cbf_tracking/src/sim/unicycle_sim.cpp at main · nocholasrift/cbf_tracking · GitHub

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#include <ros/ros.h>
#include <std_srvs/Empty.h>
#include <nav_msgs/Odometry.h>
#include <geometry_msgs/Twist.h>
#include <tf/transform_broadcaster.h>

class Robot
{
public:
    Robot(ros::NodeHandle &nh, double hz){
        odom_pub_ = nh.advertise<nav_msgs::Odometry>("/odometry/filtered", 1);

        cmd_vel_sub_ = nh.subscribe("cmd_vel", 1, &Robot::cmd_vel_callback, this);

        dt_ = 1.0/hz;

        state_ = {0.0, 0.0, 0.0};
        desired_input_ = {0.0, 0.0};

        max_v_ = 2.0;
        max_w_ = 1.8;

        is_paused = false;

        // setup timer to run update_state at dt_
        timer_ = nh.createTimer(ros::Duration(dt_), &Robot::update_state, this);

        // ros service for resetting the robot
        reset_srv_ = nh.advertiseService("reset", &Robot::reset_callback, this);
        pause_srv_ = nh.advertiseService("pause", &Robot::pause_callback, this);


        nh.param("unicycle_sim/x", state_[0], 0.0);
        nh.param("unicycle_sim/y", state_[1], 0.0);
        nh.param("unicycle_sim/yaw", state_[2], 0.0);

        nh.param("unicycle_sim/frame_id", frame_id_, std::string("odom"));
        nh.param("unicycle_sim/child_frame_id", child_frame_id_, std::string("base_link"));
    }

    void cmd_vel_callback(const geometry_msgs::Twist::ConstPtr& msg){
        desired_input_ = {msg->linear.x, msg->angular.z};
        desired_input_[0] = std::max(std::min(desired_input_[0], max_v_), -max_v_);
        desired_input_[1] = std::max(std::min(desired_input_[1], max_w_), -max_w_);
    }

    void publishTrail(){
        return;
    }

    bool reset_callback(std_srvs::Empty::Request& req, std_srvs::Empty::Response& res){
        state_ = {0.0, 0.0, 0.0};
        desired_input_ = {0.0, 0.0};
        return true;
    }

    bool pause_callback(std_srvs::Empty::Request& req, std_srvs::Empty::Response& res){
        is_paused = true;
        return true;
    }

    void update_state(const ros::TimerEvent& event){
        if (is_paused){
            return;
        }

        // use discretized unicycle dynamics
        double v0 = desired_input_[0];
        double w0 = desired_input_[1];

        if (fabs(w0) < 1e-6){
            state_[0] = state_[0] + v0*dt_*cos(state_[2]);
            state_[1] = state_[1] + v0*dt_*sin(state_[2]);
        }
        else{
            state_[0] = state_[0] + (v0/w0)*(sin(state_[2] + w0*dt_) - sin(state_[2]));
            state_[1] = state_[1] + (v0/w0)*(-cos(state_[2] + w0*dt_) + cos(state_[2]));
        }

        state_[2] = state_[2] + w0*dt_;

        // publish odometry
        nav_msgs::Odometry odom;
        odom.header.stamp = ros::Time::now();
        odom.header.frame_id = frame_id_;
        odom.child_frame_id = "base_link";
        odom.pose.pose.position.x = state_[0];
        odom.pose.pose.position.y = state_[1];
        odom.pose.pose.position.z = 0.0;
        odom.pose.pose.orientation = tf::createQuaternionMsgFromYaw(state_[2]);

        odom.twist.twist.linear.x = v0;
        odom.twist.twist.angular.z = w0;

        odom_pub_.publish(odom);
    }

    void spin(){
        ros::AsyncSpinner spinner(1);
        spinner.start();

        ros::waitForShutdown();
    }

    bool initialized;
    bool is_paused;

protected:
    ros::NodeHandle nh_;

    ros::Publisher odom_pub_;
    ros::Publisher trail_pub_;

    ros::Subscriber cmd_vel_sub_;

    ros::ServiceServer reset_srv_;
    ros::ServiceServer pause_srv_;

    ros::Timer timer_;

    std::vector<double> state_;

    std::vector<double> desired_input_;
    std::vector<std::tuple<double, double>> trail_;

    double dt_;

    double max_v_;
    double max_w_;

    std::string frame_id_;
    std::string child_frame_id_;
};


int main(int argc, char** argv) {
    ros::init(argc, argv, "unicycle_sim");
    ros::NodeHandle nh;

    Robot robot(nh, 50.);
    robot.spin();

    return 0;
}