Skill `look_at`

Version: 1.0.0
Default path: /skill/look_at
Datatype: interaction_skills/action/LookAt
Definition source: package.xml in ros4hri/interaction_skills

Defines the gazing direction of the robot. This skill can be used to either look at a specific point in space (a ROS tf frame), or to set a generic gaze policy, such as looking at people around the robot.

Using the glance policy, you can also use this skill to brielfy look at a specific point in space, before returning to the previous gaze policy.

Input parameters

policy string

One of the policies below, or empty string (in that case, the robot will look atpoint in space specified with the target parameter).

Available policies:
- random: randomly look around, with short fixations
- social: look around for faces, with fixations on detected faces
- glance: glance at a specific point in space, then return to the previous gaze policy. target must be specified.
- auto: automatic gaze policy, implementation-dependent. On PAL interactive robots, equivalent to social.
- reset: reset the gaze of the robot to looking straight.
target geometry_msgs/msg/PointStamped

tf frame to track. Ignored if the policy parameter is set to one of the predefined policies.

Quick snippets

Call the skill from the command-line

$ ros2 action send_goal /skill/look_at interaction_skills/action/LookAt # then press Tab to complete the message prototype

Call the action from a Python script:

#!/usr/bin/env python

import rclpy
from rclpy.action import ActionClient
from rclpy.node import Node

from interaction_skills.action import

class LookatActionClient(Node):

    def __init__(self):
        super().__init__('look_at_client')
        self._action_client = ActionClient(self, , '/skill/look_at')

    def send_goal(self, a, b):
        goal_msg = .Goal()

        # TODO: adapt to the action's parameters

        # check the LookAtGoal message
        # definition for the possible goal parameters

        # goal_msg.a = a
        # goal_msg.b = b

        self._action_client.wait_for_server()

        return self._action_client.send_goal_async(goal_msg)

if __name__ == '__main__':
    rclpy.init(args=args)

    action_client = ActionClient()

    # TODO: adapt to your action's parameters
    future = action_client.send_goal(a, b)

    rclpy.spin_until_future_complete(action_client, future)

    rclpy.shutdown()

Call the action from a C++ program:

#include <functional>
#include <future>
#include <memory>
#include <string>
#include <sstream>
#include <chrono>

#include "interaction_skills/action/.hpp"

#include "rclcpp/rclcpp.hpp"
#include "rclcpp_action/rclcpp_hpp"
#include "rclcpp_components/register_node_macro.hpp"

using namespace std::chrono_literals;
using namespace std;

class LookatActionClient : public rclcpp::Node
{
public:
  using  = interaction_skills::action::;
  using GoalHandle = rclcpp_action::ClientGoalHandle<>;

  explicit LookatActionClient(const rclcpp::NodeOptions & options)
  : Node("look_at_action_client", options)
  {
    this->client_ptr_ = rclcpp_action::create_client<>(
            this,
            "");

    this->timer_ = this->create_wall_timer(
            500ms,
            bind(&LookatActionClient::send_goal, this));
  }

  void send_goal()
  {
    using namespace std::placeholders;

    this->timer_->cancel();

    if (!this->client_ptr_->wait_for_action_server()) {
      RCLCPP_ERROR(this->get_logger(), "Action server not available after waiting");
      rclcpp::shutdown();
    }

    auto goal_msg = ::Goal();


    // check the LookAtGoal message
    // definition for the possible goal parameters

    // goal_msg.... = ...;

    RCLCPP_INFO(this->get_logger(), "Sending goal");

    auto send_goal_options = rclcpp_action::Client<>::SendGoalOptions();

    send_goal_options.goal_response_callback =
        bind(&LookatActionClient::goal_response_callback, this, _1);

    send_goal_options.feedback_callback =
        bind(&LookatActionClient::feedback_callback, this, _1, _2);

    send_goal_options.result_callback =
        bind(&LookatActionClient::result_callback, this, _1);


    this->client_ptr_->async_send_goal(goal_msg, send_goal_options);
  }

private:
  rclcpp_action::Client<>::SharedPtr client_ptr_;
  rclcpp::TimerBase::SharedPtr timer_;

  void goal_response_callback(const GoalHandle::SharedPtr & goal_handle)
  {
    if (!goal_handle) {
      RCLCPP_ERROR(this->get_logger(), "Goal was rejected by server");
    } else {
      RCLCPP_INFO(this->get_logger(), "Goal accepted by server, waiting for result");
    }
  }

  void feedback_callback(
      GoalHandle::SharedPtr,
      const shared_ptr<const ::Feedback> feedback)
  {
    stringstream ss;
    ss << "Next number in sequence received: ";
    for (auto number : feedback->partial_sequence) {
      ss << number << " ";
    }
    RCLCPP_INFO(this->get_logger(), ss.str().c_str());
  }

  void result_callback(const GoalHandle::WrappedResult & result)
  {
    switch (result.code) {
      case rclcpp_action::ResultCode::SUCCEEDED:
          break;
      case rclcpp_action::ResultCode::ABORTED:
          RCLCPP_ERROR(this->get_logger(), "Goal was aborted");
          return;
      case rclcpp_action::ResultCode::CANCELED:
          RCLCPP_ERROR(this->get_logger(), "Goal was canceled");
          return;
      default:
          RCLCPP_ERROR(this->get_logger(), "Unknown result code");
          return;
    }
    stringstream ss;
    ss << "Result received: ";
    for (auto number : result.result->sequence) {
      ss << number << " ";
    }
    RCLCPP_INFO(this->get_logger(), ss.str().c_str());
    rclcpp::shutdown();
  }
};  // class LookatActionClient


RCLCPP_COMPONENTS_REGISTER_NODE(LookatActionClient)

You can call this skill from QML using the following code snippet. See ros_qml_plugin to learn more.

import Ros 2.0

// ...
LookAtSkill {
    id: mySkill

    onResult: {
        console.log("Skill result: " + result);
    }
    onFeedback: {
        console.log("Skill feedback: " + feedback);
    }

}

// Call the skill
mySkill.look_at();

Skill look_at

Input parameters

Quick snippets

See also

Skill `look_at`