I. INTRODUCTION
Recently, self-balancing two-wheeled transporters, like the Segway™, have been well recognized as powerful personal transportation vehicles. The kind of transporter can be usually constructed by a synthesis of mechatronics, control techniques and software. For example, the Segway™ is made by quite high-tech and high-quality dedicated components. In contrast to the Segway™, many researchers [1]–[2] presented low-tech self-balancing transporters and claimed that the vehicle can be built using the off-the-shelf inexpensive components. With the advent of modern technology, such transporters with sophisticated safety features can be cost down so that they, like traditional bicycles, have high potential to become prevalent two-wheeled HTVs, satisfying human transportation requirements.