Lifting objects with a power assist system: Effects of friction between human's hand and object on perceived weight and load force

This paper presents the design of a 1 DOF power assist system for lifting objects. The load force (vertical lifting force applied by human) consisting of inertial and gravitational forces was considered as the desired dynamics for the system. We hypothesized that human's perception of object weight due to inertial force might be different from the perceived weight due to gravitational force. We simulated the system using Matlab/Simulink for different sizes of objects. We then changed the friction between human's hand and object and studied its effects on perceived weight and load force for lifting objects with the system. The results show that increase in friction reduces perceived weight and load force. Finally, we proposed using the findings to design human-friendly power assist systems for lifting heavy objects in various industries.