HexapodCopter.md

Hexapod Copter

A Gazebo model for a hexapod copter (a hexapod rover with motors on each arm).

The original quadruped version of this frame is the result of Ashvath's project GSoC 2020: Walking Robot Support For Ardupilot.

The frame is fully articulated. Each of the 6 legs has 3 joints, however only 16 are actuated. The middle two 'hip' joints are fixed in this example. The motor ordering and orientation is the same as a standard hexa X frame, however in this case the FRAME_CLASS 17 (Dynamic Scripting Matrix) and the motor mixing is set in the Lua script.

The legs have two positions - folded when disarmed, and unfolded when armed.

If the scripting control of the legs is disabled they may be moved using gz topic commands:

# move the mid right femur joint down from its initial position of -0.6 rad to -0.4 rad 
gz topic -t "/femur_mr_joint/cmd_pos" -m gz.msgs.Double -p "data: -0.4"

Usage

Gazebo and the plugins should be installed as per the ArduPilot Gazebo Plugin instructions.

Update the GZ_SIM_RESOURCE_PATH to include these models:

export GZ_SIM_RESOURCE_PATH=$GZ_SIM_RESOURCE_PATH:\
$HOME/SITL_Models/Gazebo/models:\
$HOME/SITL_Models/Gazebo/worlds

Run Gazebo

gz sim -v4 -r hexapod_copter_runway.sdf

Run ArduPilot SITL

Copy the script $HOME/SITL_Models/Gazebo/scripts/hexapod_copter.lua to the SITL scripts directory, then start SITL:

sim_vehicle.py -v ArduCopter -f hexa --model JSON --add-param-file=$HOME/SITL_Models/Gazebo/config/hexapod_copter.param --console --map

Dimensions

• height: 53.23 mm
• coxa_axis_width: 101.42 mm
• coxa_axis_length: 177.03 mm
• coxa_axis_to_femur_axis: 30.0 mm
• femur_axis_to_tibia_axis: 76.17 mm
• tibia_axis_to_foot: 122.0 mm

Credits

Hexapod CAD model

• Author: Tim Mills
• Model: Hexapod Robot