The Smart Car Demonstrator is an autonomous mobile robot that serves as a case study for the Time Triggered Architecture (TTA) and the Time Triggered Protocol for SAE Class A applications (TTP/A). The aim of the project was to determinine the real-life feasibility of implementing a TTP/A cluster, by validating the Smart Car’s ability to independently navigate through a static obstacle course, with the help of a combination of infrared and ultrasonic distance sensors.
The Time Triggered Protocol for SAE Class A applications (TTP/A)1 is the newest member of the family of protocols for the Time Triggered Architecture (TTA)2 developed at the Institut für Technische Informatik at the Technische Universität in Vienna, Austria. The following report will describe the design and implementation of an autonomous mobile robot that serves as a case study for TTA and TTP/A. The Smart Car is a demonstrator for the TTP/A protocol, with the aim of determining the real-life feasibility of implementing a TTP/A cluster1.
The Smart Car’s primary task was to navigate through a static obstacle course by perceiving its immediate environment with the help of a combination of infrared and ultrasonic distance sensors. The car uses a series of grid generation and navigational path planning algorithms to choose the best path. Additionally, the car is also fault tolerant, in the sense that if it makes a poor navigational path decision and encounters a dead end, the car can retrace its path backwards and take an alternative path.
The Smart Car’s operation can be categorized into 4 main fields – Software, Electrical hardware, Electro-mechanical hardware and Mechanical hardware. The first layer in the hierarchy – the software layer, refers to software code for the TTP/A nodes compiled using the AVR GCC compiler. The second layer – the electrical hardware layer, consists of a fieldbus network, complete with TTP/A nodes and the car’s TTP/A communication bus. The third layer – electrical/electromechanical hardware layer refers to the sensors, power supplies, servos, LED indicators and other components such as additional power supply busses. The fourth layer – the mechanical layer, consists if the main chassis of the Smart Car, which is an off-the-shelf four-wheeled model car fitted with a wooden mounting board.
- Elmenreich, W., Haidinger, W., Kopetz, H., Losert, T., Obermaisser, R., Paulitsch, M., Trödhandl, C. (2002), “A Smart Sensor LIF Case Study: Autonomous Mobile Robot”, DSoS Project – Deliverable PCE3, Institut für Technische Informatik der Technischen Universität Wien, Vienna [http://www.vmars.tuwien.ac.at]
- Kopetz, H., Bauer, G. (2002), “The Time Triggered Architecture”, Proceedings of the IEEE special issue on Modeling and Design of Embedded Software, October 2002