Basic Modes of Touch- a set of experience goals

We are approaching our project by build atop existing soft robotics architectures defined by the Harvard Soft Robotics Toolkit. In selecting this project, our goal is to use this platform to build a basic set of universal experiences which can be applied as modules in future soft robots. In order to do this, we require a well-defined set of subsenses comprising the primary sense of touch, also known as the somatosensory system. According to Wikipedia,

"Although touch (also called tactile perception) is considered one of the five traditional senses, the impression of touch is formed from several modalities including pressure, skin stretch, vibration and temperature."

These criteria of pressure, stretch, vibration, and temperature can serve as the initial bases of our experience set.

Elastomers and Pneumatics - Shopping

We found out that the elastomers can cure at lower temperatures (but slower), so if the mbot trial works well we can use those for actual molds from here on out. The blood pressure cuff has some complicated details involved, so we're going for a three-finger grasper first, and we'll use the blog to detail that.

A couple immediate additions to the material list are the elastomers: Ecoflex, Elastosil M4601, Sylgard 184 (aka PDMS Silicone). Those sites are the "official" sources, but if there are any cheaper sources then we should use those. We also need access to an oven for curing (40-45 C is the goal) and a vacuum chamber (which could arguably be constructed from a shopvac and a cardboard box).

These pumps are 3V, 200mA so we can probably drive them directly via H-bridge, for testing the actuators under pressure. To actually control them we need the three-way solenoids to allow for exhaust, which implies a valve manifold for organization, which implies a stronger monolithic pump. The documentation calls for this pump, but I've found some from a previous incarnation of the same manufacturer with comparable specs, at about 10% price. The listed solenoids are actually quite good, the next best option require a high minimum pressure differential to function. That manufacturer has nice manifolds, connectors, and tubing.

- 3-way solenoids = $35 each (same as official)

- Solenoid manifold = $45 (same as official)

- Pressure sensors = $20 each (vs $45)

- Air pump = $35 (vs $300)
- NPT to barb coupling = $1 each (no minimum order)
- Barb 'T' coupling = $1 each (no minimum order)
- Tubing = $12 for 30m