Segway PT

                             Segway PT

The Segway PT is a two-wheeled, self-balancing, battery-powered electric vehicle invented by Dean Kamen. It is produced by Segway Inc. of New Hampshire, USA. The name Segway is a homophone of the word segue, meaning smooth transition. PT is an abbreviation for personal transporter.
Computers and motors in the base of the device keep the Segway PT upright when powered on with balancing enabled. A user commands the Segway to go forward by shifting their weight forward on the platform, and backward by shifting their weight backward. The Segway detects, as it balances, the change in its center of mass, and first establishes and then maintains a corresponding speed, forward or backward. Gyroscopic sensors and fluid-based leveling sensors detect the weight shift. To turn, the user presses the handlebar to the left or the right.
Segway PTs are driven by electric motors and can reach a speed of 12.5 miles per hour (20.1 km/h).

 Technology

 The dynamics of the Segway PT are similar to a classic control problem, the inverted pendulum. The Segway PT (PT is an initialism for personal transporter while the old suffix HT was an initialism for human transporter) has electric motors powered by Valence Technology phosphate-based lithium-ion batteries, which can be charged from household current. It balances with the help of dual computers that run proprietary software, two tilt sensors, and five gyroscopic sensors developed by BAE Systems' Advanced Technology Centre.The servo drive motors rotate the wheels forwards or backwards as needed for balance or propulsion. The rider controls forward and backward movement by leaning the Segway relative to the combined center of mass of the rider and Segway, by holding the control bar closer to or farther from their body. The Segway detects the change in the balance point, and adjusts the speed at which it is balancing the rider accordingly. On older models, steering is controlled by a twist grip on the left handlebar, which simply varies the speeds between the two motors, rotating the Segway PT (a decrease in the speed of the left wheel would turn the Segway PT to the left). Newer models enable the use of tilting the handle bar to steer.