spot_controllers

This is a ROS 2 package that provides custom ROS 2 controllers that can be used with spot_ros2_control.

This package contains two controllers: spot_controllers/ForwardStateController and spot_controllers/SpotJointController and one broadcaster: spot_controllers/FootStateBroadcaster. Example configurations for setting up this controllers can be found in spot_ros2_control/config.

ForwardStateController

This is a generic controller allows you to directly forward a set of commands over a set of interfaces. It builds on top of ROS 2 control’s forward_command_controller. It is used with spot_ros2_control to forwad commands for position, velocity, and effort for all joints at the same time.

SpotJointController

This is a streaming controller specific to Spot’s hardware interface, used to directly forward any subset of position, velocity, load, k_q_p, and k_qd_p over any subset of Spot’s joints. It receives commands of type spot_msgs/msg/JointCommand, which is almost the same as a sensor_msgs/msg/JointState message but with extra fields for Spot’s k_q_p and k_qd_p command interfaces. This controller claims all command interfaces of the robot on activation, but your JointCommands do not have to contain commands for all interfaces – they can just contain a subset. The name field in this topic should contain the names of the joints you wish to control, and for each entry in name, you can fill one or more of the elements in postition, velocity, effort, k_q_p, or k_qd_p. Any interfaces that are not specified in this message will be left unchanged at their last commanded value.

For example, to send one position command to one joint, the joint command would be formed such as:

name: ["joint_1"]
postion: [1.0]
velocity: []
effort: []
k_q_p: []
k_qd_p: []

Or to control position, velocity, and k_qd_p of 3 different joints:

name: ["joint_1", "joint_2", "joint_3"]
postion: [1.0, 2.0, 3.0]
velocity: []
effort: [4.0, 5.0, 6.0]
k_q_p: []
k_qd_p: [7.0, 8.0, 9.0]

FootStateBroadcaster

This is a broadcaster that will publish the feet contact states of Spot onto a topic spot_msgs/msg/FootStateArray. Each message contains four FootState messages filled in with the appropriate contact field, that correspond in order to the contacts for the front left, front right, rear left, and rear right feet. 0 corresponds to an unknown contact, 1 corresponds to the foot being in contact in the floor, and 2 corresponds to the foot not being in contact with the floor. Note that in contrast to the FootState published by the high level driver, Spot’s streaming interface for foot contacts does NOT contain an estimate for the foot’s position with respect to the body. Therefore, the foot_position_rt_body field of the FootState message is not filled in and should be disregarded.