manufacturers often use a thread-locker to secure the screws more firmly, but this kit is designed to be taken apart eventually to make other robots. You should find the loose screws and put them back into place though. The black-and-white manual has generously sized pictures, but the complicated drawings are washed out and do not have enough contrast between the various parts, and that makes it difficult to interpret what goes where. Details of the exact bolt holes that you need to use are lost in the mire. I spent too much time debating where things went and counting bolt holes in a difficult three-quarter view, when a simplified overhead view or different colors would have made all the difference. I hope that the manual can be redone for future production runs to make the assembly steps clearer, especially because a key advantage of the kit is that it’s quick to build. ROBUST 6-WHEEL DRIVE
When assembled, the VEXplorer is quite a sturdy little robot. “Robust” is the word that it brings to mind. As well it should be. If you’re going to drive around your house with a very narrow view, the vehicle should be able to withstand a few bumps here and there, a few missed corners and perhaps a tumble. The six-wheel drive is a good choice for a robot that’s meant to explore unassisted. You never know which kind of terrain you’ll encounter. It had little or no hesitation on concrete floor, and it does equally well on hardwood flooring. Carpet presented some resistance and caused the batteries wear down more quickly. The VEXplorer had no problems with my doorstep, but a little more ground clearance might help it to get over larger obstacles. If you’ve ever wondered what your house looks like from your pet’s point of view, then here’s your chance to find out. Driving by television alone gives you a very different and cool perspective. After a half an hour of driving, I had an entirely new appreciation for things at that height. Although I am intimately familiar with driving remote-controlled robots, driving by television really is a new experience. It’s true; you won’t break any speed records with this kit. If you expect the speed of a radio-controlled car, you will be sorely disappointed. That’s fine because driving the unit remotely by television is pretty challenging at the kit’s regular speed. If it were any faster, you’d miss all the details of your environment. When I first heard about this kit, what sparked my interest most was the claw, and I’m glad to report that it works amazingly well. A good grasper is very difficult to make, and Innovation First has put a lot of engineering into this one. The molded cushions on the jaws have the perfect balance between springiness, stiffness and traction. It is quite powerful and can indeed pick up a full can of soda as advertised. It has a good range of motion and can descend all the way to the ground and rise to nearly vertical. Another thing that sets the VEXplorer apart from other kits is the camera. It isn’t just some cheap black-and-white job. It’s a full-color wireless camera with sound, which is a real achievement at this price. The video image is very good, but the reception falls off dramatically after only 20 feet. Though the stated range is 150 feet, your mileage may vary dramatically depending on the type of environment you’re in. At first, I felt that the sound was an unnecessary feature, but I found that it helps to hear when the claw makes contact with something. Plus, it personalizes your explorations by giving you the full reaction of any life forms you may encounter.
USING THE CLAWInitially, I thought it was distracting to see the claw in the foreground of the video image. And then I got used to it and decided that I liked to see the claw in the picture. It’s a reminder that (hello!) you’re driving around a robot with a big claw on the top. I began to understand exactly why the claw was positioned in the frame that way when I tried to pick up something remotely. Seeing the tips of the jaws makes it easier to perform the delicate maneuvers required to grasp an object, whether it’s a can, a tennis ball, or the leg of a chair.
SOLIDWORKS STUDENT DESIGN KITAs a bonus, selected big-box and Internet distribution channels in North America are including a SolidWorks Student Design Kit with th VEXplorer kit. SolidWorks is a leading professional 3D CAD (computer-aided design) software package used by designers and engineers (including the ones who designed the VEXplorer kit itself). The license is good for 150 days, and the idea is to get kids interested in the design aspects of a robotics system by modeling their designs in the computer and then building them in real life with the kit. It’s a lofty goal, and in many households, the software package may initially be overlooked as new owners dive into assembling the robot. But it’s a significant tool that you will want to try (and see our feature article on designing robots using software, which introduces some of the tools in Solidworks and how the are used). You’ve got to give Revell and Innovation First credit for including this student design package with VEXplorer. 
