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Wiki source code of 07 Adjustments

Version 13.1 by Joey on 2022/06/15 14:56
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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 identification 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" %)200|(% 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
142 Step2 Open the host computer debugging software, enter the trial run interface, set the corresponding parameters, and click "Servo on";
143
144 Step3 Click the "forward rotation" or "reverse rotation" button to confirm the travel range of the servo operation;
145
146 Step4 After the "start recognition" of inertia recognition lights up, click "start recognition" to perform inertia recognition, and the load inertia can be measured.
147
148 Step5 After the inertia recognition test is completed, click "Save Inertia Value";
149
150 Step6 Click "Next" at the bottom right to go to the parameter adjustment interface, and click "Parameter measurement" to start parameter measurement.
151
152 Step7 After the parameter measurement is completed, the host computer debugging software will pop up a confirmation window for parameter writing and saving.
153
154 (% class="table-bordered" %)
155 |(% style="text-align:center; vertical-align:middle" %)[[image:image-20220611152634-2.png]]
156 |(((
157 ✎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!
158
159 ✎For the detailed operation of the host computer debugging software, please refer to "Wecon Servo Debugging Platform User Manual".
160 )))
161
162 (% class="table-bordered" %)
163 |(% 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" %)(((
164 **Setting method**
165 )))|(% style="text-align:center; vertical-align:middle; width:168px" %)(((
166 **Effective time**
167 )))|(% 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**
168 |(% 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" %)(((
169 Operation setting
170 )))|(% style="text-align:center; vertical-align:middle; width:168px" %)(((
171 Effective immediately
172 )))|(% 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" %)(((
173 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.
174
175 1: Manual setting; you need to manually set the position loop gain, speed loop gain, speed loop integral time constant, torque filter parameter setting
176
177 2: Online automatic parameter self-adjusting mode (Not implemented yet)
178 )))|(% style="text-align:center; vertical-align:middle" %)-
179
180 Table 7-4 Details of self-adjusting mode selection parameters
181
182 == **Manual gain adjustment** ==
183
184 When the servo automatic gain adjustment fails to achieve the desired result, you can manually fine-tune the gain to achieve better results.
185
186 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.
187
188 (% style="text-align:center" %)
189 [[image:image-20220608174209-2.png]]
190
191 Figure 7-2 Basic block diagram of servo loop gain
192
193 The more the inner loop is, the higher the responsiveness is required. Failure to comply with this principle may lead to system instability!
194
195 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.
196
197 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.
198
199 (% class="table-bordered" %)
200 |(% style="text-align:center; vertical-align:middle; width:450px" %)**Function code**|(% style="text-align:center; vertical-align:middle; width:751px" %)**Name**
201 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-01|(% style="width:751px" %)The 1st position loop gain
202 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-02|(% style="width:751px" %)The 1st speed loop gain
203 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-03|(% style="width:751px" %)The 1st speed loop integral time constant
204 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-04|(% style="width:751px" %)The 2nd position loop gain
205 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-05|(% style="width:751px" %)The 2nd speed loop gain
206 |(% style="text-align:center; vertical-align:middle; width:450px" %)P02-06|(% style="width:751px" %)The 2nd speed loop integral time constant
207 |(% style="text-align:center; vertical-align:middle; width:450px" %)P04-04|(% style="width:751px" %)Torque filter time constant
208
209 **(1) Speed loop gain**
210
211 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.
212
213 (% class="table-bordered" %)
214 |(% 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" %)(((
215 **Setting method**
216 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
217 **Effective time**
218 )))|(% 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**
219 |(% 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" %)(((
220 Operation setting
221 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
222 Effective immediately
223 )))|(% 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
224 |(% 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" %)(((
225 Operation setting
226 )))|(% style="text-align:center; vertical-align:middle; width:174px" %)(((
227 Effective immediately
228 )))|(% 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
229
230 Table 7-5 Speed loop gain parameters
231
232 **(2) Speed loop integral time constant**
233
234 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.
235
236 (% class="table-bordered" %)
237 |(% 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" %)(((
238 **Setting method**
239 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
240 **Effective time**
241 )))|(% 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**
242 |(% style="text-align:center; vertical-align:middle; width:126px" %)P02-03|(% style="text-align:center; vertical-align:middle; width:185px" %)(((
243 1st speed loop integral time constant
244 )))|(% style="text-align:center; vertical-align:middle; width:132px" %)(((
245 Operation setting
246 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
247 Effective immediately
248 )))|(% 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" %)(((
249 0.1
250
251 ms
252 )))
253 |(% style="text-align:center; vertical-align:middle; width:126px" %)P02-06|(% style="text-align:center; vertical-align:middle; width:185px" %)(((
254 2nd speed loop integral time constant
255 )))|(% style="text-align:center; vertical-align:middle; width:132px" %)(((
256 Operation setting
257 )))|(% style="text-align:center; vertical-align:middle; width:161px" %)(((
258 Effective immediately
259 )))|(% 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" %)(((
260 0.1
261
262 ms
263 )))
264
265 Table 7-6 Speed loop integral time constant parameters
266
267 **(3) Position loop gain**
268
269 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.
