Arm Back Support Suit (Abs-Suit) for Parcel Delivery With a Passive Load Redistribution Mechanism

A significant part of the parcel delivery service occurs outside the warehouse, relying entirely on human resources to deliver parcels to the customer's doorstep. The parcel delivery officers carry and hold parcels of about 25 kg of weight during the delivery process through diverse terrains such as elevated ground and staircases especially in many crowded cities. As a result of holding and carrying heavy parcels repeatedly, the officers report upper body musculoskeletal disorders in the arms, and lower back. Robotic exosuits are actively being developed but are primarily oriented toward lifting assistance only and do not cater to the entire upper body assistance. In this letter, we propose a load-redistribution strategy in the form of a fully soft passive wearable robot, that provides load-dependent compression around the lower back for back support and arm assistance. This is achieved through the coupling of the load and the human body, which ensures the wearer receives appropriate assistance only when in need. The suit design parameters are as follows: the elastic component that inherently enhances comfort in breathing even in its tightened state while transmitting compression force onto the human abdominal muscles; and the number of pulleys on the belt to control the amount of belt compression in users of different size; and the length of the corset tendon. The mannequin mock-up experiment and analytical modeling demonstrate the relationship between the design parameters and pressure on the human body. Human experiment also verifies the upper body assistance performance of the suit in significantly reducing the arms' muscle efforts (p < 0.05) in parcel delivery.