ITEE Innovation Expo 2008 : Project Details

Improved navigation using a height adjustable sensor platform for the Quokka AGV

The Quokka is a small Autonomous Ground Vehicle (AGV) intended to be incorporated in mobile sensor networks. It is designed to be very versatile and has to travel over various terrains, both inside and outside. Due to the low profile of the quokka it is disadvantaged against large, taller AGVs, where higher sensor mounting gives them a better perception of the world and allows them to navigate more effectively. A large permanent structure on the robot base, however, severely reduces the versatility of the Quokka.

The aim of this project was to design, construct, develop control operations and test a dynamic lifting structure for the use of mounted sensors on the Quokka. This will allow it to see over obstacles, travel in long grass and generally increase the amount of data gathered for use in navigation. The Quokka can also be made compact when needed. A three-stage scissor lift was implemented using an electric linear actuator. An onboard mini-computer provided control of the actuator via a motor control circuit.

To test the lift module a laser range finder was mounted on the lift and used to produce 3D plots. Various range plots were taken of situations with obstacles in them. They were first viewed with the laser at regular height and then tested with the lift raised. The amount of data points intersected by the obstacle and the amount of points beyond the obstacle were compared in each of the cases and used to determine the effectiveness of the lift module.