Skip to Content

Wiki source code of 07 Adjustments

Version 14.22 by Stone Wu on 2022/07/06 16:04
Show last authors
1 = **Overview** =
2
3 The servo drive needs to make the motor faithfully operate in accordance with the instructions issued by the upper controller without delay as much as possible. In order to make the motor action closer to the instruction and maximize the mechanical performance, gain adjustment is required. The process of gain adjustment is shown in Figure 7-1.
4
5 (% style="text-align:center" %)
6 [[image:image-20220608174118-1.png]]
7
8 Figure 7-1 Gain adjustment process
9
10 The servo gain is composed of multiple sets of parameters such as position loop, speed loop, filter, load inertia ratio, etc., and they affect each other. In the process of setting the servo gain, the balance between the setting values of each parameter must be considered.
11
12 ✎**Note: **Before adjusting the gain, it is recommended to perform a jog trial run first to ensure that the servo motor can operate normally! The gain adjustment process description is shown in the table below.
13
14 (% class="table-bordered" %)
15 |(% colspan="3" style="text-align:center; vertical-align:middle" %)**Gain adjustment process**|(% style="text-align:center; vertical-align:middle" %)**Function**|(% style="text-align:center; vertical-align:middle" %)**Detailed chapter**
16 |(% style="text-align:center; vertical-align:middle" %)1|(% colspan="2" style="text-align:center; vertical-align:middle" %)Online inertia recognition|(% style="text-align:center; vertical-align:middle" %)Use the host computer debugging platform software matched with the drive to automatically identify the load inertia ratio. With its own inertia identification function, the drive automatically calculates the load inertia ratio.|(% style="text-align:center; vertical-align:middle" %)__[[7.2>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HInertiarecognition]]__
17 |(% style="text-align:center; vertical-align:middle" %)2|(% colspan="2" style="text-align:center; vertical-align:middle" %)Automatic gain adjustment|On the premise of setting the inertia ratio correctly, the drive automatically adjusts a set of matching gain parameters.|(% style="text-align:center; vertical-align:middle" %)__[[7.3.1>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HAutomaticgainadjustment]]__
18 |(% rowspan="2" style="text-align:center; vertical-align:middle" %)3|(% rowspan="2" style="text-align:center; vertical-align:middle" %)Manual gain adjustment|(% style="text-align:center; vertical-align:middle" %)Basic gain|On the basis of automatic gain adjustment, if the expected effect is not achieved, manually fine-tune the gain to optimize the effect.|(% style="text-align:center; vertical-align:middle" %)__[[7.3.2>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HManualgainadjustment]]__
19 |(% style="text-align:center; vertical-align:middle" %)Feedforward gain|The feedforward function is enabled to improve the followability.|(% style="text-align:center; vertical-align:middle" %)__[[7.3.3>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HFeedforwardgain]]__
20 |(% style="text-align:center; vertical-align:middle" %)4|(% style="text-align:center; vertical-align:middle" %)Vibration suppression|(% style="text-align:center; vertical-align:middle" %)Mechanical resonance|The notch filter function is enabled to suppress mechanical resonance.|(% style="text-align:center; vertical-align:middle" %)__[[7.4.1>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HMechanicalresonancesuppressionmethods]]__
21
22 Table 7-1 Description of gain adjustment process
23
24 = **Inertia recognition** =
25
26 Load inertia ratio P03-01 refers to:
27
28 (% style="text-align:center" %)
29 [[image:image-20220611152902-1.png]]
30
31 The load inertia ratio is an important parameter of the servo system, and setting of the load inertia ratio correctly helps to quickly complete the debugging. The load inertia ratio could be set manually, and online load inertia recognition could be performed through the host computer debugging software.
32
33 |(((
34 (% style="text-align:center" %)
35 [[image:image-20220611152918-2.png]]
36 )))
37 |(((
38 **Before performing online load inertia recognition, the following conditions should be met:**
39
40 The maximum speed of the motor should be greater than 300rpm;
41
42 The actual load inertia ratio is between 0.00 and 100.00;
43
44 The load torque is relatively stable, and the load cannot change drastically during the measurement process;
45
46 The backlash of the load transmission mechanism is within a certain range;
47
48 **The motor's runable stroke should meet two requirements:**
49
50 There is a movable stroke of more than 1 turn in both forward and reverse directions between the mechanical limit switches.
