.

src/tutorial_pkg/src/img_control.cpp

@@ -0,0 +1,56 @@
+#include <ros/ros.h>
+#include <std_msgs/Float32MultiArray.h>
+#include <geometry_msgs/Twist.h>
+
+// Set value according to your image number in your img_data folder.
+#define ARROW_RIGHT 4
+#define ARROW_UP 5
+#define ARROW_LEFT 6
+
+ros::Publisher vel_pub;
+geometry_msgs::Twist vel_msg;
+
+void objectCallback(const std_msgs::Float32MultiArrayPtr &object)
+{
+    if (object->data.size() > 0){
+        int id = object->data[0];
+
+        switch (id){
+            case ARROW_RIGHT:
+                vel_msg.linear.x = 0;
+                vel_msg.angular.z = -1;
+                break;
+            case ARROW_UP:
+                vel_msg.linear.x = 0.5;
+                vel_msg.angular.z = 0;
+                break;
+            case ARROW_LEFT:
+                vel_msg.linear.x = 0;
+                vel_msg.angular.z = 1;
+                break;
+            default: // other object
+                vel_msg.linear.x = 0;
+                vel_msg.angular.z = 0;
+        }
+    }
+    else{
+        vel_msg.linear.x = 0;
+        vel_msg.angular.z = 0;
+    }
+
+    vel_pub.publish(vel_msg);
+}
+
+int main(int argc, char **argv)
+{
+    ros::init(argc, argv, "img_control");
+    ros::NodeHandle n("~");
+    ros::Rate loop_rate(30);
+    ros::Subscriber sub = n.subscribe("/objects", 1, objectCallback);
+    vel_pub = n.advertise<geometry_msgs::Twist>("/cmd_vel", 1);
+    while (ros::ok())
+    {
+        ros::spinOnce();
+        loop_rate.sleep();
+    }
+}