This paper presents a comparative study of two
task space control approaches. The first approach, similar
to most of task space controllers, makes use of an inner
velocity loop. The second proposed approach employs an inner
proportional derivative (PD) joint position-velocity loop. A
stability proof for the second apprach is provided together
with experiments using a visual servoed robot. It is shown
that the proposed control law needs less gain at the task
space level then precluding amplification of the measurement
noise; moreover, it is shown that the first approach produces
uncontrolled movements when the task space sensor fails
whereas the proposed controller avoids uncontrolled behavior
In this paper, we study an image-based PID control of a redundant planar parallel robot using a fixed camera
configuration. The control objective is to move the robot end effector to the desired image reference position. The
control law has a PD term plus an integral term with a nonlinear function of the position error. The proportional and
integral actions use image loop information whereas the derivative action adds task space damping using joint level
measurements. The Lyapunov method and the LaSalle invariance principle allow assessing asymptotic closed loop
stability. Experiments show the feasibility of the proposed approach.
In this work a Proportional Derivative (PD) image-based visual servoing scheme applied to planar robot manipulators with revolute joints is proposed. Damping is added at the joint level using the robot active joints. The proposed control law may be though as a velocity inner loop at the joint level implementing the derivative action and a visual outer loop at the task level performing the proportional action. Since it is assumed that velocity measurements are not available, velocity estimates are obtained from active joint position measurements using a linear filter. Another feature of the proposed approach is the fact that calibration procedures for the vision system are avoided since an image-based approach is adopted. Closed loop stability is studied using Lyapunov Stability Theory. Experimental results on a laboratory prototype validates the proposed approach, moreover, it is also experimentally shown that by using a vision system for measurement of the robot end effector, kinematics errors may be tolerated in contrast with control strategies making use of the direct kinematics where performance depends on the precise knowledge of the robot kinematics.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.