Khepera IV embeds state of the art features.
The Khepera IV is a compact robot designed for any indoor lab application (table, lab floor).
Compact, it requires a small space to operate, even in swarm. With its high flexibility, the Khepera IV robot can be used in almost any application such as navigation, swarm, artificial intelligence, computation, demonstration, etc . Thanks to the KB-250 bus which allows you to stack many different extensions in a few seconds on the top of the robot, providing an unbeatable modularity.
The newest generation of Khepera is bringing with it a whole lot of new features such as embedded Linux core, color camera, WiFi, Bluetooth, USB Host, accelerometer, gyroscope, microphone, loudspeaker, 3 top RGB LED, improved odometry and precision.
Khepera IV embeds state of the art features
Based on your experience, feedback and requests, the Khepera IV now integrates a powerful Linux core with WiFi, Bluetooth, accelerometer, gyroscope, color camera and a larger battery.
More stable than ever, you can now plug more extensions on the robot. The different sensors precision has also been improved and the odometry is even better than the Khepera III.
The Khepera IV architecture provides exceptional modularity. As any K-Team robot, the Khepera IV is using an extension bus system for nearly unlimited configurations.
The robot includes an array of 8 Infrared Sensors for obstacle detection with 4 more for fall avoidance or line following as well as 5 Ultrasonic Sensors for long range object detection. The robot’s motor blocks are using very high quality DC motors for high efficiency and accuracy. The internal battery provides a running time of about 7 hours.
With its Linux core, the Khepera IV embeds a complete standard Linux Operating System. It provides a well known standard C/C++ environment for application development. Almost any existing library can be easily ported on the Khepera IV, allowing the development of portable embedded algorithms and applications.
The Khepera IV is the new standard tool for robotic experiments and demonstrations such as:
The performance evaluation of the Khepera IV is available here (courtesy of the DISAL from the EPFL).
We thank the DISAL form the EPFL for this review, especially Soares, Jorge Miguel; Navarro Oiza, Inaki; Martinoli, Alcherio.
Main Features
The pack includes
| Elements | Technical Information |
|---|---|
| Processor | Linux core running on a 800MHz ARM Cortex-A8 Processor with C64x Fixed Point DSP core and additional microcontroller for peripherals management |
| RAM | 256 MB |
| Flash | 512 MB plus additional 8GB for data |
| Motion | 2 DC brushed motors with incremental encoders (roughly 147 pulses per mm of robot motion) and gearbox |
| Speed | Max 1m/s in openloop and 0.8m/s with Factory default PID speed controller Min 0.003m/s with Factory default PID speed controller |
| Sensors | 8 Infra-red proximity and ambient light sensors with up to 25cm range, 4 Infra-red ground proximity sensors for line following applications and fall avoidance, 5 Ultrasonic sensors with range 25cm to 2 meters, 3-axis accelerometer and 3-axis gyroscope |
| Audio | 1x embedded microphone 1x 0.7W speaker (400-20’000Hz) |
| Video | Integrated color camera (752×480 pixels, 30FPS) |
| LED | 3 programmable RGB LED on top of the robot |
| AC adapter power | 9V @ 2.5A |
| Autonomy | Approximately 7 hours. Additional turrets will reduce battery life. |
| Battery | Embedded battery, 7.4V Lithium Polymer, 3400mAh |
| Communications | 1x USB 2.0 host (500mA), 1x USB 2.0 device, 802.11 b/g WiFi, Bluetooth 2.0 EDR |
| Extension Bus | Expansion modules can be added to the robot using the KB-250 bus. |
| Size | Diameter: 140 mm Height: 58 mm |
| Weight | 540g |
| Max. payload | Approx. 2000 g |
| Ground clearance | 4 mm. Use only on hard and flat surfaces |
| Turn radius | 0cm |
| Operating temperature | 0-40°C |
| Development Environment for Autonomous Application | GNU C/C++ compiler, for native on-board applications. |
| Other language | Python 2.7.9 |
The Khepera IV is running a full standard embedded Linux Operating System. All applications are developped using the embedded Linux environement which provides several major benefits for developpers. A new library, the libkhepera, is also provided to interface applications with all the robot peripherals and extensions.
Standard Linux Kernel
The Linux kernel is known for its stability and efficiency. Applications will rely on a virtually bug free kernel and will be unable to cause system failures.
Filesystem in Flash Memory
The robot supports a real flash filesystem. Applications can read, create and modify files or directories for data logging, configuration files reading, data storage, etc.
