mruby-pid

A PID algorithm library based on Temper for mruby.

Installation

Mruby uses mrbgems, which adds gems into the compilation process. Add the following to your build_config.rb in the mruby source directory:

config.gem :github => 'cadwallion/mruby-pid'

Run make or ./minirake in the mruby source directory and mruby-pid will be added.

Usage

A PID controller is based on four values:

• kp - Proportional Tuning Parameter
• ki - Integral Tuning Parameter
• kd - Derivative Tuning Parameter
• setpoint - target temperature

The PID class can either be initialized with the kp/ki/kd values, or tuned after initialization

pid1 = PID.new :kp => 1.0, :ki => 1.0, :kd => 1.0
pid1.setpoint = 200.0 # Target temperature in Fahrenheit

pid2 = PID.new
pid2.tune 1.0, 1.0, 1.0
pid2.setpoint = 200.0 # Target temperature in Fahrenheit

Once created, the heart of the PID library is in the PID#control method. Pass this method the current temperature, and it will use the modified PID algorithm to output a power level. Use this value to adjust your heating/cooling control based on the power.

pid = PID.new :kp => 1.0, :ki => 1.0, :kd => 1.0
pid.setpoint = 185.5

power_level = pid.control 95.0

For some systems, there is an upperbound to PWM control values (for example, the Arduino PWM values cannot exceed 255). The PID's minimum and maximum can be set with the :maximum and :minimum options at initialization.

Examples

See the examples directory for common applications of the mruby-pid library.