CentraleNantesROV/auv_control

Control nodes for position / velocity / wrench tracking with a AUV

Basic control nodes for a AUV

This package contains two nodes to perform position and velocity control of an AUV.

Dependencies

• thruster_manager for the thrust allocation
• simple_launch for the launch files
• slider_publisher for basic GUI to run tests

Common properties

All controllers subscribe to the following:

• cmd_pos (PoseStamped): the pose setpoint expressed in the header frame
• cmd_vel (TwistStamped): the velocity setpoint expressed in the header frame
• state (Odometry): an estimation of the current state (pose + velocity) of the vehicle
• /tf: to get the transforms between all frames

The output may be:

• cmd_thrust (JointState): only the effort field is populated with the corresponding thrust for this thruster
• <thruster>_cmd (Double): the desired thrust for this thruster. This output is compatible with Gazebo thruster plugin.

Cascaded PID

This controller takes 4 gains per axis: Kp, Kd, Ki, Kv.

In addition, two saturation values may be given: v_sat (velocity saturation) and u_sat (overall wrench saturation). u_sat can be retrieved from the model of the robot if the max thrust is given.

The parameter use_position, given per-axis, tell if the position setpoint should be used for this component.

All gains and parameters are prefixed with the name of the axis: x.Kp, x.Kv, etc.

The overall control is as follows:

• without position control: velocity error e = Kv.(v*-v)
• with position control: velocity error e = Kv.(v*-v) + sat(p*-p), -v_sat, v_sat)
• output command u = sat(Kp.e + Ki.integral(e) - Kd.derivative(e), -u_sat, u_sat)