Man Machine Interface
95. Diagram 19 shows the Man Machine Interface that is used to control and regulate the electric road vehicle. It shows the typical application of a Component Controller. It also helps to show that Component Controller hard -and software design depends on the application.
Man Machine Interface - Name Key
GPD1 .. GPD5 General Purpose Digital Interface (GPDI)
2R .. 64R Resistance Ladder
UVW Three Phase Motor Power
GL Gear Lever Switch
GL1 Gear Lever Position Value Out
RV Reverse Gear Switch
RV1 Reverse Gear Switch Value Out
NU Neutral Gear Switch Position
NU1 Neutral Gear Switch Position Out.
GP Gas Pedal
GP1 Gas Pedal Position Value Out
FW Forwards Gear Switch Position
BP Foot Brake Pedal
BP1 Brake Pedal Position Value Out
CP Clutch Pedal
CP1 Clutch Pedal Position Value Out
2W/4WCC 2 Wheel and 4 Wheel Electronic Fuse Box.
TMS Heater Switch
TMV Temperature Value in 2W/WCC Box
10KMh .. 240KMh Speed Range Verses Current Indicator
SL Serial Data Link (transmit and receive)
AD DLC Address Bus
DB DLC Data Bus (This is in fact the SLDB data bus)
R/W DLC Read/Write
M2W/4W SW Foot Brake Controlled ON/OFF Switch for 2 Wheel Drive and 4 Wheel Drive Motor Power
IG Ignition
2WS 2 Wheel Drive Switch
4WS 4 Wheel Drive Switch
IG2W 2 Wheel Drive Select
IG4W 4 Wheel Drive Select
HBR Hand Brake Switch
E2W/4WDS Hand Brake, Ignition, 2 and 4 Wheel Drive Motor
Power ON/OFF Switch
2WDMP 2 Wheel Drive Motor Power (UVW voltage)
4WMDP 4 Wheel Drive Motor Power (UVW voltage)
GPDS2 This General Purpose Digital Interface is used to monitor and control the temperature in the 2W/4WCC electronic fuse box.
GPD1, GPD3 .. GPD5 These are General Purpose Digital Interfaces as shown in Diagram 18. In the electric drive circuit being described here, they are used to convert human inputs that are GL1, GP1, BP1 and CP1 to digital values and pass them on to the Data Link Controller that is part of the Component Controller.
Special Application Note:
96. The analog outputs GL2, GP2, BP2 and CP2 shown in Diagram 19 can be used in other parts of the circuit instead of GL1, GP1, BP1 and CP1. In such implementations, the Data Link Controller in Diagram 19 would also be able to take over certain software functions that are able to modify the GL1, GP1, BP1 and CP1 signals while they are being used. There are many practical advantages to using the GL2, GP2, BP2 and CP2 signal voltages, instead of the GL1, GP1, BP1 and CP1. Example: If the BP1 signal suddenly went missing, the BP2 signal would not change, even though it is the same signal, because the Data Link Controller decides when it is all right for BP2 to change. The rate at which that signal changes over time is relevant in the decision making process. In the other parts of the circuit descriptions that follow further down below the identifiers GL1/GL2, GP1/GP2, BP1/BP2 and CP1/CP2 are used at the input of General Purpose Digital Interfaces (GPDI) and other control logic. For the said reason directly above. They are then shown as GL3, GP3, BP3 or CP3 at the output of the GPDIs to which they are connected. Some relevant advantages associated with this analog circuit design are:
A. A GPDI can be used to pass an input analog signal to other parts of a circuit while at the same time integrating that signal into a Data Link Controller so that it can be modified and or checked, before it is used.
B. There are advantages to be gain as far as circuit board size and analog signal transmission distances are concerned, because the number of Component controllers in a given circuit can be reduced by assigning the software functions to a smaller number of Data Link Controllers.
C. If a larger number of Data Link Controllers is required, for example, because power electronics is located further away from control electronics and the capability to check real world analog input values against digitally transmitted values at a point close to where a signal is applied is required, the values can be checked every step of the way from source to destination, if they are passed through GPDIs that are connected to a Data Link Controller.
97. The electric drive has the following interfaces between man and the machine:
A. Ignition (IG)
B. Hand Brake (HBR)
C. Gear Lever (GL) - that includes , one Reverse speed , Neutral and 6 Forward speeds.
D. Gas Pedal (GP)
E. Clutch Pedal (CP)
F. Foot Brake Pedal (BP)
G. 2 Wheel Drive (2WS)
H. 4 Wheel Drive (4WS)
98. From a Component Controller perspective, if Diagram 19 is compared to Diagram 20 the following is true:
A. RV, NU and FW switches of the Gear Lever (GL) as are connected to the Binary IO interface of the Data Link Controller, which is the same as saying that the Data Link Controller is an integral part of the Component Controller.
B. The 2 Wheel Drive Switch (2WS), 4 Wheel Drive Switch (4WS), and Ignition (IG) are also connected to the Binary IO interface as IGW2 and IG4W via the E2W/4WDS circuitry.
