Speed Controller for Vehicles

Abstract

A system for regulating speed of a vehicle along a road surface, the system including: at least one controller; at least one throttle sensor in communication with the at least one controller; at least one brake sensor in communication with the at least one controller; at least one gear sensor in communication with the at least one controller; at least one speed sensor in communication with the at least one controller; at least one motor in communication with the at least one controller; and at least one energy source in communication with the at least one controller and the at least one motor; wherein the at least one controller further includes a proportional integral and derivative controller; and at least one retardive braking system in communication with the at least one controller and controlled by the proportional integral and derivative controller.

Claims

1. A method of controlling speed of a vehicle traveling on a road surface; said method comprising: a. inputting a maximum required retardive torque for deceleration of said vehicle into at least one controller; b. inputting a maximum allowable vehicle speed limit value for said vehicle into the at least one controller; and concurrently: c. determining if a throttle or accelerator of said vehicle is engaged; d. wherein whenever said throttle or accelerator of said vehicle is engaged, set a current vehicle speed limit value to said maximum allowable vehicle speed limit value of step b; e. wherein whenever said throttle or accelerator of said vehicle is not engaged, said at least one controller records a current vehicle speed value at time of throttle or accelerator release and sets the recorded current vehicle speed value at time of throttle or accelerator release as a current vehicle speed limit value; f. wherein steps c-e are continuously carried out throughout operation of said vehicle; g. concurrently determining whenever at least one brake of said vehicle is engaged; h. wherein whenever said at least one brake of said vehicle is engaged the current vehicle speed limit value of step e is not changed; i. wherein whenever said at least one brake of said vehicle is not engaged, determining and recording a current vehicle speed value at time of disengaging said at least one brake of said vehicle and setting the recorded current vehicle speed value at the time of disengaging said at least one brake of said vehicle as a new current vehicle speed limit value; j. wherein steps g-i are continuously carried out throughout operation of said vehicle; k. actively compare current vehicle speed value to current vehicle speed limit value; l. wherein whenever said current vehicle speed value is greater than said current vehicle speed limit value, engaging a PID loop logic controller to determine a correction value for vehicle speed value required to set a retardive braking value greater than zero in order to maintain current vehicle speed value equal to or below said current vehicle speed limit value; m. wherein whenever said current vehicle speed value is less than said current vehicle speed limit value, set said retardive braking value as zero; n. wherein steps k-m are continuously carried out throughout operation of said vehicle; and o. wherein steps c-m are concurrently and continuously carried out throughout operation of said vehicle.

2. The method of claim 1 wherein upon setting a correction value required to set a retardive braking value in order to maintain vehicle speed equal to or below said current vehicle speed limit value, determine if directional range of said vehicle is neutral; a. wherein if said directional range of said vehicle is neutral, multiply the correction value by a neutral gain value; and b. wherein if said directional range of said vehicle is not neutral, the correction value is set as the retardive braking value; wherein the retardive brake value is an additional torque value required to decelerate the vehicle speed to maintain said vehicle speed to the current vehicle speed limit value for said road surface.

3. A method of regulating speed of a vehicle, said method comprising: a. receiving a current speed signal from a speed sensor on the vehicle i) at the instant an accelerator or throttle is disengaged and/or ii) at the instant a brake pedal is disengaged; b. determining if the current speed signal received from the speed sensor on the vehicle is greater than a current vehicle speed limit value; c. if the current speed signal received from the speed sensor on the vehicle is greater than the current vehicle speed limit value, calculating a correction value by a PID loop logic in a controller, and retardive braking is initiated to adjust the speed of the vehicle to maintain the current speed value to the current vehicle speed limit value; d. if the current speed signal received from the speed sensor on the vehicle is less or equal to the current vehicle speed limit value, no correction value is calculated; and e. repeating steps a-d throughout the operation of the vehicle.

