Robotics Command System

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The RCX (version 1.0, recognizable by a built-in 9 V connection)
The RCX (version 2.0) on a partially dismantled standard robot

The RCX (Robotic Command Explorer) of the Lego - mindstorms product series has a Renesas - H8 / 300 - microcontroller as a CPU . It is programmed by a program using an IR - interface from the PC to the CPU will download the RCX. Several development environments allow programming either by graphically combining finished modules or in different high-level languages.

After the program has been started, the robot built with an RCX can act completely autonomously and react to external and internal events, according to the programming instructions. Furthermore, can the two or more RCX another via the IR - interface communicate what competitions and cooperation possible. The RCX has three motor outputs and three sensor inputs. The power control of the motor outputs takes place via pulse width modulation .

Programming languages

The supplied software enables programs to be put together from modules with a graphical user interface . For more complex tasks, the RCX can be programmed with different programming languages, e.g. B. NQC .

  • developed by Lego (with graphical user interface):
    • RCX code
    • ROBOLAB (based on LabVIEW )
  • from other providers (text-based):
    • leJOS - programming in Java
    • NQC (Not Quite C [Eng. "Not quite C "])
    • BricxCC (Bricx Command Center) - development environment that facilitates working with NQC
    • BrickOS (formerly LegOS) - programming in C or C ++
    • Interactive C - Offers additional functions such as text output
    • Robot C - controls various systems (including RCX and NXT)
  • from other providers (with graphical user interface):

RCX sensor inputs

For many hobbyists who want to develop their own sensors, it is interesting to be able to interpret the sensor value (0 ... 1023) output by the RCX. This value results from the voltage applied to the sensor input . Without a sensor , this is 5 V, but drops off as soon as a sensor with a finite resistance is connected. The display of the RCX can be calculated from the applied voltage U as follows :

The applied voltage U in turn can, for. B. can be calculated from the connected resistor R or the electrical current I at the sensors. The maximum electrical current is 0.5 mA (a 10 kΩ resistor is connected internally to the sensor ).

The sensors can be operated in an active (light sensor, rotary sensor) and a passive mode (switch, temperature sensor ). In passive mode, as described above, only the voltage drop at the sensor inputs is measured. In active mode, the battery voltage is applied to the sensor input for 3 ms each to supply the sensor with power. The passive mode is then switched for 0.1 ms in order to record the sensor value. During this time, the active sensor must be supplied by its own power source ( capacitor ).

literature

  • Dave Baum, Michael Gasperi, Ralph Hempel, Luis Villa (2000): Extreme Mindstorms: an Advanced Guide to Lego Mindstorms . Apress, ISBN 1893115844
  • Benjamin Erwin (2001): Creative Projects with Lego Mindstorms (book and CD-ROM). Addison-Wesley, ISBN 0201708957
  • Dave Baum (2002): Definitive Guide to Lego Mindstorms , 2nd ed.APress, ISBN 1590590635
  • Ferrari et al. (2001): Building Robots With Lego Mindstorms: The Ultimate Tool for Mindstorms Maniacs . Syngress, ISBN 1928994679
  • Fraunhofer IAIS (2007): Roberta - Basics and experiments for Lego Mindstorms RCX . Fraunhofer Verlag IRB, ISBN 978-3-8167-7808-0
  • Fraunhofer IAIS (2008): Roberta - Basics for the planning and implementation of Roberta courses . Fraunhofer Verlag IRB, ISBN 978-3-8167-7806-6

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