[Rock-dev] Proposal for adding velocity information in base::actuators::Status

[Sylvain Joyeux]

On 04/05/2012 12:03 PM, Javier Hidalgo Carrió wrote:
> Hello rocks,
>
> In Sherpa robot we are receiving angular position and angular velocity
> information of every joints in the robot every 40ms coming from the
> lower level (FPGA and Monster).
>
> The rock data type base:actuators::Status is the data type in rock for
> joint information, which contains:
>
>              struct MotorState {
>               int      current;  //! current in mA
>               double   position; //! position in radians
>               double   positionExtern; //! position of external encoder
> in radians
>               float    pwm;      //! duty cycle in [-1; 1]
>
>               MotorState()
>                   : current(0), position(0), positionExtern(0), pwm(0) {}
>           };
>
> I was wondering which is the correct data type to store joint velocities
> information and if any what about include it in base:actuators::Status
>
> Any suggestion?

1/ do not add it to Status
2/ my suggestion is: let's try to rationalize all that stuff.
    Obviously, the current Status type does not scale.
3/ velocity and position information are redundant (since you can
    compute one from the other). Since joint sensors are usually
    position, we went for position. Is there a direct velocity joint
    measurement on Sherpa ? What is the point of having both values ?

Sylvain