51
52 Before performing online inertia recognition, please make sure that the limit switch has been installed on the machine, and that the motor has a movable stroke of more than 1 turn each in the forward and reverse directions to prevent overtravel during the inertia recognition process and cause accidents.
53
54 Meet the requirement of inertia recognition turns P03-05.
55
56 Make sure that the motor's runable stroke at the stop position is greater than the set value of the number of inertia recognition circles P03-05, otherwise the maximum speed of inertia recognition P03-06 should be appropriately reduced.
57
58 During the automatic load inertia recognition process, if vibration occurs, the load inertia recognition should be stopped immediately.
59 )))
60
61 The related function codes are shown in the table below.
62
63 (% class="table-bordered" %)
64 |(% style="text-align:center; vertical-align:middle; width:117px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:136px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:173px" %)(((
65 **Setting method**
66 )))|(% style="text-align:center; vertical-align:middle; width:213px" %)(((
67 **Effective time**
68 )))|(% style="text-align:center; vertical-align:middle; width:117px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:118px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:276px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
69 |(% style="text-align:center; vertical-align:middle; width:117px" %)P03-01|(% style="text-align:center; vertical-align:middle; width:136px" %)Load inertia ratio|(% style="text-align:center; vertical-align:middle; width:173px" %)(((
70 Operation setting
71 )))|(% style="text-align:center; vertical-align:middle; width:213px" %)(((
72 Effective immediately
73 )))|(% style="text-align:center; vertical-align:middle; width:117px" %)300|(% style="text-align:center; vertical-align:middle; width:118px" %)100 to 10000|(% style="width:276px" %)Set load inertia ratio, 0.00 to 100.00 times|(% style="text-align:center; vertical-align:middle" %)0.01
74 |(% style="text-align:center; vertical-align:middle; width:117px" %)P03-05|(% style="text-align:center; vertical-align:middle; width:136px" %)(((
75 Inertia recognition turns
76 )))|(% style="text-align:center; vertical-align:middle; width:173px" %)(((
77 Shutdown setting
78 )))|(% style="text-align:center; vertical-align:middle; width:213px" %)(((
79 Effective immediately
80 )))|(% style="text-align:center; vertical-align:middle; width:117px" %)2|(% style="text-align:center; vertical-align:middle; width:118px" %)1 to 20|(% style="width:276px" %)Offline load inertia recognition process, motor rotation number setting|(% style="text-align:center; vertical-align:middle" %)circle
81 |(% style="text-align:center; vertical-align:middle; width:117px" %)P03-06|(% style="text-align:center; vertical-align:middle; width:136px" %)(((
82 Inertia recognition maximum speed
83 )))|(% style="text-align:center; vertical-align:middle; width:173px" %)(((
84 Shutdown setting
85 )))|(% style="text-align:center; vertical-align:middle; width:213px" %)(((
86 Effective immediately
87 )))|(% style="text-align:center; vertical-align:middle; width:117px" %)1000|(% style="text-align:center; vertical-align:middle; width:118px" %)300 to 2000|(% style="width:276px" %)(((
88 Set the allowable maximum motor speed instruction in offline inertia recognition mode.
89
90 The faster the speed during inertia recognition, the more accurate the recognition result will be. Usually, you can keep the default value.
