initial observations, issues and questions2018-04-23T20:42:37+00:00

Forums Niryo One Troubleshooting initial observations, issues and questions

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  • duck
    Participant
    Post count: 15

    Hello Niryo One Team,

    Thank you for carefully preparing the assembled robot for safe transport to the other side of the world!

    In addition to testing the basic movement of all 6 axises on the arm that I reported last week by email, I have attached a gripper to the arm and done some preliminary tests of its functionality. I am by no means an expert (like all of you) about robots, so please forgive the naivety of my questions. Also, please excuse my posting so many questions at once, but I thought it would be best to list out my initial observations, issues and questions based on some experimentation with Niryo One with the Niryo One Studio software.

    1. fan in base is very noisy

    I will post a video in the next few days to give you an idea of how noisy it is, but I don’t notice a similar noise in any of the videos that you have posted on your Youtube channel. Perhaps in shipment part of the base interior is too close to the fan blades or there is something loose in the base that is being caused to vibrate due to the fan. I am planning to review the assembly diagrams to make sure I am familiar how to disassemble the base and investigate the cause further.

    2. “gear grinding” during calibration

    I need to review this in detail as I maneuver the robot more times (as far whether there is a pattern about particular axises, etc.). I hear some of the stepper motors “grinding” or slipping. It appears to be associated with an axis that has reached the upper or lower limit (again I’m not sure about this due to my lack of familiarity). I will endeavor to post more detail in a subsequent post and consider attaching a video.

    3. lurching (non-smooth) movement on some axises

    While the movement on all 6 axises is generally very smooth, there appear to be times when the movement is not continuous and the arm suddenly moves on one axis in a non-smooth fashion. I’ve noticed this during calibration, but I am not sure that I have seen it when issuing commands. It may just be a property of calibration.

    4. gripper hits the base when the robot goes limp

    I’ve noticed that when I turn the robot off according to the instructions on the sheet (pressing the black button on top of the base for 3 seconds) that the gripper rather quickly falls to a position where it comes in contact with the outer base shell. I am assuming that this does not cause any structural or mechanical problems for the robot. I am wondering if there are any precautions about recommended parameters for each axis at turn off to avoid damage.

    5. can the grippers be controlled to open or close partially?

    I’ve only attached gripper2 so far and I have adjusted the parameters for the speed of opening and closing successfully. I am wondering if you might be considering additional functionality to Niryo One Studio to open/close the gripper partially when using it to pick up an object. I’m assuming that I could accomplish that if/when programming directly in ROS/my own program.

    6. double calibration necessary to issue commands without receiving errors

    I am noticing that I often have to perform not one but two automatic calibrations after power up in order to issue commands in non-learning mode. Otherwise I see a red error message in Studio (e.g. “Move Robot Joints: Ros error with service”) and none of the joints move. I will continue to do some more testing to see how often this occurs and whether there are particular conditions. Sometimes I have found that I have to turn the robot off and back on again in order to successfully issue commands.

    7. no XL to male in-line pin 3-conductor cable

    It took me a while to figure out how to electrically connect the gripper tools. I wasn’t clear about whether I was supposed to use the cables provided in the kit to connect the stepper motor on the gripper to one of the ports on the back of the base. Then I watched the October 2017 demo on youtube [1] and observed the daisy chain connection to the last stepper motor on axis 6 and read about daisychaining of Dynamixel motors used for axises 5, 6 and the gripper tools. I was unable to find a 3- conductor female TTL to male RE cable, so I removed one of the 10-cm long TTL to female RE connector cables from one of the grippers and strung two of them together using a 3-pin breakaway connector from my own electronics parts.

    I would like to confirm: Ⓐ is there a cable in the Niryo One kit that I should be using for this purpose? Ⓑ What is the recommended length for this connection (currently I am using two 10-cm long cables strung together for a total of 20 cm length)?

    8. is it ok to “hot attach” gripper tool connections?

    I don’t want to cause damage to the robot. Ⓐ Is it acceptable to connect a tool to the robot when it is powered on or do you recommend powering it down and powering it back up each time a tool is connected or replaced? Ⓑ Does this include tools such as the magnetic tool that are connected through the GPI01 port on the back of the base?

    9. earlier Niryo One videos show tools not included in the kit

    I see some tools shown in earlier Niryo One videos that do not appear to be included in the assembled kit that I received. I am just curious about availability of STLs, assembly instructions, usage experience of the Niryo One team.

