Welcome to Yujin Kobuki’s documentation!¶

About¶

Introducing Korea’s first robotic turtle.

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kobuki [거북이] n. turtle

Kobuki is robotically engineered to be long-lived, tough and fast. With high performance batteries, Kobuki will tirelessly work alongside you through those long coffee-powered nights. He’ll also happily burden himself with your modded array of sensors, actuators, laptops, embedded boards, portside cannons and do it all at a speed that makes his real world cousins seem like … well, turtles.

Use him for serving 치맥 (chi-mek), chasing your neighbour’s kids or simply, to make your own robot ideas become reality.

Kobuki is still young, don’t expect him to remain as he is . Kobuki’s development has already been significantly influenced by the community and as he marches towards old age, we will continue to work with the community and you to ensure he becomes better with time.

Sincerely, Kobuki Team.

Basic Usage¶

Warning

Make sure to be aware of the safety guidelines.

Charging¶

Connect the power adapter to Kobuki or dock Kobuki in the docking station. If Kobuki is turned on, you will hear a short sound when charging starts and the LED will light up appropriately.

LED Color	Status
Green	fully charged
Blinking Green	charging
Orange	low battery

Note

The battery still charges if Kobuki is off, but you will not see the LED, nor hear sounds

First Run¶

You want to see Kobuki in action without further ado? Kobuki has a special random walker mode embedded into the firmware which you can activate on start-up:

Turn on Kobuki.
Within the first 3 seconds press the B0 button and hold for 2 seconds.
LED2 will start blinking and Kobuki wander around.

Note

This was introduced to the firmware in v1.1.0. In case your kobuki is not running this or a later version, please refer to the section about updating the firmware.

Software¶

In order to gain access to all of Kobuki’ s features, you will need an external computing unit (pc/laptop/tablet/embedded board) with software which communicates with Kobuki. Officially supported systems include:

Build Your Own Kobuki Driver Use the Serial Protocol

Linux C++ Application Use the Kobuki C++ Driver

Kobuki for ROS Use the Kobuki ROS World

Alternatively, you can get started with the Turtlebot 2 Platform which runs on a Kobuki base.

Note

Other platforms have had experimental support at one stage or another (windows/arduino/android).

Problems¶

Reach out on the following channels:

Kobuki User’s Mailing List: kobuki-users@yujinrobot.com
ROS Community Answers: http://answers.ros.org/questions/tags%3Akobuki
Yujin Sales Support: kobuki@yujinrobot.com
Dabit Industries Support: support@dabitindustries.com

Note

Kobuki comes with a 1 year warranty. In case you bought Kobuki from another one of Yujin Robot’s distributors, please contact them, otherwise email Yujin Sales Support.

Advanced Usage¶

Replacing Batteries¶

Warning

The electronics does not support the use of multiple battery packs at the same time!


Flip the kobuki	Open the cover

Unplug	Swap batteries

Replug	Replace the cover

Updating Firmware¶

If you have a ROS installation, you can find the current version by running: .. code-block:: bash

$ rosrun kobuki_driver version_info

# Version Info: * Hardware Version: 1.0.4 * Firmware Version: 1.2.0`

Alternatively you can compile version_info.cpp (no ROS) to create your own version checker.

Linux¶

The Flashing Utility¶

# Download & build the flashing utility
$ wget http://files.yujinrobot.com/kobuki/firmware/stm32flash-0.4.tar.gz
$ tar -xvzf stm32flash.tar.gz
$ cd stm32flash
$ make

Download Firmware¶

# choose the firmware version from http://files.yujinrobot.com/kobuki/firmware
# e.g. latest
$ wget http://files.yujinrobot.com/kobuki/firmware/kobuki_firmware-latest.hex

Identify ttyUSBx Port¶

If you have a udev rule installed, it will show up as /dev/kobuki, but if not, you can typically find it under one of the ttyUSB ports, e.g. /dev/ttyUSB0. If you are not sure, type dmesg into a terminal, unplug and replug the robot and type dmesg again. You should now be able to see which port is assigned to the robot (more precisely the FTDI USB to serial converter).

Switch to Download Mode¶

Connect the robot to your PC using the USB cable
Turn off the robot (switch on the side)
Switch from normal runtime mode to firmware download mode

This simply changes the type of data that is sent back and forth along the usb connection. You can do this by moving the switch illustrated below into the ‘download’ (up) position. Note that this switch is embedded into the robot cover so it isn’t easily thrown by accident – you may need thin plyers or some similar tool. You can find the mode switch mechanism on the right side of the control panel - see the image below.

