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SpiROSE: Security and interactivity

As we discussed the plans of the project, we quickly realised that allowing rather large devices to rotate at around 2,000 RPM was not inconsequential to anyone using SpiROSE with regards to safety. A first mandatory step is to use a large transparent cylinder to prevent any moving part from flying away with high energy, should the implemented fixation fail at any moment. But this is not enough. We must make sure that no one tries to move SpiROSE while it is working – you do not want to destabilise a device with blades that have a terminal speed sufficient to race with a car on German highways !

Therefore, an Inertial Measurement Unit (IMU) is planned to be placed in the fixed part of SpiROSE to monitor any movement of the device – except the vibrations caused by the rotation – in order to know whether it is safe for SpiROSE to be working. First of all, before the system is even started, it checks if it’s completely still and horizontal. Then, while it is spinning, SpiROSE is able to detect any extern action and to perform an emergency brake on the moving parts. We were thinking about mechanical brakes to quickly and significantly reduce the angular speed, but it has to be calibrated not to have a massive deceleration that could weaken or destroy parts.

Let’s jump to another feature of SpiROSE, its interactivity. We do not just want a 3D display, but a 3D display that can be, as much as possible, controlled by the user. We decided to use an LCD display for the human-computer interaction. It is attached to the fixed base. It will for instance display information from the IMU or some useful other from the SBC sent through CAN/FlexRay/IrDA/BLE. The interface will allow a user to adjust some parameters – we have not decided of all of them yet – on the 3D display. A clickable rotary encoder or an endless potentiometer allows us to navigate through the interface and set adjustments, for instance we could rotate a steady 3D image. Isn’t it pleasant to touch a knob rather than to move to the other side of SpiROSE to see the face of your favorite character displayed in 3D ?

The exact features available on the LCD display will become more and more accurate as the project keeps going. Yet we have to focus on more basic features for SpiROSE by the end of the upcoming week, such as the exact dimensions of the device thanks to the mechanic, so that we can really begin working on something that we know is feasible !

3 comments to SpiROSE: Security and interactivity

  • loikled

    If you use a brushless motor for the rotation of the structure, there are motor controller boards with electronic braking so that you don’t need to use a mechanical brake that could destroy your device.

    • VincentC

      Thank you for the hint ! I wonder though if the braking effect it produces is enough to have a fast deceleration (We would like to ensure that it quickly reaches speeds less hazardous than 1000rpm, should anything happen to the device).

  • loikled

    Approximately It can decelerate as fast as it can accelerate. So it will take as much time to brake as to reach maximum speed at full torque.
    Given that your structure will have a big inertia it might take several seconds.
    (I’ve worked on drone motor control by the way).

    So yes keep that in might and try to find a safe mechanical solution too.

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