Documentation Author
F.Lambercy and G.Caprari for K-Team S.A.
Rue Galilee 9
1400 Yverdon-les-bains
Switzerland
email: inf o@k-team.com
Url: www.k-team.com
Trademark Acknowledgments:
IBM PC: International Business Machine Corp.
Khepera: K-Team and LAMI
Legal Notice:
• The content of this manual is subject to change without notice.
• All effort h ave been made to ensure the accuracy of the content of
this manual. However, should any error be detected, please inform
K-Team S.A.
• The above notwithstanding K-Team can assume no responsibility for
any error in this manual.
Khepera III manual ver 2.2 1
Table Of Contents
1 Introduction 4
1.1 How to Use this Manual . . . . . . . . . . . . . . . . . . . . . 4
1.2 Safety Precaution . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Unpacking and Inspection 6
3 The Robot and Its Accessories 7
3.1 The Khepera III Robot . . . . . . . . . . . . . . . . . . . . . 7
3.1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.2 ON-OFF Battery Switch . . . . . . . . . . . . . . . . . 8
3.1.3 Indication LEDs . . . . . . . . . . . . . . . . . . . . . 8
3.1.4 Serial connector . . . . . . . . . . . . . . . . . . . . . 9
3.1.5 Cable un roller connector . . . . . . . . . . . . . . . . . 10
3.1.6 USB connector . . . . . . . . . . . . . . . . . . . . . . 10
3.1.7 How to plug a KoreBotLE . . . . . . . . . . . . . . . . 11
3.2 Motors and motor control . . . . . . . . . . . . . . . . . . . . 12
3.2.1 Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3 Infra-red Proximity sensors . . . . . . . . . . . . . . . . . . . 16
3.3.1 Ambient light measurements . . . . . . . . . . . . . . 17
3.3.2 Reflected light measurements (proximity) . . . . . . . 17
3.4 Ultrasonic sensors . . . . . . . . . . . . . . . . . . . . . . . . 18
3.5 Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4 Connections 20
4.1 Configuration for batteries charge . . . . . . . . . . . . . . . . 20
4.2 Configuration for Robot-Computer Communication in standalone 21
4.3 Configuration for Robot-Computer Communication with KoreBotLE 22
4.3.1 Serial link . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.3.2 USB link . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.4 Bluetooth Communication . . . . . . . . . . . . . . . . . . . . 24
4.4.1 Bluetooth communication with KheperaIII . . . . . . 24
4.4.2 Bluetooth communication with KoreBotLE . . . . . . 25
4.4.3 Log On the KoreBotLE with a Bluetooth connection . 25
K-Team S.A. 2
5 Serial Communication Mode 26
5.1 Testing the primary serial link . . . . . . . . . . . . . . . . . 26
5.2 Testing the secondary serial link . . . . . . . . . . . . . . . . 27
5.3 Serial communication protocol . . . . . . . . . . . . . . . . . 28
5.3.1 Testing a simple interaction . . . . . . . . . . . . . . . 28
6 KoreBotLE programming 30
A Communication protocol 33
Khepera III manual ver 2.2 3
1 Introduction
1.1 How to Use this Manual
This manual is introdu cing the Khepera III robot. For a quick start and
overview of the robot’s functions, please read chapter 1 to 4.
Refer to the following summary if a particular information is needed.
If the manual does not cover a particular problem, many more technical
documentation is available online from K-Team website (www.k-team.com
)
and especially a Frequently Asked Question document to solve most common
problems and questions.
Unpacking a nd Inspection: Khepera’s package description.
The robot and its accessories: Khepera Hardware overview and main
functions and accessories description.
Connections: detailed cables connections for various usage.
Serial Communication mode: detailed description for the Serial com-
munication mode between a computer and the robot.
1.2 Safety Precaution
Check the unit’s operating voltage before operation.
It must be identical with that of your local power supply. The operating
voltage is indicated on the nameplate at the rear of the power supply.
All connnections (including extension addition or disconnection) must
be made when the robot and the interface are switched OFF. Otherwise
damages can occur.
Switch OFF the robot if you will not use it for more than a day.
Disconnect the power supply removing it from the wall socket.
Do not manually force any mechanical movement.
Avoid to force, by any mechanical way, the movement of the wheels or
any other part.
If you have any question or problem concerning the robot, please contact
your local Khepera dealer.
K-Team S.A. 4
1.3 Recycling
Think about the end of life of your robot! Parts of the robot can be recycled
and it is important to do so. It is for instance important to keep batteries
out of th e solid waste stream. When you throw away a battery, it eventually
ends up in a landfill or municipal incinerator. These batteries, which contain
heavy metals, can contribute to the toxicity levels of landfills or incinerator
ash. By recycling the batteries through recycling programs, you can help to
create a cleaner and safer environment for generations to come. For those
reasons please take care to the recycling of your robot at the end of its life
cycle, for instance sendin g back the robot to the manufacturer or to your
local dealer.
Thanks for your contribution to a cleaner environment!
Khepera III manual ver 2.2 5
2 Unpacking and Inspection
Open the bag and check each item in the box. You should having the
following material.
1. Khepera III robot
2. KoreBotLE ( not included in the Khepera III base package )
3. Power Supply with a primary plug
4. Battery Pack
5. Optional KoreConnect
K-Team S.A. 6
3 The Robot and Its Accessories
3.1 The Khepera III Robot
3.1.1 Overview
Figure 3.1: Overview of the Khepera III robot.
