Servo - July 2008

Twin Tweaks ...

nonetheless it was a vexing setback.

During our fine tuning of the Robophilo we witnessed something disturbing and tragic. We were editing the range of motion on the right leg, and then the Robophilo’s arm began to quiver. We checked to see that nothing was blocking it, but the quivering only got worse. Then, the entire robot started to convulse as its LED started to dim. It was a tragic thing, watching the Robophilo run out of batteries before our eyes. The good news is that the battery pack is rechargeable, and the kit comes with a charger. A few hours later, we were ready to press on.

Philo Goes West

ROBOPHILO MANUAL.

done for the servomotors by hooking them into the PCB (printed circuit board). The kit does include a battery pack, and the tuning is a nice way to become familiar with the PCB before the more daunting task of wiring up the entire robot.

Final Touches and Fine Tuning

Once the Robophilo is given all of its limbs, there are only a few fine touches before it is finished. One of them is to ROBOPHILO REMOTE. ^wire ^it ^up,which is made very straight-

forward by helpful diagrams in the instruction manual. The mess of wires can be cleaned up with some wire sleeves included in the kit.

The penultimate step of building the Robophilo is to do the fine tuning for all of the servos, which is a laborious and time-consuming process. The major money-saving measure employed in the design of the Robophilo is in the servos, and the tradeoff for achieving a low cost becomes clear during the fine tuning process. The Robophilo servos are cheap analog servos that lack the torque of the servos in the Robonova and Bioloid, and are also more difficult to tune. Thankfully, the tuning process is more tedious than difficult and the quality of your experience will most likely depend on how perfect you insist the tuning to be.

Tuning basically consists of entering various positions for the servos and then adjusting the offset and range of motion in the Robophilo’s fine tuning editor. With 20 servos to tune, this can turn into a time-consuming affair. During the tuning process is also when the instructions recommend to connect the pushbars for the left and right leg movement and head turning into the servos. The pushbar is easy to insert into the large servo horn for the waist movement, but the other servo horns have holes that are simply too small for the pushbars. After vigorously pressing the pushbars into place, we were able to attach everything, but

ROBOPHILO PCB.

After what seemed like hours of fine tuning, we were finally ready to finish the robot. The last steps include cleaning up the wires and attaching the final body panels. Unfortunately, halfway through putting on the Robophilo’s ill fitting shoes we ran out of screws! Most robot kits like the Robophilo come with ample numbers of spare screws, and running out was a disappointing surprise. We suppose we could have seen it coming, because several other sizes of screws came in only the exact amount necessary, with no extras left over. Thankfully, we had enough screws to keep the shoes on and the main body panels on.

Unfortunately, the body casing for the Robophilo was a big engineering disappointment in that it seemed to sorely underestimate the amount of space needed for the wires to escape. Also, the front panel doesn’t even seem to consider that extra room is required on one side for the small servo that turns the head. The thin plastic is easy to modify, but it is a bit annoying that it has to come to that. Putting the final pieces onto the robot should be a triumphant experience, not the most frustrating of the entire build.