Many kinds of hardware have been developed to support locomotion. One of the oldest examples is to create an entire cockpit for aircraft flight simulation (recall Figure 1.15). Figure 10.8(a) shows an omnidirectional treadmill that enables walking in any direction and over any distance. Exercise machines, such as a stationary bicycle have been connected to VR systems so that the user can pedal and steer to guide himself through a large virtual world, as shown in Figure 10.8(b). Figure 1.1 showed a mechanical platform for virtual flying like a bird.