Make an external inspection of the robot. Note the location of the following parts:
1. Infrared sensors.
2. Ultrasonic sensors.
3. Main serial connector.
4. USB miniAB connector.
5. Power jack connector.
6. Reset.
7. On / Off.
8. Cable unroller connector.
K-Team S.A. 7
3.1.2 ON-OFF Battery Switch
It allows the user to switch the robot ON or OFF. When ON, the robot is
powered. Th e robot may even be powered without the battery pack using
the external power supply connector. See figure 3.1 number 7.
3.1.3 Indication LEDs
The Khepera II I has six indication LEDs, two for the battery charger, one
for the Power ON, one for the state of the motors controller and two programmables by the end-user (see figure 3.2).
When the Motor controller state LED is on, one of the two motor controller is in error mode. This could append when a motor is blocked or
a current limit is detected. In this case the controller must b e reset by
the dsPIC (’M’ command in serial interface mod e or call ’initKH3()’ in a
KoreBotLE program).
For the battery charger, the red one indicates that charge is in progress
and the green one signals when the charge is complete. If there’s no battery
pack when you plug an external power supply, the green one will turn on.
The led 5 and 6 can be set by the user with ’L’ command. See annexe
A Serial communication protocol.
Figure 3.2: LEDs of the Khepera III.
1. Motor Controllers state LED (redD).
2. Power ON LED (green).
3. Charge completed LED (green).
4. Charge in progress LED (red).
5. Programmable LED (green).
6. Programmable LED (red).
Khepera III manual ver 2.2 8
3.1.4 Serial connector
The serial connector contains various serial lines. One serial line which is at
TTL level (0V/+5V) is used to connect a personal computer to the Khepera
III dsPIC (with a KoreConnect). Used only when there is no KoreBotLE
connected. Please see section 4.2.
There is another RS232 (-10V/+10V) used to communicate with the
KoreBotLE, ie to see the KoreBotLE’s boot message. Please see section
4.3.
It is also possible to use the USB link of the K oreConnect to communicate
with the KoreBotLE.
The length of the serial cable should be limited to two meters
for proper operation.
11
9
5
3
1
7
12. GND
11. GND
7. USB D−
8. USB D+
1. Korebot RXD
2. Korebot TXD
3. dsPIC RXD
4. dsPIC TXD
6. VCC ( +5V )
12
10
8
6
4
2
Figure 3.3: Details of the Khepera III serial connector. Pin 5, 9 & 10 are
not connected.
Khepera III manual ver 2.2 9
3.1.5 Cable unroller connector
The cable unroller connector is a serial and a power connector (see figure 3.4). You can supply your robot and communicate with the robot
through it. This connector is usefull if you want to supply your robot with
an external power supply (+9V) and keep its mobility with an cable unroller. However, if you want to recharge your battery at the same time, it
is mandatory to use the power jack connector.
6. GND
4. GND
5. GND
1. VCC (+9V)
2. dsPIC RXD
3. dsPIC TXD
1
2
3
5
4
6
Figure 3.4: Details of the cable unroller connector.
3.1.6 USB connector
The min i-USB connector is usefull only wh en a KoreBotLE is plugged in the
Khepera III. You can connect directly your PC to the Khepera III with an
ordinary mini-USB cable. To communicate with the KoreBotLE through
the USB connector, please refer to the documentation of the KoreBotLE
(found on the web site www.k-team.com).
Khepera III manual ver 2.2 10
3.1.7 How to plug a KoreBotLE
The Khepera III has been designed to work together with a KoreBotLE,
but as it isn’t mandatory, in the default pack there is no KoreBotLE with
the robot. You can buy it at the same time, in this case, the KoreBotLE
will be mounted into the robot. But if you buy it afterward, you must first
unmount the upper body of the Khepera III, then plug the KoreBotLE on
the extansion connectors (see figure 3.5). If you have any other extansion
(KoreIO, KoreSound, KoreVision, etc...), you must only remove the black
metal plate, and plug your extension on the KoreBotLE.
Figure 3.5: Details of the K oreBotLE assembly.
Khepera III manual ver 2.2 11
3.2 Motors and motor control
Each wheel is moved by a DC motor coupled with the w heel through a 43.2:1
reduction. The motor itself having a 27:1 reduction and the gear box having
a 1.6:1 reduction. The motor has its own embedded incremental encoder,
placed on the motor axis, gives 16 pulses per revolution of the motor. This
allows a resolution of 691.2 per revolution of the wheel that corresponds to
54 pulses per ten millimeter of path of the robot (diameter of the wheel =
41mm, thus each revolution the robot make 128.8mm). By default, the robot
is set in mode encoder resolution x4, in this case for each wheel revolution
the controller motor make 2764 measures. The other encoder configuration
mode is 2x (1382 measures/turn).
Reminder: 1 revolution = 128.8mm = 2764 measures.
Each motor is driven by its own motor controller implemented in a
PIC18F4431. The PIC has direct control on the motor power through a
double H bridge and can read the pulses of the incremental encoder.
The motor control block acts as slave devices on the I2C bus. When the
KoreBotLE is not connected to the Khepera III robot, the main robot CPU
will turns itself into an i2c master. When the KoreBotLE is connectedm, it
becomes the i2c m aster.
Each motor controller switches its motor ON and OFF at a given frequency and during a given time. By this way, the motor react to the time
average of the power supply, which can be modified by changing the period
the motor is switched ON. This means that only the ratio between ON and
OFF periods is modified, as illustrated in figure 3.6. This power control
method is called ”pulse width modulation” (PWM). The PWM value is
defined as the time the motor is switched ON.
