The Australian National Univerity

DESCRIPTION.
The test-bed vehicle in our project is a 1999 Toyota Landcruier 4WD. A 4WD vehicle was chosen for a number of reasons: it provides a strong and robust platform capable of surviving the rigors of experimentation; it has a large amount of interior space for installing sensors/computers; and it allows the option of performing research into off-road autonomous driving. The overall design philosophy is to use as many off the shelf components as possible to reduce development time and to lever off existing tried and true technology.


Sensing.
The main mode of sensing used in the vehicle will be vision. Two separate vision systems are planned. First, an active vision head (called CeDAR developed previously at the ANU - see active vision page) will be mounted with two stereo camera pairs. One pair will have a short focal length, and concentrate on the near field of view, while the other pair will have a longer focal length, and concentrate on looking further along the road. The second vision system involves using a stereo pair looking from the dash back toward the driver's face. By monitoring the driver useful information as to their intention can be gathered as well as verification that they have seen a detected dangerous situation. This system is based on the faceLAB system from seeing machines. Apart from vision sensing, a Global Positioning System (GPS), Inertial Navigation Sensor (INS), and laser range finder have been installed into the vehicle. The 6 DOF INS is mounted close to the vehicle's centre of gravity at a point between the two rear-seat foot-wells. It provides a continuous stream of linear and angular acceleration data that can be used to keep track of vehicle dynamics. The GPS provides data that can be used for high-level, navigation problems, but is also very useful for correcting drift in the INS output. The laser range finder has been mounted looking forward on the vehicle's bull-bar. Its purpose will be to identify obstacles, both stationary (eg. guard-rails, parked cars, etc.) and moving (eg. other vehicles), and will provide an additional source of information for our obstacle avoidance algorithms.

Actuation.
Three actuation sub-systems are required in the vehicle: steering, braking, and throttle. We achieve throttle control by interfacing with the vehicle's cruise control module. The steering sub-system is based around a Raytheon rotary drive motor/clutch unit, which was designed for use in yacht auto-pilot applications. It was installed in the engine bay alongside the steering shaft of the vehicle. Power from an electric motor is transferred to the steering shaft using three spur gears: the first is attached to the steering shaft, the second to the motor shaft, and the third, being an idler gear, sits between the first two. A key feature in the design is that the idler gear can be engaged and disengaged from the drive-train using a lever protruding from the assembly. Then for ``manual'' driving of the vehicle, the idler gear can be disengaged, providing the safeguard that the autonomous steering assembly cannot impede normal steering in any way. A photo of the steering sub-system is shown in this image. Note the lever used to engage and disengage the idler gear. Also note the rotary drive motor/clutch unit, and the vehicle's steering shaft. The braking sub-system is based around a linear drive unit (produced by Animatics), and an electromagnet. The linear drive is connected to one end of a braided steel cable via the electromagnet. The cable passes through a guiding sheath to reach, at its other end, the brake pedal. Braking is then achieved by having the linear drive unit pull on the cable. The electromagnet must be powered in order for braking to occur (ie. if it is unpowered, then the linear drive cannot pull on the cable to activate the brake). In an emergency, power can be cut to the electromagnet so that all braking control is returned back to the driver. In our implementation, an emergency scenario is communicated to the autonomous driving system by having the human activate an emergency stop button. The braking subsystem is shown in this image. In the foreground the figure shows the linear drive and electromagnet, while in the background the brake pedal and its connection with the cable is shown.

Processing and Communication.
Processing and communication hardware is required to fuse together the various sensing and actuation subsystems into a cohesive, single unit. Our approach in this area has been to favor the use of standard PC and networking hardware. Such hardware is readily available, easily upgradable, and cheap.  An additional PC will be installed to process non-vision sensing data, and to control the throttle, steering, and braking subsystems. Communication is achieved between PCs via ethernet, with a connection from the vehicle back to a base station possible via a radio ethernet link. Due to the large number of sensing and actuation devices that communicate over serial lines, a serial port server has been installed. This device allows communication between a PC and serial devices as though these devices were connected directly to local serial ports on a PC. Finally, an Servo to go card has been installed to provide a low level communication interface between PCs and various other devices (eg. cruise control system, steering motor control, steering angle potentiometer). This module connects into the ethernet, and provides a number of functionalities, including A/D and D/A conversion, PID control, timers, etc.

	1999 Toyota Land Cruiser, diesel, with power steering, cruise control and ABS.
BRAKING SYSTEM.
	Whole brake actuator system.
	Brake pedal assembly.
	Brake actuator assembly.
	UltraMotion Smart motion linear actuator.
	Emergency stop electro-magnet.
STEERING SYSTEM.
	Whole steering system. Steering mechanism of vehicle including drive motor/clutch unit (left), idler gear (centre) and gear on steering shaft (right).
SENSORS.
	CeDAR active camera platform. FaceLAB cameras on dash board. LCD monitor in backseat with FaceLAB software on screen.
	Sick Laser Range finder.
	11 Mbit Radio ethernet traceiver.
Looks like a 10cm3 black box	3D rate and acceleration gyroscope.
Size of a bread box	12V DC - 240V AC inverter.
Cylinder with cable coming out one end.	Steering angle linear potentiometer.
looks like every other ethernet switch.	Ethernet switch.
	FaceLAB

	Distributed Client-Server based software architecture written in C/C++ and CORBA.