# All Questions

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### How to obtain dense point clouds from stereo cameras?

I am trying to use a stereo camera for scene reconstruction, but I can usually only obtain sparse point clouds (i.e. over half the image does not have any proper depth information). I realize that ...
3k views

### How can the dynamic effects of motor current on a digital compass be characterized and compensated for?

Digital compasses (magnetometers) require a hard/soft iron calibration in order to be accurate. This compensates for the magnetic disturbances caused by nearby metal objects -- the robot's chassis. (...
339 views

### How do I model a robot?

The answers I received to the question on training a line following robot using reinforcement learning techniques, got me to think on how to train a robot. I believe there are essentially two ways - ...
974 views

### Visual Odometry options? [closed]

What are the pros/cons of the different visual odometry options? Stereo Camera Optical Flow SLAM other? Criteria: how well it performs vs other odometry options/sensors (lidar, radar) sensor ...
1k views

### Inverse Kinematics in Java

I'm planning to write an Inverse Kinematics controlled 6 dof virtual robot for Android. I did some research on packages avaliable and couldn't choose the right one which will satisfy my needs on this ...
403 views

### How do you implement an INS from an accelerometer and (optionally) gyros and a magnetometer?

I'm building a walking robot that will need to know when it moves forward. I'm using on-board intelligence and I plan on using accelerometers, gyros, and magnometers (if needed) to be able to detect ...
2k views

### What is the best way to power a large number (27) servos at 5 V?

I apologize if this question may sound a little vague. I am working on a robotics project that will contain 27 servos of various sizes and I am having trouble figuring it how they should be powered. ...
2k views

I have not bought any parts yet, but I am making my own quadcopter. I have done the research and know all about the parts that I need, but many guides are sponsored and cost thousand(s) of euros/...
157 views

### Selecting an accelerometer for Deduced Reckoning

I have never used an accelerometer before, but I am aware that they come with I2C, SPI and analog outputs. If I choose to use an I2c or SPI, device, will I accumulate errors due to communication time? ...
122 views

### What is the current state of the Google Self Driving Car Project? [closed]

I am aware of the legislation's in Nevada, but what is happening with the technology currently. When is it expected to be commercialized ?
2k views

### Can I use IMUs to improve the position/posture measurement of fingers in a “data glove”?

I have been using the Cyberglove to control a humanoid robot hand, but found it disappointing as it doesn't measure the posture of the human hand very accurately. I have been wondering about the ...
24k views

### How to fuse linear and angular data from sensors

My team and I are setting up an outdoor robot that has encoders, a commercial-grade IMU, and GPS sensor. The robot has a basic tank drive, so the encoders sufficiently supply ticks from the left and ...
290 views

### Processor and command interface preference for a robot arm

I want to build a robot arm that'll be approximately 1.25 meter long and will be able to lift up to 2 kilograms. It'll have 6 dof and it is an expensive project. And most importantly, i am the only ...
1k views

### Are inverse kinematics and reinforcement learning competitive techniques?

Are inverse kinematics and reinforcement learning techniques contending techniques to solve the same problem viz. movement of robotic manipulators or arm? By a glance through the wikipedia article, ...
4k views

### Programming a line following robot with reinforcement learning

I am considering programming a line following robot using reinforcement learning algorithms. The question I am pondering over is how can I get the algorithm to learn navigating through any arbitrary ...
185 views

### What kind of performance can I expect when using an Extended Kalman Filter for calibration and localization?

Currently I have a tricycle style robot that uses an extended kalman filter in order to track 6 state variables. The inputs to the system are a steer encoder, a distance encoder, and a rotating laser ...
2k views

### restricting range of motion with complex constraints

I am looking for a way to restrict a robot's range of motion, using complex constraints such as not tearing of a cable attached to the robot. Take an articulated 6-axis robot arm as shown below, with ...
209 views

### Is subsumption architecture still an active area of research?

I am interested in learning more about subsumption architecture. I have read a number of books that talk about the idea but none of them go into great detail. I have also read a fair number of Dr. ...
2k views

### With a 6-axis robot, given end-effector position and range of orientations, how to find optimal joint values

Given a six-axis articulated robot arm holding a tool at its end-effector, if I have a desired tool position and tool orientation, there will be exactly 1 solution to the inverse kinematics equation ...
248 views

### What are some common mistakes that robots make? [closed]

Is there a taxonomy of errors that are common in robotics? Things that come to mind but I don't have names for are: Getting stuck in a stable infinite loop Going into an unstable feedback loop (A ...
137 views

### Tendon longevity

I am thinking of developing a tendon driven robot manipulator for an industrial application that requires a high level of reliability. However, I am aware that tendons in a robot are prone to wear and ...
64 views

### Is there a list of maneuvers related to control of a tracked platform?

I have a platform with two tracks and two motors. Each one uses an electronic speed control with "double tap to reverse". Each ESC takes an input pulse train frequency from at 1500 neutral +/-700. I'...
180 views

### Robot Serial Communication Error

We are using a Koro robot for our PC based automation solution. But sometimes the robot is getting the command but refuses to respond. Then I get a serial communication timeout error. The error is ...
5k views

### Learning Algorithms for Walking Quadruped

I'm building a 4 legged robot (quadruped) with 3 Degrees of freedom per leg. The goal of my project is to make this robot able to learn how to walk. What learning algorithms will I need to implement ...
157 views