Khepera III manual ver 2.2 12
time
power
OFF
ON
basic period
50µs
ON period
time
power
OFF
ON
basic period
95%
ON period
time
power
OFF
ON
basic period
5%
ON period
Figure 3.6: The “Pulse Width Modulation”(PWM) motor supply mode is
based on a ratio between the ON time and the total time. The basic switching frequency is constant.
Each motor controller can perform the control of the speed or the position
of the motor, setting the correct PWM value according to the real speed or
position read on the incremental encoders.
Both DC motors can be controlled by a PID controller. Every term of
this controller(Proportional, Integral, Derivative) is associated to a constant,
setting the weight of the corresponding term: Kp for the proportional, Ki
for the integral, Kd for the d erivative.
The motor controller can be used in two control modes: the speed or
position mode. The active control mode is set according to the kind of
command received. If the controller receives a speed control command, it
switches to the speed mode. If the controller receives a position control
command, the control mode is automatically switched to the position mode.
Different control parameters (Kp, Ki and Kd) can b e set for each of the two
control modes.
Khepera III manual ver 2.2 13
3.2.1 Speed
Used in speed mode, the controller has as input a speed value of the wheels,
and controls the motor to keep this wheel speed.
The speed value is a division of a constant value by the time between
encoder pulsations. In default mode (encoder resolution x4 and postscaler
1:4), a measure is made four times every p ulse. Then each revolution of the
wheel, 2764 measures are made. The constant value is defined by the maximum time multiplied by 256 (0xFFFF * 256 = 16’776’960). This operation
allows a better PID calculation for the lower speed.
MotorSpeed =
16′776′960
T imer5value
To convert into a real time, use the following calculation (this time is
the delay between two measures):
T ime =
T imer5value
P ostscaler
f
osc
/4
T mr5P rescaler
Where f
osc
= 20MHz and Tmr5Prescaler = 8 (default).
To get the real speed in mm/s:
RealSpeed =
W heelCircumf erence
T ime ∗ 2764
Where WheelCircumference is 128.8mm and 2764 correspond to the number
of measures per revolution of the wheel.
Here’s an example with MotorSpeed = 20’000, Tmr5Prescaler = 8, Postscaler
= 4 and encoder resolution = x4
T imer5value =
16′776′960
20′000
= 839
T ime =
839
4
20′000′000/4
8
= 0.336[ms]
RealSpeed =
128.8
0.000336 ∗ 2764
= 138.9[mm/s]
RealSpeed =
MotorSpeed
Kspeed
[mm/s]
Where Kspeed is 144.01 when default configuration is used.
The maximum reachable speed is 48’000 (= 333 mm/s) in open loop ,
and 43’000 (= 298 mm/s) in regulation mode. And the minimum is 2’000
(= 13.9 mm/s) with regulation control.
Khepera III manual ver 2.2 14
Used in position profile mode (’F’ command), the controller has as input a target position of the wheel, an acceleration and a maximal speed.
Using this values, the controller accelerates the wheel until the maximal
speed is reached, and d ecelerates in order to reach the target position. This
movement follows a trapezoidal speed profile, as described in figure 3.7.
time
time
position speed
acc -acc
start position
target position
max_speed
Figure 3.7: Speed profile to reach a target position with a fixed acceleration
(acc) and maximal speed (max speed).
The input values and the control mode of this controller can be changed
at every moment. The controller will u pdate and execute the new profile
in the position mode, or control the wheel speed following the new value in
the speed mode.
First configure the speed profile (’J’ command) with the needed parameters. Then you can perform a move with the position profile mode (’F’
command). See annexe A for more details about communication protocole.
Khepera III manual ver 2.2 15
3.3 Infra-red Proximity sensors
Khepera III hase nine sensors placed around the robot and two placed on
the bottom. The latters allow experiments like line following. They are
positioned and numbered as shown in figure 3.9.
Figure 3.8: Bottom view of the IR sensors
These sensors embed an infra-red light emitter and a receiver. For detailed description, please refer to the manufacturer’s datasheet. The eight
sensors are TCRT5000, reflective optical sensors from Vishay Telefunken.
Khepera III manual ver 2.2 16
This sensor device allows two measures:
- The normal ambient light. This measure is made using only the receiver part of the device, without emitting light with the emitter. A
new measurement is made every 33 ms. During the 33 ms, the eleven
sensors are read in a sequential way every 3 ms. The value returned
at a given time is the result of the last measurement made.
- The light reflected by obstacles (= proximity). This measure is made
emitting light using the emitter part of the device. The returned
value is the difference between the measurement made emitting light
and the light measured without light emission (ambient light). A new
measurement is made every 33 ms. During the 33 ms, the eleven
sensors are read in a sequential way every 3 ms. The value returned
at a given time is the result of the last measurement made.
The output of each measurement is an analog value converted to a 12
bit digital value . The following two sections illustrate the meaning of this
12 bit values.
3.3.1 Ambient light measurements
Ambient light measurement is strongly influenced by the robot’s environment. Depending on the light source type, color, and distance, ambient
light measurement profile m ight vary. It is not recommended to use
light source with large emission in the infrared range, as this could
confuse the IR sensors.
3.3.2 Reflected light measurements (proximity)
Sensors are mainly meant to detect obstacles around the Khepera. Measurements for reflected light depends on objects reflectivity and on ambient
light conditions. Objects color, materials and surfaces do have an influence
on the sensors response. Moreover, as any sensor, IR sensors are subject
to environmental noise. For all these reasons, graphics below are given for
information only and should not be considered as references.
