In this article we will talk about a specific ergonomic problem that we found involved different drivers. The issue emerged from several requests made by professional train drivers that felt pain and discomfort when using the master controller for many hours a day to activate the traction and the brake of the train.
Our approach was to investigate as much as possible the root causes of this issue and then to design and develop a measure to mitigate the problem.
To do this, we have moved in this way:
- Replicate as faithfully as possible the working conditions of the drivers with same constraints and the same possibility to regulate the components in the cabin.
- Investigate the possible solutions to solve the problems with the minimum impact on the system.
- Co-design the solutions with the final user.
- Prototype and test the solutions in real operating conditions.
- Validate and implement the solutions for the series production.
Replication of a real system
To have the possibility to study the movements and the constraints of the system, we replied the whole model in the 3D world. Since the cabin and the seat were manufactured 30 years ago, we have not the possibility to have the 3D geometry available. In order to avoid any kind of errors we decided to make a 3D scan of the cabin with all the different range of the possible adjustments regarding the height, the depth and the inclinations. This method allowed us to identify in a precise way the real possibility to adjust the position of the driver respectively to other interactive components in the cabin.
When we had the 3D scan ready, we put some standardized mannequins from the 5° percentile woman to a 95° percentile man and we evaluated the maximum and minimum range possible without causing pain and discomfort to the driver according to the Ergonomic ISO Normative. This analysis was mandatory to know before producing any kind of physical prototype, which could be the impact of the shape and the position of the handle on the driver’s body.
Following are represented some images that explain some examples of the ergonomic analysis:
Design and prototype solutions
The second step, was to think what we could do to solve the problems with the minimum impact in the cabin. To do this, we designed handles with a completely different shape from the original one and an armrest to support the elbow of the driver and consequently reduce the strain on the joints. The shape came out from various prototypes made firstly with digital sketching and subsequently with the 3D printer. This was a fast way to be aware of the comfort and to have the possibility to share the design and validate the solution with the final user.
Validate and implement the solutions for the series production
The shape of the handle gave the right support to the hand of the driver respecting as much as possible what emerged from the ergonomic analysis conducted with the customers.
The handle has one button on the top to activate the horn and two capacitive sensitive zones on the bottom to activate the Deadman Device.
The challenge was also to create a system in which the zones for the activation of the dead man system were without physical buttons but with a capacitive detection system. Implementing different kinds of features without compromising the ergonomic aspects was one of the main goals. In order to maintain a good compromise between ergonomics, aesthetics and functionality we decided to investigate if the 3D printing system could also be used for production parts. The difficulty was to find a material that had a good ratio stiffness to resistance, was compliant with the fire&smoke normative EN 45545 and had a good aesthetic aspect. After various tests made on different kinds of material and 3D printing techniques, we have chosen a thermoplastic material that met all the mechanical and normative requirements.
This material was born with a similar gold intrinsic colour and with a visible layers on the z axis (detectable by eyes and by human skins). This meant that we had to validate a surface finishing and painting post process in order to reduce the gap as much as possible comparing with the traditional manufacturing techniques.
Conclusions
The process was not easy to implement especially due to the poor availability of initial information both on the driver’s cab and on the various possible adjustments of the driver. Thanks to our ergonomic and technological knowledge we have consolidated a process that has allowed us to reach our target in an efficient, effective and repeatable way.
Using 3D printing not only for prototype purposes but also for the production series has completely changed the design paradigm.
This ergonomic process developed with new technologies marked an important milestone in the railways landscape, unlocking new creative horizons in which the sharing of physical prototypes and subsequent mass production will follow new flows and methods that will halve the time to market.
See you next time,
Lorenzo Olivetto