Using input shaping to repress two-mode residual vibration on aerial lifts

Aerial lifts are machines that enable human workers to comfortably work at heights that might otherwise be inaccessible. They typically have multiple long-reach arms to enable working at such heights. There is typically enough flexibility in these arms to result in deflections of the lift endpoint, the bucket where the operators are located. These deflections can be excited by either motion of the operators within the bucket or by operator commands moving the bucket around the workspace. Input shaping is one method that can drastically reduce the motion-induced oscillation. This paper investigates the application of input shaping to one category of aerial lifts, commonly called cherrypickers. When input shaping is used, the endpoint vibration is reduced. However, it is not completely eliminated due to the nonlinear nature of the system.