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LIDAR meets VCR technology for fast 360° scans

Not obsolete, just forgot. VCR head drum motor used as a base of a compact LIDAR for more advanced DIY scanners.

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The goal of this project is to create a LIDAR system to sense the surrounding space. For this instead of 3D printed base with regular DC motors, and slip-ring I will reuse an old VCR drum motor, to show a "new" way for home made LIDAR bases. Another criterion is to use components available for everybody, and the low price-tag.

Autonomous driving,  self-propelled drones, 3D mapping. All of them using fast and precise sensors to sense the surrounding space. It can be ultrasonic or optical or even radar.

One of the most advanced and widely used sensor type nowadays is the LIDAR, which is using a laser beam to measure distance continuously. 

Not the topics which first comes to your mind when you look at your old dusty VHS player on your shelf or a VCR camcorder not used since the 90’s. 

But as you already know from the title one thing is common between the two devices.

LIDAR has two main part, one is the laser and sensor module, and the other is a rotating base with position feedback. 

In the era of the 3D printing it is very easy to make the rotating base, (or even brushless motor), and cheap but precise Time-of-Flight (ToF) sensors can be bought, like the VL53L0X which is also used in this project. 

The tricky part is how to transfer data between the rotating head and the stationary base. You can scan the space back and forth, but it is not 360° than, or use slip rings, but it has limited rotational speed and not maintenance free because of the mechanical construction.

This the point where the VCR drum motor comes handy. It has two sections, a brushless motor with position feedback, and a rotating head with rotary transformer to transfer data without physical contact. All what is needed for the LIDAR, it just has to be controlled.

  • 1 × DGH-90A-R Drum motor
  • 1 × VL53L0X or VL53L1X Time-of-Flight (ToF) ranging sensor
  • 1 × NAZE32 REV6a 10 DOF 10 DOF Flight Controller for Multicopter
  • 2 × LTC4310 Hot-Swappable I2C Isolators

  • New components for the project

    Roland Varga07/31/2018 at 09:28 1 comment

    After a long time when I put off this project the new time-of-flight sensor was introduced by ST, VL53L1X, which is pin-to-pin compatible with the VL53L0X, but it's able to measure longer distances. Therefore it was a logical decision to change to this sensor.

    Also I thought a lot of sending the I2C data trough the rotary transformer lines. The  drum motor has 3 separate rotary transformer lines, and I will dedicate one line for the power supply of the sensors.  Therefore 2 remain for the data sending. One of my ideas was to place an attiny or an other small microcontroller which converts the I2C signals to a custom serial communication, or to a PWM based signal. These ideas require a dedicated circuits on the rotating head and on the base as well, and a custom SW for the coding/decoding of the signals, which probably decrease the sample rate.

    Then I came across with the LTC6820 which provides bidirectional SPI communications between two isolated devices through a single twistedpair connection. I thought it has to be created for I2C as well, and sure Analog Devices has the IC with same functionality, but for I2C.

    So this will be the next milestone to try out the LTC4310 with the rotary transformer, and send data from the VL53L1X.

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