Active Mountain Bike Suspension

Full suspension mountain bikes (those with shock absorbers on both the front and rear wheels) have been around for a number of years now and are quite popular. While the inclusion of full suspension on bikes has seen an increase in the level of rider comfort and handling over rough terrain, this type of bike suffers from what is often termed as ``pedal induced bob''. In essence, the pedalling action of the rider causes the rider and frame to ``bob'' up and down on the suspension elements of the bike. Pedal induced bob is undesirable because it means that some of the rider's pedalling energy is going into working the suspension, rather than being applied as propulsive force at the rear wheel. A number of different systems are currently offered by the various bicycle suspension manufacturers, however these systems are all low tech in nature, and it is dubious whether some even offer any positive benefit at all.

Most modern bicycle shock absorbers come equipped with a lock out valve. This valve essentially disactivates the shock's ability to compress. One of the key aspects of a "bob" elimination system is to automatically engage the lock-out valve when suspension compression is due to pedalling forces. This project is about creating a test platform for lock-out control algorithms by instrmenting a Cannondale Scalpel MTB to allow the velocities and accelerations of key points on the bike frame to be determined. A prototype lock-out control algorithm has been implemented and we are currently evaluating its performance.

Autonomous Sail Trimming

Competitive and recreational sailors often cover great distances on sailing yachts that are designed for a crew of many, but are sailed by a small crew of just one or two. During times of rest, or where other matters above or below deck need to be attended to, the desired boat heading needs to be maintained. Two main tools exist for dealing with these circumstances: wind-vane self steering systems and electrically powered self steering "autohelm" systems. Neither is ideal. The former maintains a constant boat heading with respect to the wind, so if the wind shifts direction the boat heading will be incorrect. The latter maintains the correct boat heading at all times, but if the wind shifts, the sails will not be trimmed (set) correctly, leading to reduced forward motion and possibly a dangerous situation like an an uncontrolled gybe.

This project was about implementing an autonomous sail trimming system to work with an autohelm system to continuously trim the sails so that they are correctly set. Four sensors were constructed and installed: (shown below) wind speed anemometer (top of mast), boat speed sensor (tube at front of boat with pressure sensor), boom angle (mast rotation sensor) and wind direction (front of boat). The sensory data was recroded via an Atmel microcontroller connected via serial port to a laptop pc. The sensory data was used to learn a parametric model of the test boat's sailing characteristics so that an optimal boom angle could be determined for each set of sailing conditions. The idea is to use the system to learn a model of the sailing characteristics of each boat on which it is installed, and then to select an optimal boom angle according to the conditions.