Project Scope 

The specification and design of a head positioning and sensing system, for use with disabled orthopaedic seating, that will reward the seated person with their favourite sounds when the head is positioned correctly.  The system will allow the patient’s family to quickly and easily record and store the patient’s favourite sounds.

Overview 

Mr Salt of RSP Seating & Sensors builds specialised orthopaedic seating systems for physically and mentally disabled people.  The problem with many disabled people, particularly those that are mentally disabled, is that they tend to let their head drop forward or sideways.  This causes long-term complications, mainly that of damage to the spine.

RSP Seating & Sensors has been researching ways of rewarding patients who hold their head in a correct position that is conducive to their physical well-being. Research has shown that the best way to do this is to reward the patient with their favourite music or sounds. What is required is a sensing and control system that will detect when the patients’ head is in the correct position, and automatically start the play of the patients’ favourite sounds.

Also required is a means of recording and storing sounds that are favoured by the patient and therefore be most effective in use. Sounds that will bring back fond memories of a past event, e.g. family gatherings or outings where familiar voices/sounds can be heard and thereby comfort the patient.

The West Midlands Manufacturing Advisory Service commissioned HealthTech to assist with the process of developing the specification and design of an appropriate solid state recording system.  HealthTech worked with RSP Seating & Sensors and decided to use the services of Warwick Control Technologies to produce the specification and design of the system.

Project

Sensors:

The first consideration was to determine the best sensors to use for determining the head position.  Three technologies were considered in the following four configurations:

·        Optical Proximity Sensors
·        Ultrasonic Proximity Sensors
·        Capacitive Proximity Sensors
·        Combined Proximity Sensors

The advantages and disadvantages of using each sensor technology were considered and it was decided that the optimum solution would be to use a ‘combined’ configuration.  The interaction and use of the combined sensor system is summarised as follows:

The rigidity of the Optical sensors could be compensated by the wider range sensing capabilities of the Ultrasonic or Capacitive sensors. 

The optical sensing constraints are too rigid for a liberal learning curve for the patient. 

With the use of the Ultrasonic or Capacitive sensors there is a concern with the effects of the patient’s long-term exposure to the emissions from the sensing unit.

The combination of Optical and ultrasonic or capacitive sensing will ensure course and fine sensing which will allow a liberal learning curve for the patient. 

The ultrasonic or capacitive sensing is used for the course sensing in that it will sense the head position from further distance.  As the head comes into closer proximity with the optical sensor’s fine sensing capability, the ultrasonic or capacitive sensor is disabled, and the system relies on the optical inputs. 

Figure 1 below illustrates the sensor positioning and indicates this concept.

                                     Fig 1: Combined Sensor Array 

For the control configuration, it was suggested that a powerful embedded controller be used for this project in the form of a Hitachi SH4 processor, based on a Hitex HiCO.SH4-CORE module. This Module would allow not only realization of the stated requirements above, but also allow long term historical data collection and analysis of the patients progress, without the need for constant supervision.

The control system will require sufficient I/O to allow for sensing interpretation and applying outputs for the sound system, whilst having the capability of recording and storing desired sounds when wanted. The system will have solid-state storage capability with line inputs for microphone and tape/CD devices. The self-learning historical analysis of the patient’s head position will be downloadable for later study. Also, the processor will have the capability to automatically adjust the power output to the speakers according to the patient’s head position, to ensure that the volume is constantly at the same comfortable level. Figure 2 below illustrates this configuration.

                                   Fig 2: Overall System Configuration

Outcome

While this is the ideal solution, it may not be financially viable for some customers of limited financial means. A lower cost version was also considered, but some of the essential analysis features and the solid state recording features were greatly reduced. What is needed is the backing of the National Health Services to make this therapeutic device available to all financial classes.

Mr Salt of RSP Seating & Sensors is now able to develop this project concept into the next phase of developing a prototype, taking into consideration the aesthetic needs of the patient and the ease of use by the parent.