PID控制算法的C语言实现三 位置型PID的C语言实现

 

   上一节中已经抽象出了位置性PID和增量型PID的数学表达式，这一节，重点讲解C语言代码的实现过程，算法的C语言实现过程具有一般性，通过PID算法的C语言实现，可以以此类推，设计其它算法的C语言实现。

   第一步：定义PID变量结构体，代码如下：

struct _pid{
    float SetSpeed;            //定义设定值
    float ActualSpeed;        //定义实际值
    float err;                //定义偏差值
    float err_last;            //定义上一个偏差值
    float Kp,Ki,Kd;            //定义比例、积分、微分系数
    float voltage;          //定义电压值（控制执行器的变量）
    float integral;            //定义积分值
}pid;

控制算法中所需要用到的参数在一个结构体中统一定义，方便后面的使用。

  第二部：初始化变量，代码如下：

void PID_init(){
    printf("PID_init begin \n");
    pid.SetSpeed=0.0;
    pid.ActualSpeed=0.0;
    pid.err=0.0;
    pid.err_last=0.0;
    pid.voltage=0.0;
    pid.integral=0.0;
    pid.Kp=0.2;
    pid.Ki=0.015;
    pid.Kd=0.2;
    printf("PID_init end \n");
}

统一初始化变量，尤其是Kp,Ki,Kd三个参数，调试过程当中，对于要求的控制效果，可以通过调节这三个量直接进行调节。

第三步：编写控制算法，代码如下：

float PID_realize(float speed){
    pid.SetSpeed=speed;
    pid.err=pid.SetSpeed-pid.ActualSpeed;
    pid.integral+=pid.err;
    pid.voltage=pid.Kp*pid.err+pid.Ki*pid.integral+pid.Kd*(pid.err-pid.err_last);
    pid.err_last=pid.err;
    pid.ActualSpeed=pid.voltage*1.0;
    return pid.ActualSpeed;
}

注意：这里用了最基本的算法实现形式，没有考虑死区问题，没有设定上下限，只是对公式的一种直接的实现，后面的介绍当中还会逐渐的对此改进。

   到此为止，PID的基本实现部分就初步完成了。下面是测试代码：

int main(){
    printf("System begin \n");
    PID_init();
    int count=0;
    while(count<1000)
    {
        float speed=PID_realize(200.0);
        printf("%f\n",speed);
        count++;
    }
return 0;
}

