As a result of what we learned from producing our low fidelity physical prototype (and lots of discussion), we decided to make significant changes to the form of our creature. It turns out that the vertical hinge and leg mechanisms we designed are super tricky to create in physical space. Instead we are moving to a modular design that repeats many of the same parts, and uses a horizontal hinge attached directly to servo motors. Below is an exploded diagram (triangle modules, hinges, and shells shown separately) that outlines where our design is now.
Freehand Sketches and Iterations
The new plan did not just appear out of thin air though! We took our big concept and went back to drawing board to come up with an assortment of fresh ideas. These are some of the sketches that show the iterative process behind our new form.
As part of our process for Phase II, we created new digital drawings that show several orthographic projection views of our new form. They are labelled to clearly show parts and assembly.
Now that we have a more solid form, we have started to think about just how our kinetic sculpture will move. Bearing in mind the actual servo motors we will use, the scale of our creature, and the materials at our disposal–we have prepared diagrams and a prototype that shows how it will achieve motion. The mechanism requires careful planning but is not terribly complicated. It consists of a servo motor attached to one modular unit, while its rotating disc is attached to the next unit. When the servo motor rotates it causes a “contraction” or “expansion” in the angle between one unit and next. If programmed correctly we should be able to create forward motion.
We have successfully built servo motors (and basic motion) into our medium fidelity physical prototype. Except for the LEDs (so far) we have implemented all the parts we expected. We are also using a breadboard (to facilitate connections: power, control and ground) and a laptop (code loading and power) in addition to the electronics we outlined in Phase I.
- Arduino boards
- Servo motors (3-4 per creature)
- RGB LEDs / LEDs (soon, several)
- Light sensors (slider sensor for testing)
- Many, many wires
- Laptop (code loading / power)
At this time our breadboard, Arduino unit and power source (laptop) are external. We are exploring the use of mini breadboards that we could mount inside the creature itself, battery power and tail mount for the Arduino. We plan to implement the mini breadboards for sure, in addition to wiring up and implementing RGB LED lighting in the program.
Materials and Build
Our current prototype is a hybrid of laser cut white acrylic and cardboard. The experience of cutting some pieces in acrylic will definitely help us when we need to create pieces for our final prototype. The good part about the mixed cardboard is that it makes for light weight. One issue is that it is not as robust as we would hope. In operation bolts sometimes fly off, and glue often breaks. At this point we are using a hot glue gun to attach parts (so we can easily change attachments). Eventually all parts will be acrylic and styrene. And we will attach using a more a heavy duty glue.
Issues + Next Steps
- Create second creature
- Improving triangle structure
- Add effective lighting (show energy use clearly)
- Enhance movement (make it crawl more smoothly)
- Improving creature’s response to the light energy
- Producing movement that will move forward reliably
- Connecting multiple servo motors
- Battery power and enclosing electronics
- Material weight and thickness (acrylic)
- Making creature curl into a ball
- How to add lighting with limited power