ESA / EUROPEAN SPACE AGENCY ESTEC / EUROPEAN SPACE RESEARCH AND TECHNOLOGY CENTER ACT / ADVANCED CONCEPTS TEAM BIOMIMETICS JUSSI MÄKITALO Project Antleg: INTEGRATED SENSING OF MOVEMENT AND FORCES IN A TECHNICAL LIMB -Stage report- Stagiaires report submitted in the end of traineeship in ESTEC. Noordwijk, 28.8.2009 Supervisor: Leopold Summerer, Staff Scientific supervisor: Tobias Seidl, Research Fellow Project Antleg: Jussi Makitalo Integrated sensing of movement and forces in a technical limb Acknowledgements I had great times living in Leiden and working at ESTEC. I met tons of interesting people at work and on free time. Thank you all. Great thanks to my flatmates both at Steenstraat 3c and also at Morsstraat 39. I like to give thanks to all the amazing people involved with the project. Thanks go to Tobias for making some of the groundwork for the project and of course for picking me from the vast amount of applicants. Thanks to Professor J. Schmitz for the interesting information on stick insects. Thanks to Pantelis Poulakis for 20-sim guidance and helping out with the contact model. Thanks to Alexandros, Laura and the rest of the robotics team. Thanks go to all of my good friends back in Finland and to the ones that found the time during my stay in the Netherlands to visit me. Ville, Olli, Jussi, thank you all. Hanna and Mikko, thanks for the short visit. The weekend was short, but full of action. Thanks for Tom, for crashing in my flat for a week, it was awesome. Thanks to the locals for introducing me to local life, thanks Larissa, Anton, Marjolein, Klaas and Stefan. Thanks to all the colleques, JC and David, thanks for the company. And lastly I’d like thank my fiancée for letting me go away for the summer, I know it wasn’t easy at times. Much love and respect. Noordwijk, 28.8.2009 Jussi Mäkitalo ii Project Antleg: Jussi Makitalo Integrated sensing of movement and forces in a technical limb Outline of activities I started working on this project in 2.6.2009 at ESTEC, Noordwijk, The Netherlands. I appreciate the opportunity given and I did my best to come up with useful results and also tried to learn as much as possible from the people working at ACT and ESTEC in general. My first tasks were preparatory work for the project. I was given a stack of papers for research as well as instructed to get to know the contents of the shared drive, the ACTWiki and the Intranet among other information sources. The first few weeks flew by while getting to know the people in the ACT, new stagiaires and YGT’s and my flatmates. Working the days and attending various parties in the evenings. At work, the first days went on by attending trainee sessions and studying my project materials. Simultaneously I had to prepare a Powerpoint presentation about myself for my new colleagues, write down my personal information and specific competences into the ACTWiki. Other minor tasks given, was to update the ACT web pages under ‘Bioengineering’ and ‘Biomimetics’ to match the current state of progress. I also applied for administrator rights for my computer to install all the needed software that I would be using throughout the summer. On my second week of work, I finally met my supervisor, Tobias Seidl, who returned from his vacation for a day to let me know what I’m expected to do during the summer. The same week I started writing this report with loads of research behind and still an incredible amount of research ahead. On 18th of June I had a meeting with my supervisor Tobias Seidl and Professor Josef Schmitz from the University of Bielefeld, Germany. He’s areas of expertise include neurobiology, invertebrate neurophysiology, neuroethology, biological cybernetics and systems theory, motor control, control of legged locomotion in insects and crustaceans and biorobotics. He will act in the project as a support person for me and Tobias. [Schmitz] After the meeting we gave a tour around the ESTEC facilities for Professor Schmitz and he held a Science Coffee for the people at ACT. From the meeting I compiled a memo for the project participants and the management. The project required me to do extensive research about ants, insects, robotics, control, biomimetics and engineering. I was constantly reading papers and making notes and drawing various sketches. The project is about identifying the potential working principles of a desert ant’s odometer as well as outlining the principles for force based odometry in legged robots. This will be carried out by creating a simulation model of the leg and it’s kinematics and then measuring the stresses in the links and torques