VEXPLORER FEATURESAlthough the VEXplorer is a direct descendant of the original VEX system, it’s important to note that the designers had to make certain technical changes to reduce the price of the kit for users who may just want to drive around and pick stuff up. The electronics are incompatible with previous VEX systems’. This means that the transmitter, receiver and motors in the VEXplorer cannot be used with any other VEX transmitters, The VEXplorer’s motors have roughly the same speed and torque characteristics as their VEX predecessors, but they have two-pin connectors and a redesigned gearbox that gives them a different size and shape. A great new innovation is that the VEXplorer motors are equipped with internal thermal protection, so they can run at stall indefinitely without damage. You can feel free to grip that soda can as tightly as you want all the way across the room and back. Perhaps the biggest difference is that the VEXplorer is not programmable. It can’t read any sensors or switches or act on its surroundings on its own. Of course, hardcore robotics enthusiasts and educators might turn their noses up at a kit that isn’t programmable. And they would be right. I can’t really recommend this kit for a classroom setting. The assembled modules leave little for students to sink their teeth into, and the absence of programmability and sensor feedback limits its educational value in a robotics curriculum. This product is focused on mass-market appeal. It should be used to spark a curiosity in robotics and be a springboard toward building bigger and better things. For hardcore robotics enthusiasts and educators, the original VEX kit is still a great choice for the classroom, and it will be available for years to come with more sensors and sub-routines than you can shake a stick at. GAMESIf we look at the VEXplorer kit as an entertaining robot rather than an educational platform, does it succeed in entertaining? Is it fun to play with? Yes; in fact, it has surprisingly sustained play value. Games involving items such as tennis balls and soda cans take advantage of the claw’s abilities. Be sure to choose areas in which there are lots of things to explore. It can get a little boring driving around barren wastelands and large open spaces. Can you impress and annoy your co-workers with this? Yes, definitely. With a hand-held LCD television and earphones, you can carry out covert missions in the office. Would I recommend this? Absolutely not. The camera alone could get you into big trouble. Will it be a hit with the kids? In a younger target market, it has the pizzazz to pop off the shelf, and that’s what will eventually end up under the Christmas tree in December. As far as educational toys go, it’s pretty darn cool. Also, since you’re reading Robot, chances are high that you’ll find it cool as well. It’s exciting for us to see the dawn of the era of the robotic toy. More Robosapiens, Pleos and VEXplorers in more homes means more interest and familiarity with robotics in general. Kits like the VEXplorer just might trigger the imagination of a future scientist or engineer, and let’s hope that in years to come, they’ll reminisce fondly about their VEXplorer kits while working on real robotic rovers for other planets. Grant Imahara is one of the hosts of the popular television show “Mythbusters” on the Discovery Channel. He is also a former Battlebots competitor whose robot “Deadblow” has won three trophies. Grant is the author of “Kickin’ Bot, An Illustrated Guide to Building Combat Robots,” and he has been a FIRST Robotics mentor since 2000. He has also led VEX workshops for teachers and mentored VEX robotics teams.
WHAT’S THE DIFFERENCE BETWEEN VEX-RED & VEX-BLUE?You may notice that the VEX logo on the VEXplorer packaging looks a little different from the original VEX Robotics Design Kit logo. The VEXplorer logo is blue and not the original red. Why? It’s to differentiate the electronics portions of the two kits because they’re incompatible and differ in some significant ways. Technically, the control system, motors and servos of the original VEX Robotics Design System are designated as VEX-Red, while the VEXplorer electronics and motors are code-named VEX-Blue. The VEXplorer’s VEX-Blue controller (actually, a simple receiver) is not programmable and has a total of six motor outputs: four variable proportional outputs and two digital reversible outputs. Additionally, the VEX-Blue receiver has two accessory ports to power the video camera as well future add-on modules. The fully programmable VEX-Red controller has 8 PWM motor/servo outputs, 16 sensor input/output ports, and 6 interrupt inputs. Operating the VEX-Red system on a different frequency (say, to have multiple robots running in the same area at once) is a matter of switching out a crystal on the transmitter and receiver so that each robot has its own frequency. The VEX-Blue system has a single frequency of 27MHz available at this time, and it cannot be switched out. Also important to note is that the motors in the VEXplorer kit are a little different from the VEX-Red motors. While they have roughly the same speed and torque characteristics, the difference is that each VEX-Red motor has a variable electronic speed control built in. A PWM control signal is sent to the motor to tell it speed and direction. The onboard speed control takes care of the rest. The PWM signal allows for compatibility when driving servos that do not continuously rotate but rather maintain a position that’s proportional to the control signal. The VEX-Blue motors do not have a built-in speed control and are thus not compatible with VEX-Red systems. The electronic speed controls have been moved to the VEX-Blue receiver module; this helps to cut the cost of the overall system. Since there’s no control signal being supplied to the motors (only voltage), they have two-pin connectors. Also, VEXplorer motors have a different size and shape from the original VEX motors because the gearbox has been redesigned. Perhaps the most important difference is that VEX-Blue motors have a new safety feature in the form of an internal thermistor, which helps prevent motor burnout in an overload situation, protecting the motors from damage. There are no servos in the VEX-Blue world. Interestingly enough, there are no limit switches either. Not that you need them, of course. With internal thermal protection for the motors, they can run in a constant stall condition. YOUNG ROBOTICISTS BUILD THE VEXPLORER To put the VEXplorer kit to the test in the real world, I assembled a panel of kids to build it unassisted. They ranged in age from 13 to 15, two boys and two girls. Only one had any experience with VEX and building things. The rest had some experience with Lego building blocks but had never built anything before that required the use of a wrench. They built the kits on their own, and I interviewed each one separately.
