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Electronics

We will be using a modelless logitec 720 camera – duct-taped to a 360 degree servo – the servo will be controlled via a servo shield and an arduino leonardo, and the pictures will be transmited via wiffi trough the raspberry pi. They will be bolted tot he bottom of the payload bay.

Parachute deployment will be acheaved by a servo with a razor blade glued to it – no Im dead serious – there will be a rope holding down the parachute – when said rope is cut by the razor the parachute will deploy. This servo will be activated when our accelerometer detects acceleration on its Y axis. The accelerometer will be bolted to the side of the payload bay.

 

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Finalising the lander

We opted out of 3D printing everything mostly due to time constrains – instead we made the whole body out of aluminium – Below is a picture of the the material for the payload bay and a few left over struts.20151110_114746[1]

As seen above the mechanical part of the lander is done – the parachute will be attached to the bolts on the top of the payload bay and all the electronics will be bolted to to the plexiglass bottom.

The parachute will be tied down with an additional rope – a servo with a razor will actuate when the lander detaches from the drone, cutting the rope and releasing the parachute – thus saving on weight and complexity.

Net weight with all the electronic components – 1.42 kg

 

Progress

Final Lander Design

We screwed around with the design and finally came to what will be the final one – the payload bay will be a 20X20X15 cm cube with a 3D printed top and bottom. The top and bottom will be connected with 4 6mm aluminium struts. This cube will house all the electronics including the webcam we will be using(which will be mounted on top of a servo motor to accomplish the panorama video). The payload cube will be attached via 2 60N gas shock absorbers to the legs platform – the payload bay will be able to move vertically relative to the legs platform and the shock absorbers will soften the landing for the payload bay – we believe this is a better idea than making each leg with its own suspension system – yes its dumb buuut we believe its functional.

Progress

Parachute Testing

We calculated the parachute diameter of 1.8 meters based on the following formula : S = 2 x g x m/p x Cd x V^2. We cut the thing out of nylon – put 6 ropes on it and threw it with a 2kg weight from the top of an 8 story building – it worked surprisingly well (given the fact I threw the bloody thing horizontally and not vertically) Video of the event

Like mentioned we want to land in a 1X1 meter square – the parachute design gives us 0 controll over where we land – we considered various forms of controled descent but came to the conclusion that we just cant fit such systems in the target mass – so we will just need to calculate where the lander will touch down presuming no wind will be present – then do last minute ajustments on site when we measure the wind speed and direction.

Progress

Preliminary Lander Design

The form of the lander will be similar to that of Philae – only the payload housing will be a square frame made out of aluminium struts welded together (Right now we are considering a 15X15X15cm housing), and there will be 4 legs (as oppsed to 3) positioned at the edges of the cube (currently planned to be 20 cm long) – the current plan for the suspension is as follows:

4 Legs with springs that can actaute relative to the frame of the payload bay and each other and 2 shock absorbers (1 per 2 legs). The idea with this design is that the shock absorbers weight quite a bit, they will be attached to a rail that is attached to 2 legs – this rail will be able to move side to side relative to the legs its attached to – this way we ensure that if the lander touches down on 1 leg – its adjacent one wont also contract and therefore offer no shock absortion – we plan to use 2 60N shock absorbers for this design.

This is a very poor explanation I know but soon we plan to have a 3D scetch of the whole lander – it will be easy to understand then.

Now the parachute:

We considered various forms of landing systems – raging from controlled decent using rotor blades (quad copter- like), wings on the side of the lander with control surfaces to provide steering, solid rocket boosters (god knows how we would get ahold of those) to parachutes (which we ultimately decided to go with). A parachute with a surface area of 2.2m will (in theory) bring us down with 4m/s. The parachute will be made in the next few days and thrown from the top of an 8 story building – updates will follow