# Robot Bionic Vision Technologies: A Review
## 3 Challenges and Countermeasures for Robot Bionic Vision Development  
### Challenges That Restrict Robot Bionic Vision Development  
The eye-movement control system is not only related to eye activity but also closely related to neural activity in the brain, cerebellum, and brain stem. From the medical perspective, this is an interdisciplinary and complex system. Therefore, the establishment of a machine eye-movement control system based on a biological vision mechanism is a research topic of interdisciplinary integration [158]. It is not only related to neurophysiology and medicine but also closely related to control science, bionics, biomedical engineering, and computer science. Although scholars at home and abroad have conducted many simulations and bionic studies on biological eye movement from different angles and for different purposes, there are still many problems to be further studied and discussed, mainly the following aspects:  
* Although many scholars have conducted in-depth research on human vision, bionic vision still requires further research.
* At present, most robot vision systems use only left and right cameras to obtain and process target images. Left- and right-camera-driven systems have poor coordination, slow target tracking, and easy target loss. It is difficult to compensate for the line-of-sight deviation caused by image jitter in a complex motion environment. At present, researchers have constructed a head-eye motion control model of a bionic robot, which cannot fundamentally solve the problems faced by this version of this bionic machine [159].
* Existing bionic eye models usually only realize one or two movements of the human eye, and most are one-dimensional horizontal monocular or binocular movements. The separation mechanism of saccade motion and smooth tracking motion is widely used; however, its ability to realize multi-eye motion is poor.
* Binocular linkage control and head-eye coordination control in the line-of-sight transfer process are key technologies of bionic robot eyes. At present, research on binocular head-eye coordinated movement mostly remains at the level of biological neural control mechanisms and physiological models. Research on the construction of bionic binocular head-and-neck coordinated control is still in its infancy.
* The advanced mechanisms of human vision have not been fully explored, and some mechanisms remain controversial and undiscussed. Despite research and analysis from the perspectives of neurophysiology and anatomy, there has been no breakthrough in head-eye coordinated motion control technology. Therefore, it is necessary to establish new models, theories, and methods to make a machine's eyes more intelligent, dexterous, and realistic.  
At present, most research on robot eyes is based on engineering methods. The left and right cameras are used to obtain the target images for processing. The left and right eyes and the head and neck lack a coordinated linkage mechanism. There are many technical obstacles, and the adoption of bionic technology is an important method to solve these problems. Research on bionic robotic eyes is multidisciplinary, involving neurophysiology, bionics, control science, and computer science. There are still many problems in the research on robot bionic vision that need to be explored further.