Editor’s note: PLEN2 ships from Japan as a kit or a finished unit. Depending on your preference, you can order the robot in pieces or fully assembled. For the sake of review, we’re discussing the assembled PLEN2.
What’s a PLEN2?
In short, PLEN2 (there was a PLEN1 in case you were wondering) is one of the world’s smallest consumer humanoid robots. He stands nearly 8 inches tall, about the size of a water bottle. PLEN2 is equipped with control boards and servos, so he can walk about, pick up objects, dance around, play soccer, and roller skate.
About the most important thing to note with PLEN2 is that you don’t need a degree in computer science to make him tick. PLEN2 can be programmed via a web browser or controlled via a smartphone. There’s even text-based programming if you have Sublime Text or some other text editor.
PLEN2 comes equipped with a programmable board, a head board (includes the gyro and accelerometer), a rechargeable battery, 2 LEDs, and 18 servos. Powered by a rechargeable NiMH (nickel-metal hydride) battery, the squat humanoid robot will last 20-30 minutes on a single 1-hour charge. There’s a micro-USB port for wiring up PLEN2 to a computer, but Bluetooth is also supported. There are 18 servos total; each leg is configured with 6 servos and each arm consists of 3 servos.
PLEN Connect features a number of movements: normal, box, soccer, dance, and roller skate. Each category lists 9 movements, so 45 in all. Additionally, you can control PLEN2 with a single tap joystick. No bugs were found when I was testing out PLEN Connect. The app runs smoothly on iPhone and doesn’t drain too much battery life.
Scenography is a tool for visual programming. Motions are organized vertically, and PLEN2 executes whatever’s listed in order. The app’s interface is a bit crammed on the iPhone, so it’s best for tablet use. Scenography does crash on iPhone every so often too — it’s less robust than PLEN Connect.
As an alternative to smartphone-based control, PLEN Project Company has developed a web app called Motion Editor. The app works inside any modern web browser (Chrome, Firefox, etc) and presents the user with a digital model of PLEN2. The robot’s appendages can be dragged in various ways, and each pose is saved as an individual frame. When finished animating, frames are played back on the physical PLEN2. Motion Editor is a very plug-and-play way of programming PLEN2. However, the app does require tethering PLEN2 to a computer and running a program called “ControlServer” in the background. Instructions for the setup can be found on PLEN2’s wiki.
Motion Editor programs can be saved as .JSON files. These text files can then be edited using any text editor (I prefer Sublime Text). PLEN2’s servos rotate in increments of 100, and each frame is declared by “@index:”. Say you want to pitch PLEN2’s left arm 62 degrees in the first frame. Set “left_shoulder_pitch” value to 620 and “@index: 0”. Additional frames can be added by increasing the “@index:” integer, but a frame length must be set using “@frame_length:”. When finished, the file can be uploaded to the Motion Editor.
PLEN Project Company offers multiple ways to adopt your own PLEN2. The robot is available as an assembly kit or a finished model. If you’ve got a 3D-printer handy, you can print PLEN2’s body parts and save a few bucks with the “DIY” kit. A Developer Edition with Intel Edison inside is up for grabs too. PLEN2 kits start at $480 and ship internationally from PLEN Project Company or Amazon. It’s a hefty price tag for such a small and plucky robot, but PLEN2 is as human as robots get.
PLEN2 works well with smartphones and computers. It's equipped with 18 servos for a variety of postures and movements. There's tons of example programs and general information available online for free. The battery compartment is a tricky fit and the motion editor requires a tethered USB connection.