| 摘要 |
A navigational device is disclosed. The navigational device includes a rotatable wheel. The rotatable wheel is attached in a wheel frame with a first rotatable member. The wheel frame is attached in a chassis with a second rotatable member. The navigational device further comprises a switch. The rotatable wheel pushes the wheel frame to rotate while the rotatable wheel is pressed down. The switch is closed due to a pressure by the wheel frame or the chassis. The rotatable wheel rotates with the wheel frame while being pressing down. The movement is stable without shaking.
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