Tony, age 15
Sean, age 13 “It’s pretty complicated compared to Legos or any other building thing. The group’s average assembly time without assistance was 1 hour, 24 minutes. Though they took a little longer on average than the kit’s advertised “one hour or less,” the results were astounding for me as well as them. I asked them to take on a project that required an unfamiliar skill set. At the beginning, most of them weren’t even sure that they could do it. To be honest, in the beginning, their parents were nearly as apprehensive. Would this hands-on experience pay off in the end, or would it result in total frustration and disappointment? It’s true; the build wasn’t easy for them, but having succeeded, they were all proud of their efforts, so it was an extremely valuable afternoon for four out of four youngsters. I have no doubt that they will show off their kits to jealous peers for some time. And the parents? They couldn’t have been happier to see the look of accomplishment on their children’s faces. The most telling thing is that every kid knew instinctively how to put in batteries, and after assembling this kit, they all knew how to turn a wrench.
Links
Fundamentals of SolidWorks, www.schroff.com (913) 262-2664 Innovation First (IFI), www.innovationfirst.com (903) 453-0880 Revell Monogram, www.revell.com (847) 770-6100 SolidWorks, www.solidworks.com (800) 693-9000 Robot Forum, www.botmag.com
About Revell:
Revell Inc., www.revell.com, recently acquired by Hobbico, Inc., www.hobbico.com, is the worldwide market leader in the sales of plastic model kits including cars, trucks, ships, planes, and related subjects. It also markets hobbyclass slot cars and RC vehicles. Founded over 60 years ago, the company markets under the brands of Revell and Monogram. Michael Brezette, Vice President, Marketing Revell Monogram
About Innovation First, Inc.:
Innovation First, www.innovationfirst.com, incorporated in 1996 and is a privately held S corporation. The company was founded on the belief that innovation very early in the design process is necessary to produce simple and elegant product designs. Innovation First began producing electronics for unmanned mobile ground robots, and is an industry leader in the hobby, competition and education markets.
Joel Carter, Vice President
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The VEXplorer is to a radio-controlled car what the Mars Rover is to a Ferrari. If you want to drive fast, get a radio-controlled car. If you want to explore, then get a VEXplorer.
receivers, motors or servos and vice versa. And there aren’t any servos to hold position in the VEXplorer world. Also, the system operates on a single frequency of 27MHz, and that limits you to running only one kit in a room at a time. Unfortunately, this means no head-to-head races or mock battles between VEXplorer kits, and you can’t safely run multiple kits in a classroom setting.
As far as modifications go, my guess is that the majority of VEXplorer consumers won’t tear their kits apart to make something else. At that price and level of experience, it will likely remain in its stock configuration, where it happens to work quite well. Of course, with the introduction of new modules that build easily on the existing platform (thus enhancing play value), you may see a few kits sporting upgrades. As I write this, a wrist kit and a track kit are both available as upgrade modules for the VEXplorer kit, and I’ve gotten hints directly from the manufacturer that juicy, more radical, more extreme accessories are in the works.
The difference is that the PWM (pulse-width-modulated) control signal has been removed from the VEXplorer’s outputs. The VEX-Blue transmitter and receiver in the VEXplorer cannot be used with other VEX transmitters, receivers, motors and servos (which are part of the VEX-Red line).
Molly, age 13
“Doing the prebuiltmodules was a good decision so people can get stuff up and running quickly. It prevents people from getting discouraged by the mechanical problems. The only problem is that it gets very irritating to put the screws in sometimes because parts are blocking. It was pretty easy once you figured out how to screw things in. It’s all basically screwing stuff in.
“The drivetrain’s really nice and powerful [but] it does not turn so well on the carpet. The camera was cool. It had nice resolution and everything, but it was choppy, so there are signal-receiving problems."
I have to say this is pretty complicated with [the] nuts and bolts. I like the camera idea. You can look where you’re going when you’re not right in front of it. The claw can pick up a soda can or a tennis ball. It’s really cool.
“When I began, I thought it was going to be pretty hard. When I got into it, it was hard, but I actually figured out that there are just some little tricks you have to use to get the screws and nuts into the [right] spots.”