in the joints and connecting them to appropriate environments. I had tried out the trial version of the simulation software, 20-Sim, required for creating the simulation model earlier and on my fourth week of work I finally iii Project Antleg: Jussi Makitalo Integrated sensing of movement and forces in a technical limb got some guidance on the usage of it. In meantime I had to clarify some of our bibliography in use. I started working on the simulation model on a licensed version of 20-Sim in the middle of my fifth week. It turned out to be not so easy to use. On the sixth, I finally managed to get some arbitrary movement into my model. This was a great success even though I couldn’t control the movements perfectly. After a few trial and errors I managed to produce a movement that could be considered as a stride. On the seventh week, I created some relations between the leg and the soil. The relation seems difficult to create, since so many variables are part of the equation. Also, the results from this kind of leg-soil-interaction has to be viewed critically. A model more resembling the actual thing, could be perhaps delivering more accurate results. On my eight week I got professional advice on creating the contacts between the legs and the ground from Pantelis Poulakis, a contractor well experienced in 20-Sim and robotics. He even gave me a couple of simulation models with built-in contact models for my usage. They were simulations about balls bouncing on a surface and over obstacles behaving in a natural manner. However, for unknown reasons they refused to work on my computer. My ninth week started by me presenting my progress in a Power Point presentation to my working group and some work friends. Later on in the week, I finally managed to fuse together the contact model and my own modelling work to obtain some interaction between the robot and the ground. On the last hours of the week, I managed to get the contact working as it should be. Ten weeks in and there is still lots of work to be done. Interpreting the contact and measuring the forces caused by it seems to be a little troublesome as well. I also lost my license to 20-Sim shortly during my tenth week. My supervisor wanted me to make alterations to the model and this resulted in a total breakdown of the model, this shows that the contact model apparently isn’t working correctly. On the eleventh week I continued in hunting down the reasons for the contact model breakdown. I also created a couple of other types of models for reaching my goal. I also contacted some people in order to get help on the subject. I also appeared in the Dutch newspaper ‘Leidsch Dagblad’ on a small column in the TV-pages on Saturday. My 12th week started by analysing the data received from our model. The model was considered as complete as we can make it during my stay and we decided to analyse it’s outputs with varying terrain conditions. Major part of my week went by while writing this report. The final week began by correcting some errors noticed on the week before, after which I ran some more simulations that I’d been running on the earlier iv Project Antleg: Jussi Makitalo Integrated sensing of movement and forces in a technical limb week with faulty values. On top of that, I needed to finish this report and my final presentation. During my stay here, I visited a couple of lectures held in Newton and Einstein, although that happened only on the first month or so. Also, I brought in some visitors from time to time to show them around ESTEC and to tell them about our work here. The progress of work is shortlisted on table 1 below. Table 1. Work schedule and activities realized. K MONTH DATES WEE CALENDAR WEEK OF STAY ACTIVITY June 2.-5.6. 23 1 Settling to office, understanding project, introduction presentation June 8.-12.6. 24 2 Reading papers, starting of report, website updates, sketches Meeting of Professor Schmitz, MoM, reading, writing report, sketching, 20-Sim June 15.-19.6. 25 3 trial tryout June 22.-26.6. 26 4 Guidance on 20-Sim, reading, sketching June/July 29.6.-3.7. 27 5 20-Sim license, model making starts, reading, writing July 6.-10.7. 28 6 Control of joints, reading, writing July 13.-17.7. 29 7 Starting presentation, continuing 20-Sim, reading about contact kinematics Reading about contact kinematics, 20-Sim, sitdown session on contact July 20.-24.7. 30 8 kinematics with Pantelis Poulakis July 27.-31.7. 31 9 Intermediate presentation of project, working contact model, reading, writing August 3.-7.8. 32 10 Interpreting contact, license trouble, altering model: tilted legs August 10.-14.8.