1 /**
2  * Copyright 2017 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "pidcontroller.hpp"
18 
19 #include "ec/pid.hpp"
20 
21 #include <algorithm>
22 #include <chrono>
23 #include <cmath>
24 #include <iostream>
25 #include <map>
26 #include <memory>
27 #include <thread>
28 #include <vector>
29 
30 void PIDController::process(void)
31 {
32     double input;
33     double setpt;
34     double output;
35 
36     // Get setpt value
37     setpt = setptProc();
38 
39     // Get input value
40     input = inputProc();
41 
42     auto info = getPIDInfo();
43 
44     // if no hysteresis, maintain previous behavior
45     if (info->positiveHysteresis == 0 && info->negativeHysteresis == 0)
46     {
47         // Calculate new output
48         output = ec::pid(info, input, setpt);
49 
50         // this variable isn't actually used in this context, but we're setting
51         // it here incase somebody uses it later it's the correct value
52         lastInput = input;
53     }
54     else
55     {
56         // initialize if not set yet
57         if (std::isnan(lastInput))
58         {
59             lastInput = input;
60         }
61 
62         // if reading is outside of hysteresis bounds, use it for reading,
63         // otherwise use last reading without updating it first
64         else if ((input - lastInput) > info->positiveHysteresis)
65         {
66             lastInput = input;
67         }
68         else if ((lastInput - input) > info->negativeHysteresis)
69         {
70             lastInput = input;
71         }
72 
73         output = ec::pid(info, lastInput, setpt);
74     }
75 
76     // Output new value
77     outputProc(output);
78 
79     return;
80 }
81