Support for most Common Devices using Standard Drivers
Most USB devices are supported by the Khepera using standard Linux drivers.
Support Standard Libraries for Application Development
Application developer can first rely on the standard C libraries, including all the classic utilities of a Posix system. Moreover, almost any library can be ported on the robot, providing a limitless repository for quick application development.
Quick and Easy Installation of New Software Packages using ipkg
The Linux distribution is based on the Familiar distribution for embedded devices. It supports the ipkg package system for installation of new software. New packages can be downloaded from ipkgfind website.
The gripper is a turret that can be plugged on the robot. It gives to the Khepera IV the ability to grab and move objects.
Two degrees of freedom for accurate and robust manipulation and transportation of objects of 5cm width and 50g load.
Made from high precision mechanical parts.
| Elements | Technical Information |
|---|---|
| Max load size | 5 cm |
| Max load weight | 50g |
| Power supply | By the robot |
| Size | closed and up: 108mmx115mmx155mm (HxWXL) |
| Weight | 600g |
| Sensors | Resistivity, arm position, motor current, infrared |
| Functions | Grab object, detect object, measure resistivity of the grabbed material |
| Autocalibration | Builtin |
Includes:
Requirements:
Software
The KoreIOLE is a general Input and Output extension board for the Khepera IV. It provides several interfaces for digital I/O, digital power outputs, 10 bit analog inputs. The KoreIOLE can operate in stand-alone mode or communicate with a Khepera IV or any external SPI or I2C master. A CAN bus controller is also included to connect a Khepera IV to any CAN devices.
The KoreIOLE supports the KB-250 interface. The KB-250 interface is an open standard interface to expand the functionality of a Khepera robot in a easy and fast way. Besides using a full line of off-the-shelf KB-250 modules, developers can also design their own modules. KB-250 modules can be used singularly or stacked together to give the needed functionality. Several KoreIOLE boards can be placed on one stack to allow control of a large number of I/O.
A set of high level commands is provided, to easily interface Khepera programs or for external operations.
| Elements | Technical Information |
|---|---|
| Digital IO | 16 x 5V digitial IO that can be independently configured as – Input – Ouput – PWM output |
| Digital Power Output | 6 x digital power outputs – up to 1 Amps per channel – externaly provided voltage supply – fuse protected |
| Analog Input | 12 x analog inputs – timestamped 10bit analog to digital converters – 0-5V input with a 0.005V resolution |
| Interface | I2C Interface (400kbps) KB-250 Male Interface (for communication with the Khepera IV) KB-250 Female Interface (for stacking) |
| Dimensions | 85mm x 57mm |
KoreIO is a general Input and Output extension board for Khepera IV. It provides several interfaces to additional digital IO, digital power outputs, 10 bit analog inputs and 8 bits analog outputs. A CAN bus controller is also included to connect a Khepera IV to any CAN devices.
A special PWM ouput mode is available to control standard Servo Motors. The KoreIO board is able to control up to 10 Servo Motors simultaneously, and to provide them with 5V power supply.
KoreIO board supports standalone usage using a serial or I2C interface and it can be included in a KB-250 stack as well. The KB-250 interface is an open standard interface to expand the functionality of an existing ARM base platform in a easy and fast way. Besides using a full line of off-the-shelf KB-250 modules, developpers can also design their own modules. KB-250 modules can be used singularly or stacked together to give the needed functionality.
A set of high level commands is provided, to easily interface the Khepera IV programs or for external operations with the libkhepera.
| Elements | Technical Information |
|---|---|
| Digital IO | 16 x 5V digitial IO that can be independently configured as – Input – Ouput – PWM output |
| Digital Power Output | 6 x digital power outputs – up to 1 Amps per channel – externaly provided voltage supply – fuse protected |
| Analog Input | 12 x analog inputs – timestamped 10bit analog to digital converters – 0-5V input with a 0.005V resolution |
| Analog Ouput | 8 x 8bit analog outputs – 4.5V to -5V voltage range – 15 mA drive current per channel |
| CAN bus Controller | CAN bus controller and transceiver – 1Mbps data rate |
| Interface | K-Net Interface (for communication with Khepera and Koala) I2C Interface (400kbps) RS232 Serial Interface (115kbps) KB-250 Male Interface (for communication with Khepera IV) KB-250 Female Interface (for stacking) |
| Dimensions | 85mm x 57mm |
KoreMotorLE provides two DC motor channels. It can drive up to two DC motors using separate PID’s to control position, and speed. The PID control loop is implemented with 32-bit calculations, with a 32-bit position value and a 16-bit velocity value. Current measurement feedback is also available to detect torque and stall conditions for the motors.
