Como prometi cá está a minha participação.
Quando o concurso apareceu a primeira coisa que me veio à cabeça foi como controlar o movimento de um robot só com um motor e então depois de muito pensar cheguei a este sistema que me premite andar num só sentido mas em todas as direcções, isto é, quando o motor está a rodar no sentido positivo o robot anda neste sentido mas quando o motor roda no sentido contrário o robot gira sobre si.
(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_i2teYMYP9C0%2FSiB53a6AmXI%2FAAAAAAAAAfo%2FdtIaT0XaSI8%2Fs400%2F5.jpg&hash=2c254c1450014811fb73f0a8a09cb07be83baeb2) (http://picasaweb.google.com/josescxavier/Concurso#5341403151083805042)(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_i2teYMYP9C0%2FSiB56qR_G_I%2FAAAAAAAAAfs%2FngJGK3VCxac%2Fs400%2F6.jpg&hash=191d06565975e9d714922cce3b2030fbbc5addc0) (http://picasaweb.google.com/josescxavier/Concurso#5341403206750510066)
(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh3.ggpht.com%2F_i2teYMYP9C0%2FSiB59tAYSTI%2FAAAAAAAAAfw%2FnMGLsMlK8xU%2Fs144%2F7.jpg&hash=50477394dc38e957ec403fe1f01a41db1efdd279) (http://picasaweb.google.com/josescxavier/Concurso#5341403259021576498)(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_i2teYMYP9C0%2FSiB6AbAosoI%2FAAAAAAAAAf0%2FsLuYqeVPEVo%2Fs144%2F8.jpg&hash=84cdf386968777fa2e24805a400da87aa9f68de5) (http://picasaweb.google.com/josescxavier/Concurso#5341403305730421378)(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_i2teYMYP9C0%2FSiB6FUDQOMI%2FAAAAAAAAAf4%2FEDN-gr5EGXE%2Fs144%2F9.jpg&hash=71fbe93d8282e755269434626eb3eb9e7fca9b5b) (http://picasaweb.google.com/josescxavier/Concurso#5341403389761697986)(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh3.ggpht.com%2F_i2teYMYP9C0%2FSiB6IzhTgJI%2FAAAAAAAAAf8%2Fwn1kSx8-Zg8%2Fs144%2F66.jpg&hash=05ebe1101826586ff623e54e8a5c1b2532835dfb) (http://picasaweb.google.com/josescxavier/Concurso#5341403449748848786)(https://lusorobotica.com/proxy.php?request=http%3A%2F%2Flh3.ggpht.com%2F_i2teYMYP9C0%2FSiB6LI7OtpI%2FAAAAAAAAAgA%2FIdQRDKF-i7M%2Fs144%2F10.jpg&hash=8f7cc056125eb288727ae3ae639e6c8a29d85082) (http://picasaweb.google.com/josescxavier/Concurso#5341403489854469778)
Espero que a ideia seja útil para o projecto de alguém :)