# All Questions

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### At which stage should filtering be applied to the sensors data?

Shall I filter (kalman/lowpass) after getting the raw values from a sensor or after converting the raw values to a usable data? Does it matter? If so, why? Example: Filter after getting raw values ...
731 views

### Numpy alternatives for linear algebra and kinematics in python?

Are there any decent python numerical package libraries besides numpy for python? Numpy relies on gfortan which itself must be compiled correctly for your platform to avoid hidden/insidious numerical ...
2k views

### Python libraries for image processing and feedback control on raspberry pi

I'm building a motion detection and object recognition camera with feedback control for a hexy robot. Fortunately most of the servo control is handled by the analog servo controls and the high-level ...
185 views

### How to perform this reference system transformation?

I have two quaternions that indicate the initial orientation of a four wheel robot, each one in relative to one reference systems. The robot's orientation given by a quaternion q is not the same in ...
1k views

### Increasing the rotation range of a servo motor

How do I increase the rotation range of a standard servo? Most servos have a rotation range of ~ 180 degrees. I would like to access the entire 360 degree range on the servo, partially because I would ...
1k views

### Assigning Frames and Deriving Link Parameters

The textbook I'm using doesn't have the answers to the practice questions, so I'm not sure how I'm doing. Are the following DH parameters correct given the frames I assigned? The original question is ...
426 views

### Stabilizing a Robot Arm at a Specified Height

I have a 4-bar linkage arm (or similar design) for a telerobot used in the VEX Robotics Competition. I want to be able to press buttons on my PS3-style controller to have the arm raise to certain ...
1k views

### How do I measure the distance that a cord (string) has moved?

For a pet project, I am trying to fly a kite using my computer. I need to measure how far a cord extends from a device. I also need to somehow read out the results on my computer. So I need to ...
1k views

### How to assemble brushless motors and propellers?

I'm building a quadcopter and I've received my motors and propellers. What's the right way to assemble those together? I'm not confident with what I've done, as I'm not sure the propeller would stay ...
984 views

### Is it possible to make Kite flying robot?

This question was asked in electronics stackexchange. I want to know if is it possible to make a robot that can fly kites. Is this idea practical? I was thinking that making a kite is just like making ...
4k views

### Is there a way to use a single dc motor output for two different loads?

Is there a way to use a single dc motor output for two different loads (by using gears, relays etc) ? Please see the illustration below: To clarify the illustration, I get the dc motor power at "...
61 views

### Mindsensor Motor Multiplexer jump on run_unlimited

I am trying to run a nxt motor using the mindsensors motor multiplexer at a slow speed. When I turn it on, it tends to jump approx 20 to 40 degrees before moving at a slow speed. Has anyone seen ...
532 views

### How to invert D-H parameters

I currently have a working kinematic chain made by a set of ten links in D-H convention (with usual parameters [ $A_i, D_i, \alpha_i, \theta_i$]). But my task currently requires the inversion of some ...
304 views

### Prototyping a device with 25-100 small DC 3.0V motors, is Arduino a good fit?

I want to prototype a therapeutic device that will have a lot of tiny mobile-phone type vibration motors like this one in it, and I want to be able to activate them in any configuration I want. I'm ...
5k views

### Self learning maze solving robot using 8bit microcontroller?

I want to know if there is best algorithm and technique to implement self learning maze solving robot in 8 bit limited resource micro-controller? I was looking for some well optimized algorithm and/or ...
225 views

### Perfecting Tripod Gait - Building a R-Hex Robot

I need help with figuring out the following things: I'm developing a hexapod R-Hex type model with a tripod gait. However, the angles obtained during the robot's walking in real life are not ...
3k views

### What are human-friendly terms for mobile-robot orientation and relative direction of non-robot objects?

Within robotics programming, orientation is primarily given in terms of x, y, & z coordinates, from some central location. However x, y, z coordinates aren't convenient for rapid human ...
564 views

### How do space rovers survive at very low temperatures?

For example, if a rover has working temperature range of -70 to +120 Celsius, how does it survive and then restore itself if the temperature drops to -150 degrees for several months?
2k views

### Is it possible to interface android mobile as GSM and GPS module with arduino based robotic applications?

I want to built a robot and i need bunch of modules to track it like GSM/GPS Wifi and Camera If i try to buy each of module separately it will cost me 300 dollar each aprox in Pakistan. On the other ...
990 views

### Source to learn Kalman Fusion, explanatory code snippets

Currently I am reading a book of Mr. Thrun: Probabilistic Robotics. I find it really helpfull to understand concept of filters, however I would like to see some code in eg. Matlab. Is the book "Kalman ...
526 views

### Overview - what skills are needed for sensor fusion?

I want to make a list of what knowledge is necessary for sensor fusion. Since it has a wide array of possible applications, it is not clear where to begin studying. Can we please verify add topics ...
579 views

### Resetting position of e-puck in Webots using Supervisor node - problem with getting a handle to the robot

I am writing a method (Java) that will reset the position of e-puck in Webots. I have been following tutorial on Supervisor approach. I have two controllers in my project: SupervisorController ...
574 views

### Building a balancing robot with differential drive

I've already built a two wheeled balancing robot using some continuous rotation servos and an accelerometer/gyroscope. I upgraded the servos to some geared DC motors with 8-bit encoders with the goal ...
1k views