C. When Hand Brake (HBR) is ON or Ignition (IG) is OFF, IG2W and IG4W are 0, which informs the Data Link Controller that there is no power going to the electric motors.
D. When the position of the Clutch Pedal (CP) is such that it is recognized by the E2W/4WDS circuitry as a 0, IG2W and IG4W are also 0.
E. The Gear Lever (GL), Gas Pedal (GP), Clutch Pedal (CP) and Foot Brake Pedal (BP) as well as the Temperature Measurement Value (TMV) are analog values that are collected by the GPDIs.
99. The circuit converts mechanical actions by drivers into electronic activity that drivers will experience as being the same as when driving existing mechanical vehicles. That saves extensive retraining and other problems that would occur if new vehicles that have completely different driver interfaces and drive characteristics were to suddenly start sharing the road with existing vehicles whose characteristics are already well known and expected. This statement is made here in order to ensure that lethal experience gathering is not repeated for Heat Engine applications on roads.
100. Control loops, and logarithmic input formats are used to integrate the coherent and cognitive activity of drivers into the electronics. In other words, driving and speed judgment is not a precise activity, but the electronics uses logarithmic methods to approximate driver characteristics and can therefore track and understand it quickly.
101. Ignition (IG) and Hand Brake (HBR) are recognized by the electronics as ON/OFF states, but the hand brake can have pressure sensors built into the mechanical construction and the degree of the ON state passed on to the Main Signal Processor.
102. Gas Pedal (GP), Clutch (CP) and Foot Brake (BP) supply control voltages that are in base two exponential steps. An exponential GPDI is used to convert the voltages to digital values. That means that the GPDI supplies data words that are made up of a mantissa and an exponent to the regulating logic. Whereby the mantissa is used to specify a range and the exponent is used together with the mantissa in order to specify the exact values within each range. That allows the electronics to very quickly recognize relevant changes just by first checking the value of the mantissa, which represent the range. In reference to speed, the key advantage of the method is that the precision increases at low values and decrease towards higher values. Compared to linear A/D converted values, less look up and calculating time is required by the Main Signal Processor and Component Controller in order to find the range and meaning of the values. It also matches more closely with human activity.
103. The Gear Lever (GL) also supplies control voltages that are in twos exponential steps. For example, if the Main Signal Processor receives a value from the Gear Lever(GL) whose mantissa value represent 10KMh, it will set the Band Pass (BP) that is in the Power Supply (PS) shown in Diagram 20 so that Gas Pedal (GP) can increase the speed of the vehicle up to just before the 20KMh point, which is the next Gear Lever (GL) position, but not including or past that position. Drivers then notice that they are not getting an increase in speed for an increase in Gas Pedal (GP) position and will change gear up. The same is valid when drives want to slow down from 20KMh to 10KMh. In that case when drivers ease their feet from the Gas Pedal (GP), they will also need to change down to the 10KMh gear position, if they want to continue driving with the same amount of power, otherwise the vehicle will slow down towards 0KMh. In the context of the Heat Engine in electric vehicles, the Band Pass (BP) is used together with the Gear Lever (GL1) value to construct a fail safe speed control mechanism. The Band Pass is replaced by a Low Pass in applications where linear gas pedal control is already standard practice.
104. The Gas Pedal (GP), Clutch (CP) and Foot Brake (BP) are different to the Gear Lever (GL), because those levers not only supply the voltage values at the start of each resistor in the resistance ladder, they also supply the voltage along the whole body of each resistor as the levers are positioned along them. For all practical purposes, the resistance ladders are in fact single variable resistors that have been split into sections that have the relationship shown in Diagram 19.
105. The Gear Lever (GL) switching points and associated speeds shown on the 2W/4WCC current control block of Diagram 19 mean that the switching points allow electric vehicle drivers to change gear and still use the existing tachometer scaling and numbering to judge the speed of their vehicles. The Gas Pedal (GP) is used to make speed adjustments in the usual way. The Gear Lever (GL) only supplies a different voltage value when it is set on a different tap along the resistance ladder.
106. The signal TMS is connected to a Binary IO output of the Data Link Controller. When required, it is used to turn on an heater that keeps the temperature of the 2W/4WCC electronic fuse box close to 25 degrees centigrade so that the tripping point of the fuses will be independent of the environment. The temperature inside 2W/4WCC is passed as a voltage to GPD2 where it is measured and used by the Data Link Controller to control the heater voltage that is called TMS.
