In this paper, a physically interactive control scheme is developed for a manipulator robot arm. The human touches the robot and applies force in order to make it behave as he/she likes. The communication between the robot and the human is maintained by a physical contact with no sensors. The intent of the human is estimated by observing the change in control effort. The robot receives the estimated human intent and updates its position reference accordingly. The developed method uses the principle of conservation of zero momentum for position-controlled systems. A switching scheme is developed that goes between the modes of pure impedance control with a fixed-position reference and interactive control under human intent. The switching mechanism uses neither a physical switch nor a sensor; it observes the human intent and puts the robot into interactive mode, if there is any. When the human intent disappears, the robot goes into the pure-impedance-control mode, thus stabilizing in the left position.

Human-Intent Detection and Physically Interactive Control of a Robot Without Force Sensors

This paper presents a first attempt to assist manual welding with a physically interactive robot. An interactive control scheme is developed to suppress the vibrations of torch during the welding of novice welders. The torch is attached to the end-effector of a haptic-robot. Human and robot act together on the welding torch: the human controls the direction and speed; the robot suppresses the sudden and abrupt motions. The control scheme is developed by experimenting with an air-paint-brush. The painting process emulates the actual welding. Such an emulating environment is useful to surmount the difficulties of experimentation with actual welding. The impedance parameters of the control scheme are investigated. A damping value is determined for an effective vibration suppression and minimum human effort. A variable impedance control scheme is applied to ease the manipulation of the torch while not welding. The results of real welding of novice welders with and without robot assistance are presented. There is a considerable improvement in the performance of the welders when they are assisted with the robot.

Assisting manual welding with robot

Hard materials can be cost effectively machined with standard industrial robots by enhancing current state-of-the-art technologies. It is demonstrated that even hard metals with specific robotics-optimised novel hard-metal tools can be machined by standard industrial robots with an improved position-control approach and enhanced compliance-control functions. It also shows that the novel strategies to compensate for elastic robot errors, based on models and advanced control, as well as the utilisation of new affordable sensors and human-machine interfaces, can considerably improve the robot performance and applicability of robots in machining tasks. In conjunction with the development of safe robots for human-robot collaboration and cooperation, the results of this paper provide a solid background for establishing industrial robots for industrial-machining applications in both small- and medium-size enterprises and large industry. The planned short-term and long-term exploitation of the results should significantly increase the future robot usage in the machining operations.

Hard material small-batch industrial machining robot

Mechatronics, robotics and components for automation and control

eration between human workers and intelligent assist devices, an elaborate safety system has been developed. The prototype can operate in an area of about 4.7x2.4m including travel in Z-direction of about 1.3m. It has five powered axes driven by servo drives. The axes are the X-, Y- and Z-axes, rotation about the Z-axis and pivoting up and down of the end effector. To allow simple and friendly interfacing with the human worker, a sophisticated human machine interface, based on a touch panel, has been developed.

A new generation of collaborative robots for material handling

This paper presents a novel Cobotic system with differential CVT. The new system is significantly cheaper, simpler to control and more efficient than Cobots with S-CVTs. Both path-guidance and power-assist functions can be simply realized with the new system. Basic structures, kinematic and dynamic models, as well as control algorithms, which are essential for design, control synthesis and control of the system, are briefly presented in the paper.

R. Bernhardt

Papers

New intelligent power-assist systems based on differential transmission