Multi-input shaping control for multi-hoist cranes

Multiple cranes are often used in coordination to manipulate very large payloads. These type of lifts are common in the aerospace industry, when large aircraft components are moved and when satellites are placed into testing fixtures. Such lifts also occur frequently in the construction industry to move large prefabricated components into place. These multi-hoist lifts suffer from the same fundamental limitation as simpler, single-hoist cranes: payload oscillation. However, the increased complexity of the payload dynamics make multi-hoist lifts more difficult to control. This paper presents two methods to limit payload oscillation during multi-hoist lifts. The two techniques utilize input shaping to design inputs for each of the hoists involved. One method uses the local suspension cable length at each hoist for control design, while the other concurrently designs the inputs based on the payload configuration. Experimental results from a two-hoist system verify some of the theoretical findings.