Mirko Frommberger

The role of the robot mass and velocity in physical human-robot interaction - Part I: Non-constrained blunt impacts

The desired coexistence of robotic systems and humans in the same physical domain, by sharing their workspace and actually cooperating in a physical manner, poses the very fundamental problem of ensuring safety to the user. In this paper we will show the influence of robot mass and velocity during blunt unconstrained impacts with humans. Several robots with weights ranging from 15-2500 kg are impacted at different velocities with a mechanical human head mockup. This is used to measure the so-called head injury criterion, mainly a measure for brain injury. Apart from injuries indicated by this criterion and a detailed analysis of chest impacts we point out that e.g. fractures of facial bones can occur during collisions at typical robot velocities. Therefore, this injury mechanism which is more probable in robotics is evaluated in detail.

The DLR MIRO: a versatile lightweight robot for surgical applications

Purpose – Surgical robotics can be divided into two groups: specialized and versatile systems. Versatile systems can be used in different surgical applications, control architectures and operating room set‐ups, but often still based on the adaptation of industrial robots. Space consumption, safety and adequacy of industrial robots in the unstructured and crowded environment of an operating room and in close human robot interaction are at least questionable. The purpose of this paper is to describe the DLR MIRO, a new versatile lightweight robot for surgical applications.Design/methodology/approach – The design approach of the DLR MIRO robot focuses on compact, slim and lightweight design to assist the surgeon directly at the operating table without interference. Significantly reduced accelerated masses (total weight 10 kg) enhance the safety of the system during close interaction with patient and user. Additionally, MIRO integrates torque‐sensing capabilities to enable close interaction with human beings ...

The “DLR crash report”: Towards a standard crash-testing protocol for robot safety - Part II: Discussions

After giving a rich data basis of our impact tests with standardized crash-test dummies in Part I of this work we address in Part II various aspects related to these tests in a case based discussion. The presented facts, the knowledge gained from our previous work, and the data from Part I lead us to recommendations for standardized crash-testing procedures in robotics. The proposed impact procedures will help to compare blunt robot-human impacts on a common basis. We will discuss additional requirements which will enhance the completeness of testing procedures.

Injury evaluation of human-robot impacts

Currently, large efforts are undertaken to bring robotic applications to domestic environments. Especially physical human-robot cooperation is a major concern and various design and control methodologies were developed on the way to achieve this task. In particular, this necessitates the evaluation of injury risks a human is exposed to in case he is hit by a robot. In this video several blunt impact tests are shown, leading to an assessment of which factors dominate injury severity. We will illustrate the effect robot speed, robot mass, and constraints in the environment have on safety in human- robot impacts. It will be shown that the intuition of high impact loads being transmitted by heavy robots is wrong. Furthermore, the conclusion is induced that free impacts are by far less dangerous than being crushed.

IS IMPEDANCE-BASED CONTROL SUITABLE FOR TRAJECTORY SMOOTHING?

Abstract The paper discusses the difference between explicit sensor-based control and impedance control, using an example of fast vision-based contour tracking. While explicit sensor-based control may cause a rough desired robot path with sharp vertices, impedance control is known to filter the trajectory at the expense of a bigger control error. We present a new implementation and a new approach to impedance-based control where the latter turns out to produce smooth trajectories with small control errors. Both methods are independent of actual control errors but only depend on the desired speed and the sensed shape of the contour.