summaryrefslogtreecommitdiff
path: root/src/org/usfirst/frc/team4272/robotlib/RateLimitedPIDOutput.java
blob: 70010c63ed0dd7cb1f138ee4c425835f9b7794e5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
/**
 * Copyright (c) 2012 Precise Path Robotics, Inc
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Luke Shumaker <lukeshu@sbcglobal.net>
 */
package org.usfirst.frc.team4272.robotlib;

import edu.wpi.first.wpilibj.PIDOutput;
import edu.wpi.first.wpilibj.Timer;

/**
 * TODO: Write JavaDocs
 */
public class RateLimitedPIDOutput implements PIDOutput {
	PIDOutput o;
	double m;
	double prev_rate = 0;
	double prev_time = 0;

	public RateLimitedPIDOutput(PIDOutput out, double maxChange) {
		o = out;
		m = maxChange;
	}

	public void pidWrite(double rate) {
		double time = Timer.getFPGATimestamp();
		double dTime = time-prev_time;
		double dRate = rate-prev_rate;
		if (Math.abs(dRate/dTime)>m) {
			int sign = (dRate<0?-1:1);
			rate = prev_rate+(m*dTime*sign);
		}
		o.pidWrite(rate);
	}
}