# All Questions

9 views

### Choosing motor characteristics

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
8 views

### Using i2c's SCL and GPIO pins as SDA

The beaglebone black which I work on has only 2 i2c busses. Say for some crazy reason, i need to use 8 i2c busses. I dont want to chain any of the devices. The idea is to have every device's SDA line ...
23 views

### Is the input of ESC really limited at 50 Hz and will the PID controllers work properly?

Based on the wiki page of ESC, the ESC generally accepts a nominal 50 Hz PWM servo input signal whose pulse width varies from 1 ms to 2 ms http://en.wikipedia.org/wiki/Electronic_speed_control For ...
15 views

### choosing a microcontroller [on hold]

I want to build a line follower robot which will solve a specific problem of solving a grid. I want it to be fast in terms of its mobility and and its processing speed,means less time for data to ...
28 views

### AHRS Algorithm Question

As far as i understand, AHRS use orientation reference vectors to detect orientation error. And we can use magnetometer to correct yaw drift. But i see from my ak895 magnetometer that the data is not ...
11 views

### Comparing cordless driller motors with Dremel-type motors

How is it that the small drillers (such as the Dremel and similar) can achieve such high rpm and torque from such a small motor when compared to a cordless drill motor? I know one difference is that ...
17 views

### RPM of cordless driller motors

What are the typical speeds in rpm of a 7.2v, 12v, 14v and 18v cordless driller motors with and without the gearbox attached? Is it torque or maximum rpm that varies as the voltage increases from ...
22 views

### RNN instead of a PID controller

I am building a drone using the raspberry pi and I am using 6*PID controllers to control the speed and the value for each angle, can I use a recurrent neural network (RNN) or other neural network to ...
14 views

I bought 2 brushed motor controllers from China for my hobby-weight battle robot (http://www.banggood.com/ESC-Brushed-Speed-Controller-For-RC-Car-Truck-Boat-320A-7_2V-16V-p-915276.html). These are ...
16 views

### Changing tank drive (differential) mode to single joystick drive mode

I bought 2 brushed motor controllers from China to use within my hobby-weight battle robot (http://www.banggood.com/ESC-Brushed-Speed-Controller-For-RC-Car-Truck-Boat-320A-7_2V-16V-p-915276.html). ...
8 views

### Motor controller calibration

I bought 2 brushed motor controllers from China to use with my hobby-weight battle robot (http://www.banggood.com/ESC-Brushed-Speed-Controller-For-RC-Car-Truck-Boat-320A-7_2V-16V-p-915276.html). ...
22 views

### error doesn't approach zero

I'm reading this pdf. The dynamic equation of one arm is provided which is $$l \ddot{\theta} + d \dot{\theta} + mgL sin(\theta) = \tau$$ where $\theta$ : joint variable. $\tau$ : joint torque ...
16 views

### arduino connect to laptop over rosserial gives errno111

I'm building a robot and it's currently in it's early stages, currently I'm setting up ultrasonic sensors and it worked fine yesterday but today when I run the ...
17 views

### Probabilistic Velocity Obstacles

I have been working with the Velocity Obstacles concept. Recently, I came across a probabilistic extension of this and couldn't understand the inner workings. Source: Recursive Probabilistic ...
18 views

### Scan Matching finds right rotation but false translation

I'm currently developing a SLAM software on a robot, and I tried the Scan Matching algorithm to solve the odometry problem. I read this article : Metric-Based Iterative Closest Point Scan Matching ...
10 views

### gazebo import robot gives error

I'm trying to import the tutorial robot given at this link However this gives the following error: ...
48 views

### Power switch and common ground on a battle robot

I am constructing a 5.44Kg Hobby-weight battle robot and one of the safety rules is that the robot must have a power switch that turns off power to the motors (and weapon). The robot has three ...
38 views

### Image processing in bright lights

We are working on a project which requires us to detect and hit a ball. We are trying to accomplish the task by detecting the position of ball by processing the input from a camera. The problem is ...
52 views

### tracking robot in a room

I'm trying to track a simple robot (e.g. arduino, raspberry pi, even toys) in a room using fixed location kinect sensor(s) and cameras at different parts of the room. How might one usually use to do ...
66 views

### how to power extra usb devices for beaglebone black

I'm building a robot that uses a beaglebone black, however I have several different usb devices that I want to connect to it (microphone, usb sound device and some other things). Now I have heard that ...
23 views

### Which is more useful? Instantaneous rate of change of displacement or Average rate of change of displacement?

Instantaneous rate of change of displacement is given by, v(t) = (s(t + dt) - s(t))/dt, where dt tends to 0 while average rate of change of displacement is given ...
49 views

### Learning Materials for Beginners in Robotics and Quadrocopters

I am a web developer. I am fascinated by Quadrocopters and i am trying to learn how to build one and basically i am trying to jump into robotics fields. I don't have much electric circuit and ...
20 views

### Sending a smartphone's GPS wireless

I'm building camera device which is able to take pictures of paragliders in mid air. To let the camera know where the glider is I thought about using GPS data from the pilot's smartphone. My ...
31 views

### How to find the height of a rock with a rover?

So, I am designing a rover that will navigate to a rock, and then calculate the height of the rock. Currently, my team's design involves using an ultrasonic rangefinder and lots of math. I was ...
21 views

