Lehrstuhl Kognitive Integrierte Sensorsysteme: Lego Robot Sensor Extension

A Lego Mindstorm NXT Robot as an Extendable Mobile Sensor Platform

Subject:
The lego mindstorm NXT robots have established themselves as a standard component in teaching and research in many universities. From the point of sensor technology, the currently available sensors are still limited in variety and selectivity. However, a mobile sensor platform would be highly desirable both for integration and application of sensors on a feasible demonstrator in teaching as well as for real-world data generation in research on robust sensor fusion and intelligent system design. Thus, a project was started to modularly extend software and hardware of the basic off-the-shelf lego robot by additional sensor modules. First demonstration was done by integrating the MaZeT color sensor on the platform.

Abstract:

The integration of additional sensors into the modular lego mindstorm NXT robot environment requires electronic and programming activities. On the hardware side, an interface board for the required I2C-interface of the lego robot was conceived, that will allow to connect to different sensor types using auxiliary electronics. MaZeT color sensors (MCSiAT/BT, MCS3AS, MCS3BT), which have been the basis of other related application system studies at the group, where reused as the first demonstrator. At the initiation of the activity, a color sensor was not yet available. Nowadays, this and other sensor choice is also commercially available. The following figure shows the conceived boards for the sensor integration:

The basic sensor board has been extended by active illumination employing a group of four white LEDs, which are operated using pulse-width modulation (PWM) to control intensity. The mounted sensor board is the first instance of potential robot extensions:

The individual color channels unfortunately cannot be read in parallel. Sequential read-out is required. The following block diagram shows the integration with the NXT intelligent brick and other sensors in the NXT system:

The control of the sensor board within the modular lego mindstorm NXT system requires also software effort coordinated with hardware/electronics activities, which is briefly illustrated by the following block diagram:

In one of the activities on the software side, the Labview-based lego development enviroment palette has been extended by additional sensor block:

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Configuration panel of the NXT color sensor extension with activated PWM illumination control:

Application example of the ISE color sensor block from the extended NXT palette:

Sample NXT robot set-up with the mounted ISE color sensor block:

The color-sensor module served as a vehicle for extending the lego mindstorm NXT robot by additional sensors in teaching and research. Student projects and topics in the wake of the advance of this activity are available. Integration of further sensors, e.g., gas or NIR sensors as well as CMOS vision sensors from other ISE activities (see HEIS course) are of particular interest. More details and sensor signal extraction can be found soon in the upcoming internal report (Studienarbeit) given below.

	Status:		running, started in 2007, open end
	Partner:
	Financing:		Self-Financed
	Contact:		Prof. Dr.-Ing. Andreas König
	Contributors:		Li Li, Thomas Gräf (Student assistant, HIWI), Kuncup Iswandy
	Publications:
			Internal report (Studienarbeit) in preparation