Integral force control with robustness enhancement

IEEE Trans. Automat. Sci. Eng.

Radke

2015

Abstract-We present a novel system to achieve coordinated task-based control on a dual-arm industrial robot for the general tasks of visual servoing and bimanual hybrid motion/force control. The industrial robot, consisting of a rotating torso and two seven degree-of-freedom arms, performs autonomous visionbased target alignment of both arms with the aid of fiducial markers, two-handed grasping and force control, and robust object manipulation in a tele-robotic framework. The operator uses hand motions to command the desired position for the object via Microsoft Kinect while the autonomous force controller maintains a stable grasp. Gestures detected by the Kinect are also used to dictate different operation modes. We demonstrate the effectiveness of our approach using a variety of common objects with different sizes, shapes, weights, and surface compliances.Note to Practitioners-Industrial robots traditionally are preprogrammed with teach pendants to perform simple repetitive tasks without any sensor feedback. This work was motivated by demonstrating that industrial robots can also perform advanced, sensor-based tasks such as visual servoing, force-feedback control, and tele-operation. Industrial robots are typically limited by the long delay between command and action, but with careful tuning, we show that these sensor-based methods are still feasible even with off-the-shelf sensors.The specific experimental testbed involves a 15 degree-offreedom dual-arm industrial robot with each wrist outfitted with a camera, a rubber contact pad, and a force/torque sensor. A Microsoft Kinect is used to communicate operator commands through gesture. The integrated system involves seven processes running on three computers (2 running Windows 7, 1 running Windows XP) connected through a local hub using the TCP/IP protocol. The communication between the components is based on an object-oriented distributed control and communication software architecture called Robot Raconteur.Though the implementation is for our specific testbed, the approach is sufficiently general to be extended to other robots, end effectors, sensors, and operating systems.

Section: B Hybrid Position-force Controlmentioning

confidence: 99%

“…To securely hold the object with the robot arms, the robot must apply a squeeze to result in enough friction to prevent the object from slipping out of grasp. We use the well-known integral force control, with a force-dependent gain to enhance robustness [14] and show closed loop stability for a compliant object.…”

Section: Introductionmentioning

confidence: 99%

A Sensor-Based Dual-Arm Tele-Robotic System

Kruse

IEEE Trans. Automat. Sci. Eng.

Radke

2015

“…The force error is direction-dependent since a higher squeeze force is more desirable (tighter grip) than lower squeeze force (which could cause a slipped grasp). As recommended in [11] for robust force control of a single arm, we use a directiondependent gain (damping coefficient):…”

Section: Load Motion Command With Squeeze Force Controlmentioning

confidence: 99%

“…To securely hold the box with the robot arms, the robot must apply a squeeze to result in enough friction to prevent the box from slipping out of grasp. We use the well-known integral force control, with a suitable modification to enhance robustness [11].…”

Section: Introductionmentioning

confidence: 99%

A sensor-based dual-arm tele-robotic manipulation platform

Kruse

Radke

2013 IEEE International Conference on Automation Science and Engineering (CASE)

2013

Abstract-This paper presents a novel telerobotic framework for human-directed dual-arm manipulation. Current telerobotic systems typically involve a single robot arm commanded by human through a joystick or a master arm. In contrast, our system involves a dual-arm robot manipulating a held object through human gestures without any mechanical coupling. Our experiment involves an industrial robot consisting of a torso, two seven degree-of-freedom arms, and two three-finger hands. We use the existing industrial robot controller, and only modify the position setpoint in the outer loop. The human interfaces to the robot using a set of gesture vocabulary. During object manipulation, the human gesture is interpreted as the desired configuration of the object. The robot performs autonomous vision-based target identification and alignment, grasp selection and force control, to ensure stable and robust object manipulation, with no demand on human for stable grasping. The heterogeneous components of the system are integrated through Robot Raconteur, a distributed communication and control software system. The system interfaces easily to powerful analysis and visualization tools, facilitating rapid algorithm development and prototyping. We envision that the integrated architecture will serve as the foundation for versatile, robust, and safe human-robot collaboration in increasingly complex sensing and manipulation tasks.

“…[14], where the applied squeeze force control (the control that does not cause motion) is a negative feedback of the measured squeeze force error. Assuming linear compliance of the part, the integral force control becomes…”

Section: Kinematics Based Motion and Force Controlmentioning

confidence: 99%

Dextrous manipulation of a micropart with multiple compliant probes through visual force feedback

Wason

2011 IEEE International Conference on Robotics and Automation

Dagalakis

2011

Abstract-In our recent work, we have demonstrated effectiveness of the concept of multi-probe microassembly for manipulating and inserting microscale, sub-millimeter, parts to create three-dimensional microstructures. However, the approach has been based on trial-and-error manual teaching of grasp points to ensure a stable grasp during motion. As a result, the part orientation is restricted (nearly aligned with the world reference frame and lying flat) to ensure successful grasping and manipulation. In this paper, we developed a kinematics based hybrid motion and force control based only on vision feedback. We first conduct a systematic analysis of the bending of the probes while they are in contact with the part, to estimate the grasp force based on the vision feedback of the probe configuration. A Jacobian based controller is then used for position manipulation while maintaining the desired squeeze force. Experimental results with two probes and two camera are included to demonstrate the effectiveness of the controller to move the part to specified position and orientation while maintaining sufficient squeeze force to prevent part slippage.