## 1 Introduction  
The cochlear implant (CI) has established itself as the state-of-the-art and most successful artificial prosthesis used by humans. It is an electronic device that is used to treat severe-to-profound hearing loss as an alternative to a normal mechanical hearing system [1]. An electrode array (EA) along with a mic, transmitter-receiver pair, and a speech processor directly stimulates the neurosensory auditory nerves. During the last 30 years, around 0.6 million people have received CI system whereas only 10,000 were CI recipients thirty years ago, mainly due to strict candidacy criteria [2]. Even with this success, postoperative hearing outcomes are still variable and limited partly due to inefficiency in the process of placing the electrode array (EA) in the right position inside scala typami (ST) [3]. Among several other factors, such as device parameters, aetiology, hearing loss progression, extent of residual hearing, and device programming, trauma induced during the surgical insertion of EA has paramount importance and should be reduced to minimum to achieve reasonable hearing outcomes [4; 5; 6]. The process of atraumatic insertion possesses several challenges: the size of cochlea/ST, position of facial nerve with respect to cochlea opening, the insertion axis, and associated trajectory and inconsistency of mental representation of insertion axis among surgeons. Preserving the internal tissue structuresduring insertion, such as basilar membrane, osseous lamina, and spiral ligament, are fundamentally important for better hearing perception post-surgery [6,7]. Translocation of EA from ST to scala media (SM) or scala vestibuli (SV) is a major cause of residual hearing loss that can to lead poor CI performance throughout a patient's life [8]. EA tip foldover and buckling may also cause trauma and reduces the frequency selectivity [9]. Inter-cochlear inflammatory response and fibrosis development are caused by the trauma induced during EA insertion that may result in degradation of both electrical and acoustic hearing [10]. To minimize the trauma and better position the EA, as well as eliminate the risk of insertion failure, different EA design, insertion, and surgical techniques (manual, semi-automated, and automated) have been developed [11,12]. However, there is still need for a method for prediction and correction of EA position inside the ST. The system ideally keeps track of EA trajectory with sensing capabilities and applies corrective measures where necessary. EA insertion cannot be imaged either internally or externally due to lack of line of sight from outside and very narrow internal structure. However, there is the possibility of computed tomography (CT) scans during surgery to guide the array but excessive CT scans expose the patients to the ionization radiation [13]. Some researchers have also developed electrode arrays with integrated sensors. For example, [PERSON] et al. [14] developed a magnetic guided insertion system in which a magnetically tipped EA is guided as it is inserted in to the cochlea with the help of a externally placed manipulator magnet. The external magnet placed close to the patient's head applies magnetic torque to the array tip, causing it to bend away from the ST walls. The solution provided by [15] is based on microelectromechanical (MEM) technology. High-density silicon-based electrode arrays are developed with integrated mechanism for stimulation, recording, and position control. Having mentioned these systems, it is still not possible to integrate sensors in the commercially available EAs due to rigidity introduced by the sensor that defeats the very purpose of trauma-less insertion. In addition to other paradigms, robotic systems can also help in reducing damage to the inner structure due to their potential increased accuracy compared to manual surgery by hand. Such robotic systems are experimentally used for EA insertion with preplanned paths using CT imaging technology [16,17].