layered_hardware_gazebo

A layered_hardware implementation for the Gazebo simulator, which contains 2 types of plugins;

• GazeboLayeredHardware: a layered_hardware node running on a robot in the Gazebo simulator (as a Gazebo's model plugin)
• gazebo_joint_layer: a ros_control layer plugin running in the node above and driving joints in the virtual robot

See layered_hardware to understand the layered scheme.

Several features missing in the gazebo_ros_control package has been supported.

	This pkg	gazebo_ros_control
Types of joint hw interface	Any	Pos, Vel, or Eff
Num of hw interfaces per joint	1+	1
Joint operation modes	10+ (including mimic modes)	4 (pos, pos_pid, vel, or eff)
Online switching of joint operation modes	Yes	No
Initial joint position config	Yes	No

GazeboLayeredHardware

• a layered_hardware node running on a robot in the Gazebo simulator (as a Gazebo's model plugin)

Parameters (should be defined under <robot>/layered_hardware_gazebo)

control_frequency (double, default: 10.0)

• frequency of control step (reading from the layers, updating the controllers, and writing to the layers) in Hz with respect to the simulation time

robot_description or <node_ns>/robot_description (string, default: "")

• robot description in URDF
• if both given, robot_description will be used

layers (string array, required)

• names of layers from upper (controller-side) to bottom (actuator-side)

<layer>/type (string, required)

• lookup name for each layer plugin like 'layered_hardware/JointLimitsLayer' or 'layered_hardware_gazebo/GazeboJointLayer'

layered_hardware_gazebo/GazeboJointLayer

• a ros_control layer plugin for GazeboLayeredHardware, which implements state & command interfaces for joints in a robot model in the Gazebo simulator

Layer parameters (should be defined under <robot>/layered_hardware_gazebo/<layer>)

joints (struct, required)

• joint parameters (see below)

Joint parameters (should be defined under <robot>/layered_hardware_gazebo/<layer>/joints/<joint>)

operation_mode_map (map<string, string>, required)

• map from ROS's controller names to joint operation mode names
• possible operation mode names are 'effort', 'fixed', 'fixed_pid', 'mimic', 'mimic_pid', 'passive', 'position', 'position_pid', 'posvel', 'posvel_pid', 'velocity', & 'velocity_pid'

fixed_pid, mimic_pid, position_pid, posvel_pid, velocity_pid (struct, required when corresponding modes are used)

• PID parameters which can be loaded by control_toolbox::Pid

initial_position (double, optional)

• initial position of the joint

Example

see launch/single_joint_example.launch