Wearable Extra Robotic Limbs: A Systematic Review of Current Progress and Future Prospects

Wearable robots have obtained increasing research attention for the potential to provide the wearer with greater strength, higher extensibility, and handleability. Wearable extra robotic limbs (Ex-Limb) as a new type of wearable robot become a hot research issue in recent years. Ex-Limb reconstructs various advantages of robots on the wearer as an extra body part due to the potential of the intelligent robot in promoting working efficiency by automation technology. This paper defines the concept of Ex-Limb and introduces the Ex-Limb from 5 aspects including the development process, the structural design features, the performance parameters, and the application scenario, which are the main considerations of human–robot interaction based on the reported works in the past decade. This paper also systematically summarizes and underlines the current research progress based on different classifications, and mainly analyzes the key technologies including human–robot interactive adapting (HRiA), human–robot interactive perception (HRiP), human–robot interactive control (HRiC), and human–robot collaboration (HRC), thus describing the practical challenges faced by Ex-Limb and giving a prospect of the main technical aspects to be improved in future. It is concluded that human–robot integration is the base of high-level human–robot collaboration, and the interaction between the human brain and the intelligent brain of Ex-Limb would improve the capabilities of Ex-Limb to sense the wearer’s intention and collaborate with the wearer. The essence of HRC is the natural interaction process of integrating the biological system and the physical system, making the physical system become a part of the biological system.