The hybrid manipulators have benefits of both serial as well as parallel manipulators. In this paper, a planar hybrid manipulator with six degrees-of-freedom is proposed; it consists of two parallel manipulators each having three degrees-of-freedom. The models for forward and inverse dynamic analysis of this manipulator are presented with bond graph approach. The actuators of the manipulator have ball screw feed drive mechanism to convert rotary motion into linear motion. There are basically three problems addressed in the paper. First, the models are simulated for trajectory tracking of a semi-circular path traced by the lower manipulator initially and then tracking of another semi circular path by upper manipulators. The second problem addressed is to develop the bond graph model of the hybrid manipulator with proportional control to reach a desired position from an initial position with an unity slope after few seconds. Finally, workspace analysis for given semi-circular trajectory is done with calculation of area of the workspace of lower, upper and hybrid manipulators. It is observed from the simulation that the response follows the desired trajectory within the permissible limit. The result indicates that manipulator follows nearly tangential path. It is seen from the result that the desired trajectory lies within the workspace boundary.

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This paper reports an automated image-guided microrobotic tool to perform nonprehensile magnetic manipulation of large (of the order of few hundreds of microns) microscopic biological objects in the presence of an ambient fluid flow. The developed tool comprises of ferromagnetic microrobots actuated by electromagnetic coils arranged in a quadrupole configuration, a DC power source, and a pulse width modulation (PWM) based controller to vary the coil currents. In order to accomplish the stated objective of automated micromanipulation task, a two-tier approach is adopted, namely, (1) generation of a feedback planning algorithm that invokes one of the two motion maneuvers, namely, ‘arrest’ and ‘move’ and (2) development of a proportional controller that determines the currents to be passed through the coils based on the maneuver invoked so that the resultant magnetic field actuates the ferromagnetic microrobot in the desired direction. A physical experiment was conducted and reported to authenticate the validity of the developed approach. We believe that the developed tool can be used to perform automated feedback controlled micromanipulation of large biological cells and cell aggregates in the presence of an ambient fluid flow especially in in-vivo environments. The inherent biocompatibility of the microbot material provides a possibility to functionalize it with living cells and/or appropriate chemicals rendering it feasible to implement drug delivery and also perform on-chip biological experiments.