91 )))|(% style="text-align:center; vertical-align:middle" %)rpm
92 |(% style="text-align:center; vertical-align:middle; width:117px" %)P03-07|(% style="text-align:center; vertical-align:middle; width:136px" %)(((
93 Parameter recognition rotation direction
94 )))|(% style="text-align:center; vertical-align:middle; width:173px" %)(((
95 Shutdown setting
96 )))|(% style="text-align:center; vertical-align:middle; width:213px" %)(((
97 Effective immediately
98 )))|(% style="text-align:center; vertical-align:middle; width:117px" %)0|(% style="text-align:center; vertical-align:middle; width:118px" %)0 to 2|(% style="width:276px" %)(((
99 0: Forward and reverse reciprocating rotation
100
101 1: Forward one-way rotation
102
103 2: Reverse one-way rotation
104 )))|(% style="text-align:center; vertical-align:middle" %)-
105
106 Table 7-2 Related parameters of gain adjustment
107
108 = **Gain adjustment** =
109
110 In order to optimize the responsiveness of the servo drive, the servo gain set in the servo drive needs to be adjusted. Servo gain needs to set multiple parameter combinations, which will affect each other. Therefore, the adjustment of servo gain must consider the relationship between each parameter.
111
112 Under normal circumstances, high-rigidity machinery can improve the response performance by increasing the servo gain. But for machines with lower rigidity, when the servo gain is increased, vibration may occur, and then affects the increase in gain. Therefore, selecting appropriate servo gain parameters can achieve higher response and stable performance.
113
114 The servo supports automatic gain adjustment and manual gain adjustment. It is recommended to use automatic gain adjustment first.
115
116 == **Automatic gain adjustment** ==
117
118 Automatic gain adjustment means that through the rigidity level selection function P03-02, the servo drive will automatically generate a set of matching gain parameters to meet the requirements of rapidity and stability.
119
120 The rigidity of the servo refers to the ability of the motor rotor to resist load inertia, that is, the self-locking ability of the motor rotor. The stronger the servo rigidity, the larger the corresponding position loop gain and speed loop gain, and the faster the response speed of the system.
121
122 (% class="table-bordered" %)
123 |(% style="text-align:center; vertical-align:middle" %)[[image:image-20220611152630-1.png]]
124 |(% style="text-align:center; vertical-align:middle" %)Before adjusting the rigidity grade, set the appropriate load inertia ratio P03-01 correctly.
125
126 The value range of the rigidity grade is between 0 and 31. Grade 0 corresponds to the weakest rigidity and minimum gain, and grade 31 corresponds to the strongest rigidity and maximum gain. According to different load types, the values in the table below are for reference.
127
128 (% class="table-bordered" %)
129 |(% style="text-align:center; vertical-align:middle" %)**Rigidity grade**|(% style="text-align:center; vertical-align:middle" %)**Load mechanism type**
130 |(% style="text-align:center; vertical-align:middle" %)Grade 4 to 8|(% style="text-align:center; vertical-align:middle" %)Some large machinery
131 |(% style="text-align:center; vertical-align:middle" %)Grade 8 to 15|(% style="text-align:center; vertical-align:middle" %)Low rigidity applications such as belts
132 |(% style="text-align:center; vertical-align:middle" %)Grade 15 to 20|(% style="text-align:center; vertical-align:middle" %)High rigidity applications such as ball screw and direct connection
133
134 Table 7-3 Experience reference of rigidity grade
135
136 When the function code P03-03 is set to 0, the gain parameters are stored in the first gain by modifying the rigidity grade.
137
138 When debugging with the host computer debugging software, automatic rigidity level measurement can be carried out, which is used to select a set of appropriate rigidity grades as operating parameters. The operation steps are as follows:
139
140 * Step1 Confirm that the servo is in the ready state, the panel displays “rdy”, and the communication line is connected;
141 * Step2 Open the host computer debugging software, enter the trial run interface, set the corresponding parameters, and click "Servo on";
142 * Step3 Click the "forward rotation" or "reverse rotation" button to confirm the travel range of the servo operation;
143 * Step4 After the "start recognition" of inertia recognition lights up, click "start recognition" to perform inertia recognition, and the load inertia can be measured.
144 * Step5 After the inertia recognition test is completed, click "Save Inertia Value";
145 * Step6 Click "Next" at the bottom right to go to the parameter adjustment interface, and click "Parameter measurement" to start parameter measurement.
146 * Step7 After the parameter measurement is completed, the host computer debugging software will pop up a confirmation window for parameter writing and saving.