Khepera III manual ver 2.2 17
Figure 3.9: Relative collector current vs distance
3.4 Ultrasonic sensors
In its base set, 5 sensors are placed around the robot and are positioned and
numbered as s hown in figure 3.10.
5 sensors are in fact 5 pairs of ultrasonic devices where each pair is
composed of one transmitter and one receiver.
The ultrasonic sensor are powered by a 20 Vdc source. The nominal
frequency of these transducers is 40kHz +/- 1kHz.
Parameters such as max number of echo, timeout and active sensors are
parametrizable through a configuration api (See ’C’ command in chapter A).
By default, you have maximum 3 echos, sensor 3 (front) is active, timeout
is set to see from 20cm to 4 meters.
The last parameter is if the upper body is mounted or not (default
mounted). When the upper body is mounted, there’s some noise because
of inside r ebound echo, which are deleted in software. In fact, you could
improve the detection of the nearest obstacles (20cm to 40cm) removing the
upper body.
Each measure return the number of founded echos, the distance in cm
of each echo, the amplitude of each, and the time (time stamp) when the
echo was seen.
The value returned by the command, is the white noise measured before
than a Ultrasonic pulse was sent. Then the real amplitude of each echo will
be its amplitude minus the white noise. See command ’G’ in chapter A for
more details about the ultrasonic command.
For more details about the ultrasonic sensor, please check at Midas component, the transceiver is 400ST100 and th e receiver is a 400SR100.
Khepera III manual ver 2.2 18
Figure 3.10: Position of the 5 UltraSonic sensors.
3.5 Battery
The Khepera III is equipped with a battery pack composed of two Li-Ion
Polymer element. This provides a 7.4V volt battery with a 1400 mAH
capacity. Using its embedded power, the robot is able to run completely
autonomously during more than four hours, running with a basic configuration. When additional equipment are used, the au tonomy is reduced as
Khepera’s extensions as the KoreBotLE rely on Khepera’s batteries as a
power source.
There is no specific power management system on the Khepera. When
the batteries voltage falls under 6V, the battery cut himself the power supply
to avoid a too important discharge of the cell. Users can implement their
own software power management system to handle KoreBotLE to shutdown
properly before this case happend. See command ’V’ in chapter A for more
details about battery management.
3.6 Power Supply
If an external power source is required or during batteries charge, power
can be supplied through the power jack connector or through the microMatch cable unroller conn ector. See section 4 for detailed description of
connections.
Use only the power supply deliver by K-Team. If you want to
supply the Khepera II I with another device, make sure that the
Voltage is +9V and that the power supply can deliver 2A.
SAFETY PRECAUTION: The power supply must be connected to the wall socket after all other connections are already
made.
Khepera III manual ver 2.2 19
4 Connections
4.1 Configuration for batteries charge
To charge robot’s batteries, make sure th e following are correct:
- The power supply shall be connected to the robot.
- Warning: the robot battery may be charged with the robot ON or
OFF. Be attentive that when the robot is ON, the charging time will
be a bit longer.
- The power supply have to be connected on a wall plug.
There are three leds. A green led tells if the robot is powered or not.
And two other leds are here if the robot is charging ( red led ON ) or if the
charge is complete ( green led O N ).
During the charge, the red led is switched ON and the green led is
switched OFF. The process is reversed at the end of th e charging process.
The charging time for an empty battery is about 180 minutes. At this
moment the power supply can be unplugged. When charging, the battery
can be as hot as 40 degrees.
K-Team S.A. 20
4.2 Configuration for Robot-Computer Communi-
cation in standalone
This configuration allows communicating between the robot and a host computer through a serial link. The host computer is linked to the interface
module using a standard RS232 line, while the interface module converts
RS232 signal into a TTL level signal to communicate with the robot.
To use the standalone serial communication mode, please make sure the
following are correct:
- No KoreBotLE is connected on th e Khepera III.
- The robot battery is charged that means the power led is switched on.
- The robot must be connected to a KoreConnect module using the
serial cable
- The KoreConnect should be connected to the host computer using a
standard RS232 cable. in this mode, the cable has to be connected on
the DB9 connector number 2 (see fig 4.1). You can easily purchase
such a cable from your host computer dealer.
- Serial port configured as followed : 115200bps, 8 Data bits, 1 stop bit
, no parity, no hardware control.
RS232 cables
KoreConnect
2
1
Figure 4.1: Connection when the robot is used without a KoreBotLE.
Khepera III manual ver 2.2 21
4.3 Configuration for Robot-Computer Communication with KoreBotLE
4.3.1 Serial link
This configuration allows communicating between the KoreBotLE plugged
on the robot and a host computer through a serial link. In this configuration
it is not possible to communicate with the robot base itself as explained in
the previous chapter. The host computer is linked to the interface module
using a standard RS232 line. The adaptation RS232/TTL is made on the
KoreBotLE.
To use the serial communication mode, please make sure the following
are correct:
- A KoreBotLE is connected on the Khepera III.
- The charged Battery or a power supply is plugged, and the robot is
turned ON .
- The robot must be connected to a KoreConnect module using the
serial cable
- The KoreConnect should be connected to the host computer using a
standard RS232 cable. in this mode, the cable has to be connected
on the DB9 connector number 1 (see fig 4.2) You can easily purchase
such a cable from your host computer dealer.
- Serial port configured as followed : 115200bps, 8 Data bits, 1 stop bit,
no parity, no hardware control.
RS232 cables
KoreConnect
2
1
Figure 4.2: Connection when the robot is used with a KoreBotLE.
