# Review of Advanced Medical Telerobots
## 2 Medical Telerobotic Topologies
### Single-Leader Single-Follower Topology (SL/SF)
#### 2.1.1 Sensory Augmentation through SL/SF Telerobotic Surgery  
Telerobotic systems provide the operator with complementary perceptual awareness during the conduction of tasks (such as surgery) to augment the knowledge of the operator (such as the surgeon) regarding the condition under which the operation is being conducted. This augmentation has been achieved through visual [40; 99], auditory [100] and haptic [2; 35; 101; 102] channels. Telerobotics-assisted sensory augmentation in surgery is particularly designed to address the three critical sensory restrictions, which exist in manual minimally invasive surgeries, namely (a) degraded hand-eye coordination [103] (b) lack of depth perception [20; 104], and (c) insufficient or inaccurate haptic feedback [35]. See [63] for details about desired characteristics of haptic interfaces. In most commercialized examples, visual augmentation has been the main focus. Through the use of the stereoscopic 3D vision systems at the leader robot console, surgeons can intuitively perceive the depth position information during operation while not needing to wear heavy and fatigues head-mounted displays [20; 105]. This was not achievable using conventional hand-held minimally invasive systems [65; 87]. Since the forward and inverse kinematics are solved locally, and the two robots are synced in task space, the conventional issues such as mirroring motions (which exist in manual minimally invasive surgery (MIS)) are compensated for [2; 106; 107; 108; 109]. The line of sight of vision directly collides with the hand motion frame; thus, the hand-eye coordination and visuomotor misalignments are all corrected when compared with manual MIS [10]. This has made the visuomotor control of the leader-follower telerobotic surgical system a superior compared with conventional manual MIS. Besides, surgeons have direct access to more advanced methods of augmentation, such as using fluorescent cameras in the same visual system, which allows surgeons to detect pathological tissues such as affected lymph nodes [110]. Preoperative images have been used to visually guide the surgeon during the surgeries for enhanced accuracy [67; 111; 112]. However, one has to take into account its limitations: in 2016, [PERSON] et al. stated that the use of visual haptic feedback (instead of real force) did help surgeons compensate for this lack [113], but also increased the average applied force magnitude on the tissue by 50%, and the peak applied force by at least a factor of 2, while the introduction of real force feedback decreased accidental tissue damage by a factor of 3 [114]. Besides vision augmentation in laparoscopic surgeries, advances in multimodal robotics also contributed to new image-guided percutaneous procedures [115; 116] including robotic catheterization, when recurrent X-rays imaging has helped the clinicians during navigation. In this regard, through remote manipulation of the catheter, health professionals are no longer exposed to X-rays and can navigate the medical probe using a telerobotic medium. Other benefits are better ergonomics at work for the clinician, besides higher precision of outcome, and shorter operational time (which reduces the radiation to the patient). More recent image-guided telerobotic surgical systems for vision augmentation include MRI-compatible robots and MRI-based robot navigation for MIS [117]. Deployment of visual augmentation has been successful using telerobotic surgical systems, and commercialized examples have been using mentioned advanced features [1]. Besides visual augmentation, auditory cues have also been provided for the surgeons to enhance sensory awareness [118, 119, 120]. However, since the audio channel has been occupied heavily in operating rooms for communication between surgical team members, in commercialized examples, the auditory channel has not been utilized extensively. This kind of feedback has nevertheless interesting applications in basic surgical training contexts, as demonstrated in [121].