Device to operate the foot pedal control of an electric sewing machine

Project  / Project number: 14/29/C  /  Status:

0

The challenge

Client’s requirement

This referral came from an adult neurological physiotherapist for a 67 year-old paraplegic.

“Her main hobby is sewing but [following her accident] she is unable to use the foot pedal to control her sewing machine. Some people do use the foot pedal with their knee but she has no control of her legs from the waist down. We also considered using the foot pedal with her elbow but she needs two hands free to guide the material so this isn’t possible either”.

Solution

The standard ‘sip and puff’ method was chosen as the most appropriate control as it had the least impact on the user’s freedom of movement.  A device was made into which the sewing machine foot pedal is placed. A lever ‘squeezes’ the foot pedal when the user puffs (blows) into a tube and releases it when the user sips (sucks) on the tube. Only light pressure/suction is needed and the pedal remains in its last position when the user rests. An additional ‘stop’ button is provided which overrides all other controls.

The drive system consists of a 12 volt motor and epicyclic gearbox operating a lever through twin rubber belts. To allow for differing sizes of pedal, a spring-balanced torque reaction device senses when the pedal is fully compressed or fully relaxed and switches off the motor. There is a further friction clutch between the belts and lever to limit the actuating force in case of system failure.

general view     drive system     torque sensor
Fig 1 general view                                   Fig 2 drive system                               Fig 3 torque sensor

 

see the video (5 mins – opens in new window)

Benefits to the client

  • Fully hands-free operation as requested by client’s physiotherapist.
  • Restores client’s prime hobby activity.
  • The client had led an active life up until becoming paralysed through an accident and was now able to restore her self esteem and mental well-being through regaining a sense of achievement and purpose.

Additional factors

The device:

  • adapts to any size of foot pedal enabling easy machine upgrade or replacement;
  • does not require any intervention or connection to the sewing machine;
  • uses standard sip/puff tubes;
  • needs no tools or specialist knowledge for set-up or use;
  • allows for normal foot operation.