1. A method for monitoring an actuator in a physical system, the method comprising: monitoring, based on measured system quantities, the actuator, via a processor having a computer model that describes the actuator, the behavior of the actuator being represented by a computer model function and one or more parameters of the computer model function; determining or adapting values of the parameters of the computer model with the aid of one or more particular system quantities; determining an error when a specified error condition is fulfilled, the error condition defining when at least one of the parameters, and/or at least one quantity determined from a plurality of the parameters, lies outside a corresponding specified target deviation range for a relevant parameter or the relevant quantity; and determining that a component of the actuator is faulty if the error is determined; wherein the actuator includes an electromechanical throttle valve actuator for a throttle valve in an engine system having an internal combustion engine, the position of the throttle valve and/or an electric voltage applied to the electromechanical throttle valve actuator being specified as the system quantities, and wherein for the actuator, the error condition on the basis of which a particular error can be identified include at least one of the following error types: (i) an actuator spring is broken and/or missing, and/or a low resistance, and/or a short-circuit, and/or a weak motor, and/or defective permanent magnets; (ii) an actuator friction is too high due to contamination and/or stiffness; (iii) an actuator friction is too low due to wear, missing shaft sealant, and/or a broken coupling bar; (iv) an actuator component has a high resistance; and (v) the actuator component has a low resistance due to a short circuit, a weak motor, and/or defective permanent magnets, and wherein error types (i) correspond to the following error condition: 
 α> S (α)+Δα&η/α< S (η/α)−Δ(η/α), wherein error types (ii) correspond to the following error conditions: 
 S (α)−Δα<α< S (α)+Δα& 
 μ/α> S (μ/α)+Δ(μ/α)& 
 S (η/α)−Δ(η/α)<η/α< S (η/α)+Δ(η/α), wherein error types (iii) correspond to the following error conditions: 
 S (α)−Δα<α< S (α)+Δα& 
 μ/α< S (μ/α)−Δ(μ/α)& 
 S (η/α)−Δ(η/α)<η/α< S (η/α)+Δ(η/α), wherein error types (iv) correspond to the following error conditions: 
 η/α> S (η/α)+Δ(η/α) 
 (α< S (α)−Δα& 
 μ/α> S (μ/α)+Δ(μ/α), and wherein error types (v) correspond to the following error conditions: 
 α> S (α)+Δα& 
 μ/α< S (μ/α)−Δ(μ/α), where R is a winding resistance of an actuator drive of the actuator, L is an inductance of a winding of the actuator drive, I represents an actuator current through the actuator drive, J represents a mass moment of inertia, and C m and K gear represent a gear ratio, a = LJ C m ⁢ K gear b = RJ + LD C m ⁢ K gear c = C m ⁢ K gear + RD + LC s C m ⁢ K gear d = RC s C m ⁢ K gear a 1 = 8 ⁢ a d ⁢ ⁢ T 3 b 1 = 4 ⁢ b d ⁢ ⁢ T 2 c 1 = 2 ⁢ c d ⁢ ⁢ T α = 1 a 1 + b 1 + c 1 + d β = α ⁡ ( - 3 ⁢ a 1 - b 1 + c 1 + 3 ⁢ d ) γ = α ⁡ ( 3 ⁢ a 1 - b 1 - c 1 + 3 ⁢ d ) δ = - γ - β - 1 + 8 ⁢ α ⁢ ⁢ d , and where M f ({dot over (φ)}) is a friction moment and M s (φ) is a return moment of an actuating element of the actuator, where A(p pre −p post ) is a counter-pressure moment that is exerted by a pressure differential that exists over the actuating element, and where ρ = α ⁢ ⁢ R C m ⁢ K gear μ = ρ ⁢ ⁢ M coul η = 8 ⁢ ρ ⁢ ⁢ M 0 κ = ρ ⁢ ⁢ A .