270
271 (% class="table-bordered" %)
272 |(% 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" %)(((
273 **Setting method**
274 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
275 **Effective time**
276 )))|(% 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**
277 |(% 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" %)(((
278 Operation setting
279 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
280 Effective immediately
281 )))|(% 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
282 |(% 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" %)(((
283 Operation setting
284 )))|(% style="text-align:center; vertical-align:middle; width:167px" %)(((
285 Effective immediately
286 )))|(% 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
287
288 Table 7-7 Position loop gain parameters
289
290 **(4) Torque instruction filter time**
291
292 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.
293
294 (% class="table-bordered" %)
295 |(% 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" %)(((
296 **Setting method**
297 )))|(% style="text-align:center; vertical-align:middle; width:180px" %)(((
298 **Effective time**
299 )))|(% 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**
300 |(% 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" %)(((
301 Operation setting
302 )))|(% style="text-align:center; vertical-align:middle; width:180px" %)(((
303 Effective immediately
304 )))|(% 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
305
306 Table 7-8 Details of torque filter time constant parameters
307
308 == **Feedforward gain** ==
309
310 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.
311
312 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]]__.
313
314 Torque feedforward could improve the response to the torque instruction and reduce the position deviation with fixed acceleration and deceleration.
315
316 (% class="table-bordered" %)
317 |(% 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**
318 |(% 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" %)(((
319 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.
320
321 Position deviation (instruction unit) = instruction speed[instruction unit/s]÷position loop gain [1/s]×(100－speed feedforward gain [%])÷100
322 )))
323 |(% 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
324
325 Table 7-9 Speed feedforward parameters
326
327 (% class="table-bordered" %)
328 |(% 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**
329 |(% 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.
330 |(% 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
331
332 Table 7-10 Torque feedforward parameters
333
334 = **Mechanical resonance suppression** =
335
336 == **Mechanical resonance suppression methods** ==
337
338 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.
339
340 **(1) Torque instruction filter**
341
342 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:
343
344 (% style="text-align:center" %)
345 [[image: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/40.png?rev=1.1]]
346
347 **(2) Notch filter**
348
349 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]]__.
350
351 == **Notch filter** ==
352
353 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.
354
355 **(1) Width grade of notch filter**
356
357 The notch width grade is used to express the ratio of the notch width to the center frequency of the notch:
358
359 (% style="text-align:center" %)
360 [[image: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/41.png?rev=1.1]]
361
362 In formula (7-1), [[image: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/42.png?rev=1.1]] is the center frequency of notch filter, that is, the mechanical resonance frequency; [[image: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/43.png?rev=1.1]] 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.
363
364 **(2) Depth grade of notch filter**
365
366 The depth grade of notch filter represents the ratio relationship between input and output at center frequency.
367
368 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]]__.
369
370 (% style="text-align:center" %)
371 [[image:image-20220608174259-3.png]]
372
373 Figure 7-3 Notch characteristics, notch width, and notch depth
374
375 (% style="text-align:center" %)
376 [[image: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]]
377
378 Figure 7-4 Frequency characteristics of notch filter
379
380 (% class="table-bordered" %)
381 |(% 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" %)(((
382 **Setting method**
383 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
384 **Effective time**
385 )))|(% 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**
386 |(% 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" %)(((
387 Operation setting
388 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
389 Effective immediately
390 )))|(% 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
391 |(% 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" %)(((
392 Operation setting
393 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
394 Effective immediately
395 )))|(% 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" %)(((
396 0: all truncated
397
398 100: all passed
399 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
400 |(% 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" %)(((
401 Operation setting
402 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
403 Effective immediately
404 )))|(% 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" %)(((
405 0: 0.5 times the bandwidth
406
407 4: 1 times the bandwidth
408
409 8: 2 times the bandwidth
410
411 12: 4 times the bandwidth
412 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
413 |(% 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" %)(((
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" %)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
418 |(% 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" %)(((
419 Operation setting
420 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
421 Effective immediately
422 )))|(% 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" %)(((
423 0: all truncated
424
425 100: all passed
426 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
427 |(% 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" %)(((
428 Operation setting
429 )))|(% style="text-align:center; vertical-align:middle; width:164px" %)(((
430 Effective immediately
431 )))|(% 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" %)(((
432 0: 0.5 times the bandwidth
433
434 4: 1 times the bandwidth
435
436 8: 2 times the bandwidth
437
438 12: 4 times the bandwidth
439 )))|(% style="text-align:center; vertical-align:middle; width:248px" %)-
440
441 Table 7-11 Notch filter function code parameters