4. The method of claim 3 wherein said vehicle is an electric vehicle.

5. The method of claim 3 wherein said vehicle is an internal combustion vehicle.

6. The method of claim 3 wherein said vehicle is a hybrid vehicle.

7. The method of claim 4 wherein said electric vehicle is an electric mining vehicle.

8. The method of claim 1 or 3 wherein said retardive braking is at least one retarder selected from the group consisting of hydraulic, electric and engine compression retarders.

9. The method of claim 1 or 3 wherein said method uses a system comprising: a. at least one controller; b. at least i) one throttle sensor for a non-electric vehicle or ii) one accelerator sensor for an electric vehicle, in communication with said at least one controller; c. at least one brake sensor in communication with said at least one controller; d. at least one vehicle speed sensor in communication with said at least one controller, wherein said at least one controller further comprises a PID controller; and e. at least one retardive braking system in communication with said at least one controller, wherein said at least one controller receives signals from said at least i) one throttle sensor for said non-electric vehicle or ii) one accelerator sensor for said electric vehicle, said at least one vehicle speed sensor and said at least one brake sensor and sends a signal to said at least one retardive braking system controlling speed of said vehicle based on factors including: i) maximum allowable vehicle speed limit value; ii) gross vehicle weight (Wv); iii) maximum angle of decline of said road surface (); iv) radius of a static loaded tire of said vehicle (rT); v) deceleration factor (Fd), a value of how aggressively the vehicle speed should decrease; and vi) one of: overall gear ratio (RG) between a motor of said vehicle and a wheel assembly of said vehicle for said electric vehicle, or overall gear ratio (RG) between a retarder and drive wheels linked to a tractive device for said non-electric vehicle; p1 wherein a maximum retardive torque is defined as TB=[rTWv(Fd+sin )]/RG.

10. The method of claim 9 further comprising further comprising at least one gear sensor in communication with said at least one controller.

11. The method of claim 9, wherein said at least one throttle sensor is a throttle pedal position sensor.

12. The method of claim 9, wherein said at least one accelerator sensor is an accelerator pedal position sensor.

13. The method of claim 9, wherein said at least one brake sensor is selected from the group consisting of a brake pedal position sensor and a brake pad pressure.

14. The method of claim 9, further comprising at least one gear sensor in communication with said at least one controller wherein said at least one gear sensor is a gear position sensor.

15. The method of claim 9, further comprising at least one gear sensor in communication with said at least one controller wherein said at least one gear sensor is a neutral gear position sensor.

16. The method of claim 9, further comprising at least one direction range sensor.

17. The method of claim 9, wherein said vehicle is an electric vehicle, further comprising at least one direction range sensor wherein said at least one direction range sensor is a forward, neutral and reverse (FNR) position sensor for said electric vehicle.

18. The method of claim 9, further comprising at least one motor in communication with said at least one controller.

19. The method of claim 9, further comprising at least one energy source for said at least one controller and said motor.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0088] FIG. 1 is a schematic diagram of the system components, according to one alternative.

[0089] FIG. 2 is a schematic diagram of a decision flow chart of the system and method, according to one alternative.

[0090] FIG. 3 depicts an analog sensor, for a brake sensor and/or an accelerator sensor, according to one alternative.

[0091] FIG. 4 depicts a pressure sensor, for a brake sensor, according to one alternative.

[0092] FIG. 5 depicts a ground speed sensor, according to one alternative.

[0093] FIG. 6 depicts a true ground speed sensor, according to one alternative.

[0094] FIG. 7 depicts a controller, according to one alternative.

[0095] FIG. 8 depicts a falling edge concept.

[0096] FIG. 9A depicts curves of various sensors of a vehicle with the speed controller when engaged.

[0097] FIG. 9B depicts curves of various sensors of a vehicle with the speed controller disengaged.

[0098] FIG. 10 depicts an exploded view of the motor torque of FIG. 9 while adjusting the retardive braking to maintain the speed of the vehicle at or below the vehicle speed limit value.

[0099] FIG. 11A depicts curves of various sensors of a vehicle with the speed controller when engaged, with the vehicle gear in neutral.

