fix bugs in new simulation and motor controller

Chapter03/src/lib.rs

@@ -68,11 +68,13 @@ impl<'a, W: Write> DataRecorder for SimpleDataRecorder<'a, W>
    {
       self.esp = esp.clone();
       self.log.write_all(serde_json::to_string(&esp.clone()).unwrap().as_bytes()).expect("write spec to log");
+      self.log.write_all(b"\r\n").expect("write spec to log");
    }
    fn poll(&mut self, est: ElevatorState, dst: u64)
    {
       let datum = (est.clone(), dst);
       self.log.write_all(serde_json::to_string(&datum).unwrap().as_bytes()).expect("write state to log");
+      self.log.write_all(b"\r\n").expect("write state to log");
 
       //5.4. Print realtime statistics
       print!("{}{}{}", clear::All, cursor::Goto(1, 1), cursor::Hide);
@@ -135,14 +137,17 @@ pub fn run_simulation()
       location: 0.0,
       velocity: 0.0,
       acceleration: 0.0,
-      motor_input: MotorInput::Up { voltage: 0.0 }
+      motor_input: MotorInput::Up {
+         //zero is positive force to counter gravity
+         voltage: 9.8 * (120000.0 / 8.0)
+      }
    };
 
    //3. Store input building description and floor requests
    let mut esp = ElevatorSpecification {
       floor_count: 0,
       floor_height: 0.0,
-      carriage_weight: 0.0
+      carriage_weight: 120000.0
    };
    let mut floor_requests = Vec::new();
 

Chapter03/src/motor.rs

@@ -165,7 +165,11 @@ impl MotorController for SmoothMotorController
       let gravity_adjusted_acceleration = target_acceleration + 9.8;
       let target_force = gravity_adjusted_acceleration * self.esp.carriage_weight;
       let target_voltage = target_force / 8.0;
-      if target_voltage > 0.0 {
+      if !target_voltage.is_finite() {
+         //divide by zero etc.
+         //may happen if time delta underflows
+         MotorInput::Up { voltage: 0.0 }
+      } else if target_voltage > 0.0 {
          MotorInput::Up { voltage: target_voltage }
       } else {
          MotorInput::Down { voltage: target_voltage.abs() }

Chapter03/src/physics.rs

@@ -82,6 +82,7 @@ pub fn simulate_elevator<MC: MotorController, DR: DataRecorder>(esp: ElevatorSpe
 
    //5. Loop while there are remaining floor requests
    let original_ts = Instant::now();
+   thread::sleep(time::Duration::from_millis(10));
    while req.len() > 0
    {
       //5.1. Update location, velocity, and acceleration
@@ -108,12 +109,12 @@ pub fn simulate_elevator<MC: MotorController, DR: DataRecorder>(esp: ElevatorSpe
          req.remove(0);
       }
 
-      //5.3. Adjust motor control to process next floor request
-      est.motor_input = mc.poll(est.clone(), next_floor);
-
       //5.4. Print realtime statistics
       dr.poll(est.clone(), next_floor);
 
+      //5.3. Adjust motor control to process next floor request
+      est.motor_input = mc.poll(est.clone(), next_floor);
+
       thread::sleep(time::Duration::from_millis(10));
    }
 }