ABSTRACT
Accurate Force/Moment (F/M) measurements are required in many applications, and multi-axis F/M sensors have been utilized a wide variety of robotic systems since 1970s. A multi-axis F/M sensor is capable of measuring multiple components of force terms along x-, y-, z-axis (Fx, Fy, Fz), and the moments terms about x-, y- and z-axis (Mx, My and Mz) simultaneously. In this manuscript, we describe experimental and theoretical approaches for using modular Elastic Elements (EE) to efficiently achieve multi-axis, high-performance F/M sensors. Specifically, the proposed approach employs combinations of simple modular elements (e.g. lamella and diaphragm) in monolithic constructions to develop various multi-axis F/M sensors. Models of multi-axis F/M sensors are established, and the experimental results indicate that the new approach could be widely used for development of multi-axis F/M sensors for many other different applications.
ABSTRACT
Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE) is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis) as well as the cutting moments Mx, My and Mz (i.e., moments about x-, y-, and z-axis) simultaneously. Optimal structural parameters of the EE are carefully designed via simulation-driven optimization. Moreover, a prototype sensor system is fabricated, which is applied to a 5-axis parallel kinematic machining center. Calibration experimental results demonstrate that the system is capable of measuring cutting forces and moments with good linearity while minimizing coupling error. Both the Finite Element Analysis (FEA) and calibration experimental studies validate the high performance of the proposed sensor system that is expected to be adopted into machining processes.
ABSTRACT
According to human biomechanics the ideal static equilibrium model of stooped human body was built, based on which a wearable stoop-assist device (WSAD) as an intervention to reduce the load on the erector spinae was developed. Electromyography (EMG) experiments were conducted to evaluate the effectiveness of the WSAD. Results showed that the integrated EMG of the thoracic erector spinae (TES), the lumbar erector spinae (LES), the latissimus dorsi (LD) and the rectus abdominis (RA) were reduced by 43%, 48%, 32% and 14% respectively, when Sagittal trunk bent forward to 90 degrees from the vertical. Therefore, by reducing back erector spinae activity, the WSAD could reduce the incidence of developing LBP for those who adopt the prolonged stooped posture in work.