Flashing¶

Note

The following instructions assume flashing of kobuki_firmware-latest.hex and port /dev/ttyUSB0. Modify these if necessary.

Warning

you need to execute the flashing command IMMEDIATELY after turning the robot on!

Turn off the robot
Check that the switch is in download mode
Turn on the robot

$ ./stm32flash -b 115200 -w kobuki_firmware_firmware-latest.hex /dev/ttyUSB0
  stm32flash 0.4

  http://stm32flash.googlecode.com/

  Using Parser : Intel HEX
  Interface serial_posix: 115200 8E1
  Version      : 0x22
  Option 1     : 0x00
  Option 2     : 0x00
  Device ID    : 0x0414 (High-density)
  - RAM        : 64KiB  (512b reserved by bootloader)
  - Flash      : 512KiB (sector size: 2x2048)
  - Option RAM : 16b
  - System RAM : 2KiB
  Write to memory
  Erasing memory
  Wrote address 0x0800a3f0 (100.00%) Done.

Rebooting¶

Turn off the robot power
Flick the firmware switch back to ‘Operation’ mode.
Turn on the robot power
I’m happy, you should be too!

Windows¶

The Flashing Utility¶

Download and install the windows flashing utility

Download Firmware¶

Find and download the version of the firmware you wish to flash from the Kobuki FW File Server.

Identify the COM Port¶

Usually if this will show up on COM1, but check to make sure.

Switch to Download Mode¶

Connect the robot to your PC using the USB cable
Turn off the robot (switch on the side)
Switch from normal runtime mode to firmware download mode

This simply changes the type of data that is sent back and forth along the usb connection. You can do this by moving the switch illustrated below into the ‘download’ (up) position. Note that this switch is embedded into the robot cover so it isn’t easily thrown by accident – you may need thin plyers or some similar tool. You can find the mode switch mechanism on the right side of the control panel - see the image below.

Flashing¶

Turn off the robot
Check that the switch is in download mode
Turn on the robot


Configure Properties	Check that the target is identified

Enter the Download from file (your .hex)	Success!

Rebooting¶

Turn off the robot power
Flick the firmware switch back to ‘Operation’ mode.
Turn on the robot power
I’m happy, you should be too!

Serial Port Connectivity¶

Many embedded boards do not have usb interfaces, or the embedded board doesn’t have the necessary ftdi32 serial->usb support. In these cases it is simpler to utilise the serial port on Kobuki’s expansion port to driving kobuki by serial interface instead of USB.

Pinouts¶

Pictured below are the pinouts of Kobuki’s expansion port, include the serial pins. The minimum number of required pins for serial communication is three; TX, RX, and GND. Additionally EX3.3 or EX5 can be used for powering external devices, such as line transceiver.

RX/TX : Serial data (voltage level is 3.3V)
EX3.3/EX5 : 3.3V/1A and 5V/1A power supply
DI0~3 : 4 x Digital input
high: 3.3~5V, low: 0V
DO0~3 : 4 x Digital output
open-drain, pull-up resistor required
AI0~3 : 4 x Analog input
12bit ADC: 0~4095, 0~3.3V
GND : Ground
EN : Used for detecting an external board
connect to external ground

Connections¶

RS-232 Interface¶

The voltage level of serial port is 3.3V. To connect kobuki with the standard RS-232 serial port, you should use line transceiver in the middle to convert voltage level. MAX232 chip is typical solution for it. Below diagram show simplified typical example of connections between Kobuki and SBC (your embedded board, laptop or pc). EX3.3 pin is used to powering line transceiver. It can be EV5 pin or external power sources from outside.

Logic Level Interface¶

To connect kobuki with serial port of MCU directly, below is the simplest connection diagram can be used. Serial pins of kobuki are 5V-tolerant. It accepts 3.3V and 5V voltage levels typically used by integrated circuit. Connection with power pin(EX3.3 or EX5) is optional, if you powering MCU with independent sources, such as battery, or wall adaptor.

Building an Application¶

If you’re using the ROS implementation, or building atop the kobuki c++ driver, simply re-configure the port string used for the application and everything should be ready to go.

If building an experimental driver from scratch (e.g. android driver), then you will need to implement the Kobuki Protocol specification.

