Jari M. Ahola

Calibration procedures for object locating sensors in flexible robotized machining

We present calibration procedures for localization sensor systems for flexible robotic machining. For the needs of flexible production with varying parts and locations, object detection and localizing sensor systems carry out rough global localisation with a laser profiler or a multi-camera system. For needs of machining, more accurate and local object and surface localisation is carried out with a wrist mounted high resolution laser profiler. The calibration procedures for these sensors were implemented and tested with an industrial robot. The novelty of our work is in relying on simple calibration objects, enabling easy and flexible calibration procedures.

Calibration of the pose parameters between coupled 6-axis F/T sensors in robotics applications

This paper presents a new method for calibrating the pose parameters between two coupled 6-axis F/T sensors. The pose parameters include translational and rotational parameters defining the full coordinate transformation between the F/T sensors. The sensor 1 was fixed mount in the robots flange and the sensor 2 was relocatable i.e.it was mounted arbitrarily on the last link of the robot after the wrist mount sensor. The novelty of our work is in the procedure for solving the translational pose parameters by means of contact point locations solved from systems of linear 3D-torque equations. In the calibration the operator exerts a series of diverging forces on the guiding handle which results in different amount of torque with respect to the coordinate frames of the F/T sensors depending on the respective contact point locations. The acquired forces and torques in the both sensor frames are input to the calibration function which outputs the full pose of the sensor 2 with respect to sensor 1. The influence of the sensor signal noise and the deviation of contact point location as well as unintended wrenching of the handle to the calibration accuracy were evaluated with numerical simulations in MATLAB. The performance of the calibration procedure was demonstrated with the real system including commercially available F/T sensors and medium sized industrial KUKA robot. The experiments verify the achievable calibration accuracy was in the level of 20mm and 5and in line with the simulation results. A new method for easily and quickly calibrating the location and orientation of a manual robot guidance unit, equipped with a force/torque sensor and enabling the free location of the manual guidance unit into robot last link or load.Wireless implementation, enabling physical free attachment of the manual guidance unit.The manual guidance unit has been fully implemented and tested in practice in robot assisted load handling and robot path teaching.

User-friendly task level programming based on an online walk-through teaching approach

Purpose – This paper aims to propose a new technique for programming robotized machining tasks based on intuitive human–machine interaction. This will enable operators to create robot programs for small-batch production in a fast and easy way, reducing the required time to accomplish the programming tasks. Design/methodology/approach – This technique makes use of online walk-through path guidance using an external force/torque sensor, and simple and intuitive visual programming, by a demonstration method and symbolic task-level programming. Findings – Thanks to this technique, the operator can easily program robots without learning every robot-specific language and can design new tasks for industrial robots based on manual guidance. Originality/value – The main contribution of the paper is a new procedure to program machining tasks based on manual guidance (walk-through teaching method) and user-friendly visual programming. Up to now, the acquisition of paths and the task programming were done in separate...

Development of Impedance Control for Human/Robot Interactive Handling of Heavy Parts and Loads

This paper introduces a control system for human/robot interactive handling of heavy parts and loads. The aim of the study was to demonstrate the feasibility of human/robot cooperative handling of heavy parts and loads with a robot as a load carrier and a human as a motion guide. The control system included a medium sized industrial robot and two 6-dof F/T sensors adjusting the robot motion via parallel impedance compensators. This paper shows the principles for designing stable impedance compensators for hard contact with the environment as well as for soft contact with the human operator. The impedance compensators were evaluated in MATLAB Simulink and the target impedance models were verified with the real robot system. The result was a pilot system for flexible handling of heavy and large-size parts which can substantially improve the production performance and ergonomic work conditions in mechanical and manufacturing shops.Copyright

Human-Robot Collaboration and Sensor-Based Robots in Industrial Applications and Construction

This paper presents technologies for human-robot collaborative and sensor-based applications for robotics in construction. Principles, safety and control technologies of human-robot collaboration are outlined and sensor-assisted control of industrial robots as well as a dynamic safety system for industrial robots are described in more details. Applicability of sensor-based robotics in building construction and potential of robotics in building construction in general are also evaluated.

A configurable CAD-based object recognition system for varying resolution 3D-sensors

This paper presents a configurable CAD-based object recognition system for varying resolution 3D sensors such as Time-Of-Flight (ToF) cameras and laser scanners. The object recognition system is used for recognizing and localizing target objects on the basis of the geometric and topological information extracted from STEP-files. The novelty of our system is its configurability, i.e. its ability to adjust the level of detail of the database object models to the properties of the applied sensor system, e.g., resolution, accuracy and signal to noise ratio.

Safety Assessment Process for Human-Robot Handling Tasks

The needs for using robots to assist human workers in accomplishing heavy tasks in a variety of industries are increasing. Almost by default this implies sharing the work space between robots and human operators. As a consequence, safety issues must be carefully taken into account. We have implemented a pilot system based on a standard industrial robot (KUKA KR120 R2500) for interactive handling of heavy and/or large parts and loads. Here we report the safety analysis and risk assessment of such a system following the harmonized robot standards (ISO 10218-1 & -2), including Preliminary Hazard Analysis (PHA), Use Case Safety Analysis (UCSA) and analysis of system functions and communications.Copyright