Archives for October 2017

October 30, 2017, Filed Under: featured, Raptor 2017, student experience

The Problem with AC/DC

No, I’m not talking about the rock band. I’m talking about actual alternating current and direct current. The EL wires used on the raptor bodies are AC-powered, while the LEDs used in the raptor eyes are DC-powered. Both EL wires and LEDs are necessary for the lighting design because, while EL wires are easier to use for the glowing lines on the bodies of the raptors, they cannot fade on and off. Through conversations with the designers of Enron, we determined that the raptors would be more expressive if their eyes could fade in and out, so we decided to use LEDs (which are easily programmed to fade) in the eyes. In the earlier stages of research, the other members of the electronics team and I were considering using the Sparkfun EL Sequencer (which you can read about in Justin’s blog post here) for all of our raptor needs, but we ran into a problem: the sequencer was only capable of powering EL wire with alternating current, not LEDs with direct current. It would be cumbersome to have two different microcontrollers in each raptor (one for the EL wire and one for the LEDs), so we did some research, adapted our plans, and decided to use an Arduino Uno microcontroller with the Sparkfun EL Escudo Dos shield. The Escudo Dos plugs into the pins on the Arduino and has an input for AC current from an inverter (a device that converts DC to AC current) to power up to 8 strands of EL wire. Each strand of EL wire corresponds to a pin on the Arduino, but there are a few pins that aren’t connected to the shield which we use for powering the LEDs in the raptor eyes with regular old DC current. However, we still had the problem of wirelessly communicating with the electronics. We are using Digi XBee wireless modules for wireless communication, but in order to connect the XBee to the Arduino, we had to stack the Sparkfun XBee shield on top of the EL Escudo Dos. Unfortunately, the Escudo Dos was already using the pins required by the XBee shield to communicate with the Arduino, so we had to improvise. We used two jumper cables to reroute the input and output of the XBee to pins not necessary for the operation of the Escudo Dos. Now we are able to wirelessly control both EL wire and LEDs from one microcontroller!

The leaning tower of shields. From top to bottom, you can see the XBee shield, then the EL Escudo Dos shield, then the Arduino Uno microcontroller. Note the two red jumper wires used to reroute the pins used to communicate between the XBee and the Arduino.

The whole system in action. The two black boxes in the bottom left are the inverter and its battery. The XBee Explorer dongle connected to the laptop communicates with the XBee on the Arduino via the XCTU software.

October 29, 2017, Filed Under: class resources, featured, progress report, Raptor 2017, student experience

Failing Better – Part 2

Well, I am continuing to fail successfully at this project. Here are some updates.

Through a rough series of failures, Xindi and I are learning more and more that the CNC is not the best tool for this specific project. This week, we finally got access to a laser cutter! It is so satisfying to watch this machine cut out our fingers the way they were meant to be. Plus, way less sanding or drilling. We implemented cut outs in the fingers to improve the weight. Bonus, it gives us more access to the inside of the joints for the spring adjustment. Although we plan on painting them with a metallic finish, the burnt wood aesthetic is really lovely. We still have a long way to go, though. Our file needs a lot of cleaning and better precision with dimensions.

Laser cut parts with plastic, lightweight hardware.

Another huge challenge we face is the attachment of a human hand to this thing. Rings slip out. Gloves slip out We struggle with stabilizing the actor’s palm.

We tried to implement an adjustable system to attach any sized hand using little chains and hooks at the end of the fingers. Didn’t work out. This week, we’re attempting a hybrid with rings and a glove to see if we can get more dexterity. I think next week we’ll try thimbles.

What I would like to specifically point out in this post is the value of having a space like we do to fail. The raptor lab is a mess; there are mechanical body part failures everywhere. But we have a place, a safe place to mess up. It’s ok to make something that doesn’t work. When you present a prototype each week, there are a flurry of constructive criticism and helpful suggestions. This kind of feedback is circulating constantly.

We also have a plethora of resources to learn off of. We have access to maker spaces with laser cutters and 3D printers, and an entire scene shop equipped with tools and resources. Additionally, we have professionals to vet ideas off of. This includes all of the faculty and staff of the theatre department, plus some amazing guest artists,

We also have time to fail. Don’t get me wrong, we are definitely working in a crunched timeline, but Karen and J.E. have blocked out so much time to fail and make mistakes. That’s the point of prototyping. I know its crazy, but I had never thought to give myself that time while working on a project. I just calculated how long it would take me to build a thing. That’s it.

Obviously from my last post, failure is an important, albeit sometimes painful, part of the creating process. What is equally important though, is giving yourself plenty of room, and time, to fail.

October 26, 2017, Filed Under: progress report, Raptor 2017

Week 6 Update

We are nearly halfway through the semester! That means it’s almost time to begin the transition from prototyping to producing final products. Check out this video for a preview of this week’s raptor happenings:

This week the raptor team had the privilege of working with Ron Pardini, a special effects artist with 29 years of experience. The class spent Sunday working in the lab with Ron, and enjoyed a presentation on Ron’s life and career on Monday.

Here’s a recap of this week’s major accomplishments and goals for the future:

Electronics Team

Accomplishments:

controlling two wireless modules separately from one laptop
working with Cait to establish wire placement on raptors

Goals:

3D print a new case to hold the Arduino with EL and wireless shields
develop a system to relieve strain on wires to avoid anything getting pulled out of place
have entire three-raptor system working by November 13

Skin Team

Accomplishments:

developing a pattern for the skin on the heads and feet of the raptors
experimenting with incorporating lights into the skin

Goals:

continue developing skin texture
work with EVA foam to refine skin patterns
have all skin ready by November 20

Feet Team

Accomplishments:

carving the foot’s shape out of foam
exploring integration of foot with performer’s shoe

Goals:

attach feet to legs
develop claws for feet
have final foot model ready by November 13

Hand Team

Accomplishments:

refining mechanism for performer to control finger articulation
improved finger articulation by integrating springs into hand
picking up objects with raptor hands

Goals:

improve integration of performer’s glove and raptor hand
experiment with using magnets to aid in picking up objects
have final hand model ready by November 13

Structure Team

Accomplishments:

scaling down the raptor’s body frame
adding a foam spine to the frame

Goals:

fit harnesses to two other performers
work on transition between raptor body and head
experiment with using attachments from tail to performer’s arms to control tail movement
have complete structure model ready by November 13

Leg Team

Accomplishments: