  Complex tasks require human collaboration since robots do not have enough
dexterity. However, robots are still used as instruments and not as
collaborative systems. We are introducing a framework to ensure safety in a
human-robot collaborative environment. The system is composed of a haptic
feedback display, low-cost wearable mocap, and a new collision avoidance
algorithm based on the Artificial Potential Fields (APF). Wearable optical
motion capturing system enables tracking the human hand position with high
accuracy and low latency on large working areas. This study evaluates whether
haptic feedback improves safety in human-robot collaboration. Three experiments
were carried out to evaluate the performance of the proposed system. The first
one evaluated human responses to the haptic device during interaction with the
Robot Tool Center Point (TCP). The second experiment analyzed human-robot
behavior during an imminent collision. The third experiment evaluated the
system in a collaborative activity in a shared working environment. This study
had shown that when haptic feedback in the control loop was included, the safe
distance (minimum robot-obstacle distance) increased by 4.1 cm from 12.39 cm to
16.55 cm, and the robot's path, when the collision avoidance algorithm was
activated, was reduced by 81%.
