.Figure 1 shows a cross-section through a limited angle rotary actuator used in fly-by-wire system. The actuator consists of a permanent magnet rotor and a pair of series connected coils wound onto a toroidal core. It is important to note that the conductors on the outside edge of the core are merely return conductors (so called end-windings) that play no role in generating torque. The only conductors which interact with the permanent magnet field and hence generate torque are those within the core. The axial length of the actuator (i.e. length into the plane of the paper) is 30mm. The various dimensions shown in Figure 1 include some that are specific to each student which are shown-in red text in the table in Appendix 1. Each individual coil has TURNS_ON_COIL turns. The-particular grade of magnet is MAGNET_GRADE. The airgap magnetic field is given by the simplified, but well-established, relationship:

geff is the effective magnetic which for this device includes both the mechanical clearance-gap and the coil thickness, i.e. lgeff = lg + coil thickness. The remanence of the permanent magnet, Br, is an intrinsic material property which is specific to a particular grade of magnet. By researching manufacturer's on-line data sheets/catalogue, find the room temperature(20°C or 25°C depending on manufacturer) value of the permanent magnet remanence for the manufacturer and grade specified against your name in Appendix A. Some-manufacturers specify typical / nominal and minimum values. For this assignment, please use the typical / nominal values. Calculate the airgap magnetic flux density for your grade of magnet at room temperature. ) The torque produced by the actuator for a current of PART ii CURRENT. d) Find a method for calculating the moment of inertia of the rotor and hence calculates its moment of inertia assuming that both the core and the magnet has a density of 8000 kgm ³.(Hint: You can think of the rotor as a circular rotor with two circle segments removed). e) If the load has a LOAD_MOMENT_OF_INERTIA and the friction is FRICTION, calculate the-time taken for the rotor to move through ANGLE_EXCURSION from standstill (you may-assume that during this excursion, the rotor magnet remains entirely within the span of the stator coil).