To keep bicycle self-balance, the steering angle, the roll-angle and the rear wheel velocity were taken as system outputs;

为了达到使自行车机器人保持自平衡的目的，将车把转动角度、车体倾倒角度和后轮转动速度作为系统输出；

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It is, for example, equipped with a rear-wheel steering system (Precision All-Wheel Steer) that allows the rear wheels to be pointed, independently, up to 2 degrees of toe-angle adjustment in either direction (in or out, negative or positive), for 4 degrees of articulation.

WSJ: 2014 Acura RLX Review: Larger, but It Still Comes Up Small | Rumble Seat by Dan Neil