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Robot Manipulator Control. Juhng-Perng SU Ph.D. Professor Electrical Engineering National Dong- Hwa University. Chapter 6 Independent Joint Control. Manipulator Control Determine the time history of joint inputs required to cause the end effector to execute a command motion .
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Robot Manipulator Control Juhng-Perng SU Ph.D. Professor Electrical Engineering National Dong-Hwa University
Chapter 6 Independent Joint Control Manipulator Control Determine the time history of joint inputs required to cause the end effector to execute a command motion. • Joint Inputs • Voltage Inputs to the Motors • Joint Forces and Torques • command motion • A sequence of end-effector positions and orientations (P-to-P) • A continuous path (Path Tracking)
Control Strategies • Hardware/Software Trade-off • Early aircraft were relatively easy to fly by possessed limited performance capabilities (Aerospace Industry) • Mechanical Design (Hardware) • Robot actuated by Permanent magnet DC motors with gear reduction (Linear Control) • Direct-drive robot using high-torque motors with no gear reduction (Nonlinear Control)
Simplest Type of ControlIndependent Joint Control • Each Link is controlled as a single-input/single-output system. Coupling due to the motion of other links are treated as disturbances. Tracking and Disturbance Rejection
Actuator Dynamics • DC-motors can be classified according to the way in which the magnetic field is produced and the armature is designed. Here we discuss only the so-called permanent magnet motors whose stator consists of a permanent magnet. In this case we can take the flux, to be a constant. • The torque on the rotor is then controlled by controlling the armature current.
Actuator Dynamics • Referring to Figure 6.5, we set , the equation of motion of this system is then
Actuator Dynamics • In Laplace domain:
Set-Point Tracking • PD Controller
Set-Point Tracking • PD Controller • The resulting closed-loop system is
Set-Point Tracking • The tracking error: • For a step input and a constant disturbance: • The steady state error is
Example • Consider the second-order system • The closed-loop characteristic polynomial is • Suppose . With
Set-Point Tracking • PID Controller
Set-Point Tracking • The closed-loop system is now the 3rd-order system • Routh-Hurwitz criterion: The system is stable if
Feedforward Control Then, Clearly, in addition to the stability of the closed-loop system, the feedforwardtransfer function F(s) must itself stable.
State Space Design • By choosing state variables • The system given by Eq.(6.39) and (6.40) becomes
State Feedback Control Linear Quadratic Regulation Control Subject to
Linear Quadratic Regulation Control Performance Index Subject to
Linear Quadratic Regulation Control Optimal Control Riccati Equation