Adding a Custom Sensor Array¶

Kobuki usually gets equipped with a 3d sensor These typically have limitations as obstacle avoidance sensor:

Narrow fov (58° x 43° horizontal x vertical)
Death zone on the first 45 cm
Cannot detect glass walls
Cannot detect polished metallic surfaces

In one experiment an 11 IR sensors half ring, pointing 12 degrees downward was added to compensate.

Sensor model: Sharp GP2Y0A21YK
Power supply: Kobuki’s 5V, 1A
Sensor reading: Arduino MEGA 2560
PC interface: Arduino custom firmware – Bosch adc_driver
Mounting: 3D printed frame.

The analog output of sensors is read by the Arduino board, while for power and ground they are connected to Kobuki’s 5V 1A power source. Connecting several sensors to the same power supply makes readings very noisy when there aren’t obstacles. The solution was to put decoupling capacitors on each sensor. For interfacing Arduino, we use Bosch adc_driver. A funny problem comes sometimes when looking at corners in a particular angle (~30 degrees) : sensors get a spurious reading, no idea why. We just went on with this, as is not a common problem. Different mounting frames are available for downloading and printing in our file server:

Horizontally mounted MaxBotix’s LV-Maxsonars
Horizontally mounted Sharp IR sensors
12 degrees downward pointing Sharp IR sensors

And the result:

Specifications¶

Safety Guidline¶

Do not twist or subject the power cable to extreme pressure or weight weight.
Keep the pin and interface of the power plug clean from dust or water.
Do not pull the power cord or touch the power plug with wet hands.
Do not use with a damaged power plug, power cord or loose outlet.
Use Kobuki indoors only.
Do not pour or spray water onto Kobuki.
Do not use Kobuki to pick up anything that is burning or smoking.
Always remove the battery before long-term storage or transportation.

Functional¶

Maximum translational velocity: 70 cm/s
Maximum rotational velocity: 180 deg/s (>110 deg/s gyro performance will degrade)
Payload: 5 kg (hard floor), 4 kg (carpet)
Cliff: will not drive off a cliff with a depth greater than 5cm
Threshold Climbing: climbs thresholds of 12 mm or lower
Rug Climbing: climbs rugs of 12 mm or lower
Expected Operating Time: 3/7 hours (small/large battery)
Expected Charging Time: 1.5/2.6 hours (small/large battery)
Docking: within a 2mx5m area in front of the docking station

Hardware¶

PC Connection: USB or via RX/TX pins on the parallel port
Motor Overload Detection: disables power on detecting high current (>3A)
Odometry: 52 ticks/enc rev, 2578.33 ticks/wheel rev, 11.7 ticks/mm
Gyro: factory calibrated, 1 axis (110 deg/s)
Bumpers: left, center, right
Cliff sensors: left, center, right
Wheel drop sensor: left, right
Power connectors: 5V/1A, 12V/1.5A, 12V/5A
Expansion pins: 3.3V/1A, 5V/1A, 4 x analog in, 4 x digital in, 4 x digital out
Audio : several programmable beep sequences
Programmable LED: 2 x two-coloured LED
State LED: 1 x two coloured LED [Green - high, Orange - low, Green & Blinking - charging]
Buttons: 3 x touch buttons
Battery: Lithium-Ion, 14.8V, 2200 mAh (4S1P - small), 4400 mAh (4S2P - large)
Firmware upgradeable: via usb
Sensor Data Rate: 50Hz
Recharging Adapter: Input: 100-240V AC, 50/60Hz, 1.5A max; Output: 19V DC, 3.16A
Netbook recharging connector (only enabled when robot is recharging): 19V/2.1A DC
Docking IR Receiver: left, centre, right

Software¶

C++ drivers for Linux
ROS driver
Gazebo simulation

Anatomy¶

Top View¶

Bottom View¶

Control Panel¶

19V/2A: Laptop power supply
12V/5A: Arm power supply
12v/1.5A: Microsoft Kinect power supply
5V/1A: General power supply
Status LED: Indicates Kobuki’s status
Green: Kobuki is turned on and battery at high voltage level
Orange: On - Low battery voltage level (please charge soon)
Green blinking: On - Battery charging
Off: Kobuki is turned off.
LED1/2: Programmable LEDs
USB: Data connection
BO/1/2: Buttons
Firmware switch: Enable/disables the firmware update mode

Connectors¶

Note

SOME NOTES ABOUT THE MOLEX PAGES BELOW

We do not actually use Molex connectors but we are supplied by a Korean vendor who produces connectors according to the Molex standard. These links will be more useful to internationals in helping them find a mating part that works for them.
The images on each page are representative of the series of connectors. Each series usually has a variety of connectors with a different number of pins. As a result, the pictures on some of the pages below may seem as though they have the incorrect number of pins, but do not worry about this – they are the correct links. Note that you can jump to different connectors in the series via the second part of their identification number (e.g. 43045-0224 for the 2-pin, 43045-0424 for the 4-pin).
If some linked connectors are listed as obsolete on the molex website, don’t worry. The connector you are exactly requiring are those you can find under the ‘Mates with Parts’ link on each page. If these however should become obsolete as well, please let us know via email.

