# All Questions

4,435 questions
61 views

### Arduino based quadcopter flipping problem [closed]

I have built an Arduino DUE based quadcopter and I am using HC-12 as a transmitter and receiver between my laptop and the quadcopter. What am I doing is just send a speed value from my laptop and ...
93 views

### Inverse kinematics with end effector orientation?

I'm trying to implement an inverse kinematics solver, but this time even with the end effector's orientation. I succeeded with the case when the end effector only requires the position. I learned ...
18 views

### Pnumatic sulinoid with multiple outputs

I can't figure out what solenoid I would use. Everything I search for comes up with cylinders. Not sure if it's even a sulinoid that I need. I'd like to have 8 hoses connected to a compressor. I'd ...
429 views

### ROS: catkin_make vs. catkin build

When using ROS: Why use catkin build from catkin_tools instead of catkin_make? I've been told catkin build is better but no one who tells me this can give me a reason why.
296 views

### Control a DIY Robot Arm Kit Educational Robotic Claw Set with ROS

I've just started robotics and ROS and I wondering if I can control a DIY Robot Arm Kit Educational Robotic Claw Set (I think its motherboard is arduino). You can find the kit here. Can I use ROS to ...
10 views

### What's the brand of this acoustic speaker whose operation range is 10-100 kHz?

In this paper A fully autonomous terrestrial bat-like acoustic robot - PLOS the robot that is being presented is equipped with an acoustic speaker that can generate 10-100 kHz sound waves. I want to ...
18 views

### Which algorithms to locate a static 3D object relative to a moving camera/IMU?

I am using typical setup with camera and IMU as found on a smartphone. Using this, I would like to estimate the relative pose between the camera and an object (for simplicity, let's say a cube). The ...
57 views

### Reachable Position with endeffector robotic arm

I have a 7 DOF robotic Arm. All the 7 Joints are rotational and have upper and lower joint angle limits. Now assume my end effector has a certain Pose $x = [X, Y, Z, a, b, c]$. My Question now is ...
127 views

### What is the definition of rollout' in neural network or OpenAI gym

I'm relatively new to the area. I run into several time the term `rollout'' in training neural networks. I have been searching for a while but still not sure what it means. For example, the number ...
20 views

### Why are strain-wave/harmonic gears used in robots?

Also, what is the difference between the above gear drive vs other gear drives?
37 views

### 3 arm robotic claw

I am attempting to design a 3 prong robotic claw for a robotic arm I am working on. I am planning to use sg90 servo motors, but I can't get my current design to work. My current layout is to use one ...
17 views

### Detecting and counting the number of junctions

So I am making a robot which is to follow a line. The field has both +(junctions) as well(by the intersection of two lights). I am yet to figure out what exactly is the best way to track the number of ...
11 views

### Fiducials in conjuction with AMCL

I'm having some trouble getting fiducials (using aruco_detect) to work alongside amcl. The goal here is to use normal amcl localization when a fiducial is not present, and to switch to localization ...
23 views

### Create path with minimum curvature for Ackerman drive

I'm trying to create a trajectory between two given poses for an Ackerman drive. The poses are defined as follows: Current Pose position $(x_0, y_0)$ rotation on z-axis $\theta_0$ Final Pose ...
43 views

### Can somebody explain how these forward kinematics matrix equations were formulaed?

Here's the link to the entire answer: Designing a 5 bar linkage robot: Plot Clock
69 views

### Position Estimates from sensor fusion

I have a quadcopter, and several components in play. First, I have a real position system (VICON), and I also have a SLAM platform. Then, of course, the IMU on the quadcoptor. I am trying to ...
75 views

### Inconsistent results between Simulink derivative model and tf for PD controller

I'm designing a PD controller so that the response due to unit step should exhibit an overshoot of 20% and steady-state error less 0.01. I've computed the parameters Kp and Kd and double-checked the ...
63 views

### Calculating torque required to rotate a platform

I am trying to spec out a motor's torque required to rotate a platform about an axis. This diagram makes it better to understand(it's like a rotisserie): Dimensions are in cm: I have an arbitrary ...
37 views

### Robotic Arm Senior Capstone. Electronics/Controls/Sensors Questions

I am a mechanical engineering student currently working on my senior capstone. My team of all MechEs has to build a robotic "arm" where the arm is really just a link/bar of aluminum. The thing we ...
17 views

### Stay both pointed forward and equal distance from side walls

Simple task, robot with total knowledge about the world or at least a few side mounted IR sensors which can accurately measure where the robot is relative to a long straight corridor. We want to BOTH:...
25 views

### the biases in the state vector of extended kalman filter(EKF)

I am reading one paper on observability Observability Analysis of Aided INS with Heterogeneous Features of Points, Lines and Planes. The state vector contains the current IMU state and the feature ...
38 views

### How to implement Kalman to merge the data obtained by two Leap Motion devices?

Only position data is obtained from Leap Motion devices. This data was already processed to be on the same coordinate axis by means of a homogeneous transformation. I'm reviewing WTF is Sensor ...
44 views

### 2D Transformations as Affine Matrices

I have found the following exercises about 2D Transformations as Affine Matrices. I am stuck at the second exercise that goes as follows: The 2D pose of a robot w.r.t. a global coordinate frame is ...
49 views

### Making a robot go in a straight rate - sampling rate for motor PID

I'm trying to build a robot/rover based on Raspberry Pi 3 At the moment I'm straggling with a basic driving in a straight line. I'm in a process of tuning my PID code andI'm not sure what sampling ...
88 views

### IMU and Camera Synchronization

I would like to synchronize my IMU and Camera sensors for my real-time visual-inertial SLAM algorithm in ROS. I am streaming video at 30 Hz from an android phone through IP address. IMU, however, has ...
70 views

