Evaluation of hydraulic excavator Human–Machine Interface concepts using NASA TLX

• We proposed two alternative HMI design concepts for a hydraulic excavator.
• A mixed reality seating buck simulator was developed to prototype the HMI designs.
• The ergonomic impact of HMI type on operator workload was studied using NASA TLX.
• The type of HMI design affects different aspects of operator's subjective workload.

This study evaluated newly proposed Human–Machine Interface (HMI) design concepts for improving the ergonomics of hydraulic excavators. The design concepts were based on an augmented interaction technique which involved the use of heads-up display (HUD) and coordinated control as HMI elements. Two alternative HMI designs were elaborated in order to separately evaluate the ergonomic impacts of the head-up display and the coordinated control by comparing them to the standard HMI design. The effectiveness of these three HMI designs in terms of the reduction of the operators' mental and physical workload were assessed by conducting experiments utilizing human subjects, ages 23–35 years. The National Aeronautics and Space Administration's Task Load Index (NASA TLX) method was used for collecting subjective workload scores based on a weighted average of ratings of six factors: Mental Demand, Physical Demand, Temporal Demand, Own Performance, Effort, and Frustration Level. The results showed that the type of HMI design affects different aspects of the operator's workload. Indeed, it showed how the proposed augmented interaction is an effective solution for reducing the ergonomic gaps in terms of mental workload, and to a lesser extent the physical workload, subjected by the standard HMI design.Relevance to industryThis study proposes innovative HMI solutions featuring heads-up display and coordinated control to improve the ergonomics of the hydraulic excavator HMI, particularly in reducing the operators' mental and physical workload. The results of this study promises to be an innovative approach for developing new HMI designs by hydraulic excavator manufacturers.