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S. Engleder:
"Time-optimal motion planning and control of an electrohydraulically actuated toggle mechanism";
Mechatronics, 17 (2007), 8; 448 - 456.

The aim of this paper is to significantly reduce the cycle time of an injection molding machine by operating its clamping unit with minimum time. Therefore, a two-step control concept is presented. First, time-optimal trajectories are planned with respect to the kinematic and dynamic restrictions of the toggle mechanism. Formulating the time-optimal problem as a linear program allows the consideration of nonconstant velocity and acceleration limits as well as jerk constraints for the actuating piston. Second, a nonlinear control scheme based on feedback linearization is introduced to guarantee the time-optimal movement of the toggle mechanism. The proposed nonlinear controller possesses a cascade structure and considers the different modes of the clamping unit´s hydraulic system as well as the clamping force build-up of the clamping unit. The simulation and measurement results presented in the paper show significant improvements compared to an existing open-loop control concept.

Time-optimal trajectory; Jerk constraint; Nonlinear control; Feedback linearization; Tracking control; Electrohydraulic actuation; Injection molding machine

http://dx.doi.org/10.1016/j.mechatronics.2007.05.003

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V43-4PDSYPJ-1&_user=103677&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000007978&_version=1&_urlVersion=0&_userid=103677&md5=131baedce7aec66bfb2c345acaba60a3