### Question about Lens distortion

Suppose I have a 240x180 camera with the following distortion co-efficients, $$k_1 = -0.138592767408$$ $$k_2=0.0933736664192$$ $$k_3=0.0$$ $$p_1=k_4=-0.000335586987532$$ $$p_2=k_5=0.000173720158228$$ ...
96 views

### Inverse Kinematics - How to only find a unique joint angle solution in 4 dof robot?

I have to develop an algorithm to determine the necessary joint angles to achieve a desired TCP position and orientation in a 4 joint manipulator. I have come across a concept called "degeneracies", ...
29 views

### Kalman filter with measurements indirectly determining state

I have a question regarding a 'fundamental' understanding of the Kalman filter. So, for my application I'm trying to estimate state $x = [\theta~\dot{\theta}~\ddot{\theta}]$ of a robot based on ...
76 views

### Using pre multiply or post multipy for rotational matrix to get a new homogenous transformation matrix?

I am confused about how do I multiply the rotational matrix in this case. I know that both T1 and T2 needs to be multiplied by a rotational matrix but I don't know how to multiply the rotational ...
32 views

### Why Euler Angle is set to be in ZYZ order?

We have 3 DOF for rotation in 3D space. So to describe an arbitrary rotation, we need to describe its 3 DOF. Euler angle does this by dividing a rotation in 3 steps, first rotate along the Z axis of ...
46 views

### Practically implementing a torque controller

I'm currently working on a robotics project where i have to build a quadruped. i have somewhat finished the designing for the time being and now moving into simulations. I have followed a inverse ...
70 views

### Help in Computing Inverse Kinematics of a 5 DOF Robot Config

Its is a robot config with 5 DOF. We are provided 2 offsets d1 and d2. d1 and d2 are both 0.04 meter. It is confusing for me alittle bit. I am attending lectures online but I am having trouble ...
21 views

### RF-transceiver for real-time video streaming?

I'm working on an RC-controlled model aircraft. One of the features I'd like to implement is real-time video streaming from the drone's camera. Distance is going to be a few dozen, or better hundred ...
41 views

### Wheeled Mobile Robot State Estimation Model Using Odometry

I have a process model update that follows the form: $$\mathbf{x}_{k|k-1} = \mathbf{x}_{k-1|k-1} + \delta \mathbf{x}_k,$$ where $\mathbf{x}_{k-1|k-1}$ is the posterior estimate from the last ...
23 views

### what specification required for quardcopter to pickup 5kg weight

For a college student project, I am designing a quadcopter with a payload of 3-4kg. As I am new I don't know what are the implications of such a requirement on the quadcopter design. In particular ...
80 views

### Multivariable PID controller

I'm making a robot that uses two DC motors to move, and has two distance sensors on its right side. I want to make a PID controller to control the angle of the robot (using a wall as reference) and ...
40 views

### Polylactic acid - Can I drill into it?

For a school project, I'm creating a mechanical arm and I'm thinking about using a 3D printer to create some of the pieces. Obviously, This arm is dynamic, so I wanted to make the pieces as light as ...
63 views

### Indoor GPS 3D for navigation

I'm looking Indoor GPS system for agriculture tasks in a greenhouse. I want to make an autonomous robot who can navigate by "GPS", I want the system to be 3D (x,y,z) and allowing the I can use robotic ...
42 views

### How to maintain a robot's center of gravity

I am on a robotics team where our robot has to balance on an unstable beam. However, at the same time, the robot must be able to reach to the side in order to grab field materials. What possible ...
37 views

### OpenRAVE “fast-forward” physics simulation?

I am working with OpenRAVE simulator and I am using ODE Physics (OpenRAVE plugin to support ODE). I have a robot in an environment and multiple other objects that are subject to the physics engine. I ...
22 views

### Accuracy of monocular visual-inertial odometry

I am currently considering to use monocular visual-inertial odometry to localize a smartphone relative to a known object. Now, what I would like to understand, is what kind of accuracy I can expect ...
72 views

### Driving the iRobot Create 2 straight

I am attempting to make the iRobot Create 2 drive in a straight line using the opcode 137 with the parameters specified in the OI documentation. "Straight = 32768 or 32767 = 0x8000 or 0x7FFF" I have ...
69 views

### 18 MG996R servo motors control and power

I am currently working an a personal hexapod robot project. I am building it using 18 MG996R 4.8 to 7.2 V servo motors. I would like to use a Raspberry Pi 3 B+ to control it. I purchased a 7.4&...
49 views

### Understanding the kinetic energy expressions for a 1 link vs 2 link robot arm

I'm studying these lecture notes on dynamic models of robot arm links, slides 33-36, where two examples are given for the kinetic energies for a single link and two link robot arm. In the single ...
50 views

### Benfit of behaviors & benefit of hybrid systems

I have two questions that I think are closely related: Why is it useful to introduce behaviors, e.g., goal-to-goal + obstacle avoidance? (The alternative would have been to just use a single behavior ...
89 views

### Get Yaw from quaternion

I found a formula online to extract yaw from a quaternion like so: ...
150 views

### What servos are suitable for a robot like Boston Dynamics’ Atlas?

I have seen Boston Dynamics’ robot Atlas do some pretty impressive things, like a backflip, which must put quite large torques on the servomotors. What servos are there that can generate torques like ...
124 views

### 5 DOF robot - Velocity Inverse Kinematics

I am modelling an articulated robot arm with 5 degrees-of-freedom from igus (igus Robolink). I deduced its direct kinematics equations using Denavit-Hartenberg parameters and homogeneous ...