Closed-loop control is essential for accurate torque control since it continuously checks the system's actual performance and adjusts its output accordingly in real time to the desired setpoint.
Whatever control system is used for torque, it always measures actual torque, compares it with target value, and instantly corrects any discrepancy (error) so that stable and accurate torque delivery can be assured at the output.
Most PID-Integrated Servo Drivers keep torque constant, with slight variations, through their built-in PID algorithm, which analyzes feedback and optimally commands motor output in a fast and precise manner.
By this closed-loop method, conditions under torque or over torque that entail degraded performance or accelerated mechanical wear or would really destabilize the system are eliminated.
An open-loop system has been called a "set-and-forget" kind of system where, once the parameters are inputted, nothing else ever happens. In this case, torque changes would just be passed on to the system via speed changes.
In robotics, CNC machining, and automation, where the working environment demands high-performance characteristics, closed-loop control with a PID-Integrated Servo Driver assures synchronous torque control, higher efficiency, and system longevity.