Wednesday, 29 March 2017

Motor team sprint update

Dat Z (not D)

The motor team has now got movement for the Z axis on the bottom of the lamp. We tried a few different ways of achieving this movement.

At first we did a simple mount where the servo was held on a surface away from the lamp itself. The servo had two rods so that a connection could be made to the centre bar of the lamp. One of the rods was connected directly to the servo horn. The other was connected to the end of the first rod so it was free to pivot. This allowed for linear motion of the servo to extend/retreat the bar of the lamp. There was a connector used to hook around the bar of the lamp and tied with cable ties for testing,

The next mount that we tried was mounting the motor directly onto the lamp. The turning point of the motor was placed on the turning z axis of the lamp. This time the rod was used to move the motor and hence the lamp. A block of  wood was connected to the horn of the servo and this stayed against the flat surface.

We decided the best implementation was the first iteration of the mount. We setup the mount with the motor on the board and tested this. We made the mount more robust that the first test.
below is a video of the Z motion working.

Elbow axis


The yaw which rotates whole lamp is the easiest to do from all of them, but we might have to skip it because we don't know how to do the Z axis while the laps yaws. We tried few different approaches and didn't came with good solution, so at the moment the Z motion is not compatible with any Yaw motion, because we have the pan inside the head we are slightly inclined to drop the yaw feature. Definitely this has to be discussed in the whole team. This probably would avoid problems with collisions as well.

Elbow + Z + head pan

Meeting project plan

Simulating interference

SolidWorks supports assembly where you can put all parts together and test them how they fit, where they collide etc... This allowed me to do few very quick iterations and changed which extended the range of motion by few degree.  

Would be cool to have all servos and lamp modelled and be able to do all these axis mounts and all iterations inside software:

3 axis with 2 axis joystick

Because at the moment we at have more axis than the build in joystick can support a external joystick could be handy. Two analog joysticks can be acquired from eBay for 2.23 euro:

Or searching "Joystick Arduino" in your favorite store could find the exactly same one, they are based on the PS4 gamepad replacement parts.

The case can be made from this design:

If this doesn't look attractive there are many other designs published as well.

The result looks decent and the contacts on the joystick are safe so they can't be sort circuited, this design works well for left handed and right handed people as well:

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