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Buzz on the Khepera IV
The Khepera IV is a commercial robot produced by K-Team.
A Buzz port for the Khepera IV is available at https://github.com/MISTLab/BuzzKH4. An ARGoS plugin to simulate the robot is available at https://github.com/ilpincy/argos3-kheperaiv.
Supported Devices
Actuators
- Wheels
set_wheels(lws,rws)
sets the speed of the wheels tolws
(left wheel speed) andrws
(right wheel speed). The speed is expressed in cm/sec. The maximum speed of the real Khepera is about 20 cm/sec.
gotop(ls,as)
sets the speed of the center of mass of the robot. The speed is expressed as a vector in polar coordinates, wherels
is the linear speed (i.e., the forward speed, in cm/sec) andas
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, wheresx
is the linear speed along the local x axis of the robot (i.e., the forward speed, in cm/sec) andsy
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.
- 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).
Sensors
- Proximity 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.
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:angle
, which corresponds to the angle (expressed in radians) at which the sensor is located on the body of the robotvalue
, which is the actual reading. Each individual sensor is saturated (value1.0
) 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
.