This my latest refined knee model which is running with the service DIY Servo.

I love that service by the way!! Well let say, I just love MyRobotLab!

It's incredible the evolution it has under gone since I started this project.

Before everyone starts to break it after the Manticore, I am asking Santa to implement velocity in that service to see what is smoothness of movement on payload, and if it can still control with enough power.

:)

juerg

6 years 4 months ago

hi Gael, great - fast mover - will it be able to stem up the body from e.g. a resting sitting position?

I still have my doubts about a walking InMoov but if we get there I will start to reprint one.

Hello Juerg,

It's difficult to say if it will rise from sitting to standing without calculations. But the strength of the mecanism is impressive even running at 12V. At 18V I cannot manually stop it. I must be very carefull with the beast, not to lose a finger.

You are correct walking is a dream goal!

One without dreams achieves nothing, so lets keep dreaming!

In the mean time lets try to make it keep its own balance, that will be already great.

This is awesome Gael !

To estimate torque, Do you know the total gear ratio ?

moz4r

6 years 4 months ago

Idea, wainting perfect Velocity implementation, something related to velocity can be pushed, it is MAX velocity. Goal is to tweak the PID based on frequencie. On the paper , the robot will didn't take care off the load ( or no load ) and will never go at full speed anymore.

This will consumme power , only if needed.

That is paper, need to test ...

This is nearly what i've done under labview with my brushless servo test.

I can change the output range of the PID, the effect is limiting the actuator speed, but torque too.

I think in the future, you want to do ramping of the setpoint depending on the time.

Yeh dude think to ramping of the setpoint depending on the time ( and the load )  is the goal.

I like what kwatters said few time ago, "here we like to build our own bicycles" or something similar.

one of the shortcomings of current servos is it's recognition of being unable to reach a goal e.g. move an arm when it runs into an obstacle and is unable to perform a move in the requested speed/time the move parameters request.

It might even be applied to existing standard servos? Providing the move parameters it should be possible to calculate the total time needed for the move? If this time, or maybe rather  110..120% of this time has elapsed, reset the goal to the current position therefore stopping the robot from trying to reach an impossible location and also avoid burning the servo? An error message might be nice to see that a certain requested position was modified by the time limit evaluated for the move.

yeh Juerg you re right , velocity will be dynamic and if anything prevents the targetPos to be reached at full power, a warning / autodetach / targetpos change ... will be usefull.

off course read potentiometer value off conventional servo can be usefull too in future releases

For now with DIY we can read diyServo.getCurrentPos() -> realtime current angle position

And getCurrentVelocity ( to know how the motor is reaching the pos )

Todo is cook those things

Something is cooked and pushed and it is not the capon

We need more magic ( + time, discussions, contributions and coffee ) to get it worky perfect, but seem ok with my hardware. The biggest problem is accuracy, I cannot control diy servo degrees to 1 degree. And target is emulated is most cases ( if servo is not moving anymore with few degrees error correction, we consider targetPos is reached )