Python Test - Weaving Analyzer Program

Test description

Objective:

You are tasked with developing a program designed for surface inspection, ensuring precise monitoring and synchronization of cameras, lighting, and surface movement.

This program not only needs to get images (from simulated camera controllers) and surface velocity (from simulated velocity controllers), will also need to send this data to a server that will analyse it.

Inspection System Overview:

The inspection system comprises:

• Two cameras: placed on front of the surface.
• A moving surface: Ascending vertically (vertical axes of the cameras).
  • The horizontal field of both cameras combined, covers the whole surface horizontally (60 cm).
  • Vertical field of view of the cameras: 25 cm.
  • Horizontal field of view of the cameras: 33 cm.
• Two light types: (Green and Blue) that can be flashed by the cameras.

The inspection mechanism is depicted on the following diagram:

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Requirements

1. Velocity and Displacement Measurement

   Real velocity sensors have a lot of reading noise and can read some completely wrong values. The program needs to be immune to these issues, so you need to find a way to filter the sensor output values.

   • Use the provided Velocity Sensor Controller to measure the instantaneous surface velocity.
   • Don't forget that the velocity might change over the time.
   • Address noise and other problems, such as random values, in velocity readings with at least 50 samples per second and filtering for smoother data.
   • Calculate incremental surface displacement based on velocity.
   • Keep the server aware of the current velocity and surface displacement, at a frequency of one request every two seconds.

2. Camera Triggering

   • Determine when to obtain the images for a given iteration, ensuring that all the surface is analyzed.
     • Since the velocity is changing, you need to adapt to it constantly.
   • Each iteration should trigger both light types (Green and Blue), minimizing displacement between their respective images.
   • Consider a batch of pictures valid only if it contains data from both light types, with the order being irrelevant.
   • The batch of pictures needs to be sent to the server as soon as possible.
   • Clarification: the pictures of each light type need to be taken sequentially and then wait for the right amount of the surface to pass to start another iteration.

3. Multithreading Requests Sending

   • Implement a multithreading approach to efficiently send the requests to the server.

4. Logging System

   • Create a comprehensive logging system to provide insights into program operation (hint: use debug levels carefully).

5. Testing and Documentation

   • Develop unitary tests for each functionality.
   • Ensure the correct documentation of your code.
   • Ensure that your code is well-structured and respects Python good code practices.

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Controllers

Two hardware controller simulators are available for your program implementation:

Cameras Controller

Controller to take pictures with the provided fake cameras. This controller has three available public methods:

• open_cameras()
  • Prepares the cameras to be ready to use.
• set_light_type()
  • Sets the light type to be enabled in the next captures.
• trigger()
  • Trigger the cameras' shutters to capture the pictures.
• collect_pictures()
  • Collects the pictures that were previously captured from all cameras with the trigger() method.

  It is possible to trigger the shutter to capture the pictures from both light types before collecting them.

Velocity Sensor Controller

Controller to get the surface planar velocity in centimeters per minute (cm/min). This controller has three available public methods:

• start_sensor()
  • Starts the velocity sensor.
• stop_sensor()
  • Stops the velocity sensor.
• get_velocity()
  • Gets the current surface planar velocity.

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Server

You have an available server to send the information that you obtain with your program. The server used to test your program will operate locally in the address 127.0.0.1:5000 and needs to be started as another process.

Note: It is up to you to select how to send the data to the server, for example, you can encode using JSON standard, but JSON do not support all the data that you need to send to the server. The person that implemented the server expects a well-specified body, but they will implement the encoder/decoder selected by you.

It has the next set of endpoints:

Note: The values used in the endpoint's body are only examples with any true meaning.

• /ping
  • Available methods: GET
  • Response status code:
    • 204 No Content
• /pictures_batch
  • Available methods: POST
  • Expected request body example:

    {
      "lights": [
        {
          "light": "blue_light",
          "creation_date": "2023-08-31 15:43:28.416324",
          "surface_velocity": 0.123,
          "surface_displacement":  1.152,
          "pictures": {
            "left": {
              "picture": "picture binary blue-left",
              "iso": 100,
              "exposure_time": 0.005,
              "diaphragm_opening": 2.8
            },
            "right": {
              "picture": "picture binary blue-right",
              "iso": 200,
              "exposure_time": 0.01,
              "diaphragm_opening": 2.8
            }
          } 
        },
        {
          "light": "green_light",
          "creation_date": "2023-08-31 15:43:31.214121",
          "surface_velocity": 0.12,
          "surface_displacement":  0.189,
          "pictures": {
            "left": {
              "picture": "picture binary green-left",
              "iso": 50,
              "exposure_time": 0.02,
              "diaphragm_opening": 4
            },
            "right": {
              "picture": "picture binary green-right",
              "iso": 200,
              "exposure_time": 0.005,
              "diaphragm_opening": 1.8
            }
          } 
        }
      ]
    }

  • Response status code:
    • 201 Created
• /surface_movement
  • Available methods: POST
  • Expected request body example:

    {
      "velocity": 0.123,
      "displacement": 4.431
    }

  • Response status code:
    • 201 Created

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