function y = cup_conv(x)
Vrate = x(1); % Valve opening from Silo 2
M = x(2); % Motor Speed [RPM]
time = x(3); % time 
omega = M*(2*pi/60); % Angular Frequency [rad/sec]
gear = 1000; % proportional gear 1000:1
N = 10; % number of cups
T = (2*pi)/(N*omega/gear); % the period of the cup delivered [sec]
mod = sin(((2*pi)/T)*time); % modulation 
if mod > 0.75
    y = Vrate; 
else
    y = 0;
end