The Garduino

The hygrometers work by sending a voltage through the soil and based on the amount of moisture present, it can identify the resistance of the electricity sent through the two sensor probes. If the resistance is high, the the soil is dry but if there is low resistance then the soil is wet. This data is sent to the Arduino to allow it to process the commands it sends out next.

A Nema 23 CNC Stepper Motor with a L298N Stepper Driver has been used so that the Stepper is able to be operated in an open loop via the CPU.

The Arduino Uno (CPU), commands the Stepper Driver to move a certain number of steps along the shower track axis in which to reach the correct plant. Prior to the plants being planted, this positioning is all pre programmed into the CPU. 

The shower head reaches the plant and a command to the motorised water pump is activated which draws water from the central reservation at the back through the umbilical tubing to the head and waters the plant for a timed number of seconds sufficient to hydrate the plant.

The shower's undercarriage is able to move along the track through a gear pulley belt system situated at either end of the axis directly on the Stepper motor's arm. 

To avoid system error of the shower head going too far along the track, there is a Mechanical Endstop Switch at either end of the track, controlled via two relays, who commands the shower head to return to its origin.

This Arduino Uno has a continuous loop system for each plant. When the loop series has been satisfied and the watering track reset, then a new loop will begin for the next plant following the same process but with different axis coordinates. 

In the scenario a plant isn't ready to be watered but will be soon, the Arduino is programmed to delay the watering process and will recheck the moisture levels at set time intervals such as, an hour or a day later.

Having this open loop system is crucial in managing multiple sensors and commands across the system interface.