### IPC-Bridge problem

Is anyone able to help me out getting IPC-bridge working on my ubuntu lucid installation (with matlab 2012a)? I'm not being able to finish the last step on here (Compiling the messages folders): https:...
205 views

### How much can working with CNC machines teach you about robotics?

I have built a few simple X/Y/Z CNC machines. I've learned about G-Code, motor control, firmware and open loop systems. I see machines like rovers, big dog and factory arms that seem incredibly ...
3k views

### Correct way to use Subsumption Architecture with Robot C

I've been doing a lot of reading lately about Subsumption Architecture and there are a few different ways people seem to advocate. For instance some people use a global "flag" variable to have a ...
181 views

### Which spline function would be best suited for the trajectory of a differential drive

What's the best kind of spline that can be used for generating trajectory that can be adapted during execution time? The use case is having a differential drive which has to move towards a point (x,y,...
10k views

### How can the inverse kinematics problem be solved?

The forward kinematics of a robot arm can be solved easily. We can represent each joint using Denavit–Hartenberg transformation matrices. For example, if the $i^{th}$ joint is a linear actuator, it ...
6k views

### Programming Robots with JavaScript

As somebody who is spending the majority of his time programming in JavaScript, what's the best route to get into small-robotics without needing to deviate too much from my current language focus? ...
55k views

### Which type of actuator will be suitable for a very strong robot arm

I wish to build a robotic arm that can lift a useful amount of weight (such as 3-6kg on an arm that can extend to approx 1.25 meters). What actuators are available to accomplish this. The main factors ...
9k views

### Why do I need a Kalman filter?

I am designing an unmanned aerial vehicle, which will include several types of sensors: 3-axis accelerometer 3-axis gyroscope 3-axis magnetometer horizon sensor GPS downward facing ultrasound. A ...
918 views

### Low-cost servo with digital control interfaces? [closed]

Some years ago, there where some projects that provided hardware and software to perform modifications on standard hobby servos to convert them to digital servos, with all the advantages that come ...
348 views

### Spatial tracking between two UAVs

I have two Unmanned Aerial Vehicles (planes) which work well. They can fly to various waypoints automatically using GPS. Now I would like them to fly together in formation. I would like them to fly ...
95k views

### Why are capacitors added to motors (in parallel); what is their purpose?

I've seen many motors having capacitors attached in parallel in bots. Apparently, this is for the "safety" of the motor. As I understand it, all these will do is smoothen any fluctuations--and I doubt ...
561 views

### Effectiveness of a Mobile Robot In Relation To Mass

Do mobile and/or autonomous robots become more or less effective the bigger they get? For example, a bigger robot has bigger batteries, and thus bigger motors, whereas a smaller robot has the exact ...
18k views

### What do the commutation waveforms look like for a brushless motor?

I have seen waveforms for driving a brushless motor. I guess this is the waveform used for the simpler block commutation. But if I want to do sinusoidal waveforms, what does the PWM signal look like ...
3k views

I want to use an RF beacon to localize my quadcopter for autolanding, when GPS is not precise enough, for example, when my driveway is only 10 feet wide, and the GPS is only showing 20-30 ft. accuracy ...
1k views

### What UAV kit(s) would be suitable for a beginner roboticist with programming experience? [closed]

I'm really new to robotics, however I am a programmer familiar with several different languages. I don't have a ton of money to spend and I was wondering what is a really good starter kit. My ...
774 views

### Should I switch my servo system from brushed to brushless motors?

I have a robot that uses brushed motors in its servo system. These are Maxon 3W motors, with 131:1 planetary gearboxes. The motors are controlled by a PIC microcontroller, running a 1kHz PID ...
2k views

### How does a six-axis force/torque sensor work?

I would really like a six-axis force/torque sensor for my robot, but I just can't afford one. I was thinking about making one of my own. I have experience using strain gauges, but I can't work out ...
4k views

### How to calculate serial speed and buffer requirements for PC to microcontroller communications?

A common scenario is to have a PC that sends commands to a microcontroller via RS232. My PC program is sending commands (each of which are composed of multiple bytes) as fast as it can to a small ...
2k views

### Is it better to have batteries distributed at the rotors or the center of the multicopter?

I've seen 3 approaches to mounting batteries on a multicopter: All the batteries rigidly mounted near the center of the airframe All the batteries in a bag hanging under the center of the airframe ...
5k views

### What frequency does my quadcopter output-sense-calculate-output update loop need to stay stable?

With a 600 mm (2 foot) motor-to-motor quadcopter, what frequency does my output-sense-calculate-output update loop need to stay stable? I'm estimating a total takeoff weight of very roughly 2 pounds (...
13k views

### Can ROS run on a Raspberry Pi?

Can ROS run on a Raspberry Pi? ROS is resigned to run on a network of machines, with different machines, even different cores on the same machine doing different jobs. Can one of those machines be a ...
600 views

### Red [ERROR] output in python in ROS

In ROS, I cannot get [ERROR] logs to print in red when I use python. How can I make them appear in red instead of black? For example, the following Python: ...
174 views

### Floor Segmentation to Determine Navigable Paths

In my application, my robot has the following physical setup: Differential drive mechanics with feedback (wheel encoders) Commercially available webcam mounted with a known transform to the base of ...
2k views

### Starting out advice on making robots and tinkering with microcontrollers [closed]

I'd like to start making robots and tinkering with microcontrollers. Where do I start, and what do I need? I'd like to make my own robots. I'm comfortable with programming (assembly and C) so I've ...