Power¶

5V@1A Molex PN : 43650-0218 – for custom boards
12V@1.5A : Molex PN : 43045-0224 – specially supporting the kinect
12V@5A : Molex PN : 3929-9023 – for high powered accessories (e.g. robotic arm)
19V@2A : Molex PN : 3928-9068 – for recharging netbooks

Battery¶

4S1P/4S2P Battery Pack Connector

I/O Port¶

DB25 pin D-SUB Female connector that provides the following functionality (pdf)

Cables¶

Note

If you click on the preceding links for the power connectors, under the heading ‘Mates with Part(s)’ you can find the compatible connector to use with each power source. The most important one being of course:

12V@1.5A : Molex PN : 43025-0200 – specially supporting the kinect

Models & Drawings¶

The models and drawings include both the base and parts for the Turtlebot 2.

2D mechanical drawings – DWG, PDF
3D models – IGS, STEP

The inserts in the kobuki plate are M4 threads (metric, 4mm). If you wish to build standoffs compatible for these inserts, please reference the pole pdf’s in the 2D mechanical drawings which are what we use for turtlebots.

Motors¶

Specifications¶

Brushed DC Motor
Motor Manufacturer: Standard Motor
Part Name: RP385-ST-2060
Rated Voltage: 12 V
Rated Load: 5 mN·m
No Load Current: 210 mA
No Load Speed: 9960 rpm ± 15%
Rated Load Current: 750 mA
Rated Load Speed: 8800 rpm ± 15%
Armature Resistance: 1.5506 Ω at 25°C
Armature Inductance: 1.51 mH
Torque Constant(Kt): 10.913 mN·m/A
Velocity Constant(Kv): 830 rpm/V
Stall Current: 6.1 A
Stall Torque: 33 mN·m

Control Method¶

Driven by voltage source(H-bridge)
Controlled by Pulse-width modulation(PWM)

Gyro¶

Specification¶

3-Axis Digital Gyroscope
Manufacturer : STMicroelectronics
Part Name : L3G4200D
Measurement Range: ±250 deg/s
Yaw axis is factory calibrated within the range of ±20 deg/s to ±100 deg/s

Performance¶

In-Place Rotation Test¶

This graph shows the average heading error per revolution of gyro, when robot rotates with a given velocity.

Square Path Test¶

This graph shows the position error of fused odometry with gyro, when robot moves along a square path. Robot moved with 0.1 m/s on the line segment and rotated with 30 deg/s on the corner.

This table shows the calculated angular error, when robot arrived at the diagonally opposite corner from the starting point (0.0, 0.0).

Number of turns of square path	Angular Error [deg]
0.5	0.47
1.5	1.99
2.5	3.18

Power Adapter¶

Input	Output	Other
Voltage: 100-240V	Voltage: 19V	`powerphoto` Photo
Frequency: 50/60Hz	Ampere: 3.16A	`spec1` Specification 1
Ampere: 1.5A Max		`spec2` Specification 2

Batteries¶

Kobuki by the default ships with a small Lithium-Ion battery pack (4S1P, 2200mAh, 14.8V).

Note

For extra long operation, a big battery pack (4S2P, 4400mAh, 14,8V) can be ordered as well.

Warning

The electronics does not support the use of multiple battery packs at the same time (even if there is room in the battery compartment)

Specifications¶

Data Sheet (pdf)

Pinouts¶

Red: battery (+), 9.6 V ~ 16.8 V
White: NTC thermistor to ground, 10 kΩ ± 1%
Black: battery(-), Ground

Charing Profile¶

This plot shows the voltages as measured by the robot’s hardware. Both the standard 4S1P and the extra 4S2P batteries are compared. During the test, the robot was charging via adaptor.

Discharging Profile¶

This plot shows the voltage as measured by the robot’s hardware. Both the standard 4S1P and the extra 4S2P batteries are compared. During the test, the robot was continuously spinning, with the Kinect camera running.

