Force sensors operate on the principle that the resistance of silicon-implanted piezoresistors will increase when the resistors flex under any applied force. In this, the force measurement is based on the determination of a displacement subject loading. The strain gauges have been used primilarly to analyze forces, but lately piezoelectric transducers are used for the measurement of forces. In tumbling mills, the forces on the lifter bars are quite sensitive to impact and collision. The instrumented lifters incorporating force sensors are used to monitor the performance of tumbling mills. The amount of resistance changes in proportion to the amount of force being applied. This change in circuit resistance results in a corresponding mV output level. These sensors are normally used to measure the robotic system's forces as it performs various operations.

Forced air heaters use a fan to blow air that is warmed by metal or ceramic heating elements. A forced-air heater is appropriate for quickly heating up a small- to medium-sized room. It is ideal for use in large construction, commercial, and industrial sites. It is effectively a very hot flame with a large fan running behind it pushing huge amounts of cold air past the flame. These heaters can be operated using different fuels such as natural gas, propane, and kerosene.

A forced-air heating system draws the room air through ductwork to a furnace, where the air is filtered and heated. The warmed air is then blown back into the rooms through other ductwork. The system's ductwork is usually metal wrapped in insulation to help keep in heat. In some cases, flexible ductwork is preferred.