ISO 16840-1:2006

Overview

ISO 16840-1:2006 - Wheelchair seating, Part 1 defines the vocabulary, geometric conventions and coordinate systems used to describe seated posture, body segment measures and seating support surfaces for wheelchair seating. It establishes a consistent global coordinate system and standardized terms so clinicians, manufacturers and researchers can record and communicate a person’s seated posture and the dimensions, location and orientation of seating support surfaces.
Note: this part does not prescribe measurement methods or terms for dynamic physiological movements.

Key topics and technical requirements

• Global coordinate system: a three‑dimensional reference framework that integrates measurements for the wheelchair, support surfaces and seated person.
• Axis systems defined:
  • WAS - Wheelchair Axis System (global reference tied to the wheelchair base)
  • SSAS - Support Surface Axis System (orientation/location of cushions and supports)
  • SAAS - Seated Anatomical Axis System (orientation of body segments)
• Standardized vocabulary for posture and anthropometrics (e.g., body segment line, body centreline, absolute and relative angles).
• Support surface definitions: support surface geometric centre (SSGC), support surface reference plane/position (SSRP), and linear dimensions (width, depth, length, thickness).
• Plane‑based measures: definitions and reference positions for sagittal, frontal and transverse planes to describe locations, linear measures and angles.
• Normative/informative annexes: e.g., definitions of reference lines for common seating surfaces and calculations for joint centres (useful for consistent reporting).

Practical applications

• Standardizing clinical documentation of seated posture and support‑surface geometry for assessment and prescription.
• Enabling consistent product specifications and technical communication between manufacturers, clinicians and researchers.
• Supporting research studies that require reproducible postural descriptions or cross‑study comparisons.
• Assisting procurement, regulatory submissions and interoperability where clear, standardized seating specifications reduce ambiguity.

Who should use this standard

• Rehabilitation clinicians, seating specialists and occupational therapists
• Wheelchair and seating product designers and manufacturers
• Biomedical researchers and ergonomists studying seated posture
• Procurement officers, regulators and accessibility consultants

Related standards

• ISO 16840 series: Part 2 (seat cushion physical/mechanical characteristics) and Part 3 (static, impact and repetitive load strengths for postural support devices). Parts 4 and 5 were noted as under preparation in the original series.

Keywords: ISO 16840-1:2006, wheelchair seating, seated posture, postural support, support surfaces, global coordinate system, anthropometrics, wheelchair axis system, seated anatomical axis system.