A review of the design and implementation of discretely actuated hyper-redundant manipulators

Hyper-redundant manipulators are created by stacking multiple parallel mechanisms as modules. If all the actuators of these manipulators are of the discrete type, they are called discretely-actuated hyper-redundant manipulators (DAHRMs). Discrete actuators (DAs) can only be actuated in a limited number of states. DAs have simpler control, more repeatability, higher accuracy, and a lower cost than the common continuous actuators. The number of accessible points in DAHRMs is limited, and they follow the paths segment by segment, at a non-uniform speed, and in an approximate, not exact, way. Therefore, in most cases, it is preferred to use continuous manipulators, and the use of DAHRMs is limited to certain cases. For example, the ability to use simple, light, compact, cheap and low-energy-consuming binary actuators in DAHRMs has made it possible to use them in space exploration, medical applications such as robotic endoscopy and robotic training. In this paper, different types of DAHRMs that have been made so far will be reviewed in terms of their design and capabilities so that designers can design better things in the future and use the advantages of these robots.