Force sensing system for a tensioned flexible member

A system for measuring a tension load (113) applied to a flexible member (101), for instance in an exercise machine, comprises a load pulley (104), which is rotatable about a fixed axis and is arranged to movably engage the flexible member such that it partially wraps around the load pulley and exerts a radial force (103) on it. A force sensor cell (105) communicates with the fixed axis of the load pulley and senses the physical strain caused by the radial force on the load pulley and generates an output signal proportional to the physical strain. An analogue to digital converter (114) coupled to the force sensor cell converts the output voltage signal into a digital signal. A memory (110) stores a predetermined correlation between the digital output signal and the tension load. A processor (108) is coupled to the memory and to the analogue to digital converter and is arranged to determine the tension load from the digital output signal in accordance with the predetermined correlation.