Errata
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This page contains information about errata for Feedback Systems. The errata listed here include known and corrected errors since the first printing of the book; clicking on the link will take you to a page with additional details. Typos and other relatively minor corrections are listed here but do not have separate pages with additional details (they also do not appear on individual chapter pages).
Conventions:
- Each line of text and each line of a displayed equation are counted as a line. Negative line numbers mean number of lines from the bottom of the page. First line on page = 1, last line on page = -1.
- Entries in boldface indicate errors which might change significantly the interpretation of the text.
- The version refers to the release number in which the error was found. Errors are corrected in all subsequent releases of the text.
- The status of the errata uses the following terms:
- Submitted - erratum has been submitted, but not yet processed
- Open - erratum has been received, but not yet corrected
- Pending - erratum has been corrected, but fix is not yet posted
- Closed - erratum has been corrected and revision is posted
- Rejected - erratum was rejected (see page for information on why)
Second Edition
- Beta testers: enter new errata on BitBucket
Preprint
First Edition
Third printing
Page | Line | Erratum | Version |
---|---|---|---|
10 | -1 | In the "Instrumentation" subsection, "axon of the giant squid" should be "giant axon of the squid" | 2.10c |
37 | 4 | In Example 2.1, the state space equations for the balance system are missing a divisor of J_t in one of the terms | 2.10c |
38 | 20, 21 | In equation (2.12), should be x[0] (twice) | 2.10e |
40 | 2 | In Figure 2.7, the coefficients are for an update period of one day | 2.10c |
42 | 2 | In Figure 2.9, "solid" and "dashed" should be swapped | 2.10e |
43 | 12 | In displayed equation for , leading minus sign is missing from rightmost expression | 2.10d |
47 | -6 | In Example 2.5, expression for the step response is missing some factors | 2.10d |
49 | 19 | In the normalized state space model for the spring-mass system, the derivative should be with respect to | 2.11b |
49 | -10 | In Example 2.7, reference to the previous example should be Example 2.1, not Section 2.1 | 2.11b |
49 | -8 to -4 | In Example 2.7, q should be replaced by p (three places) and theta (one place) | 2.10d |
61 | -4 | In Exercise 2.3, disrete should be discrete | 2.10e |
62 | -10 | In Exercise 2.4, a = 0.25 should be a = 0.75 | 2.10e |
84 | 11 | In the online version of the text, there is a formatting error in equation (3.23) | 2.10c |
86 | -1 | In equation (3.26), q_0 is not defined | 2.10c |
100 | -6 | In Example 4.4, second simplifying assumption should be l/J_t = 1 (remove extra factor of m) | 2.10d |
105 | -3 | On right hand side of displayed equation, x should be x_j | 2.10c |
107 | -7 | At the end of Example 4.6, the roots should have negative real part instead of being positive | 2.10d |
110 | -5 | Near end of Example 4.11, denominator of f'(z_2e) term should be squared | 2.10d |
113 | -14 | In Example 4.10, \dot V = 0 should be treated as negative semidefinite, not positive | 2.10d |
116 | 3,6 | In Example 4.11, Lyapunov equation entries for f'_1 and f'_2 are switched (solution is correct) | 2.10d |
121 | 10 | In Example 4.13, inequality should be for x_1 instead of x_2 | 2.10c |
127 | 4 | In Exercise 4.2, the q_in term should be positive | 2.10d |
