Let's Make Robots!

A.T.T.R - All Terrain Track Robot. Robot able to move in rough terrain from point A to B skipping obstacles on its way. For now it will be cotroled by human, but finall version will be full autonomous.

 

Costs are given "so far..", everything depends on the cash flow.

 

 

 

 

 

 

 

 


Drill Motors:

Drill

Motor & rack. That how I want to propel the tracks. I think that this is more reliable solution.

motor&rack

Track test on tmp chassis. I've used a PC power source. On 6 volts works great. On the next pic you'll see step which wasn't any problem for this track. I bought not enough c-shaped aluminum profile so track has some 'holes'. Soon I'll add a test movie with both tracks and motors on wider chassis.

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ignoblegnome's picture

CtC has made comments that drill motors are not a great choice, and he has the experience with Walter to back that up.

They are electrically noisy, draw a LOT of power, and tend to run faster in one direction than in the other. Since one drill will always be running backwards (because one is on the left and the other on the right), you have to account for the difference in speed with careful feedback and software coding.

Drill motors are way more powerful than those servo motors. If the servo motors are strong enough to move the platform you are planning, they are a great choice. If you need a powerful alternative to drill motors, try power car window motors, which are available in left and right pairs.

OddBot's picture

Although I agree that the drill motors are not perfect they are a good choice for an all terrain robot when used properly. They need a decent motor driver and good noise suppresion.

The biggest problem is that some drill motors may go faster forwards than reverse. It depends on if the drill had a reverse function to work as screw driver or not.

This can be corrected by loosening the crips that hold the back of the motor onto the body. The back of the motor hold the brushes that pass power to the commutator. By twisting the rear of the motor slightly you can effectively change the timing of the motor.

This changes when exactly the winding of the motor get power from the commutator relative to the permanent magnets in the body of the motor. By twisting the end of the motor while it is running you can calibrate the motor to have equal speed and power in both directions.

As a kid I used to modify my motors so that my toy cars ran a lot faster in forward but barely moved in reverse. The downside is the motor draws a lot more current in forwards which can drastically reduce the life of the batteries and the motor. I have had a motor run so hard that the windings came loose inside due to centrifical force and siezed the motor.

OddBot's picture

Although I agree that the drill motors are not perfect they are a good choice for an all terrain robot when used properly. They need a decent motor driver and good noise suppresion.

The biggest problem is that some drill motors may go faster forwards than reverse. It depends on if the drill had a reverse function to work as screw driver or not.

This can be corrected by loosening the crips that hold the back of the motor onto the body. The back of the motor hold the brushes that pass power to the commutator. By twisting the rear of the motor slightly you can effectively change the timing of the motor.

This changes when exactly the winding of the motor get power from the commutator relative to the permanent magnets in the body of the motor. By twisting the end of the motor while it is running you can calibrate the motor to have equal speed and power in both directions.

As a kid I used to modify my motors so that my toy cars ran a lot faster in forward but barely moved in reverse. The downside is the motor draws a lot more current in forwards which can drastically reduce the life of the batteries and the motor. I have had a motor run so hard that the windings came loose inside due to centrifical force and siezed the motor.

hardmouse's picture

Depands on your budget I think. For sure driller motor are nice but you might spend more time and money to work it out. Beside if this is a first robot and to prevent any human errors to cause any injure or accidents, smaller machine probably better to start from.

birdmun's picture

that the drill motors would be the better way to go. They should offer a better power range, but, you will need to gear them down. You should consider Walter as a robot to copy as far as the motors go. If you were to use the servos you should not need the H-bridge, because the electronics would be contained inside the servo case. You should only need to send the proper PWM signals for the speed you are after. Once again, the drill motors should give you better performance.

I removed electronics from the servos, so now they are pure motors with gearbox. For now I will use drill motors connected directly to the racks. If they wont give enough power I will try with servos or with chains and racks to gear down. Soon I will add new photos with this.