147
148 (% class="table-bordered" %)
149 |(% style="text-align:center; vertical-align:middle" %)[[image:image-20220611152634-2.png]]
150 |(((
151 ✎There may be a short mechanical whistling sound during the test. Generally, the servo will automatically stop the test. If it does not stop automatically or in other abnormal situations, you can click the "Servo Off" button on the interface to turn off the servo, or power off the machine!
152
153 ✎For the detailed operation of the host computer debugging software, please refer to "Wecon Servo Debugging Platform User Manual".
154 )))
155
156 (% class="table-bordered" %)
157 |(% style="text-align:center; vertical-align:middle; width:121px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:73px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
158 **Setting method**
159 )))|(% style="text-align:center; vertical-align:middle; width:168px" %)(((
160 **Effective time**
161 )))|(% style="text-align:center; vertical-align:middle; width:134px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:85px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:430px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
162 |(% style="text-align:center; vertical-align:middle; width:121px" %)P03-03|(% style="text-align:center; vertical-align:middle; width:73px" %)Self-adjusting mode selection|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
163 Operation setting
164 )))|(% style="text-align:center; vertical-align:middle; width:168px" %)(((
165 Effective immediately
166 )))|(% style="text-align:center; vertical-align:middle; width:134px" %)0|(% style="text-align:center; vertical-align:middle; width:85px" %)0 to 2|(% style="width:430px" %)(((
167 0: Rigidity grade self-adjusting mode. Position loop gain, speed loop gain, speed loop integral time constant, torque filter parameter settings are automatically adjusted according to the rigidity grade setting.
168
169 1: Manual setting; you need to manually set the position loop gain, speed loop gain, speed loop integral time constant, torque filter parameter setting
170
171 2: Online automatic parameter self-adjusting mode (Not implemented yet)
172 )))|(% style="text-align:center; vertical-align:middle" %)-
173
174 Table 7-4 Details of self-adjusting mode selection parameters
175
176 == **Manual gain adjustment** ==
177
178 When the servo automatic gain adjustment fails to achieve the desired result, you can manually fine-tune the gain to achieve better results.
179
180 The servo system consists of three control loops, from the outside to the inside are the position loop, the speed loop and the current loop. The basic control block diagram is shown as below.
181
182 (% style="text-align:center" %)
183 [[image:image-20220608174209-2.png]]
184
185 Figure 7-2 Basic block diagram of servo loop gain
186
187 The more the inner loop is, the higher the responsiveness is required. Failure to comply with this principle may lead to system instability!
188
189 The default current loop gain of the servo drive has ensured sufficient responsiveness. Generally, no adjustment is required. Only the position loop gain, speed loop gain and other auxiliary gains need to be adjusted.
190
191 This servo drive has two sets of gain parameters for position loop and speed loop. The user can switch the two sets of gain parameters according to the setting value of P02-07 the 2nd gain switching mode. The parameters are are below.
192
193 (% class="table-bordered" %)
194 |(% style="text-align:center; vertical-align:middle; width:450px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:751px" %)**Name**
195 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-01|(% style="width:751px" %)The 1st position loop gain
196 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-02|(% style="width:751px" %)The 1st speed loop gain
197 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-03|(% style="width:751px" %)The 1st speed loop integral time constant
198 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-04|(% style="width:751px" %)The 2nd position loop gain
199 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-05|(% style="width:751px" %)The 2nd speed loop gain
200 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-06|(% style="width:751px" %)The 2nd speed loop integral time constant
201 |(% style="text-align:center; vertical-align:middle; width:450px" %)P04-04|(% style="width:751px" %)Torque filter time constant
202
203 **(1) Speed loop gain**
204
205 In the case of no vibration or noise in the mechanical system, the larger the speed loop gain setting value, the better the response of servo system and the better the speed followability. When noise occurs in the system, reduce the speed loop gain. The related function codes are shown as below.
