hauptmech
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Having trouble getting correct homogeneous transformation matrices for my robotic arm
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A quick partial answer to help move you forward: 1) Your axis are labeled for a left-handed coordinate system. Use right-handed (swap the x and y axis in your diagram) 2) There is no prismatic ...

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How timer interrupt is handled in the presence of other interrupt services?
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No. The actual time is calculated from counter registers that automatically increment. The timer interrupt will be delayed, and things the timer interrupt is triggering will be delayed. This is called ...

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Calculate ticks with three encoders?
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To measure position more accurately you need to use all three. They are used for choosing which motor phase to energise, which is called commutation. Searching for "6 step commutation" will give you ...

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Understanding the SICK S300 RS422 data output
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To answer your question. Yes, myself and others have done this before. In practice you only need a subset of the telegrams for a given application. I think you would be surprised how quickly you can ...

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Problem with moving heavy computation into ISR's (dspic33E)?
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A great article on this approach is Build a super simple Tasker. I have implemented this on dsPIC33e mcu's. The biggest issue I faced was priority inversions that came from me trying to share ...

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How to configure a DC power distribution bus
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Electrical cables and connectors are a very common failure point in distributed electro-mechanical systems. So minimizing the number of wires and connectors is often a priority. In which case a single ...

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Do I have to use the CAN protocol that the motor controller uses in order to communicate with it?
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CANopen is a application level protocol and socketcan is at the transport level. You can send Canopen messages using socketcan without any problems. You can compose canopen messages by hand but it ...

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How to get the accurancy of the position system?
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The amount of rotation that the motor is capable of depends on the physical design of the motor. Usually the motor is combined with a transmission (eg gears) of some kind which also influence how far ...

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Simple explanation of PID control
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The farther away the actuator is from the goal, the harder the actuator tries to reach the goal. That is the (P)roprtional part of PID. The longer amount of time the actuator is blocked from the goal,...

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Mavlink data parsing offline from buffer, on Linux in C
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To use file parsing functions with in-memory data, you need to make sure the memory layout matches the file layout. Likely problem sources are leaving out header info or using data structures ...

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Which sensors can be used to feel breeze blowing by the robot?
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Microphone chips have been used as a transducer for this due to their low cost. (This being high density pressure measurements)

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Open source robotics projects that have complex software structure?
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4D/RCS is a more complicated system. I recall that there were only a couple systems implementing it that had publications written. It's the most comprehensive system design I've seen published. I ...

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Struggling to understand Jacobian Inverse Kinematics
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You will find it helpful to keep the physical robot and the math separate. The kinematics equations map joint parameters (which are often grouped as a vector $q$) to Cartesian coordinates ($x$,$y$,$z$...

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Why is the contact force of the rigid-body robot model ks*xr?
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This paper is a thought experiment, using simplified models and mathematical analysis to try to gain some insight into the observed instabilities in real systems. As such they make simplifications as ...

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Will a change of motor driver improve motor performance?
2 votes

If you want to test the motor, just apply a DC source to it directly rather than using the l298. A 12V car battery is a source you likely have access to that can supply enough current so you can test ...

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Practically implementing a torque controller
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You can often find used or surplus industrial controllers capable of current control for good prices, including your range. Elmo Motion Control and Copley Control both have controllers with a small ...

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How to manipulate the magnetic field around a robot?
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The magnetic field is proportional to the current. A fixed geometry coil can generate a field that is positive or negative or zero based on how much current is driven through the coil and which ...

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Serious about robotics programming, should I start with an Arduino?
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Arduino boards are simple microcontroller boards that are a good complexity for learning. The arduino IDE hides the details of typical bare metal microcontroller development, but not in a bad way. ...

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Denavit-Hartenberg convention in practice
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CAD is used as a first estimate. Often the kinematics (coordinate frames) are part of the design specification, and you can use those numbers directly. Where they are not, all mechanical design CAD ...

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Alternative to ROS?
3 votes

Arduino is not really relevant since its output is a bare-metal microcontroller code. You can gain experience with more complex microcontroller systems by using a realtime OS on your arduino board. I ...

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Data saving/sharing standards for objects, actions and senses
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"ontology" is the search term you are looking for. There are a few. You will have to review them to see if any meet your needs. A little background learning about ontologies will help you navigate ...

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Is Programming/Coding necessary to pursue a masters degree in robotics?
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You can study and practice robotics control without dealing with much programming. Look at mechanical engineering or electrical engineering departments with a degree in control systems. Their ...

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How to install a CAN port on PC (under Ubuntu)
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3 votes

For low cost, but well designed and well supported in linux, I can recommend the USB2CAN from 8Devices. If you will be booting windows occasionally to set up industrial drives or sensors, or doing ...

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What is the best SE3 library for python?
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I wrote my own and learned useful things about numpy and python object initialization in the process. I don't regret it.

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What knowledge should I have if I want to establish a robotics company?
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If having a company is more important to you than working in robotics for someone else, business skills and people skills are more important than technical skills. Being successful requires ...

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The reason(s)/benefit(s) to use realtime operating system instead of while-loop on MCU
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Using an RTOS on a microcontroller is for reducing the complexity of developing your solution, and reduces the need for programmer expertise for device drivers, at cost of increasing the complexity of ...

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How can I measure latency in a CAN bus?
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Use an oscilloscope. Place oscilloscope probes on an i/o line on the master and a motor phase line on the slave. Toggle the i/o line just before sending the can bus command for a step change in the ...

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Denavit-Hartenberg Exam Question
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The question is meant to see if you have learned anything about the underlying math and geometry associated with kinematics rather than just blindly following the basic steps for calculation. Draw ...

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Ontology/marketplace of robotics components and integration environment (BPEL or CAD for robotics)?
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Do professional robot designers use semi or fully automated toolchains to implement physical systems? Of course. Especially if you broaden your definition of robot to electro-mechanical system. ...

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Why do roboticists choose a bird-like leg over a humanoid leg?
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One chooses different leg designs for different reasons. Sometimes there are specific design goals, involving the workspace, manipulability, and dynamics, but sometimes the designs are less ...

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