Kohdevaltio

Kohdevaltio (target state) is a concept used in control theory and robotics to describe the desired or reference state that a dynamical system should reach or track. It represents the values of the system’s state vector, such as position, velocity, orientation, or other relevant variables, that the controller aims to achieve. In mathematical models, the current state is often denoted x, while the kohdevaltio is denoted x_d or x_ref and can be constant or time-varying.

Use and role in control systems: The kohdevaltio serves as the reference against which the controller minimizes error. In tracking problems, the objective is to drive x toward x_d, typically by minimizing a cost function that includes terms like ||x - x_d||. In model predictive control and trajectory planning, x_d(t) may be a time-dependent reference trajectory that the system follows. The concept is also essential in regulation tasks, where the kohdevaltio represents the steady-state or nominal operating point.

Time variation and constraints: A kohdevaltio can be fixed (regulation to a steady state) or dynamic (tracking a varying reference). Real-world limitations, such as actuator saturations, safety constraints, or environmental disturbances, may prevent exact attainment of the kohdevaltio, leading to feasible, near-target solutions.

Examples: A drone reaching a specified waypoint and orientation, a robotic arm attaining a particular end-effector pose, or an autonomous vehicle maintaining a target position within a lane.

See also: setpoint, reference trajectory, state-space representation, model predictive control, feedback control.