Posts by Darknight2

Quote from SkyeFire

I'm not sure. It's just that this forum is mostly about industrial robots -- most of us are integrators of robots we've purchased from major manufacturers like ABB, KUKA, Fanuc, etc, rather than create new robots from scratch. Your question is more related to mobile robotics/AMRs. This is a much more nebulous field, especially in the open-source area.

https://github.com/mjyc/awesome-robotics-projects

https://navigation.ros.org/

Quote from SkyeFire

I'm not sure. It's just that this forum is mostly about industrial robots -- most of us are integrators of robots we've purchased from major manufacturers like ABB, KUKA, Fanuc, etc, rather than create new robots from scratch. Your question is more related to mobile robotics/AMRs. This is a much more nebulous field, especially in the open-source area.

https://github.com/mjyc/awesome-robotics-projects

https://navigation.ros.org/

Again, thank you very much

Quote from panic mode

what is the scale/size of the boat? what is environment?

probably do not need to stop at 15cm mark if this is a container ship crossing the ocean.

where boat is where exactly? indoor/outdoor? swimming pool or open water? stagnant or flowing?

15cm relative to what? i am guessing this is some sort of model being tested in a pool, possibly indoors. in this case indoor positioning system (local GPS or cameras) could be used.

thank you very much

Quote from SkyeFire

This is probably not the best forum to ask this question in, but I will make an attempt.

This probably requires a multi-layered solution. Odometry on the drive wheels will be useful, but cannot detect slippage between wheel and hull. So some sort of additional sensing is required, independent of the wheel motion.

A flow camera, or a sensor similar to that of an optical computer mouse, would be a good addition, located to see the surface of the hull orthogonal to the robot's motion path. This is not free from error, but combined with the wheel odometry should reduce errors.

However, a flow camera may not detect rotation of the robot -- for example, if one wheel slips but the other does not. An IMU or multi-axis gyro, as used in most modern smartphones, would detect this. IMUs are very useful, but can only detect acceleration, which means that using IMU along for location relies on double integration of the detected accelerations over time. This leads to an accumulation of errors. So most IMUs in real-world use rely on being "reset" periodically using some sort of external navigational reference to reliably update the robot's real position.

The best positional data would be to use GPS, or a "local" equivalent -- DGPS, Indoor GPS, or some other beacon-based system. DSLAM might be an alternative.

Most modern mobile robots use a hierarchical combination of all these navigation methods, in a sort of "sensor fusion". The details of which sensor's data is treated as most or least reliable is situational, and usually must be tuned for each robot application.

Display More

thank you very much.I will think about that. And if I have the same question about robot like that what forum I should post ? thanks

Hello everyone, I am a newbie in the robot sector. I have to make a mobile robot(differential drive robot) that can climb the hull ship in manual mode(automated not autonomous). The problem is I don't know how to make the robot drive straight. The robot in the ground can drive straight if you have v left and v right at the same speed but always has errors. So how about on the hull ship? I want the robot to run straight 15 cm and stop then continuously run 15cm and stop. It is a loop. Should I use odometry(encoder) and IMU to determine a position? (It still has errors?) or just use PID to control the speed of v left and v straight in the manual mode?. Please help me. Thanks, everyone.

Quote from panic mode

if you are climbing, you need to overcome couple of things:

1. gravity

2. friction

3. air resistance etc.

the air resistance is not going to be the problem due to (assumed) low velocity.

friction if a function of contact force and friction coefficient.

the gravity is by far the largest component (if this are done correctly).

this can be done differently with varying degrees of complexity. the quickest and simplest way is to use energy.... height is a factor in potential energy. speed is a factor in kinetic energy. mass is a factor in both of them. energies add up. power is a rate at which energy changes. so knowing how fast the climb need to be along with how much energy is needed you can calculate power.

from there you can get torque. you can use mechanical advantage (gearbox, pulleys, wheel size...) to get more torque. tradeoff is the speed.

Display More

thanks u very much

Hi everyone. I have a big project to build a mobile robot that can climb and clear the hall ship container. However, I have a problem with calculating the torque for the motor. As you can see in this picture, Fr=545N is the thrust of the pressure nozzle. Fms1 is the friction force of the wheel. FA=2000N is a magnetic attraction. H is the distance between the hall ship and the vehicle's center of gravity. It is a 3-wheel mobile robot with 2 driving wheels and 1 multi-directional wheel ( caster wheel). So I don't know how to calculate the torque to pick the motor. Can anyone give me an idea to solve that? Thanks very much. Sorry for my bad English.