People wanting to help:

Tasks:

Spiny gripper:

- develop new spine design that is very light-weight.

- Develop strong but light linkage mechanism that can make the spines grasp together, and can also allow them to move up and down and rotate if the surface isn't parallel to the bottom of the plane. Also ideally increases shear force as you pull in the normal direction.

- Develop actuation scheme and interface with their servocontroller board -- pretty much, use a servo or some small motor to drive the linkage. Must be able to disengage also! Ideally using low power and disengaging quickly. Maybe use a cam.

Wet adhesion gripper:

notes about various resources and materials for wet adhesion can be found at:

• WetAdhesion (notes about specific adhesives considered for during prototyping process)
• WetAdhesion (list of papers related to wet adhesion)
• Public/WetAdhesion (papers on adhesion, specifically tree frogs)
• Public/AdhesionPrinciples (basic descriptions of different types of adhesion)
• Public/AdhesionModels (papers on different adhesion models)

- designed to work especially well on roof tile and galvanized wavy sheet metal, because superglue doesn't work on these. If it works on tar paper covered with little rocks that come off really easily that would be awesome too, although a separate gripper could be developed for this.

- Prototyping: make lots of little rubber/silicone discs on stalks. Cover them in a thin coat of some viscous glue stuff. Build up a hierarchy by gluing the stalks to bigger discs/stalks.

- Literature review: figure out variables which make a difference in the amount of adhesion we can generate, e.g. viscosity of the liquid, perimeter of the rubber thing being stuck on with the liquid, etc.

- Figure out good actual liquids to use as a wet adhesive layer, that won't evaporate and may slowly harden like a real glue

- Figure out how to get the liquid on the rubber things, either pre-wet them and peel off a protective coating before flying the plane or have the liquid expelled somehow

- Figure out how to make it detach -- it's ok to leave the rubber thing behind.

Deadlines:

- Full demo: Feb. 19 (Thursday)

- give them functional prototype a week before -- Feb. 12 (Thursday)

Requirements:

2.2 Gripper Requirements

2.2.1 Performance and Utility

2.2.1.1 The gripper payload shall provide at least 6 hours of perch grip.

2.2.1.2 The gripper payload shall provide multiple grips per mission (greater than two grips per mission).

2.2.1.3 The gripper payload shall operate in temperatures ranging from 0° to 180°F.

2.2.1.4 The gripper payload shall function in extremely humid environments.

2.2.1.5 The gripper payload shall function in extremely dusty environments.

2.2.1.6 The gripper payload shall grip to sandy and wet objects.

2.2.1.7 The gripper payload shall grip or release in less than 5 seconds.

2.2.1.8 The gripper payload shall grip to bricks, tiles, concrete, wood, glass, tar paper, standard shingle, plaster, rock, terracotta, glass, painted walls and metal

2.2.1.8.1 Each type of gripper is not required to grip to all of the above surfaces. However between the two of them, gripping to all of the surfaces shall be achieved.

2.2.1.9 The gripper payload shall be capable of holding 5 pounds in tension and shear (relative to the aircraft's position on the landing surface)

2.2.1.10 The gripper payload shall require no power during "perch", it shall only require power during deployment and release.

2.2.1.11 The gripper payload shall have at least a 2-year shelf life.

2.2.2 Aircraft Interface

2.2.2.1 The gripper must be able to integrate into the bottom of an SP2S? aircraft (within a standard payload bay, see dimension below)

2.2.2.2 The gripper shall be packaged in a modular unit that can be easily inserted and removed from the SP2S? aircraft's standard payload bay.

2.2.2.3 The modular payload unit shall include a mechanical latch to secure it into the SP2S? standard payload bay.

2.2.2.3.1 AV will provide the mechanical interface geometry

2.2.2.4 The modular payload unit shall include a blind-mate electrical connection to communicate with the aircraft's autopilot.

2.2.2.4.1 AV will provide the blind-mate connectors and geometric position details.

2.2.3 Gripper payload size, weight and power

2.2.3.1 The maximum volume of the modular gripper payload unit shall not be greater than 10 in3.

2.2.3.2 The maximum thickness of the modular gripper payload unit shall not be greater than 0.75 inches.

2.2.3.3 The maximum weight of the modular gripper payload unit shall not be greater than 25 grams. (Total weight with packaging and electrical connector)

2.2.3.4 The maximum power required during deployment shall not exceed 0.5 Watts.

2.2.3.5 The maximum power required during release shall not exceed 0.5 Watts.

2.3 Build prototype gripper payloads and aircraft mockups

2.3.1 The sized grippers shall be integrated into a modular payload mockup. This payload mockup will then be installed into an aircraft mockup. The aircraft mockup shall represent the SP2S? general airframe structure with no specific geometric details with the exception of the payload bay (i.e. flat plate with a simple fuselage and the standard payload bay).

2.3.2 This gripper payload shall be deployed and retracted via an electrical connection to the gripper payload from the aircraft mockup. The aircraft structure mockup shall contain the battery required for operation. No battery shall be included in the payload. The aircraft mockup shall contain the remote control receiver for remote control deployment and retraction.

-- AlanAsbeck - 21 Jan 2009