Position-controlled tensioner system

1. Field of the Invention Apparatus and method for controlling tension of one or more fiber tows preferably including a support frame having a spool holder, a motor for driving the spool holder, a dancer arm having a free end with a redirect roller mounted thereon and a fixed end pivotally mounted to coact with an angular-position sensor, a low-friction pneumatic cylinder mounted to the dancer arm and a support plate to exert a force thereon, a second redirect roller mounted to coact with a second angular-position sensor, and a controller and associated circuitry to control the tension of the fiber by controlling the motor in response to the position of the dancer arm.Preferably, a microcontroller mounted on a single printed circuit board (PCB) having signal buffering circuitry to control a plurality of individual tensioners is provided. The PCB preferably plugs into a backplane which allows communication between several microcontrollers, thereby allowing the control of at least 32 individual tensioners. Communication between a fiber placement machine main, or master, controller and each tensioner controller is also provided. The second angular position sensor coacting with its respective redirect roller provides fiber speed, allowing better control of the dancer position, estimation of current spool diameter to better track fiber usage, and to detect any malfunctions in fiber travel.