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Mechanical Design

Air Pump System

PillAgenda relies on air suction to pick up pills and dispense them. To provide the necessary suction force required to lift a pill, a 12V air pump is used. The pump has an inlet that sucks in air which is blown out through an outlet. Only the inlet will be used for the air pump system. One end of a silicon tube is fitted to the opening of the inlet, while its other end acts as the contact point with the pills. A small straight plastic connector was also added to this end of the tube to slightly decrease the surface area of contact in hopes to increase suction.

Suction Arm

The suction arm mechanism involves movements in two directions – vertical and rotational. A rack attached to a pusher and a pinion powered by a servo motor determines the vertical movement of the suction arm, while its angular position is controlled by another set of gears and a servo. The end of the rotating arm has a hollow tube in which the silicone tube attached to the air pump system goes through. As the suction arm is rotated to the position above the correct pill compartment, the pusher is moved down to bring the silicone tube close to the pills to provide the necessary suction to pick one up. The pusher then moves back up with the pill, and the arm rotates to the dispensing slot before releasing the pill. Note that from the moment the pill is picked up until it is released, the air pump has to stay on, since the suction force is what keeps the pill from falling.

Pill Compartment

The pill compartment is designed as a concave bowl with an angle that is steep enough to allow pills to slide down easily. A vertical semicircular tube is placed above the point where the pills would collect in order to prevent them from piling up at that point. The suction arm will go through the tube when it extends down to pick up a pill. Additionally, flat walls will be placed around the bowl to give it an outer trapezoidal body. These walls are produced using laser-cut clear acrylic, while the bowl itself will be 3D-printed.

Assembly

The entire assembly for the device consists of one central arm suction mechanism, with seven pill compartments surrounding it. The whole device is enclosed by flat walls which form an outer octagonal shape. This leaves an open side that is unoccupied by a pill compartment, and thus will be used as the dispensing slot. The enclosure has a height of 45cm and a width of 43.5cm.