Question 10.3.7: A conveyor drive system to produce translation of the load i......
A conveyor drive system to produce translation of the load is shown in Figure 10.3.11. To translate the load a specified distance, the drive wheels must rotate through a required angle, and this can be accomplished by controlling the speed, often with a trapezoidal speed profile. The equivalent inertia of the load and all the drive components felt at the motor shaft is I_e. The effect of Coulomb friction in the system produces an opposing torque T_{Fe} at the motor shaft, and the damping in the system is negligible. Develop the block diagram of a proportional control system using an armature-controlled motor for this application. Assume that the drive wheel speed ω_L is measured by a tachometer and that the motor speed ω_m is related to the drive wheel speed by ω_m = Nω_L , where N is the speed ratio due to the reducer and the chain drive.
As shown in Example 3.3.6, t the mechanical subsystem is described by
I_e \frac{d \omega_m}{d t}=T-T_{F e} (1)
where the motor torque is T = K_T i_a. The system is like that shown in Figure 10.3.4. The block diagram can be obtained by modifying Figure 10.3.8 using equation (1) and collecting the various gains into one gain: K_P = K_{tach}K_1K_a. The resulting diagram is shown in Figure 10.3.12.