Khepera III manual ver 2.2 22
4.3.2 USB link
This configuration allows communicating between the KoreBotLE plugged
on the robot and a host computer th rough a USB link. There are two ways
to connect the USB to the KoreBotLE. With a KoreConnect and standard
USB cable or with only a mini-USB cable.
For more information about the USB communication protocole with a
KoreBotLE, please refer to the KoreBotLE documentation (found on web
site www.k-team.com).
To use the USB communication mode, please make sure the following
are correct:
- A KoreBotLE is plugged on the Khepera III.
- The charged battery or a power supply is plugged, and the robot is
turned ON .
- The robot must be connected to a KoreConnect module and then a
USB cable or a mini-USB cable is plugged directly on the USB miniAB
connector of the robot (see figure 3.1).
- The US B cable (standard or mini) should be connected to the host
computer. These two type of cable can be easily purchased from any
computer dealer.
Khepera III manual ver 2.2 23
4.4 Bluetooth Communication
A Bluetooth device is mount on every KheperaIII with the firmware 2.0 or
bigger. The device is a WT12 from BlueGiga, has the I-Wrap license and
is configured by AT command. The device is completely configured for a
cable replacement for the KheperaIII. But can be used with the KoreBotLE
too when plugged on the KheperaII I. Then the bluetooth connection will be
available via the serial port /dev/tts/1 of the KoreBotLE. The configuration
is the following:
- 115200bps data rate
- 8 data bits
- no parity
- one stop bit
- no hardware flow control
- connection securised (security code is: 0000)
4.4.1 Bluetooth communication with KheperaIII
Here a procedure as example to etablish a Bluetooth communication between
KheperaIII and a PC, and how to validate the connection with a terminal
(example for WinXp). No KoreBotLE must plugged on the KheperaIII for
this case.
- First connect your Bluetooth dongle to your PC (if necessary).
- Check if your system recognize your dongle and then install the driver
If you have Bluetooth integrated in your laptop, just activate it.
- Verify that your connection is securised and that a COM port is
reserved for the Bluetooth serial communication (Menu: BluetoothAdvanced Configuration-Client Application)
- Check if your KheperaIII is correctly powered (Led green ON)
- Start a device research ”View device in range”
- The KheperaIII must appear with a PDA logo and the name KHIII
SerialNumber. The Serial Number is the same as the label on the
bottom.
- Create a connection with the KheperaIII, your program will ask you
for a security code then enter 0000.
- Your program assign a COM port to your device.
- Open a terminal with the assigned COM port and the correct configuration as above
- Try to read the IR sensor value (or another command see chapter A)
to validate the communication
- Then you can use any other program which used a COM port (like
Matlab) to remote control your KheperaIII
Khepera III manual ver 2.2 24
4.4.2 Bluetooth communication with KoreBotLE
The procedure will be the same as above but with a KoreBotLE plugged on
the KheperaIII.
- Create a Bluetooth a connection with the KheperaIII as explained
above
- To validate the communication, connect a KoreConnect to the KoreBotLE (see section 4.3)
- Log on the KoreBotLE (login: root , password: rootme)
- open a minicom on the KoreBotLE (minicom -s /dev/tts/1)
- Configure your terminal as describe above and select the /dev/tts/1
device.
- Now the KoreBotLE can send/received information to/from the PC
via Bluetooth.
4.4.3 Log On the KoreBotLE with a Bluetooth connection
There’s a way to use the /dev/tts/1 (Bluetooth serial Port) to log on the
KoreBotLE. To do this, you need to modify th e inittab file in the directory
/etc of the KoreBotLE as following:
With a Kernel 2.4
- Log on the KoreBotLE with a KoreConnect (login: root , password:
rootme)
- Open the /etc/initab files (vi /etc/inittab)
- In the end of the files, you will see this line :T0:23:respawn:/sbin/getty
-L ttyC0 115200 vt100
- Modify it to: T1:23:respawn:/sbin/getty -L /dev/tts/1 115200 vt100
- Save and close the file. Then in the next restart, you will be able to
log on your KoreBotLE with Bluetooth.
With a Kernel 2.6
- Log on the KoreBotLE with a KoreConnect (login: root )
- Open the /etc/initab files (vi /etc/inittab)
- In the end of the files, you will see this line S :2345:respawn:/sbin/getty
115200 ttyS0
- Modify it to: S0:2345:respawn:/sbin/getty 115200 ttyS0
- And add this line below: S1:2345:respawn:/sbin/getty 115200 ttyS1
- Save and close the file. Then in the next restart, you will be able to
log on your KoreBotLE with Bluetooth.
Khepera III manual ver 2.2 25
5 Serial Communication Mode
5.1 Testing the primary serial link
Before any further operations, the serial link between the host computer and
the rob ot should be tested. Please read the following instructions to test
the serial communication mode:
- Make sure all connections are correct (see chapter 4 for details).
- The robot should be placed on a flat and safe surface. The battery
switch must be OFF.
- A terminal emulator should be running on the host computer. Make
sure the terminal is connected to the correct serial port. The termi-
nal configuration must be set to 115200 Baud, 8 bit, 1 start
bit, 1 stop bit, no parity and no hardware control.
When powered on, the robot should send a message (see fig 5.1) to the
terminal emulator.
To test that the KheperaIII is able to receive command, try to send the B
command to ask the Khepera for the operating system version and revision.
Figure 5.1: Boot message of the Kherpera III.
K-Team S.A. 26
5.2 Testing the secondary serial link
As the robot is suited to be used with a KoreBotLE it is important to test
the serial link between the host computer and the KoreBotLE itself.
- Make sure all connections are correct (see chapter 4 for details).
