Stair Trainer for Children with Cerebral Palsy

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Stair Trainer for Children with Cerebral Palsy

Designers: Harleen Khanijoun, Dina Halwani, Monalisa Ghosh
Client Coordinator: Marliese Delgado, UCP Hand in Hand

 

A stair trainer was built for the Hand in Hand program of the United Cerebral Palsy (UCP) of Greater Birmingham to help promote gross motor function in children aged two to five with cerebral palsy.  The ascending and descending of stairs employs an increase in the lower-limb movement and more intense muscular activity than walking [1].  Currently, stairs on the administrative side of the program’s building are being used to continue to train the children.  A stair trainer designed two years earlier by a UAB Senior Design team was abandoned due to safety concerns and its size.  A modification of the previous stair trainer was requested, differing from the previous in size, material, and appearance.

An isolated stair trainer which provides an incentive for children to repeatedly climb a set of stairs was to be designed.  The stair trainer had to allow for easy adult supervision and be easily disassembled and stored when needed.  Based on the Safety Standards for Playground Equipment, the railings were designated an appropriate height of 24 inches for toddlers and 24 inches apart to not allow holding of both railings during climbing. Based on input from the representatives of UCP, a height of three feet was designated for the platform with railings as dictated by Safety Standards.  Additionally, wood was the material preferred by the client, and the use of metal was to be avoided due to its “hospital-like appearance”.

The space for use of the stair trainer was a corner of a room with an area of 18 ft x 18 ft.  The design had to be disassembled into large modular components each of which could be moved by two adults who could lift a combined weight of 150 lbs.  The components had to fit into a storage area with a single door entryway. The maximum number of children expected on the set of stairs was three per stair and five on the platform, and a safety factor of 2 was employed. The following dimensions for the stairs were prescribed:  height: 8 inches, width: 10 inches; length: 24 inches.

The smallest child on the stair trainer would be of 19 inches in height and 20 lbs in weight while the largest would be one of 46 inches in height and 68 lbs in weight.  Appropriate fall zones had to be taken into account at a minimum of 6 ft in each direction.  To avoid head entrapments, openings could not exceed 9 inches and could not be smaller than 3.5 inches.  Additionally, the structure could not possess any sharp edges or corners, the supports had to be sturdy, and the device stable.  According to the Safety Standards for Playground Equipment produced by the Consumer Product Safety Commission, the angle of the stairs could not exceed 35 degrees.  The angle of the slide could not exceed 50 degrees at any portion and had to maintain an average angle of 30 degrees.  The ideal slide would re-orient the child to a sitting position at the exit.  The project had to be completed within four months and within a $1,500 budget.

Technical Description

 

The final design consists of the three following subsystems:  one set of stairs, one platform, and a slide (Fig 6). Because of its well-known properties, low cost, and machinability, birch plywood comprised the primary material.  The density of ¾” birch plywood (0.01987 lbs/cu in) was used in the calculations. To reduce bulkiness, a small platform of 26 inches x 26 inches was designed. The completed weight of the structure was 200 lbs. A lightweight commercial polyethylene slide component was used as an incentive to climb the stairs and was relatively lightweight at around 40 lbs (Table 1).  The final structure was also carpeted per client request and to reduce the noise created while playing.  As dictated by the design criteria, the stair trainer was built as an isolated structure which because of its ninety degree angle against the corner of a wall allows for easy adult supervision.  It is of the requested 36 inch height with additional 36 inch railings on the platform for safety.  Additionally, there are no places where the children might crawl through, no sharp edges, the device is stable, and the railings are placed for safety and supervision.  The project was completed within the specified four month time period and met all safety standards with the stairs and slide angle.  Due to higher than expected cost of labor, the project exceeded the budget by $260.

21 - stair trainer
Figure 21.  Schematic of the Stair Trainer, showing the three separate components: slide, platform and stairs.