How can I control torque for screwdriving?

In traditional manual screwdriving, torque wrenches with driver bit adaptors were used to tighten fasteners to a desired torque. Modern automatic screwdriving takes this same concept and puts the torque limiting function of the torque wrench directly into a powered screwdriver, allowing the screwdriver’s spindle to approach and brake within a very tight tolerance of the target torque rating. Several different technologies can achieve this type of torque control, all dependent on the screwdriver and level of automation selected. Simplistic screwdrivers may utilize a mechanical limiting clutch, and more advanced screwdrivers may use a DC electric controller powering a motor encoder.