### Web mapping that can be used for autonomous vehicles/robots

Is there web mapping tool that allows developers to use it to plot GPS data of autonomous vehicles/robots? Google Maps forbids it. See 10.2.C. ...
329 views

### What is the actual physical actuated quantity when controlling the position of a servo?

I'm trying to learn about servo control. I have seen that the most generic position control method for servos is PID, where the control input is position error. However, I am not sure about what is ...
4k views

### How is PIV control performed?

I'm considering experimenting with PIV control instead of PID control. Contrary to PID, PIV control has very little explanation on the internet and literature. There is almost a single source of ...
4k views

### Cant see Kinect Data in ROS

I am working on this project that involves using the Kinect for XBOX 360S with ROS. I did all the steps mentioned in the ROS Tutorials to have Openni Installed and the Prime sense and other drivers. ...
591 views

### Servo motor considerations for a quadruped

I'm building a quadruped and I'm not sure of the features I should be looking for in a servo motor. e.g. digital vs analog, signal vs dual bearings. Some of the ones I'm considering are here
163 views

### looking for a miniature joystick, but in reverse

Does anyone know if small mechanical actuators exist which can be controlled electrically, sort of like a miniature joystick, but in reverse. Instead of it picking up mechanical movement and ...
6k views

### How to make an “invisible line following robot”?

I would like to build a robot which follows a virtual path (Not a visible path like a 'black line on a white surface', etc). I'm just enthusiastic by seeing some sci-fi videos which show robots carry ...
313 views

### Connecting multiple different voltage servos to the same controller

I am using the Pololu Micro Serial Servo Controller connected to an Arduino and multiple other servos (4 total) to make a robot arm. Two of the four servos require 4-6 volts, while the other 2 ...
2k views

### How would I go about making an art drawing robot like this?

I saw this art drawing robot on youtube: http://www.youtube.com/watch?v=Wo15zXhFdzo What do I need to learn in order to build something like that? What are some beginner oriented projects that could ...
3k views

### Charging multiple LiFePO4 batteries at the same time?

I'm looking to use 4 of these 3.2V LiFePO4 batteries. I intend to have 2 pairs of 2 in series in parallel. So two 6.4V battery packs in parallel. Because my setup will be run off of this, it will also ...
908 views

### Taylor Series expansion for EKF

In Probablistic Robotics by S. Thrun, in the first section on the Extended Kalman Filter, it talks about linearizing the process and observation models using first order Taylor expansion. Equation ...
194 views

### Controlling the Power of a Solenoid

I am trying to control the force of a solenoid. My current system has a bank of capacitors connected to a relay. In order to control the force (how hard I am trying to hit the object) I am increasing ...
791 views

### For servos, can it be implied that Holding Torque = Operating Torque * 2 like with steppers?

I am following a guide that recommends using stepper motors and it has an approximate holding and operating torque. It says that if you don't know the operating torque, it is often half of the holding ...
503 views

### Motors response different with high-frequency PWM

We are making a junior soccer robot and we just got our brilliant motors from Maxon. Setting the PWM timer to low-frequencies (around 39kHz or 156 kHz ) the robot acts as expected. But this produces ...
283 views

### How do we make our robot work?

As a holiday project we are building a surveillance robot that is capable of transmitting live images using a webcam and is also capable of lifting small objects. It uses a CC2500 module for ...
440 views

### Chaining Kalman filters

My team is building a robot to navigate autonomously in an outdoor environment. We recently got a new integrated IMU/GPS sensor which apparently does some extended Kalman filtering on-chip. It gives ...
101 views

### Conventional Land Vehicle Dynamic Models for GPS/INS augmentation

I am looking to augment a GPS/INS solution with a conventional land vehicle (car-like) model. That is, front-wheel steered, rear wheels passive on an axle. I don't have access to odometry or wheel ...
196 views

### Local Localisation with particle filter

I am doing Local Localisation with sonar, particle filter (i.e all particles are initially with robot pose). I have grip map of environment. When I execute algorithm in environment (where doors are ...
909 views

### problem in serial communication between PC and ATMEGA 8535(AVR)

I have written code to send data from controller to pc through serialport using interrupt but it echos garbage value exactly 3 times back. ...
797 views

### Which is easier/cheaper: Hbridge vs ESC for controlling a motor?

I was able to find a small ESC for about $12 off of ebay. If you were designing a robot, would you see that and think? \$12 bucks for an ESC that connects to simple pulse-wave interface - sign ...
89 views

### Does anyone know what might be giving me this error coming from an i2c device

Here is the background. I am trying to write a service for the HiTechnic prototype board. Using the Appendix 2 from the blue tooth developers kit from Lego's site I am able to understand what is ...
5k views

### One BEC for multiple ESC (Quadcopter)

I'm building a quadcopter and have discovered that most ESC have a built-in BEC, but I was wondering if it wouldn't be better to use only one. What if I delivered power to my four ESC with a unique ...
2k views

### What is a good approach to a Quadruped Gait?

I have a small quadruped with three degree of freedom legs which I have been working on: 3DOF Mini Quadruped. My original code for it was a simple servo controller on the arduino, and Scala code ...
432 views

### Why do space probes need heating?

I know that temperature influences the characteristics of semiconductors and other materials, but we know how and can take that into account. Furthermore, lower temperatures makes electronics more ...
6k views

### Do magnets affect IMU values?

Im in the process of making a robot which requires 12 3x10mm cylindric magnets for the construction. They are 30mm from the center of the robot where I plan to have the IMU. I was thinking about ...