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/*
*
* Copyright 2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef GRPC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H
#define GRPC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H
/* \file Simple PID controller.
Implements a proportional-integral-derivative controller.
Used when we want to iteratively control a variable to converge some other
observed value to a 'set-point'.
Gains can be set to adjust sensitivity to current error (p), the integral
of error (i), and the derivative of error (d). */
typedef struct {
double gain_p;
double gain_i;
double gain_d;
double initial_control_value;
double min_control_value;
double max_control_value;
double integral_range;
} grpc_pid_controller_args;
typedef struct {
double last_error;
double error_integral;
double last_control_value;
double last_dc_dt;
grpc_pid_controller_args args;
} grpc_pid_controller;
/** Initialize the controller */
void grpc_pid_controller_init(grpc_pid_controller *pid_controller,
grpc_pid_controller_args args);
/** Reset the controller: useful when things have changed significantly */
void grpc_pid_controller_reset(grpc_pid_controller *pid_controller);
/** Update the controller: given a current error estimate, and the time since
the last update, returns a new control value */
double grpc_pid_controller_update(grpc_pid_controller *pid_controller,
double error, double dt);
/** Returns the last control value calculated */
double grpc_pid_controller_last(grpc_pid_controller *pid_controller);
#endif /* GRPC_CORE_LIB_TRANSPORT_PID_CONTROLLER_H */
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