Can X4M300 detect human presence when the radar is moving?

Discussion in 'Presence Sensor' started by Sheng Chong, Oct 3, 2017.

  1. Sheng Chong

    Sheng Chong New Member

    Hi all,
    I'm an university student, I'm doing a rescue robot project right now and I need a sensor that could detect vital signals. Could the sensor work correctly while the robot is moving? Or the robot must stop while the sensor is collecting the data? If it must stop, how frequently will it stop? Can I modify that? Thanks.
  2. Sheng Chong

    Sheng Chong New Member

    An additional question, the datasheet shows that the radar has a detection orientation( not 360 degrees) right? Should I rotate the sensor to cover 360 degrees?
  3. Aksel Johnsby

    Aksel Johnsby Moderator Staff Member

    Hi Sheng Chong
    The sensor must be stationary in order to detect presence and/or vital signs. It can work very well on a robot, however it need to stand still for a couple of seconds to sample, using some clever signal processing might shorten this though. The sensor does not cover 360 degrees, using two sensors might be a better idea then to rotate it.

    The sensor is however a great tool for rescuing due to its ability to see through rubble and snow.

    Good luck on your project :)
  4. Lovexethru

    Lovexethru New Member

    Somewhat related to this: So, if not 360 degrees, it does cover 180 degrees - the opposite side of that cage/radar chip (as I picture below)? Is there a way to limit or deactivate certain sites? i.e. the vertical detection to prevent detecting anything above (i.e. 5m) and below the sensor's facing side but do allow detection happening horizontally (maybe up to 9m). Imagine a situation in a high rise appartment building where you would want to cover movements in a larger room horizontally, but not up or down to the floors of your neighbors.

    The datasheet talks about a detection zone (which I only see two boundary numbers in the APIs for (min/max), which then would apply to all sides equally? It also mentions a detection range but that seems to cover what kind of presence the sensor looks for (i.e. respiration, fast, slow movement). On the latter: where is the Python API for that? I mean the below; assume the picture (0,0), means it has the highest detection range (9m) in all directions facing the sensor (180 degrees)?
  5. Øystein Bjørndal

    Øystein Bjørndal New Member

    The radar sensor basically looks in all 360 degrees around it, and is only able to distinguish radial distance from the sensor (as long as you are using only a single sensor). Due to the physical nature of the antenna, energy from certain angles will however be suppressed, so that amplitude at say the 0/0 angle will be significantly lower than the 90/0 angle. Google "antenna gain" for more information.

    What Novelda is reporting in the above table is that at 0/0 the backscattered signal is strong enough so that you can detect respiration at 9.4 meters, while, due to the low sensitivity at the 90/0 angle, you need to be closer than 1.8 meters.

    To achieve: "Is there a way to limit or deactivate certain sites?" Short answer: No, long answer:
    You can theoretically develop your own antenna with your desired antenna profile or use multiple sensors. Theoretically you could also use the amplitude of the backscattered signal to distinguish angle, but this will be very unreliable.

    Hope that clarifies,