### Parameter $r$ of Denavit-Hartenberg

By watching this video which explains how to calculate the classic Denavit–Hartenberg parameters of a kinematic chain, I was left with the impression that the parameter $r_i$ (or $a_i$) will always be ...
82 views

### Build a ROS robot with SLAM without laser

I've build a simple wheeled robot based on two continuous servos, controlled by Raspberry Pi running ROS-groovy, with a smart phone mounted on top to provide additional sensors. I'd like to situate ...
41 views

### PID Control Tuning [duplicate]

Im currently designing a robot for my undergraduate project. One of the task of this robot is to follow the wall. For the purpose I'm using a PID control system, where the reference is given from a ...
18 views

### Survey for Local Navigation [on hold]

I was wondering if there was a good book or paper that surveys current techniques in local navigation? The earliest one I could find was from 2005 and I was hoping to find something more recent. I ...
16 views

### How do I get this transformation matrix?

I've just started taking a robotics course and I am having a little problem. I need to rotate the $O_i-1$ coordinate system into a position, where $X_i-1$ will be parallel with $X_i$. The ...
10 views

I am writing a kinematics library in Go as part of my final year project. I am working with Product of Exponentials method and have successfully implemented the Forward Kinematics part of this. I need ...
28 views

### Tilt-Compensated Compass Problem MPU9150 [on hold]

I am implementing a tilt-compensated eCompass, using MPU9150's accelerometer and magnetometer. My steps: Reading magnetometer's data. Hard-iron compensation. Normalize data after Hard-iron ...
12 views

### Wheeled Robot Motion Primitives: Is throttling forward and crab motion considered as one?

I am simulating a wheeled robot of six-wheels and can be independently steered, like MER-Opportunity. The wheeled robot can perform throttling forward, ...
30 views

### Can I make an automatically-parking robot car with IR sensor?

It would be easy to understand if you imagine a robotic vacuum cleaner. (For some models) It goes back to a specific place automatically to recharge. Like this, I want to make a robot which ...
21 views

### ros node does not seem to do anything

I have the following code for the ros turtlesim: ...
9 views

### Recursive Tree Representation for Multi Agent Robots?

I have been going through a code base for multi agent motion planning. And I came across a recursive tree building algorithm for the agents. I haven't been able to figure out the algorithm. Does ...
23 views

### biped walking using Genetic Algorithm

I am working on a project but I lack advanced programming knowledge, especially about genetic algorithms. I am developing a prototype using WEBOTS 7.4.3 for the simulation. The project is to use ...
11 views

### Hokuyo URG-04LX-UG01 and Mac compatibility issues

I've got my hands on this laser range scanner but seem to have some problem receiving any output from it. I can't find any guide on how to set it up on the internet, so I was wondering if it is even ...
14 views

### Brush-less motor specs vs efficiency for multi-copters

I am looking for some figures surrounding the specs of brushless motors and their relative efficiency (in power usage terms) for multi-copter use. There are 4 basic specs for motors themselves: - ...
33 views

### How to convert PID outputs to appropriate motor speeds for a quad copter

I am building an autonomous robot using PID control algorithm. So, far I have implemented PID using online resources/references. I am testing for stabilizing an axis of the quad copter. However, I am ...
24 views

### Motor recommendation for spinning disk weapon

Any suggestions for an inexpensive but effective motor for a spinning disk weapon (vertical spin) for a hobby-weight (5.44Kg) battle robot please? I have no experience at all with brush-less motors ...
31 views

### Detect road surface in a traffic scene point cloud

I want to analyze a traffic scene. My source data is a point cloud like this one (see images at the bottom of that post). I want to be able to detect objects that are on the road (cars, cyclists ...
31 views

### Motor for weapon for Hobbyweight

I am currently building a hobby-weight (5.44kg) robot. The weapon will be a vertical spinning disk at the front. It will probably be a commercial one from the hardware store or I could maybe get one ...
18 views

### control a robot with pymorse on MORSE simulator question

I am new to Morse and robotics. This code control the robot by giving the linear and angular velocity. This is the scene description ...
67 views

### Rotate (and stop) a large disk in very tiny increments

In a lab build I'm doing, I'm stuck at this problem, so I am fishing for suggestions. I'm creating a turn-table type setup where I need to make readings (with a nanotube-tip probe I've already ...
29 views

### Spinning disk Weapon

I am building a Hobby-weight robot and my weapon of choice is a spinning disk at the front. As regards the disk I was thinking of buying commercial (grinder-type) disks and change type of disk ...
33 views

### Diode or capacitor across terminals of brushed motor

I am currently building a hobby-weight robot (5.44kg) and will be using 2 x 14.4v cordless drill brushed motors to drive my wheels. I have read somewhere that due to "induced currents" when I turn ...
20 views

### Amperage on brushed motors

I am currently building a hobby-weight (5.44kg) robot and will be using 2 x 14.4 cordless driller motors for my wheels. The thing is I keep reading about high amperages when working with r/c models ...
88 views

I have this idea or a very curious question in my mind. I am no where near professional though, but i would like it to be answered. We all know how wind turbines can be used to generate electricity. ...
40 views

### Advice on mounting a servo for a nerf sentry gun

I am trying to make a nerf sentry gun to shoot my co workers. I am building it more or less from scratch and have come to the part where I need to come up with plans to assemble it. I am looking for ...
43 views

### A general question about PID Controller

I have a basic question because I'm trying to understand right now a concept that I thought it was obvious. Looking at this video he is going to feedback the variable state x with the input of the ...

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