A robotic system for overlapping radiofrequency ablation (RFA) in tumor treatment is disclosed. The robot assisted navigation system is formed of a robotic manipulator and a control system designed to execute preoperatively planned needle trajectories. Preoperative imaging and planning is followed by interoperative robot execution of the ablation treatment plan. The navigation system combines mechanical linkage sensory units with an optical registration system. There is no requirement for bulky hardware installation or computationally demanding software modules. Final position of the first needle placement is confirmed for validity with the plan and then is used as a reference for the subsequent needle insertions and ablations.