Our Tactically Expandable Maritime Platform (TEMP) is a 1:12 scale of the system being proposed by DARPA.
We have built a system of shipping container sized robotic boats that can hook onto each other. We demonstrate the conceptual design of a system that is capable of constructing bridges and various shaped islands that can be made compliant to waves.
Movie of Project Highlights
A future vision of the TEMP platform would be to have floating modules the size of ISO shipping containers (20ft x 8ft x 8ft) off loaded into the ocean and self assemble and self reconfigure in some desired location. Modules would assemble in a brick laying staggered pattern to conform to any shape desired. Each module would be capable of moving and docking to other modules autonomously. It is hoped the modules will also be able to submerge themselves to a depth of 100ft in future full scale system. Whilst the movement operations of the modules are homogeneous and each module would be able to move on its own accord, each module could serve as a different function for the overall system such as providing fuel, military living quarters, gun batteries, ammunition, or providing extra buoyancy at some points on the platform. The floating system needs to be flexible enough to withstand rough seas and my be required to change the stiffness of the connections between modules to survive changes in seas states.
Thrusters and holonomic motion
Modules that have the ability to move unassisted on the surface of water are referred to as active modules. These modules have four thrusters below the water surface in each corner. When vectored together these thrusters produce holonomic motion, that is, each active module is capable of moving in any combination of linear and rotary velocities at any point in time. Holonomic motion increases the modules mobility in water and the added agility allows the modules to dock and undock easily from one another.
Docking connector design
Docking operates on a gender based principle where the front and back sides of each module have male and female docking components respectively. The front side of the module has sweeping retractable hooks that are designed to catch onto a rope.
Our scale system is not exact and the modules are sitting further above the water line than what the real system would experience. For this reason, we needed to add a keel to the modules to stay afloat and to maintain a stable orientation.
Vision system considerations
For our system of modules we achieve localization using overhead cameras with software designed to detect 2D barcodes (‘April tags’ generated by the ‘April Robotics Laboratory’). For this reason each module is required to display a 2D barcode on its top.
Main electronic components:
- 1 x Embedded linux Gumstix module
- 1 x Custom embedded linux module breakout board
- 3 x Dual serial motor drivers
- 2 x 5000mAh, NiMH Batteries
- 4 x DC brushed motors (thrusters)
- 2 x DC brushed motors with encoders (loop arms winch motors)
- 2 x Analog sail winch servo, 3.5 turns (hooks)
- 1 x Water leak sensor
- 1 x LED debug output
- 1 x 25 channel 1.8v to 5v logic level converter
- 1 x Mounting PCB for logic converter and motor drivers