[0100] FIG. 11B depicts curves of various sensors of a vehicle with the speed controller when disengaged, with the vehicle gear in neutral.

DETAILED DESCRIPTION

[0101] Referring now to FIG. 1, there is depicted a vehicle speed modulator 10 for a vehicle 20, and in particular an electric vehicle. The speed modulator 10 comprises a number of components, including a controller 30, that may be a PID controller, in communication with a plurality of sensors, in particular a vehicle speed sensor 40, an optional brake sensor 50, a accelerator (or throttle) sensor 60, and an optional directional range, or gear position (or FNR position) sensor 70, a vehicle motor 80 (for a non-electrical vehicle, 80 is a retardive device, such as, but not limited to, a hydraulic retarder, a Direct Current motor, or the like for non-electric vehicles), and a power source 90. Sensors 40, 50, 60 and 70 are in communication with the controller 30 sending signals from each of the sensors to the controller 30. In particular, sensor 40, may be a digital sensor sensing rotation of the vehicle motor 80 and sending a pulse per second value to the controller 30, providing the rotations per minute of the vehicle motor 80 which is then converted to vehicle speed by the controller 30. Alternatively, sensor 40 may be true ground speed sensor working on the principle of a Doppler wave. Alternatively, a Global Positioning System (GPS) sensor may be used as understood by a person of ordinary skill in the art. Alternatively, the Hall-Effect may also be used as understood by a person of ordinary skill in the art. Referring now to brake sensor 50, the sensor may be an analog potentiometer, in one alternative a linear or rotational potentiometer, which measures the brake engagement, in one alternative, the relative position of the brake pedal from a non-engaged first position to an engaged second position, wherein a non-engaged first position is sensed as 0% depression and an engaged second position is sensed at greater than 0% up to 100%. Wherein at full depression, said second position is sensed at 100%. In this alternative the signal from the brake sensor to the controller is selected from a voltage value or a current value. In another alternative, said brake sensor is a force load cell, measuring the load on the brake pedal. In another alternative, said brake sensor is a brake pressure sensor measuring brake pressure by a pressure transducer sending voltage or current signal to the controller.

[0102] The accelerator (throttle) sensor 60 may be an analog potentiometer, in one alternative a linear or rotational potentiometer, which measures the accelerator engagement, in one alternative, the relative position of the accelerator pedal from a non-engaged first position to an engaged second position, wherein a non-engaged first position is sensed as 0% depression and an engaged second position is sensed at greater than 0% up to 100%. Wherein at full depression, said second position is sensed at 100%. In this alternative the signal from the accelerator sensor 60 to the controller 30 is selected from a voltage value or a current value converted by the controller to 0% non-engaged up to 100% fully engaged. In another alternative, said accelerator sensor 60 is a force load cell, measuring the force exerted on the accelerator pedal.

[0103] The optional gear position sensor (or FNR sensor) 70 is at least one switch, preferably a plurality of switches, more preferably a digital switch, sensing if switch is engaged or disengaged. Preferably said at least one switch controls the gear position from at least one of Forward, Neutral and Reverse. In one alternative, there are two switches, wherein one of said two switches engaging Forward position and the other of said two switches engaging Reverse position. Preferably there are three switches, one for Forward, one for Neutral and one for Reverse position. Said gear position sensor 70 sending a digital voltage signal to the controller sensing if Forward, Neutral or Reverse is engaged or not. Alternatively, an analog potentiometer may be used to determine the gear position of the vehicle. Alternatively, a capacitive touch sensor may be used to determine gear position and send a digital signal to the controller.

