Computers stay normally where they are. Man-machine interactions depend thus only on the part of the human being. On the other hand, autonomous mobile robots have a radically expanded work space, shared with that one of human beings. It enables them to initiate an interaction by themselves. This gives rise to a new kind of man-machine interactions under circumstances which would not have happened otherwise, for instance with people without technical experience. It is therefore desirable to design mobile robots in a deliberative way, keeping their appearance friendly, decent and not dangerous.Pygmalion is an autonomous mobile robot whose design principles are safety, friendliness and a high degree of autonomy. It is small, light weight and therefore less dangerous than many robots in its performance class. The design is oriented towards its application as a service robot, doing e.g. transportation tasks, and as a personal robot, working close together with people.
With the blinkers, its bilingual speech processor (E, F) and its friendly appearance it attracts the necessary attention for a machine those work space is to be shared with that one of people. The differential drive kinematics allows prediction of its maneuvers and always offers a secure zone at the sides of the vehicle. Concluding from own experience, people can easily understand and follow its movements. The kinematics avoids furthermore the mechanical design to become unnecessarely complex and heavy.
# Main component: VME-based six axis controller for embedded mechatronic real-time systems.
# CPU (currently): MVME16001 PPC 604@100MHz card with standard peripheral IP-modules for analogue, digital I/Os and encoder inputs.
# Acuity AccuRange4000 laserscanner with a full view on the environment (minus four blind zones from the vertical supports of the load platform)
# Pulnix TM-9701 full frame, gray-scale CCD camera, EIA (640 x 480), which sends a standard RS-170 signal to a Bt848 based frame grabber (not on the pictures)
# Bumpers are subdivided into eight tactile zones at two different heights
# It has several RS-232 channels, wireless ethernet and galvanically isolated sensor/actor and CPU/periphery lines.
# Batteries provide autonomous operation up to seven hours.
# The drive modules consist in two EC-motors with 1:100 harmonic drives with an encoder resolution of 50’000 pulses per revolution.
# The wheels have an antistatic coating and include a fast lock/unlock mechanism which enables a rapid mechanical decoupling from the harmonic drive/motor side.
# By using industry standards like Ethernet, VME, IP, PMC and CAN-busses, extensibility is provided for further processors, periphery and sensors, e.g. PCs with touch panel, infrared communication system, ultrasonic sensors or cameras, etc.
# Size and weight: 45cm width x 45cm depth x 65 cm heith, about 50 kg.
The programming environment of Pygmalion is the dead-line driven hard real-time operating system (HRTOS) XOberon. XOberon has been developped at the Institute of Robotics from the Swiss Federal Institute of Technology in Zurich. It serves Motorola 680×0 and PowerPC based targets and hosts with Win95, WinNT and UNIX. XOberon solves most of the usual real-time issues by implementing a deadline-driven scheduler with admission testing. Run-time memory accesses are guarded by the address translation done by hardware and software. The very fast strong-typed Oberon-2 compiler and the presence of a dynamic loader, which checks for interface compatibility, allow short edit-compile-run cycles. The run-time performance has been carefully tuned: The system schedules tasks with a 100 microseconds time-slice, with a kernel overhead of less than one percent on a PowerPC 604, clocked at 100 MHz. A growing library of board support packages, driver software and target data visualization tools exist.
XOberon relies on the Oberon programming language which belongs to the Pascal family. It has been designed by Niklaus Wirth, who is known as the creator of Oberon’s predecessor languages Pascal and Modula-2. Oberon retains the proven advantages of Pascal and Modula-2 (structured syntax, strong typing, modularity) and adds support for object-oriented programming. Due to its strict nature it is an adequate choice for programming real-time systems since they inherently offer many opportunities for buggy programming.
The Name ‘Pygmalion’
Short and informal: The story of Pygmalion and Galatea is rooted in Greek mythology. Pygmalion, King of Cyprus, was a talented sculptor. Among the statues he carved was one of a beautiful woman that he named Galatea. In time he fell wildly in love with Galatea. Aphrodite, the Goddess of Beauty and Love, took pity of the lovesick Pygmalion. She turned Galatea into a living woman and presided over the marriage of the two.
Ovid’s Pygmalion is one example in history where a non-living matter was transformed into a living matter. This is, more or less, what we try as well.