I got it buddy thank you

hi marc, welcome to the forum...

You've used this code a couple of times ....

 
  if (v>100) v=100;
  if (v<-100) v=-100; 

Nothing wrong with it, it works, but take a look at the "constrain" function. It toes the job in one go ....

v = constrain(v, -100, 100);

The only thing I've found at first glance is the following. You define motor speed to be -100 to +100. And later you multiply the speed with 2.55.
The range of analogWrite is 0 to 255. I'm wondering if this mixed usage of float ( 2.55 ) and int ( v ) might confuse the analogWrite command, as
the type cast to int is missing.

/*
   v - motor speed can be set from -100 to 100
*/
...
    analogWrite(motor[2], v*2.55); 

I haven't tried it, but maybe

analogWrite(motor[2], (int)(v*2.55)); 

could help.
Otherwise use the map() function like this

analogWrite(motor[2], map(v,0,100,0,255); 

rgs

//////////////////////////////////////////////
//        RemoteXY include library          //
//////////////////////////////////////////////

// RemoteXY select connection mode and include library
#define REMOTEXY_MODE__SOFTSERIAL
#include <SoftwareSerial.h>

#include <RemoteXY.h>

// RemoteXY connection settings
#define REMOTEXY_SERIAL_RX 2
#define REMOTEXY_SERIAL_TX 3
#define REMOTEXY_SERIAL_SPEED 9600

// RemoteXY configurate 
#pragma pack(push, 1)
uint8_t RemoteXY_CONF[] =
  { 255,5,0,0,0,62,0,10,0,0,
  5,48,67,28,29,29,12,24,31,5,
  46,4,29,29,29,12,24,31,2,1,
  39,56,21,5,12,24,31,31,79,78,
  0,79,70,70,0,129,0,25,1,50,
  6,12,82,67,45,88,68,32,67,111,
  110,116,114,111,108,108,101,114,0 };
 
// this structure defines all the variables and events of your control interface
struct {

    // input variables
  int8_t Steering_x; // =-100..100 x-coordinate joystick position
  int8_t Steering_y; // =-100..100 y-coordinate joystick position
  int8_t Acceleration_x; // =-100..100 x-coordinate joystick position
  int8_t Acceleration_y; // =-100..100 y-coordinate joystick position
  uint8_t switch_1; // =1 if switch ON and =0 if OFF

    // other variable
  uint8_t connect_flag;  // =1 if wire connected, else =0

} RemoteXY;
#pragma pack(pop)

/////////////////////////////////////////////
//           END RemoteXY include          //
/////////////////////////////////////////////
/* defined the Steering motor control pins */
#define in1 7
#define in2 6
#define enA 10

/* defined the Acceleration motor control pins */
#define in3 5
#define in4 4
#define enB 9

/* defined the LED pin */
#define PIN_SWITCH_1 13

/* defined two arrays with a list of pins for each motor */
unsigned char SteeringMotor[3] = 
  {in1, in2, enA};
unsigned char AccelerationMotor[3] = 
  {in3, in4, enB};

/*
   speed control of the motor
   motor - pointer to an array of pins
   v - motor speed can be set from -100 to 100
*/
void Wheel1 (unsigned char * motor, int v)
{
  if (v>100) v=100;
  if (v<-100) v=-100;
  if (v>0) {
    digitalWrite(motor[0], HIGH);
    digitalWrite(motor[1], LOW);
    analogWrite(motor[2], v*2.55);
  }
  else if (v<0) {
    digitalWrite(motor[0], LOW);
    digitalWrite(motor[1], HIGH);
    analogWrite(motor[2], (-v)*2.55);
  }
  else {
    digitalWrite(motor[0], LOW);
    digitalWrite(motor[1], LOW);
    analogWrite(motor[2], 0);
  }
}
void Wheel2 (unsigned char * motor, int v)
{
  if (v>100) v=100;
  if (v<-100) v=-100;
  if (v>0) {
    digitalWrite(motor[0], HIGH);
    digitalWrite(motor[1], LOW);
    analogWrite(motor[2], v*2.55);
  }
  else if (v<0) {
    digitalWrite(motor[0], LOW);
    digitalWrite(motor[1], HIGH);
    analogWrite(motor[2], (-v)*2.55);
  }
  else {
    digitalWrite(motor[0], LOW);
    digitalWrite(motor[1], LOW);
    analogWrite(motor[2], 0);
  }
}
void setup()
{
  /* initialization pins */
  pinMode (in1, OUTPUT);
  pinMode (in2, OUTPUT);
  pinMode (in3, OUTPUT);
  pinMode (in4, OUTPUT);
  pinMode (PIN_SWITCH_1, OUTPUT);
 
  /* initialization module RemoteXY */
  RemoteXY_Init ();

}

void loop()
{
  /* event handler module RemoteXY */
  RemoteXY_Handler ();
 
  /* manage LED pin */
  digitalWrite(PIN_SWITCH_1, (RemoteXY.switch_1==0)?LOW:HIGH);

  /* manage the Steering motor */
  Wheel1 (SteeringMotor, RemoteXY.Steering_y - RemoteXY.Steering_x);
  Wheel1 (SteeringMotor, RemoteXY.Steering_x + RemoteXY.Steering_y); 
 
  /* manage the Acceleration motor */
  Wheel2 (AccelerationMotor, RemoteXY.Acceleration_y - RemoteXY.Acceleration_x);
  Wheel2 (AccelerationMotor, RemoteXY.Acceleration_x + RemoteXY.Acceleration_y);
  // TODO you loop code
  // use the RemoteXY structure for data transfer
  // do not call delay()

}