Dynamics modelling and control of a strawberry harvesting robot

Nowadays, robotic solutions have become important applicable techniques in micro-precision agricultural systems. Robotic harvesters such as fruit shakers have been developed using planar mechanisms with high degree of complexity. In this study, an analytical model of forced vibration of fruit stem system is presented. So, the motion equations are solved to obtain the dynamic behaviour of system. Then, design procedure of three proposed controllers including optimal, high-passed filter and low-passed filter controllers is also investigated to control the displacement and angular velocity of fruit which is assumed as the last arm of mechanism. The Robotic harvester has been studied to perform a specific manoeuvre of harvester´s arms to pick the strawberry from its stem. Results showed that optimal controller had an appropriate performance to harvest the fruits with acceptable settling time and maximum overshoot in time response of desired state variables. Modelling results also showed that the desired path can be tracked with insignificant error by the harvester´s arms using this controller.