Serial Port¶

RX / TX: Serial data connection (RS232; used voltage level is 3.3V!)
EX3.3 / EX5: 3.3V/1A and 5V/1A power supply
DI0 - 3: 4 x Digital input (high: 3.3 - 5V, low: 0V)
DO0 - 3: 4 x Digital output (open-drain, pull-up resistor required)
AI0-3: 4 x Analog input (12bit ADC: 0 - 4095, 0 - 3.3V)
GND: Ground
EN: Used for detecting an external board (connect to external ground)

Firmware¶

Communication¶

Baud rate: 115200 BPS, Data bit: 8 bit, Stop bit: 1 bit, No Parity
Electronic protocol: USB / RS232 (@ DB25 connector)

Protocol Specification¶

The driver communicates with the robot by using predefined protocol. In general, the driver sends the commands to the robot and the robot sends some feedback data or sensor readings. This command and feedback data are converted into bytestreams for communication via serial interface. The protocol specify that rules and forms of bytestream.

For more detailed information, visit: - http://yujinrobot.github.com/kobuki/enAppendixProtocolSpecification.html

Version Checking¶

Every time the robot comes alive (because it is connected or powered on), the driver checks the compatibility between software (i.e. driver) and firmware. Firmware versions are of the form M.m.p, where:

M(ajor) represents a deep rebuild of the code that almost surely breaks protocol compatibility. In consequence, if mayor version doesn’t match, the driver will show an error, suggest the required update and shutdown.
m(inor) represents a new feature that could not work if the driver is outdated, but the protocol itself is spared. In consequence, if minor version doesn’t match, the driver will show a warning suggesting the required update and continue working.
p(atch) represents a fix on the code and is not checked at all.

You can check which firmware version your robot is running on the log (check the first lines on stdout at driver startup), by running the version_info program included on the kobuki driver, or if you are using ROS, just echoing /mobile_base/version_info topic. Generally speaking, it’s recommended to upgrade the firmware to the latest stable version.

Special Firmware Modes¶

Activating¶

Kobuki has some special firmware modes, which can be activated on startup. Currently implemented are: #. Random walker mode #. Arduino/Embedded board support mode

To activate one of them, follow these instructions: #. Turn on Kobuki. #. Within in the first 3 seconds press and hold button BO(I) / B1 (II) for 2 seconds. #. If you see LED2(I) / LED1(II) switching between red and green, your chosen mode is activated.

Note

These modes have been introduced to the firmware with version 1.1.0. In case your Kobuki is not running this or a later version, please refer to the section about updating the firmware.

Random Walker Mode¶

In the random walker mode Kobuki is driving around until it hits an object with the bumper or a cliff is detected. In both cases, Kobuki will stop, turn by a random amount of degrees and continue driving .

Note

In this mode Kobuki’s wheel drop sensors are not activated. So, be careful when lifting up Kobuki!

Arduino / Embedded Board Support Mode¶

In this mode the serial port (DB25 connector) gives access to basic controls of Kobuki. You can hook up the digital/analog inputs/outpus of your Arduino or other embedded boards and start writing simple control programs.

Below is the special pin setting listed. Please refer to the serial port description for the name to pin mapping. - DI0: Not used - DI1: Not used - DI2: Not used - DI3: Not used - DO0: Bumper left (pressed/released) - DO1: Bumper centre (pressed/released) - DO2: Bumper right (pressed/released) - DO3: Wheel drop sensors (at least one wheel is dropped / none is dropped) - AI0: Wheel speed right (0V - full speed backward, 3.3V - full speed forward) - AI1: Wheel speed left (0V - full speed backward, 3.3V - full speed forward) - AI2: Not used - AI3: Not used

All other pins (GND, RX, TX etc.) remain unchanged.

Note

To enable the motors you need to press button B0.

Resources¶

Changelog¶

1.0.0 : official release
1.0.1 : upgrading firmware link fix
1.0.2 : documentation link fix
1.0.4 : updating the spec. of serial communication
1.0.5 : fixing battey & connector link
1.0.6 : updating link after Kobuki web site revision
1.1.0 : reorganised and collapsed website howtos into the guide
2.0.0 : Port to sphinx, readthedocs, and rst2pdf

License¶

The Kobuki user guide is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Frequently Asked Questions¶

Contact¶

This documentation is copied from the Kobuki User Guide provided by Yujin, and formatted into a reStructuredText document using Sphinx.

Except where otherwise noted, these design documents are licensed under Creative Commons Attribution 4.0 International License.