Motorised Head Support

The solution

It was decided to use square aluminium tube to support the cushion and to use plywood for the base of the support. The plywood base goes under the front corner of the sofa and a leg of the sofa passes through a hole in the plywood to ensure the base cannot move away. There is sufficient friction with the fabric-coverred frame of the sofa to prevent rotation of the support’s base. So as not to rely on short woodscrews, aluminium ‘U’ channel section was fixed tightly over two edges of the plywood. For strength, custom laser-cut steel brackets were used to support a vertical aluminium post, with rivet nuts placed into the aluminium.

There is a tube connector at the top of the post which gives the desired horizontal and vertical angles. This complex shape was machined from solid aluminium and the facet edges rounded. It would have been nice to make the angles adjustable but it was decided that a tube connector would be much neater at the front of the sofa.

The cushion is supported on telescopic tubes, allowing the amount of support to be adjusted. From the outset, the use of a motor in the form of a linear actuator was seen as an option. Initially the telescopic action could be set manually to give the desired amount of support. The support of the head proved successful but our client found it difficult to move along the sofa into position. A linear actuator was therefore fitted which gives up to 100mm of travel at a speed of only 4mm per second. It is powered from a 12 volt plug-in power supply. Our client simply controls the linear actuator using two buttons. A relay is used to reverse the polarity applied to the motor and three diodes are used so only one of the buttons reverses the motor. Surpringly for a small linear actuator, it is capable of providing a force up to 150 Newtons.

The cushion is mostly medium-density foam but, for comfort, with some soft-density foam stuck on top. It is supported on a sheet of plastic with some positional and angle adjustment options. The fabric cover is held by Velcro so can be removed for washing.

The benefit

Our client is now able to bring the head support up into position after sitting on the sofa. The occupational therapist hopes the support will aid eating and in particualar aid swallowing. As the support is towards our client’s left-hand side, she is still able to watch television. Unexpectedly, our client has found using the linear actuator to vary the amount of support improves long-term comfort.