Compliant actuator technology aims at building robots capable of physically interacting with humans and the environment, matching the versatility and capacity of biological systems. Recently, they underwent a significant evolution with the introduction of damping to improve performance. Such development reflects on several aspects, including energy-saving and oscillation mitigation. However, large values of damping tend to increase the impedance of the systems, worsening both robot resilience and the safety of a human in the case of impacts. That suggests the importance of a correct trade-off.

This paper reviews the application of damping solutions to compliant actuation. We classify the different damper systems based on the amount of active control, their physical operation principle, and the topological position of the damping element used in the various actuators. Then we study the fields of application of these devices and analyze how the different design aspects correlate with each other and with the applications. This analysis yields some insight on how the various design choices can influence the characteristics of actuators and the robot using them, from the viewpoint of aspects such as robot resilience, human safety, power consumption, and energy storage.

Finally, we provide the annotated database of all the papers considered to redact this review.