The heating system for the Cookmate product was designed to operate using an induction heater to minimize the transfer of heat to secondary components, and therefore maximize safety.
This sub-system was developed by repurposing an off-the-shelf heating product and making modifications to this product to allow it to be controlled programmatically.
Modifications To Off-the-Shelf Product
To allow for programmatic control, the off-the-shelf induction heater was dismantled, and a relay module was connected to the button interfaces of interest. This allowed specific buttons to be actuated programmatically.
Software Design of Heating Control Module
The software driver developed to control the heating sub-system followed a state-machine architecture and implemented a ‘bang-bang’ controller. The flow chart below shows an overview of the program.
The heating driver sits in the ‘IDLE’ state and is activated when an external API call is made. This activation process causes the correct button combinations to be actuated to turn the induction heater on at the highest temperature setting. Once the temperature of the pot (measured by an infrared, non-contact temperature sensor) reaches the target temperature (plus some threshold), the heating system is turned off by actuating the correct buttons. Once the temperature drops below a certain threshold from the target temperature, the heating system is activated once again.
An external API call is required to disengage the heating system and send it back to its ‘IDLE’ state.
