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Currently Existing Prototype: Blaze Robot
A prototype robot is already available. This robot prototype was baptized BR (Blaze Robot). It was entirely designed by Bernard FROMENT, the instigator of the present MOSAIC project. Its development represents approximately 24 person-months of work. The BR robot was designed to be modular, powerful, fast-moving, silent, solid and reliable.

Blaze robot is a 3-wheel, non-holonomic robot of industrial design. Two linear actuators (able to move quickly and silently) raise the robot slightly after it stops, so that it remains perfectly stable while it works or while someone works on its surface. Another specificity of the Blaze robot is that it can be pushed, allowing it to be moved manually by an operator to another location.
But the real objective of designing this capability is that it allows the robot to memorize a path by "learning". This is one of the methods by which the robot can be programmed to reach a destination.

The current batteries (48V) are sealed lead batteries, but the final version of the BR robot will include a LiFePo4 battery in its central compartment.

The most difficult technical issue to resolve during development was the motor noise. In order to be silent, the stepper motors are driven in a closed loop. This driving method also allows the implementation of a major improvement: each stepper motor only uses the current it needs for the force to be applied, greatly reducing the unit ’s global power consumption.
Generally, a significant effort was made to cancel or reduce all noise sources:
- No fans (except in case of overheating)
- Motors and linear actuators mounted on anti-vibration plots (to counter structural noise)
- Sound protection hood (to counter airflow noise)
- Direct transmission (no gears)
- Electronic switching modules selected to be outside the human audible spectrum
- Low noise linear actuator (normally dedicated for medical use)

robot large view

On this photo we can see the temporary module which is used for development and tests (the yellow multimeter for controlling the battery voltage during the charge and the dedicated radio for an emergency stop)

 

BLAZE ROBOT – CURRENT STATE OF DEVELOPMENT
At the time that these lines are being written (November 2012), the principal specifications for this prototype are:

Material Aspects (current state of development):
- Propulsion by 2-wheel drive nonholonomic and freewheel
- Propulsion by 2 stepper-motors of 450W each and motor driven in closed-loop (low energy consumption and low noise)
- Maximum speed = 0.84m/s (3 km/h)
- Maximum acceleration = 1m/s2
- Emergency stop = -1.6 m/s2
- Aluminum frame and stainless steel (630mm x 690mm)
- Height of propulsion compartment = 125mm
- Battery 48V/10Ah rechargeable by plug (no docking-station)
- 48V main power supply (regulated, protected and temperature-monitored)
- 32-bit RISC card PC104+ format (a non-standard card specifically designed for this project)
- Rugged PC Card PC104+ format (ATOM N450 + 4GB flash-soldered for this project)
- Rugged Wifi card 802.11 a/b/g/h
- Long-range radio for remote control
- Dedicated power supply boards (high MTBF) and totally protected
- Temperature monitoring of the robot’s vital elements
- 2 linear actuators for the robot’s stabilization and blocking (when stationary)
- Additional module for testing / development (emergency stop via dedicated radio and charging plug)

PROPULSION/ENERGY managed through a 32-bit RISC card.
At the end of the development phase, this card will be redesigned in PC104+ form factor.

Modular power supply cards. These cards provide the different
voltages that are required, and also monitor defaults and system temperatures

Embedded Software (existing):
- Robot movement is controlled through simple commands (translation, rotation, different curves, rotation, starting with accelerating curve, etc.)
- All types of planned trajectories are implemented (straight, clothoid, anticlothoid, circular rotation, etc.)
- Commands are sent via radio or RS485 link (IEEE 802.15.4 standard)
- Definition of speed-profiles implemented
- Definition of strength-profiles implemented
- Odometry time-stamped and synchronized

Main features of the external software (PC):
- Transmission of commands to ROBOT (by radio or RS485)
- Graphic display of robot real path (odometry)
- Graphic display of robot real speed-profile
- DEBUG Mode
- Miscellaneous tools (data exportation to TextFile or EXCEL, translation of binary commands in clear, simulation files, etc.)

Robot Simulator (PC):
- Simulates the robot’s movements. Limited use for test.

Miscellaneous:
- Complete documentation (written simultaneously during the development)

The linear actuators raise the robot slightly when the robot is stopped, in order to ensure complete stabilization of the unit.
Only one linear actuator is installed on the current prototype, but 2 are planned for the final version of the robot.

The power compartment is designed with a backplane and receives the different power cards. On the floor, the fan used to lower the temperature in case of overheating. The huge capacitor is used to absorb the energy provided by the stepper motors when robot decelerates.

BLAZE ROBOT / WORK REMAINING TO FINALIZE THE PROPULSION/ENERGY PORTION

Material Aspects (to do):
- New mechanical chassis (lighter / space-saving)
- New, larger wheels (160mm) equipped with professional tires
- Develop a system that facilitates the changing of the wheels
- Integrating of a LiFePo4 battery
- Integrating a cleaning system for wheels
- Selecting and integrating a reliable connection system (military-grade plugs)
- Complete tests in real conditions(endurance, strength, borderline situations, etc.)

Embedded Software (to do):
- Self-calibration of wheel diameter (odometry correction)
- Linear actuator control (hard and soft)
- Intelligent calculation of the remaining battery capacity
- Commands for Instantaneous Trajectory Modification (for future implementation of the dynamic obstacle avoidance feature)

Rugged embedded wifi card and the ATOM N450 PC card. This PC card is PC104+ form factor

Screen shots of developed software  

 

The main remote interface that controls the BR robot. The window is divided in 3 main sections : DEBUG (left), odometry and speed (centre) and programmed orders for the robot's movements (right)

The sub window for the TRANSLATION command.

The X,Y graph of robot trajectory

The sub window for the ROTATION command

The speed-profile graph of the trajectory

A software module for testing the different curves that can be executed by the robot (clothoid, circle, anticlothoid, starting with accelerating curve,...)