128 | 6 | In Exercise 4.12, some additional assumptions are required for oscillation | 2.10e |
132 | 1 | Add a comma after "For other systems" for clarity | 2.10c |
135 | 10 | In displayed equation above equation (5.5), there is an extraneous infinity symbol after the summation | 2.10f |
138 | 14 | In Example 5.3, dot missing from q in middle term of displayed equation for dynamics with damping | 2.10d |
138 | -11 | In Example 5.3, omega_d should have terms in the square root reversed | 2.11b |
140 | 0 | In Figure 5.3, state labels are incorrect | 2.10e |
140 | -7 | In displayed equation after equation (5.11), exponential is missing parenthesis; should be | 2.10d |
141 | -4, -8 | In Example 5.4, there is a sign error in one of the terms | 2.10c |
145 | 8-9 | At end of Example 5.5, eigenvalue approximations are incorrect | 2.10d |
145 | 8-9 | At end of Example 5.5, real part of eigenvalues has incorrect sign | 2.10e |
147 | 10-15 | Impulse response does not include the direct term in the proper manner | 2.11b |
148 | 2 | In the caption for Figure 5.7, "drive" should be "driven" | 2.10c |
157 | 7 | In equation (5.26), the u(k) term in the integral should be u(tau) | 2.10c |
158 | 13, 22 | In Example 5.11, the parameter should be | 2.11b |
158 | -8 | After equation (5.31), rolling friction term disappears if v = 0 | 2.10c |
158 | -7 | After equation (5.31), the equilibrium velocity should be m/s | 2.11b |
158 | -5 | After equation (5.31), the parameter listed in the text should be | 2.11b |
161 | 3 | In Example 5.12, expression non-equilibrium condition has wrong symbols | 2.10d |
162 | 7 | In equation (5.37), the parameter should be | 2.11b |
163 | 10 | In equation (5.39), Coriolis term should be + C(q, \dot q) | 2.10d |
165 | -4 | In Exercise 5.8d, the left hand side of the first equation should be x(k+1) | 2.10c |
178 | -12 | In Example 6.4, the initial control signal is u(0) = k_r r = \omega_c^2 r | 2.11b |
179 | -12 | In equation (6.17), elements of the output matrix should be in the opposite order | 2.10d |
179 | -8 | In displayed equation after equation (6.17), a_l should be a_1 | 2.10d |
182 | 16-20, 25 | In Example 6.5, reference variable should be L_d instead of r | 2.10d |
182 | 3 | In Example 6.5, definitions of z1 and z2 are switched | 2.11a |
182 | 17 | In second line of displayed equation, missing minus sign in front of the gain matrix | 2.10d |
182 | 21 | In the last paragraph of Example 6.5, r_h should be u | 2.10d |
183 | 4 | In the caption for Figure 6.7, L_e=20 should be L_e=30 | 2.10d |
183 | -7 | In equation (6.22), should be | 2.11b |
184 | 17 | For underdamped second order system, eigenvalues are listed incorrectly | 2.10d |
185 | -3 | The formula given for the rise time of a second order system in Table 6.1 is only approximate | 2.11a |
186 | 5 | Before Example 6.6, "is Q-value" should be "its Q-value" | 2.10d |
186 | -3 | In Example 6.6, the output equation has 'x' for the state instead of 'c' | 2.10c |
188 | -2 | In Example 6.7, the A matrix has an error in the (3,4) entry | 2.11b |
189 | 5 | In Example 6.7, the open loop eigenvalues are incorrect | 2.11b |
189 | 15 | In Example 6.7, the imaginary part of the first pair of eigenvalues is missing factor of i | 2.10d |
191 | -5 | In Example 6.8, the state space dynamics have errors in the trigonometric terms | 2.10c |
192 | 4-14 | In Example 6.8, the state error should be \xi and the input should be F | 2.10d |
192 | -15 | Diagonal entries for Q_v should be rho | 2.10c |
196 | 19, 23 | In Example 6.10, the system input for the linearized model should be w instead of u | 2.11a |
