Let's Make Robots!

Balance Robot using DAGU 6WD

Balance on two Wheels

This is the first prototype of the Balancing Robot. In this version , I used two sharp sensors to control the motors.this is as first step till the IMU comes from sparkfun. I used Kalman Filtering to reduce the sensors noise. The PID parameter still need more tuning. i will upload the video after finishing the fine tuning.

this picture is for the Geared motor with ratio 34:1 and the rubber tyres.

the following picture is for the sharp sensor. I used 80cm type.

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Why did you choose to place the battery so high?

it is not so high. it is in the upper half of the body. I think at this height it will make the system more stable and will make it less senstive to small effects. of course the load at the motors will increas as the height increases.

thanks OddBot. I did not know the 6WD is your design.

I still have problems with the PID tuning. the robot can not be stable more than few seconds. i dont know what were is  the problem exactly.


The ratio is 34:1

The battery is the heaviest part of the body. Maybe I should fix it at lower height.

 At this time I m using the inclination angle only as the input to the control algorithm. I know it is not enough; better algorithm should use Acceleration and Gyro sensors and maybe the tacho on the wheels to stabilize the movement. However, I expected better results for the current configuration.

i think the total weight is larger than the motors ability. i removed the battery from the body and connect it with long wires. i got some improvemnt. but still not very stable. maybe i should change the SLA battery to lipo battery. 

I could not record a clear video. i will try again tommorrow hope to get better results.

The PID controller should have the rate of change in the D part. the input is only the sharp sensors reading which represents inclination angle. 

I put the battery at the top of the platform. the stability is a bit better but both of the motors stop working after about 15 minutes. it is appearant that these motors can not handle this weight...i must buy larger motors or use the 75:1 gear box


it is about 1.5kg . at a height of about 35cm from the motors shaft. The torque will be (53 kg.cm). So each motor should be at least (27 kg.cm)

the 1:34 is (4kg.cm) and the 1:75 is (8kg.cm)

I think larger motors should be used.

I order 2 brushless motors but I m not sure if they are suitable for this gearbox! It can run up to 20000rpm

The gearbox ratio did not affect this. Usually lower gearbox ratio gives higher wheel speed. i think you can solve this problem by reducing the PWM frequency. This will give more time to the motor to release the kinematic energy inside it. I m not sure that you can change the PWM frequency in Arduino platforms.