Robin, just under a year ago, a robot in Russia broke a child's finger in a game of chess. The robot arm accidentally grabbed not the chess piece but one of the boy's fingers. Could something like this also happen with your robot arms?
With our work we make sure incidents like that cannot occur. Our robot arms are tactile, unlike the robot arm that moved the chess pieces. They sense contact with an obstacle and react to it accordingly, e.g., by stopping. In our research, we are concerned with two main questions. On the one hand, we investigate the occurrence of human injury, so to say “how high may contact forces be without causing injuries?”. On the other hand, we are concerned with finding out how precisely the robot can measure, adapt to, and apply forces: “Can my robot control and measure forces well enough to comply to safety force thresholds and ensure reliable task execution?”. For a comparison of the systems, we use test procedures and setups with which we can test various robot arms from different manufacturers. These benchmarks can then be used, for example, in our SafeRoBAY human-robot collaboration (HRC) safety research project to enable biomechanically safe and efficient HRC.
New metrics: How sentient is a robot?
What does that look like in practice?
Currently, for example, we have attached a sphere to this robot arm from Kuka that presses on a force plate with a predefined force. A force controller tells the robot the motor torques needed to achieve a desired force, and torque sensors built into each of the seven joints are designed to help it estimate the actual force being generated. My question is: If we ask the system to apply a predefined force, how accurately will it reach this force? There are many factors that influence how exactly the actual force corresponds to the desired one. The sensing technology that is applied for contact force estimation for example. With systems using contact force estimation via motor current readings we see a higher deviation from the desired force and a larger effect of the robot run time on the measurement than for robots using torque sensors, like this Kuka robot. As the main part of my doctoral thesis, I develop a standardized set of basic metrics, benchmarking procedures, and test setups required to describe robot tactility and to transfer them into a model that allows me to estimate the performance of force control of robot arms. In order to then find out whether injuries can still occur at all in the HRC with the robot systems that show high tactility in our benchmark tests, we use both standardized test devices and biomechanical injury tests as part of the SafeRoBAY project. Altogether, this results in a basic set of metrics for robot tactility and a tool for predicting the necessary safety measures for HRC - our big formula for safe force-controlled robots.
What are the differences between the robot arms?
The handling, mechanics and control methods are very different. You can already feel this when you guide the robot by hand. The robot arms from Kuka and Franka, for example, which have the higher tactility than most other systems here, feel very smooth-running, others less so. In addition, we have found in studies that the risk of injuries in HRC with more tactile systems, for example from the Franka Emika robots, is very low. We currently have a set of more than 20 metrics, with respective measurement setups and procedures that we can use to quantify the differences in tactility and safety of the robotic systems. By now, we tested 11 different robot systems (publication upcoming) and in the meantime, we have become quite experienced in this field, so that the first industrial customers are already having their robot arms tested by us.
Selected publications by Robin Kirschner
