By Jack Lane
Navidad arrived early this past week in Chavin when one of John Rick’s graduate students, John Wolf, arrived with a suitcase full of new parts for our robot. John Wolf, better known as “Lobo,” brought with him the following: new 3D printed wheel-hub attachments from our friends at the PRL (thank you Dan, Elliot, and Thom!), replacement wheels for those we had lost, a new set of motors, two fish-eye cameras, and a fresh spool of wire, as well as various switches and connectors. He also bought a lifetime full of unpredictable, engrossing stories and excellent taste in music. This past week in the lab, Lobo has entertained us with tales of learning how to weld in order to help his friend build a 52-foot, concrete boat and getting kicked out of college in the 60s because he occupied the student union in an anti-war protest. He also introduced us to the soulful, rock/blues crooning of Beth Hart and Dana Fuchs, which has provided a welcome soundtrack to the (at times tedious) task of rebuilding our robot. We still haven´t completely adjusted to the daily novelty of seeing Lobo working on human skulls in the lab.
After losing our first set of wheels and MacGyvering a solution out of extra wheels and epoxy, we embarked on a full overhaul of the robot. As described in our last post, this overhaul includes many small changes and improvements. The largest change has been a rearrangement of the main internal components of our robot in order to narrow the wheelbase and reduce the overall height. We have also, however, used this opportunity to redesign our software, build a graphical user interface, transfer controls from a computer keyboard to a joystick, add a backup camera, and mount a distance sensor on the front of the robot. One of the most challenging constraints on our work in Peru has been our limited access to tools, parts, and prototyping materials. We’ve had to make changes to the chassis of our robot using a hacksaw and a hand drill, often holding the parts by hand because we lack any proper means of fixturing. Aside from the bounty we received from Lobo, we are generally limited to using the parts and tools that we brought with us. Our hot glue gun has arguably been our most indispensable tool, and we have become more and more reliant on its gooey goodness in order to support wiring, adhere lights, and mount cameras. Increasingly, we are cannibalizing parts for use beyond their original, planned purposes. We have taken the majority of the 1/8 acrylic parts that we laser cut before leaving the states, sheared them into pieces, and added them (with hot glue, of course) as extra support for wiring and camera mounts. Overall, the process of shrinking and refining our robot has required improvisation and arts-and-crafts know-how, making for an entertaining week in the lab.
After making many of the above changes, we returned to the site for more exploration, this time in the underground canal system. As we briefly described in a previous post, there are broadly three types of underground spaces in the Chavin monument: galleries, ducts, and canals. The galleries are ceremonial spaces enclosed inside the temple buildings – within they are tall enough to stand upright and at times wide enough to walk two abreast. Ducts are small tunnels that connect galleries and are thought to have provided ventilation and illumination to the galleries– the largest ducts are just big enough for me to squeeze inside while the smaller ducts are around 8 inches wide and tall. Canals, on the other hand, are completely below-ground, and their primary purpose seems to be for draining and moving water through the site. Like ducts, canals vary in size, but they are generally larger, sometimes big enough to allow a small person to walk through them in a crouch. Until recently, all of our explorations with the robot have all taken place inside ducts, but that changed this past week. With the arrival of two Peruvian hydrological engineers and encouragement from John Rick, we began exploring canal systems in the site. We hope to generally extend knowledge of the canal system by further mapping underground canal spaces. The holy grail of our canal search would be uncovering an intake from the Wacheqsa river or outtake to the Mosna river. In particular, an intake to the canal system from the Wacheqsa river would provide strong evidence that the Chavin could control water flow into the canal system and even pressurize the system in order to send water uphill towards some of the temple buildings. If true, it would make Chavin the only known site in the New World with a pressurized water system.
So far, our exploration of the canals has been a process of rediscovery more than a successful uncovering of new spaces. Current knowledge of the canal system among the archaeologists here is extensive but fragmented. Oftentimes they are unsure exactly what lies at the end of various canals – it could be a complete blockage, or it could be a small opening just large enough for a wheeled robot. Oftentimes we need to crawl into the canals ourselves in order to find spaces for our robot to explore. Last week, after crawling for about 45 minutes through tight underground spaces, we found that one of the main canals ended in a narrow tunnel extending to the north. It was just a smidge too small for the last version of our robot, and we hope to return with our smaller, improved robot. Our search was limited by the size of robot in other locations as well, and by the end of the week we were left, once again, unfulfilled in our quest to discover new spaces in the site.
In the process of exploring the canals, we ran into yet another unexpected problem with our wheels and motors. The large MacGyvered wheels that we made were slipping, bouncing, and generally losing traction in the canals. Upon closer inspection in the lab, we realized that the gear boxes of our motors were severely worn. The gears didn’t seem to be slipping, yet, but they were suffering from pronounced backlash, and the cantilevered motor shafts now wiggle 5 to 10 degrees off their axes. We suspect that this wear was particularly pronounced because the large motors stuck out markedly from the body of our robot and placed a large, perpendicular moment on our motor shafts. The final step of our robot redesign over the past week therefore became, once again, the process of replacing our motors and wheels. We have now returned to our original wheel and 3D printed hub attachment design. The hub attachments, however, are now printed out of a rigid resin, and the connections are reinforced with epoxy. We hope that these changes are enough to prevent the wheel-loss tragedy that we faced two weeks ago. Every day our robot becomes more compact, more refined, and closer to what feels like a final, finished product. We have three more weeks left in our program, and we hope to spend the majority of that time exploring in the site rather than tinkering in the lab.
In non-robot news, the past week was a busy time in Chavin. The town fiesta started last Friday with a street party featuring two bands and a castillo (firework tower). That night of music was followed by about 48 hours of nonstop fireworks, marching bands, and dancing throughout Chavin, especially in the main plaza. The fiesta concluded with a bull fight on Wednesday in the plaza de los toros de Chavin. Most of the Stanford students, Daniel and I included, were trepidatious about the fight, but ultimately decided that the experience was too novel to pass up. The show started with beautiful dances featuring Caballos de paso Peruano, a type of Peruvian show-horse, and then progressed to the first of three toros de muerte. The bull fighter was from out of town, and went by the moniker, “el poeta.” His garb was a bedazzled piece of anachronistic colonialsm, the traje de luces – royal blue with gold bangles and knee high pink socks - and a montera hat. The fighting and the killing of the bull itself was surprisingly tidy, but gruesome all the same. The matador would bait the bull with his red cape before attempting to slide a meter-long sword directly between the bull’s shoulder blades as the bull charged past. The first bull took four swords, the last buried to the hilt, before falling to its knees. My curiosity more than satisfied, I left after the first bull died.
It is hard to believe that we only have three weeks left here! They will be a busy time. I (Jack) have joined a band with two of the Peruvian archaeologists, and we intend to perform on the first day of August. Currently, we go by the name Cabrones del Swing and play an eclectic mix of English and Spanish rock. The Peruvian Fiestas Patrias are this coming weekend, and Daniel plans to put on his archaeologist knee-pads and help John Rick with some below-ground excavations in one of the canals. We are also excited about the arrival of Margaret Coad, a graduate student from Stanford who is bring another robot with which we will explore the site. But we’ll write more about that in the next post.
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