Adds the possibility to fly with precise height control. Using the ToF sensor VL53L0x the Crazyflie 2.0 can measure the distance from the sensor to a ground object at up two 2 meters.

• VL53L0x ToF sensor to measure distance up to 2 meters.
• 1-wire memory for automatic expansion deck detection
• Designed for mounting under the Crazyflie 2.0
• Mechanical specification:
  • Weight: 1.6g
  • Size (WxHxD): 21x28x4mm

Z-ranger expansion deck schematic

The Z-ranger deck will be automatically detected when it is mounted. By default the range is available on the log variable “range.range” but is not used by the firmware internal algorithm.

To enable altitude control using the Z-ranger, the Crazyflie firmware has to be recompiled with the following config.mk:

config.mk

ESTIMATOR=kalman
CFLAGS += -DUPDATE_KALMAN_WITH_RANGING -DKALMAN_DECOUPLE_XY

Once the recompiled firmware, precise height control using the altitude-hold mode. To activate precise height control press the altitude hold button on the gamepad and release the thrust. This will “lock” the height as the Crazyflie 2.0 goes into automatic height control mode. The up and down commands will then control the desired vertical speed instead of thrust.

The sensor can measure distances up to 2 meters but often fails at distances above 1.5m. In case of unreliable readings the Crazyflie 2.0 will slowly drift. If that happens bring it down to the detection range.

Note: Currently the mobile clients does not support this functionality!