The objective of the AQUA project is to produce a fully-autonomous amphibious robot which can explore underwater environments
and gather data with minimum disturbance of the indigenous marine life. Its advanced vision system in combination with six
independently-controlled flippers for locomotion gives AQUA its
incredible manoeuvrability in the water allowing it to safely pass over coral in shallow waters as well as to explore a sandy
bottom without physical contact.
The body of the AQUA version 1.0 robot is 50 by 65 by 13 centimeters and weighs approximately 18 kilograms. The shell is made of anodized aluminum.
Later versions of AQUA are smaller and lighter.
AQUA's legs are interchangeable: flippers for swimming
and for limited walking along the beach, and rubber-treaded legs for walking. The legs are individually controlled by single-axis motors,
allowing for large flexibility in fine-tuning the robot's walking and swimming gaits.
AQUA can be tele-operated via a fiber-optic tether, or it can be used in an unthered mode.
AQUA has both rear- and forward-facing video camera for use in both tele-operation and visual servoing. The acoustic localization sensor
and the trinocular sensor are presently being developed as external modules by the Dalhousie and York teams and can be used in conjunction with the AQUA platform, the
intention is to integrate them into the body of the robot in the future.
AQUA (and most RHex robots, if not all) is controlled using a C++ library called RoboDevel, which is a
collection of libraries for programming the RHex family of robots. RoboDevel is made up of libraries and tools that are robot-independent, as well
as code that is specific to each robot derived from the original RHex architecture. RoboDevel runs on a 1KHz loop in a real-time operating system (QNX for AQUA),
operating the gait-generation and proportional servo software. The swimming and walking functionalities
are implemented as RHexLib modules. A visual processing module for AQUA is being developed with VXL as the vision library.
As a part of the regular development cycle, AQUA and its external modules are tested locally. In McGill's case,
for instance, this is done at the pool in the Atheletics Facility. When all the components have reached the next milestone in development, a field trial is scheduled.
There has typically been a trial in early winter at the Bellairs Research Institute each year since the project's inception. The water is clear,
allowing for the vision systems to be run through their paces, and also warm. The latter is important for the researchers who are swimming
with AQUA. Even with wetsuits, the temeratures several metres below the surface can prove to be decidedly chilly. Perhaps most importantly,
field trials at Bellairs allow AQUA to be put through its gaits in one of the primary environments it is envisioned being used in: a coral reef.
Two other opportunities for testing AQUA under different conditions have arisen. AQUA was tested in the cold waters of the Atlantic Ocean off
of the shores of Peggy's Cove, Nova Scotia in the fall of 2005. There, it was being evaluated for its usefulness in the fishing industry. August
of 2006 found AQUA taking a swim in some particularly shallow and silty waters of Lac Ouareau, a lake in the Laurentian Mountains north of Montreal.