Equipment Ergonomics: Console, Machine and Interface Design

An ergonomic error embedded at the design stage lives for the entire product life cycle: ten years of production means ten years of operators reaching for a far lever and technicians crawling to a filter. The reverse is also true: the right decisions, made once in CAD, replicate for free across the whole series. Let's break down five core principles and three areas of their application.

Five principles of ergonomic equipment

1. Anthropometry: design for the 5th–95th percentiles

There is no "average person". The work zone must simultaneously fit a shorter woman (5th height percentile, ~153 cm) and a taller man (95th, ~186 cm). Practical conclusion: anything non-adjustable is designed to the limiting percentile — reach zones to the 5th, clearances and openings to the 95th. Height adjustment of the work surface or operator platform removes the problem entirely and costs little against a production series.

2. Reach envelope

The space in front of the operator divides into three zones: optimal (grip with a bent arm close to the body), normal (extended arm without trunk flexion) and maximum (with bending and twisting). Frequent operations belong in the optimal and normal zones only. Every work cycle is verified in 3D with anthropometric manikins: if the 5th-percentile manikin is forced to bend in simulation, the design will fail in metal too.

3. Indicator visibility

The primary indicator belongs in the normal line of sight: ±15° from the horizontal gaze line at working distance. Typeface, contrast and character size are derived from reading distance: character height should be at least 1/200 of the distance for important data. Critical indicators are duplicated: light + sound, digit + colour zone. Verification is mandatory under real shop-floor lighting, including glare and dust.

4. Tactile feedback

The operator should not have to look at a control to know the command went through. A click, a defined travel, a change in resistance, surface texture — tactile confirmation reduces errors and lets people work without taking their eyes off the process. Different functions must be distinguishable by touch: shape, size, texture, direction of movement.

5. Force requirements

Frequent controls — single-digit newtons; rare and emergency ones — tens of newtons. This gradation solves two problems: it reduces fatigue in repetitive operations and protects critical functions from accidental actuation. An emergency mushroom button is large, requires force that excludes accidental pressing, yet can be struck with a palm from any position.

Control consoles

Console layout starts with the frequency/importance matrix: all functions are plotted on two axes, and each cell of the matrix dictates its place on the panel.

• Frequent + critical — the centre of the optimal zone, large elements, blind operation;
• Frequent + non-critical — near periphery, compact grouping;
• Rare + critical — a visible spot with protection against accidental activation (cover, two-step action);
• Rare + non-critical — far zone, service level, can go into a menu.

Viewing angles define panel tilt: the plane is rotated perpendicular to the gaze line of the working position — typically 15–30° from vertical for a sit/stand post. Colour coding follows industry standards: red is emergency only, yellow is warning, green is normal; no "decorative" red elements near the emergency button.

A separate item — working in gloves. If the process requires hand PPE, the minimum control size is 20–25 mm, centre-to-centre spacing grows to 35–40 mm, and capacitive touchscreens give way to resistive ones or hardware keys. This must be fixed in the specification before components are selected.

In the Silaron operator console case we applied the full set: the frequency/importance matrix separated frequent keys from rare service functions into zones, the panel got a tilt matched to the working posture, and tactilely distinct key groups enabled blind operation without looking away from the process.

Machines and enclosures: maintenance access

Machine ergonomics is above all maintenance access: how technicians reach the units serviced daily, weekly and yearly. The rule is simple: service frequency defines the access class.

• Every shift (loading, cleaning, checks) — no tools, no guard removal, at hand level;
• Weekly (lubrication, filters, quick adjustments) — quick-release panels on latches or knurled-head screws, opening in seconds;
• Yearly (major service) — dismantlable access is acceptable, but without removing adjacent units.

Quick-release connectors instead of bolted terminals cut unit replacement time several-fold and eliminate reassembly errors: connectors of different circuits have different shapes — connecting them wrong is physically impossible. The same poka-yoke principle, transferred to mechanics.

Gas springs and counterweights on heavy doors and covers turn a two-person job into a one-person job: a 20 kg panel opens with one hand and stays fixed at the top. Guards, meanwhile, are designed so nobody wants to remove them "for convenience": if a guard obstructs an every-shift operation, the operator will find a way to dismantle it — and injury becomes a matter of time. A proper guard is transparent where you need to look and opens where you need to reach.

In the SXS512 cylindrical grinding machine enclosure case, every-shift service zones were grouped along the machine's frontal axis, inspection windows aligned with control points, and wide gas-spring doors gave full access to the machining zone without panel removal — setup got faster, and the guard stopped being an obstacle.

Industrial interfaces

The HMI of a machine or instrument is cognitive ergonomics: how quickly the operator finds what matters and how rarely they err under load. Three working principles:

Information hierarchy. The main screen carries only what is needed every minute: process state, the key parameter, deviation from normal. Everything else lives on the second and third levels. The test is simple: the operator looks at the screen for two seconds and names the system state. If they can't — the hierarchy doesn't work.

Alarm signals. An alarm must differ from normal across three channels at once: colour, shape, position. A list of twenty identical lines with one red is not an alarm system — it's a "spot the difference" game. An active alarm is shown large, with action text ("Check coolant supply"), not just an error code.

Poka-yoke — error-proofing. The interface must not allow impermissible actions: commands inactive in the current mode are hidden or locked, critical operations require confirmation, action sequences are guided by a wizard. Every error an operator "might make" will eventually be made.

The IEK ARMAT front panel redesign case is telling: the previous panel overloaded the operator with visually equal elements, and critical functions did not stand out. We built a clear zone hierarchy (display, control, service), strengthened tactile distinguishability of key controls and removed competing accents. Measured on pilot samples, operator errors dropped by 67%, and typical operation time by a third.

Virtual verification tools

All the solutions described are verified before metal — in CAD with digital manikins:

• Siemens NX Human Modeling — manikins of specified percentiles right in the assembly: reach zones, fields of view, postures during operations;
• RAMSIS — specialized posture and force analysis, joint-load and discomfort calculation for specific work cycles;
• DELMIA — process simulation with humans: operation times, collisions, movement trajectories at shop level.

Virtual verification of one workstation takes days and costs a percentage of fixture rework. The rule: no control goes into design documentation until 5th and 95th percentile manikins have completed the full work cycle with it.

Checklist: 15 questions before releasing design documentation

1. Have reach zones been verified for the 5th percentile?
2. Have openings and clearances been verified for the 95th percentile?
3. Are all frequent operations within the optimal or normal zone?
4. Is the primary indicator within ±15° of the gaze line?
5. Are typefaces legible from the working distance (character height ≥ 1/200 of distance)?
6. Do frequent controls provide tactile confirmation?
7. Are controls distinguishable by touch?
8. Do forces match operation frequency (frequent — single-digit newtons)?
9. Are emergency functions protected against accidental actuation?
10. Can the equipment be operated in gloves where the process requires them?
11. Is every-shift service tool-free and dismantle-free?
12. Can heavy panels be opened by one person (gas springs, counterweights)?
13. Does any guard obstruct every-shift operations?
14. Does the alarm stand out across three channels at once?
15. Are impermissible actions excluded in the interface (poka-yoke)?

Conclusion

Equipment ergonomics is not a decorative layer but engineering decisions with measurable effect: −67% errors on the ARMAT panel, faster setup on the SXS512, blind operation on the Silaron console. All of them are made at the design stage and are nearly free in series production — unlike rework of finished products. The assessment methodology for existing workstations is covered in the article on workplace ergonomics, and the economics of such projects in the article on ergonomics and productivity.