Assessing the impact of human–robot collaborative order picking systems on warehouse workers

Figures & data

Figure 1. Conceptual model.

Schematic overview of the conceptual model and corresponding hypotheses.

Figure 2. Warehouse lab layout (units in mm).

Schematic layout of the warehouse drawn in cad. Depicts the warehouse racks and sections, the positions of the robots, the quality control station, the standard S-route used in picking, and the dimensions of the warehouse.

Figure 3. The participant's experimental journey.

Graphic description and summarising of the experimental procedure, as well as the manipulation of the experiment (i.e. the introduction of human–robot collaborative order picking).

Figure 4. Left: Manual order picking with cart (Phase 1). Middle and Right: human–robot collaborative order picking (Phase 2; human leading and robot following, human following and robot leading).

Compilation of three photos of the order picker performing manual order picking (left), collaborative order picking with the human leading and robot following (middle), collaborative order picking with the human following and robot leading (right).

Table 1. Descriptive statistics (mean, standard deviation) and measurement timing of outcome variables.

	Before	After	After	After
	Manual	Manual	Human Leading	Human Following
Job Satisfaction		3.45 (0.73)	3.62 (0.75)	3.88 (0.89)
Core Self-Evaluations
Rosenberg Self-Esteem		2.74 (0.45)	2.86 (0.46)	3.00 (0.48)
Generalised Self-Efficacy		2.21 (0.36)	2.70 (0.42)	3.00 (0.48)
Self-Efficacy in HRI	2.91 (0.66)		3.14 (0.71)	3.22 (0.67)

Notes: All variables were measured on scales following the original instructions. ‘Job Satisfaction’ was measured on [1–5], ‘Rosenberg Self-Esteem’ and ‘Generalised Self-Efficacy’ were measured on [1–4], and ‘Self-Efficacy in HRI’ was measured on [1–6].

Table 2. Linear mixed-effects models predicting Job Satisfaction, Self-Esteem, Self-Efficacy, Self-Efficacy in Human–Robot interaction.

	Dependent variables
	Job Satisfaction [M1]		Rosenberg Self-Esteem [M2]		Generalised Self-Efficacy [M3]		SE-HRI [M4]
Independent variables	estimate	Std. error	estimate	Std. error	estimate	Std. error	estimate	Std. error
Constant	0.718	0.722	2.986	0.448	1.955	0.440	0.695	0.641
Experience (months)	0.012	0.014	0.003	0.010	0.017	0.008	−0.004	0.014
Competence (Correct picks/20 min)	0.016	0.008	0.003	0.002	0.003	0.005	0.002	0.006
Order set #2	−0.017	0.079	−0.024	0.021	0.001	0.047	0.079	0.053
Order set #3	−0.047	0.079	−0.020	0.021	0.067	0.047	0.027	0.054
Setup: Human leading	0.183	0.079	0.017	0.021	−0.013	0.047	0.455	0.053
Setup: Human following	0.325	0.090	0.070	0.025	−0.028	0.054	0.487	0.063
Perceived Usefulness (average)	0.408	0.102	0.004	0.077	0.015	0.063	0.107	0.103
Perceived Ease of Use (average)	0.074	0.137	0.041	0.105	0.172	0.085	0.386	0.139
Restricted maximum likelihood criterion	334.0		0.8		159.4		245.1
Number of subjects	60		60		60		60
Number of assignments	2		2		2		2
Number of observations	180		180		180		180

Note: Bold type = significant at p < 0.05.

Figure 5. Hypothesis testing results.

Schematic overview of the conceptual model and corresponding hypothesis testing results. Bold type = significant at p < 0.05.

Data availability statement

The data that support the findings of this study are available (anonymized) from the corresponding author, upon reasonable request.