196 | -1 | In Example 6.10, the reference gain should be k_r = a_1/b | 2.11b |
204 | 6 | In Example 7.1, the output equation has 'x' for the state instead of 'c' | 2.10c |
206 | 2 | In expression for W_0, (3, 1) entry should be (remove factor of in second term) | 2.10c |
207 | 13 | "going zero" → "going to zero" | 2.10d |
213 | 8 | Estimator dynamics in Theorem 7.3 are missing B k_r r term | 2.10c |
217 | -6, -5 | In Example 7.5, descriptions for (disturbance) and are switched | 2.10c |
219 | -5 | Change gain matrix to for consistency | 2.10d |
220 | 17 | In expression for B(t), missing parenthesis at end of subscripted expression | 2.11a |
220 | -12 | Above displayed equation for the gain scheduled control law, should be replaced by | 2.10d |
221 | -15 | In Example 7.5, "where were" → "which were" | 2.10d |
224 | 4 | Output in Kalman decomposition for Example 7.7 is missing state error term | 2.10c |
225 | -4 | "phenomena knows" → "phenomena known" | 2.10c |
229 | 10 | Henrik Bode should be Hendrik Bode | 2.11a |
233 | -8 | In equation (8.6), matrix inverse is computed incorrectly | 2.10d |
235 | 14 | In displayed equation above equation (8.9), exponential term on right hand side should be (no minus sign) | 2.10d |
236 | -9 | In Example 8.2, resister should be resistor | 2.11b |
238 | -9 | In equation (8.15), second order partial derivative is written incorrectly | 2.10c |
238 | -1 | In Example 8.4, boundary condition and coefficients for psi(x) are incorrect | 2.10c |
241 | -12 | Before Example 8.5, "related" → "relate" | 2.10d |
242 | 7 | In Example 8.5, leading term in denominator for H_\theta F should be cubic in s | 2.10d |
247 | 2 | In Example 8.6, numerator gain term for G_ur should be k_r instead of k_1 | 2.10d |
247 | 11 | Last equation in Example 8.6 has sign error in the second term | 2.10c |
247 | 11 | Last equation in Example 8.6 has errors in numerator expressions | 2.10d |
249 | 6 | In Example 8.7, remove from numerator of expression for | 2.10d |
256 | -10,-9 | In Example 8.9, u should be v in the first displayed equation and the following line | 2.11a |
262 | -2 | In Exercise 8.2, text should read "transfer function from to " (instead of ) | 2.10d |
263 | -13 | In Exercise 8.5, k in the denominator of G(s) should be (k+1) | 2.10c |
264 | 9 | In Exercise 8.6, second term in expression for b_n should be | 2.10d |
272 | 10, 11 | In the paragraph above Example 9.3, G(*) should be L(*) | 2.11a |
272 | -1 | In Example 9.3, intersection of negative real axis should be at -0.5. | 2.10d |
273 | -5 | In Example 9.4, "that that" → "that" | 2.10d |
274 | -2 | In right hand expression of last displayed equation of Example 9.4, in the denominator should be | 2.10d |
275 | 1 | In the caption for Figure 9.7, the transfer function should match equation (9.4) | 2.11a |
275 | 3 | In caption for Figure 9.7, "intersections" → "intersects" | 2.10d |
275 | -5 | In Example 9.5, "it is seems" → "it seems | 2.10d |
282 | -11, -9 | In Example 9.9, 'gain margin' g_m should be 'stability margin' s_m | 2.10d |
282 | -7 | In Example 9.9, the gain margin for Figure 9.12 should be | 2.10d |
283 | 12 | In equation (9.8), the right hand side should be evaluated at omega0 | 2.11a |
283 | -6 | Missing parenthesis in | 2.10d |
284 | -13 | In Example 9.10, transfer function zero is at | 2.10d |
289 | 7 | In equation (9.14), should be | 2.10d |
292* | 10 | In Exercise 9.7, should be | 2.11a |
296 | 1 | Caption for Figure 10.3b should be "Derivative action" | 2.10c |
297 | 11 | After equation (10.5), low frequency limit bound be 1/T_d instead of T_d | 2.10c |