- The robot should be placed on a flat and safe surface. The battery
switch must be OFF.
- A KoreBotLE needs to be plugged on the appropriate socket.
- A terminal emulator should be running on the host computer. Make
sure the terminal is connected to the correct serial port. The termi-
nal configuration must be set to 115200 Baud, 8 bit, 1 start
bit, 1 stop bit, no parity and no hardware control.
When powered on, the KoreBotLE will s en d the normal linux boot mes-
sage to the terminal emulator (see fig 5.2).
If any of the serial link is not working properly it is then important to
ensure that the serial communication settings has been configured correctly.
Figure 5.2: Boot message of the KoreBotLE.
Khepera III manual ver 2.2 27
5.3 Serial communication protocol
When the robot is used as standalone ( without a KoreBotLE ), the serial
communication pr otocol is designed to control all Khepera’s functions using
a RS232 serial line. The serial line configuration (baudrate as well as data,
start, stop and parity bits) for the host computer must match the rob ot’s
configuration.
The host computer and the Khepera robot are communicating with
ASCII messages. Each single interaction is composed by:
- A command, beginning with one ASCII capital letters and followed,
if necessary, by numerical or literal parameters separated by a comma
and terminated by a carriage return or a line feed, sent by the host
computer to the Khepera r obot.
- A response, beginning with the same one ASCII letters of the command but in lower-case and followed, if necessary, by numerical or literal parameters sep arated by a comma and terminated by a carriage
return and a line feed, sent by the Khepera to the host computer.
During the entire communication, the host computer is acting as a master
and the Khepera as slave. All communications are initiated by the master.
Two different types of interactions are possible. The first set of interactions is used to set up the robot configuration from the host computer
(set up serial line, changing controllers configuration,...), the second set of
interactions is used to control the robot (controlling motors, reading sensors
value,...).
A set of commands is available as detailed in appendix.
5.3.1 Testing a simple interaction
Testing some basic commands is the best method to understand the serial
protocol and tools available on the Khepera. Using a properly configured
serial link between the robot and a computer, please follow the instructions
bellow:
- Type the capital letter B followed by a carriage return or a line feed.
- The robot must respond with b followed by an in dication of the version
of software running on the robot and terminated by a line feed.
- Type the capital letter N followed by a carriage return or a line feed.
- The robot must respond with n followed by 11 numbers separated by
a comma and terminated by a line feed. These numbers are the values
of the robot proximity sensors presented in section 3.1.6.
- Retry the same command (N) putting some obstacles in front of the
robot. The response must change.
- Type the protocol command D,l10000,l-10000 followed by a carriage
return or a line feed.
Khepera III manual ver 2.2 28
- The robot must start turning on place and respond with d and a line
feed.
- To stop the robot type the protocol command D,l0,l0 followed by a
carriage return or a line feed.
- Try other commands following the d escription given in Appendix A.
Khepera III manual ver 2.2 29
6 KoreBotLE programming
This section explain how to write a simple program for the KoreBotLE to
control the Khepera III base. The Khepera III will act as peripheral of the
KoreBotLE.
Please refer to the KoreBotLE user manual (found on www.k-team.com)
for further details on KoreBotLE programming. This document only provides a basic example of program compilation and execution.
The first simple executable for KoreBotLE/Khepera III will be built
assuming:
- A working arm-linux toolchain is installed on your host computer.
- The NFS link is active and a shared d irectory (mySharedDirectory) is
mounted on /mnt/nfs.
A source file should be first created and edited with a very simple C
program such as the following. People familiar with the KoreMotor will
notice that the code is quite similar. The controlers have been embedded in
the robot but act as two I2C slaves.
/* kh3test.c */
#include <korebot/korebot.h>
static knet_dev_t * mot1;
static knet_dev_t * mot2;
int main()
{
kh3_init();
/* open various socket and store the handle in their respective pointers */
dsPic = knet_open( "Khepera3:dsPic" , KNET_BUS_I2C , 0 , NULL );
mot1 = knet_open( "Khepera3:mot1" , KNET_BUS_I2C , 0 , NULL );
mot2 = knet_open( "Khepera3:mot2" , KNET_BUS_I2C , 0 , NULL );
/* initialize the motor controler 1 */
kmot_SetMode( mot1 , kMotModeIdle );
kmot_SetSampleTime( mot1 , 1550 );
kmot_SetMargin( mot1 , 6 );
kmot_SetOptions( mot1 , 0x0 , kMotSWOptWindup | kMotSWOptStopMotorBlk
| kMotSWOptDirectionInv );
K-Team S.A. 30
kmot_ResetError( mot1 );
kmot_SetBlockedTime( mot1 , 10);
kmot_ConfigurePID( mot1 , kMotRegSpeed , 400 , 0 , 10 );
kmot_ConfigurePID( mot1 ,kMotRegPos,620,3,10);
kmot_SetSpeedProfile(mot1 ,30,3);
/* initialize the motor controler 2 */
kmot_SetMode( mot2 , kMotModeIdle );
kmot_SetSampleTime( mot2 , 1550 );
kmot_SetMargin( mot2 , 6 );
kmot_SetOptions( mot2 , 0x0 , kMotSWOptWindup | kMotSWOptStopMotorBlk );
kmot_ResetError( mot2 );
kmot_SetBlockedTime( mot2 , 10);
kmot_ConfigurePID( mot2 , kMotRegSpeed , 400 , 0 , 10 );
kmot_ConfigurePID( mot2 ,kMotRegPos,620,3,10);
kmot_SetSpeedProfile(mot2 ,30,3);
/* For ever loop */
while(1)
{
/* Wait 5 seconds */
sleep(5);
/* Tell to the motor controller to move the Khepera III forward */
kmot_SetPoint( mot1 , kMotRegSpeed , -motspeed );
kmot_SetPoint( mot2 , kMotRegSpeed , motspeed );
/* Wait 5 seconds */
sleep(5);
/* Tell to the motor controller to stop the Khepera III */
kmot_SetPoint( mot1 , kMotRegSpeed , 0 );
kmot_SetPoint( mot2 , kMotRegSpeed , 0 );
}
}
This s ou rce code can be cross-compiled using arm-linux-gcc which sup-
ports most standard gcc options:
arm-linux-gcc kh3test.c -o k3test
An kh3test executable file should be created, that can be executed on
the KoreBotLE, or eventually another arm-linux machine.
