To My Robot Gallery built at Oxford University


LICAR1 Mobile Robot

LICAR2 Mobile Robot

The vehicle base and the steer unit

LICAs

Robuter, GEC Turtle, Navigator JTR1

A Tracked Robot Vehicle

Aramis, Athos and Porthos

Outdoor Navigation





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LICAR1 Mobile Robot


The LICAR1 mobile robot was designed by me and built at Oxford in 1996 for both indoor and outdoor navigation, funded by EPSRC Grant GR/K39844. It has a complete modular structure so that it can be readily extended and easily configured without a major redesign. The front wheels are steered together using a leadscrew driven by a DC motor. The rear wheels are driven by a DC motor with a differential gearbox. There are two 12V 38Ah sealed batteries on board to provide power. The robot has been equipped with multiple sensors for navigation, including optical encoders, laser localization system, laser range finder, SICK scanner, optical proximity sensor, and a ring of 12 sonars. An LICA-based control system has been used to implement sensing, planning, navigating, and control tasks. The vehicle has a dimension of 1m x 0.6m x 1.2m and a maximum speed of 1m/s.


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LICAR2 Mobile Robot


After successful construction of the LICAR1 mobile robot, the LICAR2 was built in 1997 at EPSRC grant GR/L08472. It has the exactly modular design as its old brother, except for its frame built by black aluminum tubes instead of silver ones. The LICAR2 also has a distributed control system based on the Locally Intelligent Control Agents (LICAs). The LICA is distributed control architecture specially developed at Oxford in 1992 for intelligent control of mobile robots. It is based on the state of art microprocessors such as PowerPC, SIEMENS 80C166, and transputers. The modular structure of the robot provides the flexibility for testing and debugging in such a way that any sensors and motor drivers are easily taken off or added on the vehicle.



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Photo 1: the vehicle base

Photo 2: the front steering unit


The LICAR1 and LICAR2 were built in such a fashion that the modular design approach was applied to every aspect of the robot, i.e. mechanical, electrical and computing components. It is very flexible to change its configuration or to take off and add on different sensors and actuators. Photo 2 shows the steering unit being taken off from the vehicle by releasing 4 screws on the top of the unit. The vehicle base has a 2-axes motion control system and a LICA-based controller to integrate different sensors such as sonars, SICK scanner, IR proximity and optical encoders, as shown in Photo 1. It can run autonomously to implement a specified task.



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Photo 1: Locally Intelligent Control Agent (LICA)

Photo 2: LICA-based control rack


I developed the Locally Intelligent Control Agents (LICAs) for autonomous mobile robots at Oxford during 1991 and 1992. Each LICA is a single generic module or building block (Photo 1), and many of them can be used to implement the distributed sensing and control architecture for advanced mobile robots (Photo 2). A typical LICA board includes the following components:


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Robuter(left), GEC Turtle (middle), and Navigator JTR1 (right)


The Turtle vehicle was donated by the GEC Rugby in 1988, and was originally controlled by an industrial GEM80 PLC system. It has three wheels: two passive wheels on the back and one front wheel being driven and steered. A rotating laser scanner and barcode targets were used to locate the vehicle position. From 1988 to 1992, this vehicle was a main platform for us to implement different sensor-based planning and control algorithms. The main aim of our research is to develop advanced AGVs (Autonomous Guided Vehicles) for manufacturing. I developed a multiple sensor system and the distributed control architecture to replace the GEM80 controller, based on transputer technology.



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A Tracked Robot Vehicle for Outdoor Applications


The base of this tracked vehicle was originally donated by an UK defense research agent in 1987. After a very short period of operation, its drive system was damaged. The vehicle was left in the storage for few years. In 1996, I designed the top frame and control system using a modular approach. Then I used it as a platform for undergraduate final projects. Two forth-year students worked on it to build a LICA-based control system and a LICA-based laser localization system under my supervision. It started full operation in the summer of 1997. Since it has the same modular design like the LICAR1 and LICAR2, all the sensors built for those robots could be directly added on it to operate.



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Aramis, Athos and Porthos


This is a team of cooperative mobile robots built at Oxford in 1997 by two forth-year undergraduates under my supervision. Again, a modular approach was adopted in the design and construction. Each robot has three layers: a base layer for the embedded control computer (80C166 microcontroller), a middle layer for 4 sonar range finders to detect obstacles, and a top layer for radio link to communicate with other robots. Each robot has a circular body with a diameter of 160mm. The robot height is about 230mm (not include antenna). The project won the 2nd prize in the research project competition organized by the Department of Engineering Science in 1997.



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Outdoor testing at Oxford


This was the outdoor testing carried out at Oxford in the summer of 1997. The LICAR2 mobile robot was used in the testing. An extended Kalman filter was used to integrate the data from optical encoders and the angle observations from a rotating laser scanner (3Hz) looking for known targets to locate the vehicle position. A Notebook computer was used to issue commands and collect real data.



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