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I have been trying to create a sensor that detects when a golf club hits a golf ball. My idea was to have a LIDAR sensor continuously poll the head of the golf club, and return a positive indication when the distance has changed significantly. To do this, I use the VL50l0X. However, as I get further away from the golf club (>15 cm only), the LIDAR stops sensing where the head is, returns an out of range signal. I have tried different range profiles but the same error is returned.

It is connected to the 3.3 V output on an Arduino Uno, using the example code provided by Adafruit.

I believe this may be due to the fact that the golf club is angled away from the LIDAR (about 70 degrees), as, when I substitute the golf club head for a flat surface, it works as intended. I would like to ask if there are different sensors I can look at to this application, or some other way to approach this problem. I was advised that a shock sensor would not be the best idea due to the time difference between the golf club hitting the ball and the sensor.

Null
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vernal123
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  • What time resolution do you need? and position accuracy before/during/after initial contact. 150 MPH = 67 um/us – Tony Stewart EE75 Feb 22 '22 at 17:51
  • You can use an accelerometer, either in the ball or on the club. High G Accelerometers can sample at ~10KHz. – Lior Bilia Feb 22 '22 at 18:02
  • Although the sensor has a 30 degree sensitivity cone, the laser beam is narrower. The clubhead may be leaving the cone of illumination. And as you suggest, a shiny clubhead that's angled may reflect the beam in the wrong direction. I think you'd do better with a high speed camera off to the side of the action. – Mark Leavitt Feb 22 '22 at 18:34

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What time resolution do you need? and position accuracy before/during/after init contact.

The speed of sound in air is 343 m/s. Tiger Woods has a clubhead speed is less than 150 MPH = 67 m/s or < 20% of the speed of sound.

Your ability to mount an electret mic near the sound of impact and have a low comparator threshold to the neglect the air swoosh sound but detect the start of impact sound and comparator fall time will determine how close to impact you can trigger that event.

Tony Stewart EE75
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"... if there are different sensors I can look at ..."

Before you look at other sensors, try some of these experiments, based on experience with colourimeters (NOT calorimeters!).

Cover a small ball (e.g ping-pong ball) with white, matt paint and try that. The idea is to have a) a convex surface, b) diffuse reflections. I was surprised to find that the VL50l0X datasheet does not discuss the difference between diffuse and specular reflections. (Aside: a convex surface is the opposite of what you want for a stealth fighter, which is constructed of flat panels with sharp edges. In this case it's radar, but the principles are the same).

If the above works better, try a club with with a rounded surface (a "wood", I think, but I'm not a golfer) and paint that, if the owner allows!

Next, or maybe you want to skip straight here, paint some surfaces of the iron, particularly those surfaces that are rounded.

Lastly, screen as many as possible of bright lights, particularly daylight.

GeBJT
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Use retroreflective paint, which will always return the illumination back at the source even if the angle is non-normal:

retroreflector

http://www.roadvista.com/reflective-glass-beads/

You can buy this inexpensively online and will massively increase the distance at which you can detect a tilted object optically.

user1850479
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