Khepera III manual ver 2.2 31
To execute the program, simply copy kh3test to the nfs shared directory, then execute it from a KoreBotLE terminal. If the shared directory is
mounted on the default /mnt/nfs, first change working directory:
cd /mnt/nfs
Then check that kh3test is present:
ls -l
And execute it:
./k3test
Khepera III manual ver 2.2 32
A Communication protocol
This communication protocol allows complete control of the robot functions
through a RS232 serial line. The required configuration is presented in
section 4.3. The serial line set-up on your host computer must m atch the
one set on the robot according to the chosen running mode.
The protocol is made of commands and responses, all in standard ASCII
codes. A command is sent from the host computer to the robot: it is starting
with an upper case character and followed, if necessary, with numerical or
literal parameters separated with comma and terminated by a line feed. The
response is sent by the robot to the host computer: it is starting with the
same character that was initiating the command but using lower case, and
followed, if necessary, with numerical or literal parameters separated with
comma and terminated by a line feed.
When a command ask for a value bigger than 8 bits (bigger than 256)
the following prefixes must be added:
- d : for a 16 bits value
- l : for a 32 bits value
- f : for a floating value
Example to set the Speed: D,l20000,l20000
To better understand this protocol, please refer to the following simple
test:
- Set the connection configuration presented in section 4.3.
- Start a terminal emulator on your host computer with the serial line
set to 115200 Baud, 8 bit data, 1 start bit, 1 stop bits, no parity.
- Type the capital letter B followed by a carriage return or a line feed.
- The robot must respond with b followed by an indication of the version
of software running on the robot and terminated by a line feed.
- Type the capital letter N followed by a carriage return or a line feed.
- The robot must respond with n followed by 11 numbers separated by
a comma and terminated by a line feed. These numbers are the values
of the proximity sensors presents on the robots.
- Retry the s ame command (N) putting some obstacles on the front of
the robot. The response must change.
- Try other commands...
K-Team S.A. 33
A Start Braitenberg mode
Command: A, mode (8 bits)
Answer: a
Effect: Start the Braitenberg mode with the Infrared sensor (mode
= 0) or with the ultrasonic sensor (mode = 1). To stop the
Baintenberg mode, send the A,2 command.
Syntax: A,0
B Read software version
Command: B
Answer: b, version
of BIOS, revision of BIOS
Effect: Give the software version stored in the robot’s EEPROM.
C Configure the current firmware operation
Command: C, array index(8bits), array value(16bits)
Answer: c
Effect: Configure the actual firmware state. The configuration array
is to be seen as a table. Each line in the table means a
parameter and a value may be associated with.
Syntax: C,0,d3
Index Default Value Description:
0 0b00000100 Decide how many US sensor will be active. See
the table bellow for supported configurations.
1 3 Decide the maximum echo numbers.
2 0 Not Used.
3 0 Not used.
4 0xFFFF IR sensor mask, man age the active IR sensor
(bit0 = IR0, bit1 = IR1, etc...).
5 12 IR gain for Braintenberg.
6 1 Upper body mounted. If the upper body isn’t
mounted, change this value to 0 to get better
US measure.
Khepera III manual ver 2.2 34
The supported US sensors configuration are listed in the following table.
Mask Binary Decimal Description:
NONE 0b00000000 0 None of the US sensor.
US1ONLY 0b00000001 1 Only the US sensor 1.
US2ONLY 0b00000010 2 Only the US sensor 2.
US3ONLY 0b00000100 4 Only the US sensor 3.
US4ONLY 0b00001000 8 Only the US sensor 4.
US5ONLY 0b00010000 16 Only the US sensor 5.
US1TO2 0b00000011 3 US sens or 1 to 2.
US2TO3 0b00000110 6 US sens or 2 to 3.
US3TO4 0b00001100 12 US sensor 3 to 4.
US4TO5 0b00011000 24 US sensor 4 to 5.
US1TO3 0b00000111 7 US sens or 1 to 3.
US2TO4 0b00001110 14 US sensor 2 to 4.
US3TO5 0b00011100 28 US sensor 3 to 5.
US1TO4 0b00001111 15 US sensor 1 to 4.
US2TO5 0b00011110 30 US sensor 2 to 5.
USALL 0b00011111 31 All US sensors.
D Set speed
Command: D, speed motor left (32bits), s peed motor right (32bits)
Answer: d
Effect: Set the speed of the two motors. See in section 3.2.1 to
calculate the equivalent Speed.
Syntax: D,l20000,l20000
E Read speed
Command: E
Answer: e, speed
motor left, speed motor right
Effect: Read the instantaneous speed of the two motors. See in
section 3.2.1 to calculate the equivalent Speed.
