Differences

This shows you the differences between two versions of the page.

--- buzz_kh4 [2018/03/20 00:33] – [Actuators] root
+++ buzz_kh4 [2019/03/31 19:39] – [Sensors] ilpincy
@@ Line 11: / Line 11: @@
   * **Wheels**
-    * ''set_wheels()''
+    * ''set_wheels(lws,rws)'' sets the speed of the wheels to ''lws'' (left wheel speed) and ''rws'' (right wheel speed). The speed is expressed in cm/sec. The maximum speed of the real Khepera is about 20 cm/sec.
-    * ''gotop()''
+    * ''gotop(ls,as)'' sets the speed of the center of mass of the robot. The speed is expressed as a vector in polar coordinates, where ''ls'' is the linear speed (i.e., the forward speed, in cm/sec) and ''as'' is the angular speed (i.e., in rad/sec). The vector is internally transformed into wheel actuation.
+    * ''gotoc(sx,sy)'' sets the speed of the center of mass of the robot. The speed is expressed as a vector in cartesian coordinate, where ''sx'' is the linear speed along the local x axis of the robot (i.e., the forward speed, in cm/sec) and ''sy'' is the linear speed along the local y axis of the robot (a vector pointing left, according to the right-hand rule). The vector is internally transformed into wheel actuation.
+    * To activate this actuator in ARGoS, use the ''differential_drive'' actuator.
-    * ''gotoc()''
   * **LEDs**
-    * ''set_leds()''
+    * ''set_leds(r,g,b)'' sets the color of the three LEDs on top of the Khepera IV. The color is expressed with 0-255 values for each of the channels (red, green, blue).
+    * To activate this actuator in ARGoS, use the ''leds'' actuator.
 ==== Sensors ====
-  * Proximity sensors
+  * **Proximity sensors**
-  * Light sensors
+    * The Khepera IV proximity sensor is a set of 8 infrared emitter/receiver pairs distributed regularly in a ring around the robot. The sensors are numbered 0 to 7. Sensor 0 looks straight ahead, and the numbers increase counterclockwise when looking at the robot from above.
-  * Ultrasound distance sensor
+    * ''proximity'' is the Buzz table that contains the proximity readings. Each element of this table (e.g., ''proximity[0]'', ''proximity[1]'', ...) is in turn a table that contains two elements:
-  * LIDAR
+      * ''angle'', which corresponds to the angle (expressed in radians) at which the sensor is located on the body of the robot
+      * ''value'', which is the actual reading. Each individual sensor is saturated (value ''1.0'') by objects closer than 4 cm; the maximum range of the sensor is 12 cm. Between 4 and 12 cm, the readings follow an exponential law with the distance: ''%%4.14*exp(-33.0*distance)-.085%%''.
+      * To activate this sensor in ARGoS, use the ''kheperaiv_proximity'' sensor.
+  * **Light sensors**
+    * The Khepera IV light sensor is a set of 8 infrared emitter/receiver pairs distributed regularly in a ring around the robot. The sensors are numbered 0 to 7. Sensor 0 looks straight ahead, and the numbers increase counterclockwise when looking at the robot from above.
+    * ''light'' is the Buzz table that contains the light readings. Each element of this table (e.g., ''light[0]'', ''light[1]'', ...) is in turn a table that contains two elements:
+      * ''angle'', which corresponds to the angle (expressed in radians) at which the sensor is located on the body of the robot
+      * ''value'', which is the actual reading. The sensors all return a value
+between 0 and 1, where 0 means nothing within range and 1 means the perceived
+light saturates the sensor. Values between 0 and 1 depend on the distance of the perceived light. In ARGoS, each reading ''R'' is calculated with ''%%R=(I/x)^2%%'', where ''x'' is the distance between a sensor and the light, and ''I'' is the reference intensity of the perceived light. The reference intensity corresponds to the minimum distance at which the light saturates a sensor.
+      * To activate this sensor in ARGoS, use the ''kheperaiv_light'' sensor.
+  * **Ultrasound sensors**
+    * The Khepera IV ultrasound sensor is a set of 5 emitter/receiver pairs distributed regularly in an arc in front of the robot. The sensors are numbered 0 to 4. Sensor 0 looks straight ahead, and the numbers increase counterclockwise when looking at the robot from above.
+    * ''ultrasound'' is the Buzz table that contains the ultrasound readings. Each element of this table (e.g., ''ultrasound[0]'', ''ultrasound[1]'', ...) is in turn a table that contains two elements:
+      * ''angle'', which corresponds to the angle (expressed in radians) at which the sensor is located on the body of the robot
+      * ''value'', which is the actual distance of the detected obstacle in cm. Each individual sensor is saturated by objects closer than 25 cm; the maximum range of the sensor is 200 cm.
+      * To activate this sensor in ARGoS, use the ''kheperaiv_ultrasound'' sensor.
+  * **LIDAR sensor**
+    * The Khepera IV LIDAR sensor returns 682 readings in a 270 degrees arc (if not configured to return less readings in the ''.argos'' file).
+    * ''lidar'' is the Buzz table that contains the LIDAR readings. Each element of this table (e.g., ''lidar[0]'', ''lidar[1]'', ...) is the distance of the object detected by a specific laser beam.
+      * To activate this sensor in ARGoS, use the ''kheperaiv_lidar'' sensor.
+  * **Battery sensor**
+    * This sensor returns the state of the battery.
+    * ''battery'' is a table that contains two elements:
+      * ''%%available_charge%%'', a value between 0.0 and 1.0
+      * ''%%time_left%%'', the number of control steps before battery depletion
+      * To activate this sensor in ARGoS, use the ''battery'' sensor.
+  * **Positioning sensor** (ARGoS only)
+    * This sensor is a sort of GPS, only available in ARGoS. The positioning sensor returns the current pose of the robot.
+    * ''pose'' is a table that contains two elements:
+      * ''position'', a 3D array ''{x, y, z}''
+      * ''orientation'', an array ''{yaw, pitch, roll}''
+      * To activate this sensor in ARGoS, use the ''positioning'' sensor.