KoreMotorLE does not support standalone operation. The board must be connected to a Khepera IV using the KB-250 stack.
The KoreMotorLE supports the KB-250 interface. The KB-250 interface is an open standard interface to expand the functionality of an existing Khepera robot in a easy and fast way. Besides using a full line of off-the-shelf KB-250 modules, developers can also design their own modules. KB-250 modules can be used singularly or stacked together to give the needed functionality. Several KoreMotorLE boards can be placed on one stack to allow control of a large number of motors.
Features:
The expansion turret can be plugged on the top of the Khepera IV to improve the capabilities of the Khepera IV. This turret will provide many different options to the Robot:
· Laser Range Finder (LRF) connection capability (Hokuyo URG-04LX-UG01)
· StarGazer (indoor global position and bearing) connection capability
· Additional battery for a larger autonomy with the K4 external charger pack
· IOs accessibility
With the expansion turret it is now possible to connect and use on the same Khepera robot a LRF module and a stargazer module at the same time.
The expansion turret give access of different GPIO’s of the Khepera by soldering a wire:
Includes:
Requirements:
Software
User Manual
The K4 external charger pack is an option to the expansion board. Composed by two batteries, an external charger and a power supply. It is used to add autonomy to the Khepera IV robot. The additional battery of 3600mAh adds about 5 hours of autonomy to the Khepera IV. It is particulary indicated when you use a Stargazer and / or a LRF module, in order to save the autonomy of the robot.
Another advantage is that you are able to change the additional battery while the nattive battery inside the robot is still powering the robot, making unnecessary to restart your robot and allowing you to run a virtualy unlimited experimen
tation time.
The additional battery is plugged into the expansion board (not included in the K4 external charger pack).
The pack include two additional batteries and the charger which can charge up to 2 batteries in about 4 hours.
Here is a brief summary of the gain of autonomy with the additional battery :
| Setup | Autonomy without additional battery | Autonomy with additional battery |
| KheperaIV alone | about 7 hours | about 12 hours * |
| KheperaIV with LRF | about 5 hours | about 8.5 hours * |
| KheperaIV with StarGazer | about 4 hours | about 7 hours * |
| KheperaIV with LRF+StarGazer | about 3 hours | about 5 hours * |
| KheperaIV with Gripper | about 4 hours | about 7.5 hours * |
| KheperaIV with Gripper+LRF+StarGazer | about 2.5 hours | about 4.5 hours * |
*Time indicated above are average, depending of the CPU and motor use.
The expansion turret can receive in option a Laser Range Finder module. It is used to do navigation, specially for mapping and localization. A laser inside the sensor is scanning the robot environment, measuring each 0.36 degres the distance from any object at its height.
The model which can be used is the URG-04LX-UG01 from the Hokuyo company. The turret gives the mechanical support for the sensor and the connectivity for it. In option, you can add a battery with the external charger pack in order to save the Khepera IV robot autonomy.
Technical specification of the LRF module:
| Elements | Technical Information |
|---|---|
| Range | 20 mm to 5600 mm |
| Accuracy | 60 to 1000mm : ±30mm , 1000 to 4095mm : ±3% of measurement |
| Angular resolution | approx. 0.36 degree |
| Autonomy | 2 hours |
| Weight | 300g |
| Software | Libkorebot |
| Scanning time | 100ms / scan |
Includes:
Requirements:
Software
User Manual
The Stargazer is a module allowing the Khepera IV robot to have indoor global position and bearing from passive landmarks marks.
It is used to do navigation, specially for mapping and localization. The module has IR Led’s for lighting landmarks and a camera for capturing the image, which is processed by on-board electronics. It computes position and bearing related to landmarks stuck on the ceiling. It uses the StargazerTM module from Hagisonic co. Ltd.
This a top module. No module can be plugged above this one.
| Elements | Technical Information |
|---|---|
| Range | 2.5-3 m of diameter with 1 landmarks (for ceiling height of 2.4 m; can be improved by adding landmarks) |
| Accuracy | 3.5 cm / 3 degrees |
| Measurement time | 10 times /sec |
| Autonomy | 2h30 ; Li-Pol battery |
| Weight | 117 g |
| Software | Libkhepera |
| Compatibility | Khepera IV extensions (KB-250 specifications) |
Includes:
Requirements:
Software
User Manual
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