Binary and Hybrid Work-Condition Maps for Interactive Exploration of Ergonomic Human Arm Postures

Abstract

Ergonomics of human workers is one of the key elements in design and evaluation of production processes. Human ergonomics have a major impact on productivity as well as chronic health risks incurred by inappropriate working postures and conditions. In this paper we propose a novel method for estimating and communicating the ergonomic work condition called Binary Work-Condition Map, which provides a visualized feedback about work conditions of different configurations of an arm. The map is of binary nature and is derived by imposing the desired thresholds on considered ergonomic and safety related criteria. Therefore, the suggested arm postures in the map guarantee that all considered criteria are satisfied. This eliminates the ambiguity compared to state-of-the-art maps that uses continuous scales derived from weighted sum of multiple ergonomics criteria. In addition, to combine the advantages of both the binary map and the continuous map, we additionally propose a Hybrid Work-Condition Map that rules out unsuitable workspace with the binary map approach and renders the suitable workspace with the continuous map approach. The proposed approach was tested in simulation for various tasks and conditions. In addition, we conducted subjective evaluation experiments to compare the proposed methods with the state-of-the art method regarding the usability. The results indicated that the binary map is simpler to use, while the hybrid map is a good tradeoff between the binary and the continuous map. In selecting the map, strong points of each map should be considered with respect to the requirements of a specific application and task.

PREDICTOR: A Physical emulatoR enabling safEty anD ergonomICs evaluation and Training of physical human-rObot collaboRation

“…Since the interactive process of a PHRC task can be emulated by PREDICTOR in a risk-controlled manner, detailed biomechanical (and cognitive) assessment during the process can be assessed by using different sensors. For instance, by attaching motion markers and EMG sensors to the human body doing the emulated tasks, the measured marker positions and muscle activity levels together with the measured force applied by the human hands can be used as inputs for a human musculoskeletal model to estimate biomechanical quantities of the operator during the emulations, e.g., joint trajectories (Fang et al, 2018 ), Cartesian and joint stiffnesses (Fang et al, 2017 ; Ajoudani et al, 2018a ), joint torques (Peternel et al, 2021 ) and muscle forces (Peternel et al, 2019 ). These estimates can be further used to evaluate the safety and ergonomics of the emulated PHRC task.…”

Model Predictive Impedance Control with Gaussian Processes for Human and Environment Interaction

“…Nevertheless, to adapt to these di erent aspects, the robot should be able to infer the human state, which o en requires complex sensory setups [15,16]. However, complex measurement systems are not always available or feasible for practical applications, thus some states can be modeled, such as the desired motion of the robot/payload [17][18][19][20], human actions [21] and preferences [22,23], human physical fatigue [11], cognitive stress [24], and suitability of shared workspace [25][26][27][28].…”

“…Ergonomic costs are more naturally expressed in terms of human joint torques [16,28], so we also consider a 4-DOF kinematic model of the human arm with three rotational DOF at the shoulder and one rotational joint for the elbow extension. is model has parameters of l 1 and l 2 , for the length of the upper and lower arm, and x sh ∈ R 3 for the spatial position of the human shoulder.…”

“…Human arm manipulability plays a key role in ergonomics [26,28], as it relays the information about how well the joint torques can be transferred into the end-e ector force where the task is produced. erefore, we de ned the ergonomic cost as…”

A Multi-metric Modular Framework for Human-like Gait Analysis Based on a Recorded Set of Variable Gait Patterns

“…A more direct way to minimise fatigue is to use fatigue models that operate based on integrated effort over time. These models can be distinguished by how they estimate the effort, e.g., using muscle activity [17], limb endpoint force [18], or joint torque [19]- [21] in humans, and motor temperature [22] in robots. Nevertheless, fatigue models have been more commonly employed in upper limbs or whole-body analysis and control of ergonomics in manufacturing processes.…”