Capabilities and Demos
The general design is presented using layers: The bottom layer supports the physical components, which compose the robot: Motors, IR sensors, expansion socket and modules, Rgb Led, Lipo Battery, Lipo charger, and global positioning system using an overhead camera. The peripheral layer is powered by the ATmega168A microcontroller, it allows to manage and drive all the physical components Above, the control layer performs the necessary actions to drive the robot in a safe way in their environment and complete tasks. The application layer describes the individual and collective actions that emerges when the robot, or the group of robots are operating. Finally the top layer, allows user trought the communication layer, debug, run, start/stop, and programming the robots.
The complete hardware, is described in the previous picture. It is compound by: robots, computer, web-cam and controller board (the green one attached to computer). In the computer the user can write codes to program the robots (using AVR-Studio), also it runs the "Central controller" software that allows both send commands to robots, and process the web-cam information to global positioning system. The "Central controller" software is compatible with any web-cam with a minimum resolution (340x480 and 30 fps). The computer application communicates via USB with a Central Controller board designed to send user commands to robots wirelessly. The "Central controller board", has an AT90USB162 microcontroller that receives USB data from computer and send to the robots using the module NRF24L01, it also allows wire programming via (AVR-ISP).
Robot Main Board
The robot system is described in the block diagram above. The main parts are:
- Embedded Computing: The embedded computing is powered by an Atmega168A microcontroller, which has an 8 bits architecture,running at 8MHz with 16K of memory, and a set of peripherals to manage different components. The programming language using is C and we provide the necessary libraries to drive the basic functions of the robot.
- Locomotion subsystem: It is based only on the contact between the rotor of two tiny 3V electric motor and the surface. The manage of the motors speed and direction is done by the microcontroller, using PWM and digital pins, using the TB6552 driver .
- Communication: Here, we use an ultra low cost transceiver RF (at 2.4GHz) module NRF24L01, which gives the robot the possibility to interchange data with the operator and other robots.
- Power and Charging Management: The electronics are powered by a 3.7V, 200mAh LiPo battery. A voltage regulator is used to maintain a constant voltage of 3.3V and enable operation above 5 hours of constant working. Also an external LiPo charger has been built that uses an MCP73833 to manage battery reload.
- Assembly and Costs: Three custom 3D print parts for easy setting-up and calibration of the motors and IR sensors are designed. These two pieces do not need to use glue or screws. An exploded view of mechanical assembly is shown. The 3D pieces models are available Here.
- The Electronic design is available Here.
The Lipo charger board is USB (5V) compatible, it allows to charge a single cell Lipo battery, using the IC MCP73833. It recommendable to use a GP connector between battery and board (take care about polarity !!). The design and fabrication files are available Here
Central Controller Board
The Central controller board is also USB (5V) compatible. It has two functions:
- First one: It can be used as a programmer emulating the AVRISPmkII programmer. Refer to the software section to it usage. When you have configured the Central controlled board as a AVIPSmkII programmer you just have to interconnect the ISP pins of this board and the ISP robot socket and avr studio to code and run your code.
- Second one: It can be used as Wireless commander to the robots, for this you just have to plug-in the board and install the required drivers (Software Section)....