206
207 (% class="table-bordered" %)
208 |(% style="text-align:center; vertical-align:middle; width:120px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:151px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:170px" %)(((
209 **Setting method**
210 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
211 **Effective time**
212 )))|(% style="text-align:center; vertical-align:middle; width:112px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:99px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:321px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
213 |(% style="text-align:center; vertical-align:middle; width:120px" %)P02-02|(% style="text-align:center; vertical-align:middle; width:151px" %)1st speed loop gain|(% style="text-align:center; vertical-align:middle; width:170px" %)(((
214 Operation setting
215 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
216 Effective immediately
217 )))|(% style="text-align:center; vertical-align:middle; width:112px" %)65|(% style="text-align:center; vertical-align:middle; width:99px" %)0 to 35000|(% style="width:321px" %)Set speed loop proportional gain to determine the responsiveness of speed loop.|(% style="text-align:center; vertical-align:middle" %)0.1Hz
218 |(% style="text-align:center; vertical-align:middle; width:120px" %)P02-05|(% style="text-align:center; vertical-align:middle; width:151px" %)2nd speed loop gain|(% style="text-align:center; vertical-align:middle; width:170px" %)(((
219 Operation setting
220 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
221 Effective immediately
222 )))|(% style="text-align:center; vertical-align:middle; width:112px" %)65|(% style="text-align:center; vertical-align:middle; width:99px" %)0 to 35000|(% style="width:321px" %)Set speed loop proportional gain to determine the responsiveness of speed loop.|(% style="text-align:center; vertical-align:middle" %)0.1Hz
223
224 Table 7-5 Speed loop gain parameters
225
226 (% style="text-align:center" %)
227 [[image:image-20220706152743-1.jpeg]]
228
229 Figure 7-3 Speed loop gain effect illustration
230
231 **(2) Speed loop integral time constant**
232
233 The speed loop integral time constant is used to eliminate the speed loop deviation. Decreasing the integral time constant of the speed loop can increase the speed of the speed following. If the set value is too small, is will easily cause speed overshoot or vibration. When the time constant is set too large, the integral action will be weakened, resulting in a deviation of the speed loop. Related function codes are shown as below.
234
235 (% class="table-bordered" %)
236 |(% style="text-align:center; vertical-align:middle; width:126px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:185px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:132px" %)(((
237 **Setting method**
238 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
239 **Effective time**
240 )))|(% style="text-align:center; vertical-align:middle; width:114px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:102px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:335px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
241 |(% style="text-align:center; vertical-align:middle; width:126px" %)P02-03|(% style="text-align:center; vertical-align:middle; width:185px" %)(((
242 1st speed loop integral time constant
243 )))|(% style="text-align:center; vertical-align:middle; width:132px" %)(((
244 Operation setting
245 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
246 Effective immediately
247 )))|(% style="text-align:center; vertical-align:middle; width:114px" %)1000|(% style="text-align:center; vertical-align:middle; width:102px" %)100 to 65535|(% style="width:335px" %)Set the speed loop integral constant. The smaller the set value, the stronger the integral effect.|(% style="text-align:center; vertical-align:middle" %)(((
248 0.1
249
250 ms
251 )))
252 |(% style="text-align:center; vertical-align:middle; width:126px" %)P02-06|(% style="text-align:center; vertical-align:middle; width:185px" %)(((
253 2nd speed loop integral time constant
254 )))|(% style="text-align:center; vertical-align:middle; width:132px" %)(((
255 Operation setting
256 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
257 Effective immediately
258 )))|(% style="text-align:center; vertical-align:middle; width:114px" %)1000|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 65535|(% style="width:335px" %)Set the speed loop integral constant. The smaller the set value, the stronger the integral effect.|(% style="text-align:center; vertical-align:middle" %)(((
259 0.1
260
261 ms
262 )))
263
264 Table 7-6 Speed loop integral time constant parameters
265
266 (% style="text-align:center" %)
267 [[image:image-20220706153140-2.jpeg]]
268
269 Figure 7-4 Speed loop integral time constant effect illustration
270
271 **(3) Position loop gain**
272
273 Determine the highest frequency of the position instruction that the position loop can follow the change. Increasing this parameter can speed up the positioning time and improve the ability of the motor to resist external disturbances when the motor is stationary. However, if the setting value is too large, the system may be unstable and oscillate. The related function codes are shown as below.
