Modeling and Control Design for a Hand Held Nutrunner System

Sammanfattning: Due to high competition on the market the industry aims at increasing the efficiency in their assembly production line. The production cycle time is determined by many factors such as operation time at each production step, the reliability of the tool and so forth. Many of the assembly applications are performed with hand held power tools which mean that a person, called operator, is holding the tool. Hence, physical stress is acting on the operator during tightening procedures and is therefore an important issue. As a result, development of better power tools is always needed. The goal with this thesis work is to build a simulation model of a hand held assembly tool. The simulation is to be use for development and evaluation of the present computer controlled tightening strategies. The model includes control unit, tool, joint and operator. Based on the model the aim is also the exploit the possibilities to improve the tightening algorithms in an automatic control fashion. The control structure investigated is MPC, (Model Predictive Control). The result is that the simulation model with good correlation describes the system and can therefore be used as an aid in the development of tool components and software. The proposed tightening control strategy, MPC, show excellent performance regarding operation tine and the reduction of operator energy input. The drawback is that the robustness of the controller is somewhat limited due to fast process time. Also the real-time implementation  as to be further developed.