107. The control voltages from the Gear Pedal (GP), Gas Pedal (GP), Clutch (CP) and Foot Brake (BP) levers are supplied to the exponential GPDIs through resistance ladders. That means that by checking the mantissa, the logic inside the DLC will be able to recognize within 8 comparisons, which speed range a vehicle should be traveling in. The DLC sends the values to the Main Signal Processor where it is checked against the value supplied by the speedometer and the frequency of the electric motors. If for example, a Gas Pedal (GP) value jumps from 10KMh to 40KMh, it will add a word of warning to the data that it sends to the Main Signal Processor indicating that, as the driver was moving the Gas Pedal (GP) it did not pass through the 20KMh range, before it entered the 40KMh range. That will cause the Main Signal Processor to ignore the speed increase instruction and begin reducing speed by sending the appropriate instruction to the Power Supply (PS) shown in Diagram 20. It will also send a statement to the Board Computer so that the driver is informed. Regardless of whether the value GP is passed to the Power Supply (PS) as GP1 or GP2 or GP3, it's Component Controller will also see the discrepancy in the new value and not accept it.
108. Reverse (RV) is passed on as the binary state Reverse (RV1). It is interpreted as a sign bit in the application being described, because negative voltage states are not allowed in the analog signal paths being described. If any of the GPDIs produce a digital word that contains a sign bit, that will mean that it is definitely not working correctly. In the circuit shown in Diagram 20, Reverse (RV) will not be accepted, unless Speedometer ( SPF) as well as the motor frequencies M2F and M4F are both 0. It gets that information over the serial connection with the Main Signal Processor (MSP).
109. Neutral (NU1) tells all functions associated with the electric drive circuit that signal voltages from Gear, Brake Pedal , Clutch Pedal and Gas Pedal can not have a value.
110. The length of the Main Signal Processor (MSI) software execution cycle must be shorter than the time it takes for the rotors of electric motors to rotate 3 steps around their axis so that Speedometer Frequency ( SPF) measurements will be valid, when they are used. The system would then have more than enough time to see, if any of the relevant voltages have remained hanging at a value that is no longer valid and take appropriate action, if it is in a position to do so. Example: Changing gear and braking at the same time is not allowed. Changing gear with the clutch pedal out is not allowed.
111. The Foot Brake Pedal (BP) always turn off the power supply to the electric motors in the M2W/4W SW unit just before it has any effect on the wheels.
112. The Clutch Pedal (CP) output voltage can be varied between maximum and 0. When it is activated, it turns off the power supply to the electric motors that are connected to the E2W/4WDS unit.
113. The Forwards Gear (FW) position is used to drive the vehicle forwards.
114. The Reverse Gear (RV) position is used to change the direction of the electric motors.
115. The Neutral Gear (NU) position is the power off position for the GP and CP. It also turns off power to the motors, because if the Gas Pedal (GP) does not receive a voltage from NU, it passes 0 volt to the power switches in the E2W/4WCC.
116. Table 1 shows the Gear Lever (GL) positions in relationship to speed.
Table 1
1 = 2R = 1/32
represents 0 to 10KMh
2 = 2R = 1/16
represents 10 to 20KMh
4 = 4R = 1/8
represents 20 to 40KMh
8 = 8R = 1/4
represents 40 to 80KMh
16 = 16R = 1/2
represents 80 to 160KMh
32 = 32R = 1/1
represents 160 to 320KMh
The maximum speed that a vehicle is allowed to travel is set at the digital Band Pass (BP) that is shown in the Power Supply (PS) section of Diagram 20.
117. Table2 shows the resistance ladder ranges in relationship to speed. The system has finer driver control at lower speeds than at higher speeds.
Table 2
1 = 2R = 1/64
represents 0KMh to 5KMh
2 = 2R = 1/32
represents 5KMh to 10KMh
4 = 4R = 1/16
represents 10KMh to 20KMh
8 = 8R = 1/8
represents 20KMh to 40KMh
16 = 16R = 1/4
represents 40KMh to 80KMh
32 = 32R = ½
represents 80KMh to 160KMh
64 = 64R = 1/1
represents 160KMh to 320KMh
118. The digitized GL1, GP1, BP1 and CP1 values that are set in the Man Machine Interface (MMI) by a driver are collected by the Data Link Controller and sent to the Main Signal Processor over the serial connection. They are processed there and the modified or duplicated values that the Main Signal Processor generates are joined together with the original GL1, GP1, BP1 and CP1 signals in other parts of the circuit as shown in Diagram 20 in order to produce the correct values for the actuators that they control. It can once again be noted that the GL2, GP2, BP2 and CP2 signals or as shown in Diagram 20, BP3 and CP3 can be used instead of the original GL1, GP1, BP1 or CP1 signals.
119. The use of the original (GL1, GP1, BP1 and CP1) or (GL2, GP2, BP2 and CP2 ) analog values together with the values produced by software in the Component Controllers and Main Signal Processor (MSI) and placed at the input of analog circuits through the use of General Purpose Digital Interfaces(GPDI), mean that an individual controllers will not be able to make modifications outside of predefined ranges, without the error being detected by one of the other controllers in the chain, because they will contain parameter values that allow them to check the limits of values to which they have access over the GPDI data bus that is the same as the SLDB data bus shown in Diagram 14, Diagram 15 and
Diagram 16.
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Diagram 19
Page 8
The Man Machine Interface circuit for electric vehicles
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