274
275 (% class="table-bordered" %)
276 |(% style="text-align:center; vertical-align:middle; width:113px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:164px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:134px" %)(((
277 **Setting method**
278 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
279 **Effective time**
280 )))|(% style="text-align:center; vertical-align:middle; width:120px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:94px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:355px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
281 |(% style="text-align:center; vertical-align:middle; width:113px" %)P02-01|(% style="text-align:center; vertical-align:middle; width:164px" %)1st position loop gain|(% style="text-align:center; vertical-align:middle; width:134px" %)(((
282 Operation setting
283 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
284 Effective immediately
285 )))|(% style="text-align:center; vertical-align:middle; width:120px" %)400|(% style="text-align:center; vertical-align:middle; width:94px" %)0 to 6200|(% style="width:355px" %)Set position loop proportional gain to determine the responsiveness of position control system.|(% style="text-align:center; vertical-align:middle" %)0.1Hz
286 |(% style="text-align:center; vertical-align:middle; width:113px" %)P02-04|(% style="text-align:center; vertical-align:middle; width:164px" %)2nd position loop gain|(% style="text-align:center; vertical-align:middle; width:134px" %)(((
287 Operation setting
288 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
289 Effective immediately
290 )))|(% style="text-align:center; vertical-align:middle; width:120px" %)35|(% style="text-align:center; vertical-align:middle; width:94px" %)0 to 6200|(% style="width:355px" %)Set position loop proportional gain to determine the responsiveness of position control system.|(% style="text-align:center; vertical-align:middle" %)0.1Hz
291
292 Table 7-7 Position loop gain parameters
293
294 (% style="text-align:center" %)
295 [[image:image-20220706153656-3.jpeg]]
296
297 Figure 7-5 Position loop gain effect illustration
298
299 **(4) Torque instruction filter time**
300
301 Selecting an appropriate torque filter time constant could suppress mechanical resonance. The larger the value of this parameter, the stronger the suppression ability. If the setting value is too large, it will decrease the current loop response frequency and cause needle movement. The related function codes are shown as below.
302
303 (% class="table-bordered" %)
304 |(% style="text-align:center; vertical-align:middle; width:117px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:200px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:141px" %)(((
305 **Setting method**
306 )))|(% style="text-align:center; vertical-align:middle; width:180px" %)(((
307 **Effective time**
308 )))|(% style="text-align:center; vertical-align:middle; width:139px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:359px" %)**Definition**|(% style="text-align:center; vertical-align:middle" %)**Unit**
309 |(% style="text-align:center; vertical-align:middle; width:117px" %)P04-04|(% style="text-align:center; vertical-align:middle; width:200px" %)Torque filter time constant|(% style="text-align:center; vertical-align:middle; width:141px" %)(((
310 Operation setting
311 )))|(% style="text-align:center; vertical-align:middle; width:180px" %)(((
312 Effective immediately
313 )))|(% style="text-align:center; vertical-align:middle; width:139px" %)50|(% style="width:359px" %)This parameter is automatically set when “self-adjustment mode selection” is selected as 1 or 2|(% style="text-align:center; vertical-align:middle" %)0.01ms
314
315 Table 7-8 Details of torque filter time constant parameters
316
317 == **Feedforward gain** ==
318
319 Speed feedforward could be used in position control mode and full closed-loop function. It could improve the response to the speed instruction and reduce the position deviation with fixed speed.
320
321 Speed feedforward parameters are shown in __[[Table 7-9>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HFeedforwardgain]]__. Torque feedforward parameters are shown in __[[Table 7-10>>https://docs.we-con.com.cn/bin/view/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/#HFeedforwardgain]]__.
322
323 Torque feedforward could improve the response to the torque instruction and reduce the position deviation with fixed acceleration and deceleration.