299 | -10 | Closed loop time constant after equation (10.6) has an extra factor of 2 | 2.11a |
300 | 4 | The b k_i term in the characteristic polynomial has an extra factor of s | 2.10c |
300 | 7 | In displayed equation above equation (10.7), the final term should be (not squared) | 2.10d |
302 | 0 | In Figure 10.7b, should be | 2.10c |
304 | -8 | In Example 10.4, z should be zeta | 2.11a |
304 | -1 | In Example 10.4, proportional gain should be | 2.10d |
305 | -1 | In equation (10.12), should be | 2.11a |
306 | 1 | Right after equation (10.12), should be | 2.11a |
308 | -9 | In Section 10.5, PID derivative filter should have time constant | 2.10d |
309 | 9 | In equation (10.4), upper limit of the integral should be t, not infinity | 2.11a |
310 | -4 | The expressions for the PID parameters for the op amp implementation are incorrect | 2.10d |
318 | -4 to -1 | Reference input not included in Figure 11.2 and dimensions of blocks are listed incorrectly | 2.10c |
319 | 0 | In Figure 11.3, the label 'y' at the input to P_2 should be removed | 2.10c |
326 | -1 | In equation (11.11), delete extraneous "[rad]" | 2.10d |
328 | -11 | In Example 11.5, "" should be "" | 2.10c |
328 | -6 | In Example 11.5, "dotted" line is actually "dash-dotted" line | 2.11a |
329 | 3,5 | In the Figure 11.10 caption and Example 11.5 text, "dotted" line is actually "dash-dotted" line | 2.11a |
330 | 2 | In the caption for Figure 11.11, Fz should be F1 | 2.10c |
334 | 0 | In Figure 11.13a, curves should be labeled with z instead of b | 2.10d |
338 | -6 | At end of Example 11.11, "the can be achieved" should be "that can be achieved" | 2.10d |
339 | -9 | In expression for I_1, limits have an extra factor of i | 2.10c |
340 | 3-9 | Contour integral in derivation of Bode's integral formula is analyzed incorrectly | 2.10c |
341 | -8 | In Example 11.12, value for -mg should be -39.2 | 2.11a |
341 | -5 | In Example 11.12, transfer functions for inner loop and outer loop dynamics are incorrect | 2.11b |
342 | 5 | In Example 11.12, error should be in , not | 2.11a |
342 | 13 | In Example 11.12, after displayed equation for C_o(s), frequency where phase lead flattens out should be b_o/10 | 2.10d |
342 | -16 | In Example 11.12, transfer functions for inner loop and outer loop dynamics are incorrect | 2.11b |
342 | -10 | In Example 11.12, gain term in should be -2 instead of 0.8 | 2.11a |
344 | -4 | In Exercise 11.5, final expression for should be | 2.11a |
345 | -10 | In Exercise 11.10, controller gain at frequency should be | 2.10d |
357 | -6, -8 | For Youla parameterization, P = b(s)/a(s) = B(s)/A(s) and C0 = G0(s)/F0(s) | 2.10c |
359 | -6, -4 | In equation (12.13) and the displayed equation above it, T should be -T | 2.10d |
361 | 13 | Missing end parenthesis at end of sentence | 2.10c |
363 | 17 | In Example 12.8, repeated in denominator of transfer function for should be | 2.10d |
365 | -13 | The reference to the maximum complementary sensitivity should be to equation (12.7) | 2.10c |
366 | -16 | In equation (12.16), a is not defined and a factor of a is missing in numerator the last term | 2.10c |
367 | -8 | In equation (12.18), a factor of is missing from the numerator | 2.10c |
368 | 7 | In equation (12.21), final term in expression for should be | 2.10d |
369 | -12 | Replace "dashed" with "shaded" in the description of Figure 12.16a | 2.10c |
371 | -4 | Reference to Figure 12.17b should be to Figure 12.17 (right) | 2.10c |
376 | 2 | In Exercise 12.11, first term in numerator for should be | 2.10d |