# Tag Info

### How do the PID parameters (Kp, Ki, and Kd) affect the heading of a differential driving robot when they are increased individually?

Proportional term: this controls how quickly to turn the steering when the heading is not at the set value. A low P will lead to sluggish steering, reacting only slowly to set heading changes. It may ...
• 1,051

### Inverse kinematics for differential robot knowing linear and angular velocities

Your linear velocity should be the average of both wheel values. Assuming there's some wheel radius of WHEEL_RADIUS, as you've stated, then you should get each ...
• 15.9k
Accepted

### Adjusting the PWM frequency and duty cycle to achieve the desired angular velocity in differential drive robots

At first, I did not go trough your code to check for errors in the formulas but from a high level perspective this seems ok. Therefore, your position controller is fine. What you lack is a lowlevel ...

### Extended Kalman filtering for IMU and Encoder

EKF sensor fusion is achieved simply by feeding data streams from different sensors to the filter. So all you need to do is setup your implementation to accept both encoder and IMU data. This is ...
• 1,363

### Understanding differential drive

Your instincts are correct if you are talking about rotating both wheels forward (or reverse) with the same rotational speed. In that case, the robot would move linearly forward (or backward), just ...
• 4,396
Accepted

### Understanding differential drive

The answer is very simple; Steer drive is what you know from a car where one motor powers both the wheels (either the front or the rear wheels) and then steering is achieved by turning the front ...
• 136

### How do the PID parameters (Kp, Ki, and Kd) affect the heading of a differential driving robot when they are increased individually?

Andy's response is good, and he hits all of the important points but to fully understand PID control in the context of a differential drive robot, it might be useful to take a step back and consider ...
• 926

### What is difference between 2 wheels and 4 wheels and tracked differential mobile base kinematics?

The short answer is that the equations/models for these different vehicle should be different but there is no value in using more accurate equations. All these equations are approximations that make ...
• 4,445
Accepted

### Arduino for mobile robot

It depends what Arduino you are going to use. I don't think that you can use Arduino Nano/Micro for this because you will not have enough I/O and memory. You can use Arduino Mega (maybe UNO) but you ...
• 161

### Motor acceleration and position with PID control

I believe the resource https://robotics.stackexchange.com/a/21571/6941 already pretty much answers your question. In essence, both the following approaches are valuable and can be combined together: ...
• 4,005

### Advantage of Kalman filter in differential drive planar robot

It seem that your are missing some intuition about the function of a Kalman filter type filtering method. To a large degree the working principle of the Kalman filter is combining information from ...

### How to make my robot move parallel to edge of the table?

The problem you are describing is quite similar to line following from a controls perspective, there is a difference in how the line is detected. Line following robots use a wide variety of ways to ...
• 6,682
Accepted

### How to make my robot move parallel to edge of the table?

I can't use any line-following method. Actually, you are quite wrong, the way I understand the problem. It is a line-following. It is just that the line is not painted (like on the road). The line is ...
• 301

### How to handle motor stall zones in differential drive point-forward go to goal algorithm?

For a similar problem (TT motors can't start the bot rolling on a carpet) I have been toying with the idea of setting up PID control for the angular velocity. If it stays stuck, the integral term ...
• 1,271

### How to choose closest angle when crossing -180 degrees

This looks like a common angle wrapping mistake. I am assuming you're defining your angles between -180° ($-\pi$) to +180° ($\pi$). Let's say your current heading is -170°. And you desired heading is ...
• 298

### Drive unicycle kinematics equations through the geometry

tl;dr: don't worry about it Your system really operates in continuous time, described by differential equations. It's a convenient, even necessary, approximation to use discrete time and difference ...
• 1,271
Accepted

### Center line steering with differential drive

Based on the suggestion “look into PID”l controller” I did some more research on that for line following and that’s exactly what I was looking for. Funny in some ways my naive algorithm already uses a ...
• 23
Accepted

### How do I make a robot imported using urdf and ROS2 gravity? It just floats

You can start by checking the e-puck URDF. It can be a good source of inspiration. The problem may come from the conversion of the URDF, which is not creating any physics for the whole robot node. One ...

### SW2URDF model is floating in Gazebo

The instructions to attach the base link to "world" would apply if you're modeling a robot with a fixed base, e.g. a fixed robot arm. For mobile robots, you should not need this joint. You ...
• 411
Accepted

### SW2URDF model is floating in Gazebo

I resolved it by changing the model (redesigning the model on Solidworks) All the wheels should be touching the floor, in my case the caster wheel is above the ground by 1mm and gazebo is not happy ...
Accepted

### How to make 4 wheeled robot work with DiffDrive plugin and ROS2 Control?

There is currently no ros2_controller supporting omniwheels. If it has standard wheels, use the diff_drive controller as in this demo. Consider the wheels_per_side parameter.
• 1,709
1 vote

### How to use SLAM generated map to navigate my robot to the destination?

Once you have a map, you need to use a planning algorithm to get the robot from point A to point B. I'd reccomend reading up on RRT algorithm. How to go from point A to point B is mostly independent ...
1 vote

### How do robots move parallel to a wall/line?

The simplest method line following robots use is 3 sensor system: Consider the 2 block sensors, let's assume they sense color. The middle one senses white, the remaining two senses grey. This robot ...
• 6,682
1 vote

### How to design a robot chassis so as to avoid bending issues?

It is difficult to provide a specific answer due to not knowing details of your design, but consider these factors for the deflection of a beam. They should give you ideas. For a beam supported at ...
• 4,396
1 vote
Accepted

### Going from Spline to Differential Drive Command

If you have the path you want the robot to stay on, it sounds like you need Pure Pursuit. In this simple algorithm, you steer the robot to some look-ahead point on the path. The gist of it is ...
• 5,865
1 vote
Accepted

### How to drive mecanum wheels robot: code or algorithm

I've built one and added the code here: https://github.com/charlch/MecanumBot/blob/master/MecanumBot.ino The core of the maths is this: Firstly turn the 1000 to 2000 input into -1.0 to 1.0 ...
1 vote

### 4 wheeled differential wheeled (skid-steer) robot steering problem

The most likely cause is that your motor torque is too small. Another way to look at this is that the friction between wheel and ground is too large. You can reduce this friction by using smoother ...
• 946
1 vote

### how to implement autonomous navigation using lidar and hector?

http://wiki.ros.org/amcl You should try this and take a look at http://wiki.ros.org/turtlebot_navigation/Tutorials/Autonomously%20navigate%20in%20a%20known%20map It provides the code to use amcl and ...
• 501
1 vote

### Motor encoders randomly start counting backward, then go back to normal

What kind of motors are you using? Because the behaviour you describe makes me think of a brushless motor, due to the fact that you have a rotating magnetic field having the rotor spin. But in the ...
• 66
1 vote

### 4 Wheel Differential Drive Robot with different speeds

Dynamic friction is always lower than static friction. If you are purposefully putting your wheels into a slip mode, then you are putting the wheels into a condition where they have less traction. ...
• 15.9k

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