Design Of A Linear Ocsillatory Actuator For Oil Palm Mechanical Cutter

At the early stage of their use, linear motors were particularly dedicated to transportation systems. Nowadays, linear motors are meant to replace a system using a rotating motor and a transmission to realize a linear movement. With linear motors, the performance of the system increased considerably since the mechanical limitations are removed. This leads to a better precision, a higher acceleration and a higher speed of the moving part. Therefore, direct drives with linear motors are increasingly used in industrial applications although these solutions normally lead to more investment costs. In this research, the linear motor would be applied as part of an oil palm motorized cutter system. Due to it advantages especially in term of producing linear motion the efficiency of the existing motorized cutter system is expected to improve. The existing system uses intermediate shaft and gears in order to convert rotary motion to linear motion for harvesting activity. However, the rotational transmissions become ineffective when it is used for palm trees higher than 5 meters. It is due to the fact that intermediate shaft bends as the length increases. On top of that, it will increase the overall weight of the mechanical system as the length increases. The new system of oil palm motorized cutter employs the linear oscillatory actuator (LOA) to replace the intermediate shaft and gear to produce linear motion. It eliminates the mechanical limit because there is no more intermediate shaft used in this system. The function of the intermediate shaft will be replaced by the copper wire in order to energize the LOA. The LOA is an actuator in which a mover performs a reciprocating motion in a range of stroke as a result of being driven by a current having a sinusoidal or pulse wave form. The structure of LOA has been designed using FEM software by previous researcher. The drawback of the previous model is the lack of force to perform harvesting activity. Therefore in this research, the LOA design has been optimized to achieve high thrust of LOA. The method used in this design optimization is Permeance Analysis Method (PAM). The design optimization is done by varying the size of permanent magnets and coils. In this design, it is ensured that the magnetic density saturation does not occur because, if it does, the thrust of the LOA will not increase even though the input current is increased. The constrain in this research is to develop the LOA within its limited overall weight. It is to make sure the LOA is mobile to the users. As a result, not only the high starter thrust of LOA about 200 N has been developed, but it is also light in weight which 2.0 kg and small in size which is 3.14×10-4 m3 in volume.

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