[0104] Vehicle speed sensor 40 measures the speed of the vehicle 20. In one alternative, the speed of the vehicle 20 is measured at a frequency of 10 ms. In another alternative, the frequency is 1 to 1000 ms, more preferably 1 to 500 ms. This measurement may be carried out as known to a person of ordinary skill and may include measuring the RPMs of the vehicle motor 80. The vehicle speed sensor 40 may be selected from the sensors described herein. The vehicle speed sensor 40, when it is a digital sensor or a Hall-effect type sensor, may be positioned anywhere along the power transmission path. One alternative is a vehicle speed sensor 40 at each wheel 21 on a common axle. Another alternative, said sensor may be positioned at any position of a rotating member connected to the tractive device. For a sensor using the Doppler wave, the sensor may be positioned on the vehicle 20 where there is a clear line of sight to the ground surface. For a GPS sensor, the sensor may be positioned on/in the vehicle 20 with communication to a satellite.

[0105] Brake sensor 50 measures the level of braking on the vehicle 10 from the brake. It may be measured based on brake pedal position (i.e. engaged or not) or other braking measurements known to persons of ordinary skill, including, but not limited to, measuring motor torque and/or motor amperage. Brake sensor 50 may be selected from those described herein. In one alternative, the brake sensor 50, when an analog potentiometer and/or force load cell, may be positioned on or proximate the brake pedal. When the brake is a pressure pad, brake sensor 50 is a brake pressure sensor, it may be positioned anywhere within the brake hydraulic circuit to measure the pressure on the brake pressure pad.

[0106] Accelerator (or throttle) sensor 60 measures the acceleration (or throttle position) of the vehicle 20. This measurement may involve measuring the position of the accelerator (or throttle) pedal position in a vehicle 20 or other methods known to persons of ordinary skill as described herein. Accelerator (or throttle) sensor 60 may be selected from those described herein. Accelerator sensor, when an analog potentiometer or force load cell may be positioned at or proximate the accelerator pedal.

[0107] Optional directional range or gear position or FNR position sensor 70 measures if the gear or FNR position of vehicle 20 is in forward, neutral or reverse. This measurement may involve measuring the position of the gear shift lever or other methods known to persons of ordinary skill as described herein. Directional range sensor 70 may be selected from the sensors described herein. Gear position sensor 70 may be positioned at or proximate to the tractive device sensing the direction of rotation of said tractive device, when said vehicle is an electric vehicle. Alternatively, said gear position sensor 70 may be positioned at or proximate to the transmission sensing the gear engaged, when said vehicle 20 is a non-electric vehicle.

[0108] In on alternative, vehicle motor 80 not only gives the tractive motion to the vehicle 20 but also acts as the retardive braking system. Vehicle motor 80 also acts as a generator for the retardive braking as determined by the PID in the controller 30.

[0109] Power source 90 provides power to the controller 30 and may be charged by the vehicle motor 80.

[0110] The communication between vehicle motor 80 and controller 30 is one-way (from 30 to 80), but a signal from 80 is sent to controller 30 via vehicle speed sensor 40, and communication from power source 90 and controller 30, is two-way to facilitate retardive braking as required by the PID logic in controller 30 to ensure power source 90 has capacity to store energy from 80.

EXAMPLE 1

[0111] The following is an example of the system and method described herein.

[0112] The first step involves inputting values into said controller to allow for calculating the maximum designed retardive torque for safe deceleration of a vehicle from maximum speed including: i. input the maximum allowable vehicle speed limit value allowed at the site the vehicle will be implemented; ii. input the gross vehicle weight rating; iii. input the maximum design angle of decline for the vehicle (maximum steep of a decline for the vehicle); iv. input the radius of the static loaded tire (i.e. static loaded radius). The static loaded radius is the loaded radius of a stationary tire inflated to the recommended pressure. The loaded radius is the distance from the centre of the tire contact to the wheel centre measured in the wheel plane; v. input the deceleration factor, which is a value of how aggressively the vehicle speed should decrease; vi. input the overall gear ratio between the motor and the wheel assemblies (allowing for the PID logic to be used in vehicles that have a transfer case or a transmission or different axles). If there is no transmission or transfer case for an electric vehicle, use a overall gear ratio of 1:1; and vii. inputting these values into the following formula will calculate the required retardive torque in order to decelerate the vehicle depending on the angel of decline and other factor identified below: [0113] TB=[rTW.sub.v(F.sub.d+sin )]/R.sub.G, where TB=maximum required retardive torque, rT=radius of static loaded tire, W.sub.v=gross vehicle weight, F.sub.d=deceleration factor, =angle of decline of the road surface, R.sub.G=overall gear ratio between motor and wheel assembly.