Robyn, robot ya Urusi ilivunja kidole cha mtoto mmoja wakati wa mchezo wa chess. Kwa bahati mbaya, mkono wa roboti haukukamata kipande cha mchezo wa chesi bali kidole kimoja cha mvulana huyo. Je, jambo kama hilo laweza kutokea pia kwa mikono yako ya roboti? Kwa kazi yetu tunahakikisha kwamba matukio kama hayo hayawezi kutokea. Mikono yetu ya roboti huweza kuguswa, tofauti na mkono wa roboti uliohamisha vipande vya mchezo wa chesi. Wao kuhisi kuwasiliana na kizuizi na kukabiliana nayo ipasavyo, kwa mfano, kwa kuacha. Katika utafiti wetu, tunajihusisha na maswali mawili makuu. Kwa upande mmoja, sisi kuchunguza kutokea kwa jeraha la binadamu, hivyo kusema <unk>ni kiasi gani nguvu za kuwasiliana inaweza kuwa bila kusababisha jeraha?<unk> Kwa upande mwingine, tuna wasiwasi na kujua jinsi hasa robot inaweza kupima, kurekebisha, na kutumia nguvu: <unk>Je, robot yangu kudhibiti na kupima nguvu vizuri kutosha kufuata usalama nguvu mipaka na kuhakikisha utekelezaji wa kazi ya kuaminika?<unk> Kwa kulinganisha mifumo, sisi kutumia taratibu za majaribio na kuweka na ambayo tunaweza mtihani mikono mbalimbali robot kutoka wazalishaji tofauti. "Kama mfano, katika mradi wetu wa utafiti wa usalama wa ushirikiano wa binadamu na roboti (HRC) wa SafeRoBuy, tunaweza kutumia viwango hivi ili kuwezesha HRC salama na yenye ufanisi wa biomekaniki. """ Vipimo vipya: Roboti ina uwezo gani wa kutambua mambo? Hilo linaonekanaje katika mazoezi? Kwa mfano, kwa sasa, tumeweka mviringo kwenye mkono huu wa roboti kutoka Kuka ambao unaficha kwenye sahani ya nguvu na nguvu iliyowekwa mapema. Msimamizi wa nguvu anaambia robot torque ya injini inayohitajika kufikia nguvu inayotakiwa, na sensorer za torque zilizojengwa katika kila moja ya viungo saba zimebuniwa kusaidia kukadiria nguvu halisi inayotokezwa. Swali langu ni: Kama sisi kuuliza mfumo kutumia nguvu predefined, jinsi sahihi itakuwa kufikia nguvu hii? Kuna mambo mengi ambayo huathiri jinsi hasa nguvu halisi inavyolingana na ile inayotakiwa. Teknolojia ya kuhisi ambayo ni kutumika kwa ajili ya makadirio ya nguvu ya mawasiliano kwa mfano. Kwa mifumo ya kutumia nguvu ya kuwasiliana makadirio kupitia motor sasa masomo tunaona kupotoka kubwa kutoka nguvu taka na athari kubwa ya robot kukimbia muda juu ya kipimo kuliko kwa roboti kutumia torque sensors, kama hii Kuka robot. Katika sehemu ya msingi ya thesis yangu ya udaktari, mimi kuendeleza seti ya kiwango cha msingi metrics, benchmarking taratibu, na vipimo seti zinahitajika kuelezea robot tactility na kuhamisha yao katika mfano kwamba inaruhusu mimi kukadiria utendaji wa nguvu kudhibiti mikono robot. Ili kujua ikiwa majeraha bado yanaweza kutokea katika HRC na mifumo ya roboti ambayo inaonyesha tactility ya juu katika vipimo vyetu vya benchmark, tunatumia vifaa vya majaribio ya kawaida na vipimo vya majeraha ya biomechanical kama sehemu ya mradi wa SafeRoBoy. Kwa pamoja, hii ina matokeo katika seti ya msingi ya vipimo kwa ajili ya robot tactility na chombo kwa ajili ya kutabiri hatua za usalama muhimu kwa HRC - formula yetu kubwa kwa ajili ya salama nguvu-kudhibitiwa roboti. Ni nini tofauti kati ya mikono ya roboti? Usimamizi, uendeshaji na mbinu za kudhibiti ni tofauti sana. Unaweza tayari kuhisi hii wakati wewe kuongoza robot kwa mkono. Kwa mfano, mikono ya roboti ya Kuka na Franka, ambayo ina uwezo wa kugusa zaidi kuliko mifumo mingine mingi hapa, inahisi kuwa inakwenda vizuri sana, wengine sio hivyo. Kwa kuongezea, tumeona katika masomo kwamba hatari ya majeraha katika HRC na mifumo ya kugusa zaidi, kwa mfano kutoka kwa roboti za Franka Emika, ni ya chini sana. Kwa sasa tuna seti ya vipimo zaidi ya 20, na mipangilio ya kipimo na taratibu zinazohusiana ambazo tunaweza kutumia kuhesabu tofauti katika kugusa na usalama wa mifumo ya roboti. Kwa sasa, tumejaribu mifumo 11 tofauti ya roboti (uchapishaji ujao) na wakati huo huo, tumekuwa na uzoefu mkubwa katika uwanja huu, kwa hivyo wateja wa kwanza wa viwanda tayari wana mikono yao ya roboti ikijaribiwa na sisi. Machapisho yaliyochaguliwa na Robin Kirschner