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Brake demand unit and max value

jozef.bucha
Hello everyone, can some explain me how is brake demand outputed from testrig to brakes subsystem from shared directory.
 
Help says:
 
The torque on the rotor depends on a number of parameters. The front right torque function is:
T = 2 x PistonArea x BrakeLinePressure x µ x EffectivePistonRadius x STEP
where:
BrakeLinePressure is calculated as follows:
BrakeBias defines the front and rear proportioning of the brake line pressure...
 
From thi it looks like brake demand unit is force, its maximum value which can be applied to brakes is defined by parameter variable pvs_max_brake_value.
 
Default value of this parameter is 100, unit Newton [force]. Help about this parameter says it is unit less. This parameter is outputed to testrig.
 
Help about this communicator says:
 
cis_max_brake_value parameter_real any Output from brake subsystem (maximum brake signal value).
 
For me still looks like brake demand si force applied on brake pedal in Newtons.
 
But when i want to make full vehicle analysi:braking with demo vehicle input for final brake value is accepting 0-100, from this it looks like brake demand is in percents??
Capture
Event from this maneuver shows
Capture
Note current field unit (Newtons).
 
Changing pvs_max_brake_value in brake template is AFAIK not changing brake demand
brake_demand
this plot is unitless, but request for braking demand is also in tesrig/driver_demands/brake, which produce same results, but with force on y axis.
brake_demand_force
manualy changing value for braking in event builder to 200, produce logical result for me, step is changing more rapidly to achieve 200 in same time as step 100, but again it is cutted to value 100.
brake_demand_force_step
 
So what is actually brake demand force? max value is maximum 100? I am confused
 
Thanks for response
Jozef
 
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  • 0
    There's an easy solution: Build your own brake template.
    I did that in the past and in my model I chose brake pedal force as an input. Main reason was that we have a standalone brake calculation that works that way and I enhanced it to dump out appropriate subsystems that fit our A/Car brake template.
     
    So the only task was to find out what range the driver is sending via the drake_demand.
    It's always something like 0-1 or 0-100 depending on ADAMS version.
     
    Therefore I introduced my own parameter variable max_pedal_force in the brake subystem and used this in an algorithm to calculate pedal force from the pedal % that the driver is sending.
Reply
  • 0
    There's an easy solution: Build your own brake template.
    I did that in the past and in my model I chose brake pedal force as an input. Main reason was that we have a standalone brake calculation that works that way and I enhanced it to dump out appropriate subsystems that fit our A/Car brake template.
     
    So the only task was to find out what range the driver is sending via the drake_demand.
    It's always something like 0-1 or 0-100 depending on ADAMS version.
     
    Therefore I introduced my own parameter variable max_pedal_force in the brake subystem and used this in an algorithm to calculate pedal force from the pedal % that the driver is sending.
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