Multi-Service Modification to the Winsford Feeder
Multi-Service Modification to the Winsford Feeder
Students: Ben Jones, Paul Felkins, Alethia Baldwin
Client Coordinators: Gary Edwards, PhD, Marlese Delgado, PT, United Cerebral Palsy of Birmingham
The Model 5 Winsford Feeder is an automated feeding aid presently used in the Physical Therapy and Occupational Therapy Clinics of Children’s Hospital of Alabama. The feeder can be operated by a slight move of the head and can also be controlled by hands, shoulders, hips, or knees with the use of the rocker switch. The original design can only bring food able to fit on a teaspoon to the mouth of the user. The staff wished to add components to the feeder that would hold a single, larger item, such as a sandwich, as well as a napkin and a drink that would give the children more independence. The present design includes a sandwich holder that accommodates sandwiches up to 2 inches thick. The napkin holder holds the napkin securely and is curved outward enough that it can be used comfortably. The device is corrosion resistant and electrically safe, with all wires insulated and hidden. The arm accelerates and decelerates at less than 27.57 ft/s2 to prevent spillage. The additions to the feeder have a combined weight of less than 15 lbs and fit into one suitcase.
The final design consists of an instrument box, on which a circular plate rotates with partitions for the napkin, the cup and the sandwich, and a mechanical arm that, upon activation of the switch, engages one item and brings it forward to the client’s mouth (Figure 10). The instrument box has two sections at different heights. One section where the plate is mounted is 3.375 inches high measured from the base of the unit. The top surface of the instrument box, which is triangular in shape, is 5.5 inches high measured from the base of the unit. This extra height provides a vertical-mounting wall for the mechanical arm and also to provide additional space in the instrument box for the mechanical and electrical system.
The plate is supported on three rollers and is rotated about a ¼” stainless steel drive shaft mounted at bottom of the plate. The drive shaft enters into the enclosure through a bearing assembly mounted on the instrument box. The opposite end of the drive shaft is fixed to a steel bracket and bearing assembly located inside the instrument box. A cam block and pulley is mounted on the steel drive shaft via a socket head screw and is utilized for the drive motor switching system and plate rotation, respectively. For the plate, the material chosen was acrylic, which is approved by the U.S. Food and Drug Administration as safe to be used as a food contact surface and can be cleaned using soap and water. The plate motor is mounted on a steel bracket and drives a beveled gear system mounted on a 0.250-inch diameter shaft located between two sealed bearing units. The sealed bearing units provide for rotation of the drive shaft that contains a drive pulley. A timing belt that rotates the plate drive shaft connects the two drive pulleys and the idler pulley.
The arm mechanism is 9-1/2 in. long by 2 in. tall by 0.5 in. wide and is mounted to the 45-degree vertical wall on the instrument box. It has a diameter of 0.3125” and is made of stainless steel. The arm rotates 130 degrees at an average angular velocity of 0.58 radians per second. The arm interior contains a drive belt that holds the arm at a level position as it lifts to the feed position. The arm mechanism consists of a 7.7-rpm motor that drives a crank and connecting rod. One-half of the revolution of the drive motor raises the arm and the next half lowers it. The switch stops the motor after each half revolution. The torque needed to lift the arm was calculated to be 400 in-oz and a motor was chosen accordingly. A .5” x .5” Type 304 SS square bar that is 4.00 in. long extends from the lifting arm and is held parallel to the ground by the arm assembly mentioned earlier and will lift the holders off of the plate. A 0.365” x 0.365” square peg extends 2 in. vertically out of the bar and is centered in the peg at a distance 3.19 in. from the center of the shaft in the bar. Welded on the end of the sandwich, cup and napkin holders are a 0.5” x 0.5” square tube with a nominal wall thickness of 0.0625 in. The peg on the end of the bar inserts into the tube upon lifting of the arm.
The switching control system addition consists of three single throw switches, an additional wiring harness, a 6-lead system and a 4-position switch. Pushing and releasing the control switch starts the arm motor. When the arm starts to lift, the arm position switch closes to keep the arm moving. The arm stops at the top of its travel. Pushing and releasing the other control switch starts the plate motor. The material for the gears is nylon, the same material as the gears in the present feeder. Also the motor, made by Pittman Motors, is the same as in the original feeder. The instrument box is chosen a cold-rolled steel, (AISI 1011) coated with the same primer paint. Total cost of the modification = $1,200.