Development of An Adaptive Iterative Learning Controller With Sensorless Force Estimator for The Hiptype Exoskeleton Nowadays industrial loads lifting still heavily relies on manual operation. Longterm lifting job can hugely increase low back strains and even cause lumbar diseases. With the rapid development of exoskeleton systems, it is essential to develop a hiptype exoskeleton for the porters. This paper proposes a modified adaptive iterative learningbased control algorithm with a sensorless force estimator. The advantage of this algorithm is that the exoskeleton joint can move precisely along the desired trajectory as well as generate an external assistance torque based on the force estimator while the wearer lifting the load. A hiptype exoskeleton device has been developed to evaluate the effectiveness of this algorithm. We carried out experiment works of bending and lifting heavy loads. Experimental results show that when choosing the IEMG of LES as the evaluation criteria, our exoskeleton device with the proposed control algorithm can significantly reduce the strain force of the wearerxe2x80x99s lumbar over 40% when they lift heavy loads. Thus it can improve the work efficiency of wearers and reduce their risk of lumbar diseases.

Performance Analysis of Torquesensorless Assist Control of a Powered Exoskeleton Using Highly Backdrivable Actuators For human motion support, there is an active focus on research and development of powered exoskeletons. A powered exoskeleton is directly fitted to the human body; thus, it is necessary to consider the safety of the humanrobot interaction, including improving the backdrivability. Toward this problem, a powered exoskeleton that uses a highly backdrivable reduction gearbox even at a high reduction ratio is proposed, and a userxe2x80x99s external force can be estimated without using a torque sensor even though the system has very high total gear ratio of 408.57:1. This paper investigated the apparent mechanical impedance of an exoskeleton during assist control execution and examined the performance and operability of the assist control. Finally, a questionnaire of participants was conducted and the mechanical impedance that resulted in a high operability was examined by implementing admittance control.