Example: e,20000,20000
Khepera III manual ver 2.2 35
F Set Target Profile
Command: F, target position motor left (32bits), tar-
get
position motor right (32bits)
Answer: f
Effect: Set a position to be reached. The move will be performed
with three phase, a acceleration to reach the maximum
speed, a constant speed and a deceleration phase before the
finish position. The unit is the pulse, each one corresponds
to 0,047 mm (with encoder resolution x4 (default)).
Syntax: F,l1000,l1000
G Get a measure from the US peripheral
Command: G, US number (8bits)
Answer: g, EchoNbr, Dist1, Ampl1,Time1,Dist2,Ampl2, Time2,
Dist3, Ampl3, Time3, Dist4, Ampl4, Time4, Dist5, Ampl5,
Time5, Noise
Effect: Retrieve US measures from a given sensor number. The
sensor number is supposed to be 1 to 5.
Syntax: G,3
Example: g,1,27,2900,100000,0,0,0,0,0,0,0,0,0,0,0,0,1800
H Configure the PID controler
Command: H, T (16bits), Kp (16bits), Ki (16bits), Kd (16bits)
Answer: h
Effect: Set the proportional (Kp), the integral (Ki) and the deriva-
tive (Kd) parameters of the T regulator where T can be 0
(speed controler) or 1 (position controler).
Syntax: H,d1,d200,d5,d10
I Set position
Command: I, position motor left (32bits), position motor right (32bits)
Answer: i
Effect: Set the 32 bit position counter of the two motors. The unit is
the pulse, each one corresponds to 0,047 mm (with encoder
resolution x4 (default)).
Syntax: I,l1000,l1000
Khepera III manual ver 2.2 36
J Configure the speed profile controller
Command: J, max speed (16bits), acceleration (8bits)
Answer: j
Effect: Set the speed and the acceleration for the trapezoidal speed
shape of the position controller. The max
speed parameter
indicates the maximal speed reached during the displacement. See section 3.2.1 for more details. At the reset, these
parameters are set to standard values: max
speed to 20000,
acc to 64.
Syntax: J,d15000,10
K Set Programmable Led
Command: K, LED (8bits), State (8bits)
Answer: k
Effect: Set the state of the two Programmable Leds ( see section
3.1.3, Led 5 & 6). LED select which one must be set (0 =
led 5, 1 = Led 6).
State select the operation (0 = OFF, 1 = ON, 2 = Change
state).
Syntax: K,0,1
L Set speed open loop
Command: L, speed motor left (32bits), speed motor right (32bits)
Answer: l
Effect: Set the speed of the two motors without a PID controller.
Where a value of 1023 correspond to PWM of 100%.
Syntax: L,l500,l500
M Init Motors
Command: M
Answer: m
Effect: Initialise or reset the motor controllers. Must be used if an
error like motor blocked or current limit occured
Khepera III manual ver 2.2 37
N Read proximity sensors
Command: N
Answer: n,val
sens back left, val sens left 90, val sen s left 45,
val
sens front left, val sens front right, val sens right 45,
val
sens right 90, val sens back right, val sens back,
val
sens ground right, val sens ground left, time stamp
Effect: Read the 10 bit values of the 11 proximity sensors. The
last argument is the relative time stamp of the measure.
(section 3.3), from the front sensor situated at the left of
the robot, tur ning clockwise to the back-left sensor.
O Read ambient light sensors
Command: O
Answer: n,val
sens back left, val sens left 90, val sen s left 45,
val
sens front left, val sens front right, val sens right 45,
val
sens right 90, val sens back right, val sens back,
val
sens ground right, val sens ground left, time stamp
Effect: Read the 10 bit values of the 11 light sensors (section3.1.6),
from the front left sensor turning clockwise to the back-left
sensor. The last argument is the relative time stamp of the
measure.
P Set Target Position
Command: P, target position motor left (32bits), tar-
get
position motor right (32bits)
Answer: p
Effect: Set a position to be reached. The move will be performed
without acceleration and decceleration. The unit is the
pulse, each one corresponds to 0,047 mm (with encoder resolution x4 (default)).
Syntax: P,l1000,l1000
Q Unused
Khepera III manual ver 2.2 38
R Read position
Command: R
Answer: r, position
motor left, position motor right
Effect: Read the 32 bit position counter of the two motors. The
unit is the pulse, each one corresponds to 0,047 mm (with
encoder resolution x4 (d efault)).
S Unused
T Unused
U Enter the serial boot loader mode
Command: U
Answer: u
Effect: Switch to the firmware upgrade mode. Be careful, not to
upload a bad hex file into the dsPic memory space. If the
dsPic memory is corrupted, an external programmer will be
required to reflash the memory.
Do not tu rn off or reset the KheperaIII when the uploader
mode running. This will corrupt the dsPic memory. If you
have run the mode by mistake, wait until the timeout occurs
(5-7 seconds).
V Get Battery State
Command: V, index (8bits)
Answer: v, battery
measure unit, battery measure decimal
Effect: 0: Read the voltage of the battery (Units: 1V , 0.1mV) .
1: Read the current of the battery (Units: 1A, 0.1mA).
2: Read the battery Average Current (Units: 1A, 0.1mA).
3: Read the battery Absolute Remaining Capacity (Units:
1Ah).
4: Read the Temperature of the battery (Units: 1 C, 0.1´).
5: Read the battery Relative Remaining Capacity (Units:
%).
W Unused
Khepera III manual ver 2.2 39
X Unused
Y Unused
Z Zero the relative time stamp
Command: Z
Answer: z
Effect: Reset the relative time counter.
Khepera III manual ver 2.2 40
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