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2.1.0  Jan 20, 2020 
1.0.0  Jul 24, 2018 
#68 in Hardware support
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PID Controller for Rust
A proportionalintegralderivative (PID) controller.
Features
 Visibility into individual contribution of P, I, and D terms which often need to be logged for later analysis and parameter tuning.
 Output limits on a per term basis.
 Threeterm control output limit.
 Mitigation of integral windup using integral term limit.
 Mitigation of derivative kick by using the derivative of the measurement rather than the derivative of the error.
 Onthefly changes to
setpoint
/kp
/ki
/kd
. Mitigation of output jumps when changing
ki
by storing the integration ofe(t) * ki(t)
rather than onlye(t)
.
 Mitigation of output jumps when changing
 Generic float type parameter to support
f32
orf64
.  Support for
no_std
environments, such as embedded systems.  Optional support for Serde. Enable the
serde
Cargo feature, if you needPid
to implementSerialize
/Deserialize
.
Example
use pid::Pid;
// Create a new proportionalonly PID controller with a setpoint of 15
let mut pid = Pid::new(15.0, 100.0);
pid.p(10.0, 100.0);
// Input a measurement with an error of 5.0 from our setpoint
let output = pid.next_control_output(10.0);
// Show that the error is correct by multiplying by our kp
assert_eq!(output.output, 50.0); // <
assert_eq!(output.p, 50.0);
// It won't change on repeat; the controller is proportionalonly
let output = pid.next_control_output(10.0);
assert_eq!(output.output, 50.0); // <
assert_eq!(output.p, 50.0);
// Add a new integral term to the controller and input again
pid.i(1.0, 100.0);
let output = pid.next_control_output(10.0);
// Now that the integral makes the controller stateful, it will change
assert_eq!(output.output, 55.0); // <
assert_eq!(output.p, 50.0);
assert_eq!(output.i, 5.0);
// Add our final derivative term and match our setpoint target
pid.d(2.0, 100.0);
let output = pid.next_control_output(15.0);
// The output will now say to go down due to the derivative
assert_eq!(output.output, 5.0); // <
assert_eq!(output.p, 0.0);
assert_eq!(output.i, 5.0);
assert_eq!(output.d, 10.0);
Assumptions
 Measurements occur at equal spacing. (
t(i) = t(i1) + C
)  Output limits per term are symmetric around 0 (
limit <= term <= limit
).
Formulation
There are several different formulations of PID controllers. This library uses the independent form:
where:
 C(t) = control output, the output to the actuator.
 P(t) = process variable, the measured value.
 e(t) = error = S(t)  P(t)
 S(t) = set point, the desired target for the process variable.
kp
/ki
/kd
can be changed during operation and can therefore be a function
of time.
If you're interested in the dependent form, add your own logic that computes
kp
/ki
/kd
using dead time, time constant, kc
, or whatever else.
Todo
 Helper for (auto)tuning by detecting frequency & amplitude of oscillations.
License
Licensed under either at your discretion:
 Apache License, Version 2.0 (LICENSEAPACHE or http://www.apache.org/licenses/LICENSE2.0)
 MIT license (LICENSEMIT or http://opensource.org/licenses/MIT)
Dependencies
~98–330KB