下面是经过1000次的调节后输出的1000个数据（具体的参数整定过程就不说明了，网上这种说明非常多）：

---

83.000001
11.555000
59.559675
28.175408
52.907421
38.944152
51.891699
46.141651
53.339054
51.509998
55.908450
55.944631
58.970680
59.882936
62.225001
63.537254
65.527707
67.011058
68.810646
70.355318
72.042040
73.595658
75.207620
76.745444
78.301526
79.812136
81.321929
82.800304
84.268909
85.713108
87.143455
88.553005
89.946960
91.322078
92.680996
94.022234
95.347186
96.655242
97.947180
99.222808
100.482601
101.726572
102.955049
104.168125
105.366066
106.549019
107.717187
108.870756
110.009898
111.134811
112.245652
113.342615
114.425860
115.495564
116.551897
117.595029
118.625116
119.642331
120.646826
121.638767
122.618307
123.585603
124.540813
125.484079
126.415549
127.335383
128.243715
129.140691
130.026459
130.901149
131.764909
132.617870
133.460162
134.291942
135.113308
135.924419
136.725382
137.516332
138.297401
139.068697
139.830352
140.582499
141.325237
142.058701
142.782985
143.498218
144.204509
144.901969
145.590726
146.270843
146.942486
147.605718
148.260674
148.907425
149.546109
150.176794
150.799612
151.414626
152.021959
152.621696
153.213951
153.798781
154.376315
154.946626
155.509812
156.065958
156.615146
157.157471
157.693012
158.221871
158.744097
159.259826
159.769078
160.271991
160.768588
161.258996
161.743264
162.221494
162.693737
163.160075
163.620593
164.075347
164.524422
164.967877
165.405795
165.838235
166.265257
166.686967
167.103377
167.514610
167.920681
168.321682
168.717670
169.108719
169.494862
169.876198
170.252740
170.624605
170.991799
171.354406
171.712487
172.066080
172.415265
172.760077
173.100594
173.436838
173.768895
174.096796
174.420594
174.740352
175.056096
175.367915
175.675818
175.979886
176.280136
176.576656
176.869444
177.158600
177.444121
177.726087
178.004510
178.279458
178.550967
178.819094
179.083860
179.345315
179.603504
179.858466
180.110241
180.358866
180.604388
180.846849
181.086262
181.322699
181.556172
181.786733
182.014396
182.239222
182.461226
182.680475
182.896971
183.110768
183.321881
183.530369
183.736239
183.939545
184.140301
184.338555
184.534321
184.727651
184.918558
185.107080
185.293243
185.477080
185.658625
185.837886
186.014930
186.189745
186.362382
186.532859
186.701207
186.867437
187.031605
187.193713
187.353802
187.511884
187.667997
187.822151
187.974384
188.124700
188.273148
188.419728
188.564488
188.707429
188.848592
188.987995
189.125644
189.261576
189.395801
189.528364
189.659258
189.788528
189.916170
190.042233
190.166702
190.289633
190.411007
190.530867
190.649236
190.766119
190.881544
190.995531
191.108087
191.219243
191.329005
191.437382
191.544428
191.650111
191.754504
191.857565
191.959350
192.059857
192.159119
192.257135
192.353919
192.449511
192.543890
192.637105
192.729137
192.820032
192.909776
192.998410
193.085920
193.172360
193.257700
193.341993
193.425214
193.507408
193.588568
193.668715
193.747847
193.826004
193.903175
193.979391
194.054643
194.128963
194.202349
194.274828
194.346393
194.417073
194.486854
194.555777
194.623820
194.691027
194.757390
194.822919
194.887626
194.951536
195.014633
195.076965
195.138496
195.199273
195.259270
195.318547
195.377060
195.434856
195.491918
195.548283
195.603919
195.658886
195.713145
195.766734
195.819654
195.871912
195.923517
195.974472
196.024791
196.074478
196.123558
196.172016
196.219859
196.267115
196.313778
196.359851
196.405363
196.450296
196.494672
196.538492
196.581753
196.624494
196.666678
196.708363
196.749493
196.790138
196.830267
196.869889
196.909019
196.947656
196.985803
197.023493
197.060701
197.097449
197.133733
197.169558
197.204940
197.239872
197.274378
197.308436
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199.325345
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199.350336
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199.481995
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199.554583
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199.602260
199.607218
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199.828755
199.830902
199.833006
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199.837155
199.839194
199.841210
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199.852784
199.854621
199.856449
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199.874997
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199.892518
199.893845
199.895180
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199.897783
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199.900322
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199.902797
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199.905222
199.906392
199.907576
199.908720
199.909875
199.910985
199.912108
199.913193
199.914287
199.915352
199.916423
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199.918505
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199.920526
199.921513
199.922496
199.923452
199.924415
199.925348
199.926275
199.927198
199.928108
199.929019
199.929903
199.930788
199.931653
199.932509
199.933353
199.934187
199.935002
199.935816
199.936617
199.937420
199.938195
199.938971
199.939733
199.940477
199.941228
199.941961
199.942685
199.943392
199.944111
199.944804
199.945491
199.946181
199.946854
199.947518
199.948165
199.948824
199.949456
199.950083
199.950714
199.951326
199.951930
199.952532
199.953125
199.953714
199.954290
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199.955424
199.955979
199.956538
199.957073
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199.958671
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199.959693
199.960203
199.960689
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199.987800
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199.988094
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199.988386
199.988526
199.988675
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199.989231
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199.989491
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199.989757
199.989889
199.990012
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199.990253
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199.991180
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199.991616
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199.992701
199.992792
199.992878
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199.993047
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199.993554
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199.993726
199.993806
199.993881
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199.994241
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