General Results to Date

From 2021 to 2023, a total of 125 subjects participated in the study.
(Box Handling (Logistics): n=21; Car Assembly (Automotive): n=21; Welding: n=52; Sack Handling (Logistics): n=7; Installation of Rail Systems (Construction): n=15; Drywall (Construction): n=9)

The subjects were young men and women aged 17 to 34 years and an average age of 24 years, who were familiar with the work they had to do in the Parcours.  

The experiments took place at Audi Education Lab, Neckarsulm, Wilhelm Maybach Berufsschule Stuttgart, Messe Duesseldorf, SLV Nord Hamburg, and Steinbeisschule Stuttgart.

Exoskeletons from different manufacturers were randomly assigned to the subjects to maintain market neutrality and not indicate the advantages and disadvantages of a particular system.

We thank all the wonderful contributing people and institutions for making this great experiment happen. The CONTRIBUTING PARTNERS List includes them all.

Subjective Feedback

Subjective Feedback on the activity, wearing comfort and usability of the exoskeleton is collected via a questionnaire. 

The results are presented as a median.

Effort of the task

The BORG-Scale (0-10) was used to describe the task's effort. Generally, the task's effort is lower with an exoskeleton than without an exoskeleton.
In all six Parcours, the task's effort decreased with the exoskeleton. The highest reduction, with a difference of 3 points of Borg-Scale, was recorded for Drywall construction.
There is a 2-point reduction in Borg-Scale in car assembly, welding, bag handling, and installation of rail systems. Box Handling is rated five without an exoskeleton and 4 with an exoskeleton.
Welding and drywall were rated the highest of all tasks without an exoskeleton, with a median score of 6.  
The Bag Handling and Drywall results must be handled carefully due to the small number of subjects involved.

Body Discomfort

The questions on body comfort measure the discomfort of body areas during the task. The graphs show the areas that are explicitly supported by the exoskeleton. Back-supporting exoskeletons were used in the box and bag handling tasks; therefore, the focus is on the lower back, buttocks and upper and lower legs. The upper body is particularly stressed during car assembly, welding, the installation of rail systems and drywall construction, so the body's neck, shoulder, forearm and upper back areas are addressed in more detail.


Overall, the exoskeletons relieve physical discomfort in certain areas. In box and bag handling, the exoskeletons provide the greatest relief in the lower back area. In bag handling, the buttocks are also less stressed with an exoskeleton. The exoskeleton in the chest and abdominal area has little or no difference. The neck, shoulder and upper arm are the areas of the body subject to the greatest strain without an exoskeleton when it comes to tasks involving strain on the upper body. In drywall construction and welding, the neck, shoulder and upper arm are rated at 6; in vehicle assembly, the neck is rated at 5, the shoulder at 6 and the upper arm at 5; and in the assembly of rail systems, the rating is 6 for the neck, 6 for the shoulder and 5 for the upper arm. In all upper body parcours, the stressed body regions can be relieved, except the forearm/hand and upper body in drywall construction. There is no difference here between working with and without an exoskeleton.

System Usability Scale

The System of Usability Scale (SUS) uses validated questions and a mathematical formula to show the usability of devices such as exoskeletons. The test subjects evaluated the ease of use of the exoskeletons in all six Parcours, from just below good to excellent.
The SUS score for Welding is 72.5 and for Installation of Rail Systems, 72.7. These two tasks have the lowest SUS score, followed by Bag Handling (75), Drywall (75.8), and Car Assembly (77.4). In the Box Handling task, the test subjects rated the ease of use of the exoskeletons best with 80.

Quality

In Parcour Car Assembly, the time is measured to check compliance with the "Methods-Time-Measurement" (MTM) from the automotive industry. In addition, error scoring is carried out during the painting task.

Parcour Welding detects the quality of the welding seam via a score of the system. 

In the Parcour Drywall, the number of screws not countersunk into the drywall is counted. 

The results of the quality are represented with the mean.

Car Assembly: Method-Time-Measurement

The method-time-measurement (MTM) is a common predetermined time system in the automotive industry for short-cycle manual processes.

The MTM increases with the exoskeleton in all tasks. In almost all tasks, except Assembly and Disassembly Clips, the test subjects are still in the MTM times.

In Disassembly Clips, the difference between without and with the exoskeleton is the largest at 12.7%. The difference is the smallest in Assembly Screws with 1.2% and Disassembly cables with 3.1%.

Car Assembly: Painting error score

The painting error score is calculated by counting the number of pixels painted over a specified line. The mean error score in the last round was 247.97 without an exoskeleton and 254.74 with an exoskeleton, an increase of 2.79%.

Looking deeper into the individual painting scores shows great variability. Comparing the error score and the corresponding working time shows that the error score is higher when the required working time is shorter and vice versa.

Drywall: Number of unsunk screws

The accuracy of whether a screw is countersunk into the drywall is measured in comparison without preload (test 1) to with preload (test 6) as well as without an exoskeleton and with an exoskeleton. It is expressed as a percentage of incorrectly placed screws.

The quality of screw placement on the ceiling decreases in comparison to the wall. In the last run (test 06 wall), the quality of screw placement in the wall increased, which could indicate familiarization with the activity despite the previous familiarization phase.

Overall, the quality increases with the exoskeleton, although only marginally in some cases. In "trial 01 wall" (15.74% error rate without exoskeleton and 15.12% with an exoskeleton) and in "trial 06 ceiling" (20.37% error rate without exoskeleton and 19.79% with an exoskeleton), the slightest improvement of 0.62 percentage points and 0.58 percentage points were recorded. In "trial 06 wall", the quality with an exoskeleton increased by 1.85 percentage points. The greatest improvement in quality with an exoskeleton was 3.7 percentage points in the "trial 01 ceiling".

Muscle Activity

To date, muscle activity has been measured in two Parcours.

The erector spinae muscle is recorded during Box Handling, and the deltoideus acromialis (medial) and clavicularis (medial) muscles are recorded during Drywall construction.

The muscle activity results are presented as an average value over the entire time.

Box Handling: Muscle Activity M. Erector Spinae

During Box Handling, the average muscle activity in the M. erector spinae decreases across all tests with an exoskeleton. In the M. erector spinae left, the difference between the average muscle activity without and with an exoskeleton is 22%, and in the M. erector spinae right, 27%.

In the M. erector spinae right, the average muscle activity is significantly lower with an exoskeleton (p = 0.015) than without an exoskeleton.

Drywall: Muscle Activity M. Deltoideus

In Drywall, the average muscle activity in the M. deltoideus acromialis (left and right) is lower than in the M. deltoideus clavicularis (left and right). However, average muscle activity with an exoskeleton decreases for all muscles compared to without an exoskeleton. The reduction in average muscle activity with an exoskeleton is between 26 % (M. deltoideus acromialis left) and 29 % (M. deltoideus clavicularis left).

Overall, the average muscle activity is low (under 15 %MVC). The arm being repeatedly lowered could explain this.

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Parcours

Specific parcours modules are developed with industrial relevance to simulate realistic work processes. 

 

Impressions

Impressions and pictures of the experiments already performed.

 

Contributing Partners

Contributing partners as experts, exoskeleton manufactures and industries. You want to be part?