324
325 (% class="table-bordered" %)
326 |(% style="text-align:center; vertical-align:middle; width:125px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:330px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:746px" %)**Adjustment description**
327 |(% style="text-align:center; vertical-align:middle; width:125px" %)P02-09|(% style="text-align:center; vertical-align:middle; width:330px" %)Speed feedforward gain|(% rowspan="2" style="width:746px" %)(((
328 When the speed feedforward filter is set to 50 (0.5 ms), gradually increase the speed feedforward gain, and the speed feedforward will take effect. The position deviation during operation at a certain speed will be reduced according to the value of speed feedforward gain as the formula below.
329
330 Position deviation (instruction unit) = instruction speed[instruction unit/s]÷position loop gain [1/s]×(100－speed feedforward gain [%])÷100
331 )))
332 |(% style="text-align:center; vertical-align:middle; width:125px" %)P02-10|(% style="text-align:center; vertical-align:middle; width:330px" %)Speed feedforward filtering time constant
333
334 Table 7-9 Speed feedforward parameters
335
336 [[image:image-20220706155307-4.jpeg]]
337
338 Figure 7-6 Speed feedforward parameters effect illustration
339
340 (% class="table-bordered" %)
341 |(% style="text-align:center; vertical-align:middle; width:125px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:330px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:746px" %)**Adjustment description**
342 |(% style="text-align:center; vertical-align:middle; width:125px" %)P02-11|(% style="text-align:center; vertical-align:middle; width:330px" %)Torque feedforward gain|(% rowspan="2" style="width:746px" %)Increase the torque feedforward gain because the position deviation can be close to 0 during certain acceleration and deceleration. Under the ideal condition of external disturbance torque not operating, when driving in the trapezoidal speed model, the position deviation can be close to 0 in the entire action interval. In fact, there must be external disturbance torque, so the position deviation cannot be zero. In addition, like the speed feedforward, although the larger the constant of the torque feedforward filter, the smaller the action sound, but the greater the position deviation of the acceleration change point.
343 |(% style="text-align:center; vertical-align:middle; width:125px" %)P02-12|(% style="text-align:center; vertical-align:middle; width:330px" %)Torque feedforward filtering time constant
344
345 Table 7-10 Torque feedforward parameters
346
347 = **Mechanical resonance suppression** =
348
349 == **Mechanical resonance suppression methods** ==
350
351 When the mechanical rigidity is low, vibration and noise may occur due to resonance caused by shaft twisting, and it may not be possible to increase the gain setting. In this case, by using a notch filter to reduce the gain at a specific frequency, after resonance is effectively suppressed, you can continue to increase the servo gain. There are 2 methods to suppress mechanical resonance.
352
353 **(1) Torque instruction filter**
354
355 By setting the filter time constant, the torque instruction is attenuated in the high frequency range above the cutoff frequency, so as to achieve the expectation of suppressing mechanical resonance. The cut-off frequency of the torque instruction filter could be calculated by the following formula:
356
357 (% style="text-align:center" %)
358 [[image:image-20220706155820-5.jpeg]]
359
360 **(2) Notch filter**
361
362 The notch filter can achieve the expectation of suppressing mechanical resonance by reducing the gain at a specific frequency. When setting the notch filter correctly, the vibration can be effectively suppressed. You can try to increase the servo gain. The principle of the notch filter is shown in __[[Figure 7-3>>https://docs.we-con.com.cn/bin/download/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/WebHome/image-20220608174259-3.png?rev=1.1]]__.
363
364 == **Notch filter** ==
365
366 The VD2 series servo drives have 2 sets of notch filters, each of which has 3 parameters, namely notch frequency, width grade and depth grade.
367
368 **(1) Width grade of notch filter**
369
370 The notch width grade is used to express the ratio of the notch width to the center frequency of the notch:
371
372 (% style="text-align:center" %)
373 [[image:image-20220706155836-6.png]]
374
375 In formula (7-1), [[image:image-20220706155946-7.png]] is the center frequency of notch filter, that is, the mechanical resonance frequency; ​​​​​​​[[image:image-20220706155952-8.png]] is the width of notch filter, which represents the frequency bandwidth with an amplitude attenuation rate of **-3dB** relative to the center frequency of notch filter.