    Here are some tools that I found in the March 2017 kickstarter video [2]:

    Ⓐ 0:49 gripper fingers which appear to have plastic ridges, not the rubber covers that all the grippers have in the kit. Did you change the design of some of the original grippers?
    Ⓑ 0:56 a drill bit effector tool. Is there an STL for this? what parts (motor, etc.) are needed?
    Ⓒ 1:02 is this the same tool as PenHolder in the Tools directory of the STLs? I didn’t see a PenHolder tool included in the kit. I am planning to print it on a 3D printer and assemble it myself.

    I’d appreciate any feedback that you might be able to provide to the above points. I will endeavor to post more detail on particular issues in subsequent posts. Thank you for all of your hard work! It is great to see the robot working with my own eyes and I look forward to developing some useful applications and interesting demos.

    FOOTNOTES

    [1] OCT17 DEMO https://www.youtube.com/watch?v=mXhjNqzCa4U

    [2] MAR17 KICKSTART https://www.youtube.com/watch?v=do2q3f30eag

    Edouard Renard
    Keymaster
    Post count: 35

    Hi,

    Thanks for the detailed feedback ! This will help us to provide a better product and service, and I’m sure many Niryo Makers will also be glad to find some answers here.

    So, let’s get started 🙂

    1. fan in base is very noisy

    It’s normal that the base fan makes some noise when “learning mode” is turned off (so the motors are activated). In some previous video (before end of 2017), we didn’t have this fan in the base, so it explains why you can’t notice the difference.

    One advice for the fan base : make sure that it is properly fixed. If not 100% correctly fixed, the noise can be higher. Also, if the fan is still on when you deactivated the motors (–> so when you activated the learning mode), there is a problem on the microSD card and you need to update the Niryo RPi image to latest version.

    2. “gear grinding” during calibration

    Axis 1-4 needs to be calibrated, because we use stepper motors with multiple rotations (due to gear ratio with belt). Basically, the way we calibrate a motor is to make it go to the high limit of the axis, and check when stepper the motor starts to miss some steps. Don’t worry though, forcing a little bit on a stepper motor like we use, to make it miss steps, will not damage it at all.

    3. lurching (non-smooth) movement on some axises

    During calibration, the move commands are more basics so the robot can seem to move a little bit “abruptly”. For normal move commands, at the end of each command, the stepper motors will sometimes make a very small move (less than 1 degree) to keep up with the calibration.

    Also, you may encounter cases when the acceleration of a trajectory is not linear (the robot will accelerate, decelerate multiple times in one trajectory). This is a bug in the ROS framework, and it seems that it will be fixed soon !

    4. When you power off the robot, the motors will be deactivated before the Raspberry Pi 3 shuts down. So you need to keep one hand on the button, and another hand on the gripper so it will not fall. We may fix that in in a previous version (the robot will first move to “home” position, then deactivate the motors).

    5. For now you can only give a open/close command to a gripper, along with a speed. The gripper will automatically adjust its torque when the object is detected. For now we don’t plan to add a functionality to partially open or close a gripper (but yes, you could do it by yourself, as all the code to modify is open source). Could you give an example when you would need this functionality ?

    6. double calibration necessary to issue commands without receiving errors

    We already got this feedback from another user, and are working on fixing this bug.

    7. no XL to male in-line pin 3-conductor cable

    It seems that you are missing one wire to connect the Axis 6 motor (Dynamixel) to the gripper. This was a problem in the previous sent batch. We’ll contact you directly by email to solve this issue.

    8. is it ok to “hot attach” gripper tool connections?

    Yes, you can plug/unplug the tools at any moment without any problem.

    One more precision concerning the digital I/Os panel : pay attention not to connect an input sensor (such as a button) to a pin previously set as output. (this doesn’t apply to tools, which are all output actuators)

    9. earlier Niryo One videos show tools not included in the kit

    After some more tests since the Kickstarter campaign (April, 2017), we decided to remove the drill and the pen holder. Niryo One is not precise enough to drill or right with a pen. The difficulty is not to go from point A to point B, but to keep a specified trajectory between 2 points. Also, the drill is a too dangerous tool for Niryo One, we removed it for safety concerns.

    The 3 grippers have been modified since last year. We improved the design a lot, added some bearings to reduce the friction, and change the motors from standard hobby servos to Dynamixel servos. The gripper you saw on the video (at 0:49) is the previous version of Gripper 2.

    Every Niryo One comes with a Gripper 1. Gripper 2 and Gripper 3 are available in the additional Tool Set. (for now there are not so much information about that on our website, but we’ll update it soon with a new online store, more visuals and explanations).

    I hope this answers most of your questions, and feel free to ask more questions/continue the discussion 🙂

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