A lidar 3d scanner built for lidar lite (HP) units. It takes one measurement per angle and calculates them into a 3d grid. It uses two SG90 servo motors for moving along X and Y axis.
The project includes firmware + software (GUI) and build instructions.
DEMOS (3D Web View):
- room.fscan
- room2.fscan
- room_with_mirror_and_door.fscan
- humans_fast_scan.fscan
- room_quad_mode.fscan
- stairs_and_hall.fscan
I have 3D printed the arm from a model by @fbuenonet on thingiverse. After that I just drilled holes to mount the Lidar Lite, they fit perfectly into the edges.
Connect LiDAR and servos as following:
| LiDAR / Servos | PICO |
|---|---|
| 5V (servos and LiDAR) | VBUS |
| GND | GND |
| SDA LiDAR | GP16 |
| SCL LiDAR | GP17 |
| Servo X | GP18 |
| Servo Y | GP19 |
I have added a breakout board with capacitors and some resistors to add stability and ease of use.
TODO: schematic of breakout board
To build the fimware for a RP2040 controller you need the pico SDK and the cmake toolchain.
mkdir build && cd build && cmake .. && make
A lidar.uf2 executable will be built and to flash it, just hold down the BOOTSEL button on the Pi Pico and drag the uf2 file to the flash drive.
If everything is connected right and the firmware is flashed, the Pico should appear as a serial device, e.g. /dev/ttyACM0 on Linux or COM6 on windows. Note that these may vary depending on which system you are using. Run lidar_3d_gui/main.py, select the correct LiDAR port (baud rate is already set to 115200) and click connect. You will see a success dialog indicating that the sensor is connected properly.
Note: When you reboot the device or disconnect it, you have to restart the software.
Horizontal FOV: maximum horizontal scan angle is hardcoded to 180°, as the servos I used and the ones fitting into the case only have a range of 0° - 180°
TOP / LOWER FOV: The field of view over or under the middle position. They are hardcoded to limited values because else the sensor and motors can be damaged when going into the construction.
You may select an already recorded .fscan file and plot it in your browser.
In the first box you can either select single or quad mode:
- single: In single mode one measurement is taken per angle
- quad: In quad mode 4 measurements are taken per angle and the average is calculated. This mode results in better quality scans and a sharper image overall, but the scan time is a lot longer. Not recommended for test scans
I will quickly explain the buttons underneath:
- Start Scan: run full scan wil FOV settings from settings tab. Save the finished
.fscanfile at specified location. - Go Scale: Move the motors along an outline of the area to be scanned. Basically only useful when a visible laser diode is attached to the device to get an overview of the area to be scanned.
- Park Position: In my setup, the sensor had a big overhang before it. In Park Position the sensor will move up left and reboot into BOOTSEL mode. The desktop application will shut down.
I don't think I have to add to this one
The configuration for the LiDAR Lite v3 HP is written in lidar_lite_v3hp.h:
#define LIDAR_ACQ_COMMAND 0x00
#define LIDAR_STATUS 0x01
#define LIDAR_SIG_COUNT_VAL 0x02
#define LIDAR_ACQ_CONFIG_REG 0x04
#define LIDAR_LEGACY_RESET_EN 0x06
#define LIDAR_SIGNAL_STRENGTH 0x0e
#define LIDAR_FULL_DELAY_HIGH 0x0f
#define LIDAR_FULL_DELAY_LOW 0x10
#define LIDAR_REF_COUNT_VAL 0x12
#define LIDAR_UNIT_ID_HIGH 0x16
#define LIDAR_UNIT_ID_LOW 0x17
#define LIDAR_I2C_ID_HIGH 0x18
#define LIDAR_I2C_ID_LOW 0x19
#define LIDAR_I2C_SEC_ADDR 0x1a
#define LIDAR_THRESHHOLD_BYPASS 0x1c
#define LIDAR_I2C_CONFIG 0x1e
#define LIDAR_PEAK_STACK_HIGH_BYTE 0x26
#define LIDAR_PEAK_STACK_LOW_BYTE 0x27
#define LIDAR_COMMAND 0x40
#define LIDAR_HEALTH_STATUS 0x48
#define LIDAR_CORR_DATA 0x52
#define LIDAR_CORR_DATA_SIGN 0x53
#define LIDAR_POWER_CONTROL 0x65To use other LiDAR Lite models replace the hex values with corresponding ones in the datasheet.