376
377 **(2) Depth grade of notch filter**
378
379 The depth grade of notch filter represents the ratio relationship between input and output at center frequency.
380
381 When the notch filter depth grade is 0, the input is completely suppressed at center frequency. When the notch filter depth grade is 100, the input is completely passable at center frequency. Therefore, the smaller the the notch filter depth grade is set, the deeper the the notch filter depth, and the stronger the suppression of mechanical resonance. But the system may be unstable, you should pay attention to it when using it. The specific relationship is shown in __[[Figure 7-4>>https://docs.we-con.com.cn/bin/download/Servo/2.%20User%20Manual/06%20VD2%20SA%20Series%20Servo%20Drives%20Manual%20%28Full%20V1.1%29/07%20Adjustments/WebHome/44.png?rev=1.1]]__.
382
383 (% style="text-align:center" %)
384 [[image:image-20220608174259-3.png]]
385
386 Figure 7-7 Notch characteristics, notch width, and notch depth
387
388 (% style="text-align:center" %)
389 [[image:image-20220706160046-9.png]]
390
391 Figure 7-8 Frequency characteristics of notch filter
392
393 (% class="table-bordered" %)
394 |(% style="text-align:center; vertical-align:middle; width:113px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:197px" %)**Name**|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
395 **Setting method**
396 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
397 **Effective time**
398 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)**Default value**|(% style="text-align:center; vertical-align:middle; width:102px" %)**Range**|(% style="text-align:center; vertical-align:middle; width:391px" %)**Definition**|(% style="text-align:center; vertical-align:middle; width:248px" %)**Unit**
399 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-05|(% style="text-align:center; vertical-align:middle; width:197px" %)1st notch filter frequency|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
400 Operation setting
401 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
402 Effective immediately
403 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)300|(% style="text-align:center; vertical-align:middle; width:102px" %)250 to 5000|(% style="width:391px" %)Set the center frequency of the 1st notch filter. When the set value is 5000, the function of notch filter is invalid.|(% style="text-align:center; vertical-align:middle; width:248px" %)Hz
404 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-06|(% style="text-align:center; vertical-align:middle; width:197px" %)1st notch filter depth|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
405 Operation setting
406 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
407 Effective immediately
408 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)100|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 100|(% style="width:391px" %)(((
409 0: all truncated
410
411 100: all passed
412 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
413 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-07|(% style="text-align:center; vertical-align:middle; width:197px" %)1st notch filter width|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
414 Operation setting
415 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
416 Effective immediately
417 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)4|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 12|(% style="width:391px" %)(((
418 0: 0.5 times the bandwidth
419
420 4: 1 times the bandwidth
421
422 8: 2 times the bandwidth
423
424 12: 4 times the bandwidth
425 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
426 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-08|(% style="text-align:center; vertical-align:middle; width:197px" %)2nd notch filter frequency|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
427 Operation setting
428 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
429 Effective immediately
430 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)500|(% style="text-align:center; vertical-align:middle; width:102px" %)250 to 5000|(% style="width:391px" %)Set the center frequency of the 2nd notch filter. When the set value is 5000, the function of the notch filter is invalid.|(% style="text-align:center; vertical-align:middle; width:248px" %)Hz
431 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-09|(% style="text-align:center; vertical-align:middle; width:197px" %)2nd notch filter depth|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
432 Operation setting
433 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
434 Effective immediately
435 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)100|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 100|(% style="width:391px" %)(((
436 0: all truncated
437
438 100: all passed
439 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
440 |(% style="text-align:center; vertical-align:middle; width:113px" %)P04-10|(% style="text-align:center; vertical-align:middle; width:197px" %)2nd notch filter width|(% style="text-align:center; vertical-align:middle; width:143px" %)(((
441 Operation setting
442 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
443 Effective immediately
444 )))|(% style="text-align:center; vertical-align:middle; width:127px" %)4|(% style="text-align:center; vertical-align:middle; width:102px" %)0 to 12|(% style="width:391px" %)(((
445 0: 0.5 times the bandwidth
446
447 4: 1 times the bandwidth
448
449 8: 2 times the bandwidth
450
451 12: 4 times the bandwidth
452 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
453
454 Table 7-11 Notch filter function code parameters