[0114] In one instance, the TB value may be used as is and, in another instance, the required retardive torque value may be converted into a vector which may be a scaled mathematical value from a value of zero to a value of 100, depending on controller. Zero being no retardive torque on the vehicle and 100 being the calculated maximum retardive torque on the vehicle.

[0115] In a basic system, the TB calculated value is inputted manually into the vehicle speed controller. In a more advanced system, each parameter of the TB equation is inputted into the vehicle speed controller and the controller calculates the TB.

[0116] The system is always active, if the vehicle power is engaged, regardless of gear setting or position. The system is active in neutral (when the gear system is not engaged or when the FNR direction range is in neutral). As stated herein, one drawback of prior art systems is the retardive system is not engaged when the vehicle is in neutral which may result in the vehicle operator circumventing the retardive system by placing the vehicle in neutral. One benefit of having the system active in neutral is mitigating vehicle operator misuse that may put the vehicle in neutral to avoid gear limitations and try to glide down a decline and either surpass vehicle speed limited by controls and/or wear down the braking system. The only time the system is not active is when the vehicle is off and when in tow mode.

[0117] Referring now to FIG. 2, there is depicted a flow diagram of the method of the system herein. The method commences at startup of the vehicle. From start 200, the system determines if the throttle is engaged or not (or if the throttle or accelerator pedal 202 is depressed), if yes, the vehicle speed limit value is set to the maximum allowable vehicle speed limit value 204. The maximum allowable vehicle speed limit value 204 is determined by the OEM or the work site limitations or regulatory speed limitations. The vehicle operator engages the gear of the vehicle and engages the throttle to move the vehicle to a certain speed no greater than the maximum allowable vehicle speed limit value 204. The instance the throttle is disengaged, in other words, the throttle is not depressed or engaged, the system records the current vehicle speed at the instance of throttle disengagement and sets a vehicle speed limit value 205 as the recorded current vehicle speed at the time of throttle disengagement. Concurrently, the system determines if the brake is engaged (or if the brake pedal is depressed) 206. When the brake pedal is engaged, the vehicle speed limit set above, as 205, is not yet changed. When the brake pedal is released, or disengaged, the system records the current vehicle speed value 207 at the instant the brake pedal is released or disengaged and sets it as the new current vehicle speed limit value 205. The system measures and records the new vehicle speed value instantaneous and up to 50 milliseconds from the action (i.e. brake engaged or not, throttle engaged or not). In a preferred alternative, the time period is between 10-500 milliseconds. As soon as the pedal is released, the throttle resets. This concept is known as the falling edge.

[0118] Once the system records the current vehicle speed value and sets it as the new current vehicle speed limit value 205, the system then actively compares the new current speed limit value limit 205 to the current vehicle speed value 207 as long as the accelerator pedal is not depressed (or not engaged). When the accelerator pedal 202 is depressed (or engaged), the system compares at 300 the maximum allowable (or pre-programmed) vehicle speed limit value 204 to current vehicle speed value 207.

[0119] When the accelerator pedal 202 is not depressed, the system then determines at 300 if the current vehicle speed value 207 is greater than the current vehicle speed limit value 205.

[0120] Upon comparison to 207, if 300 is no, the current vehicle speed value 207 is below or equal to the current vehicle speed limit value 205 and there is no need for retardive braking 222. Given there is no need for retardive braking, the system sends a 0 or zero signal 214 to the retardive device and the system returns to step 200.

[0121] If 300 is yes, and the current vehicle speed value 207 is greater than the current vehicle speed limit value 205, the system then calculates, as determined by the PID loop logic in the controller, the required correction value 216 for the retardive braking 222.

[0122] The PID loop logic is described above. The brake pedal depression angle is multiplied by a predetermined gain value and the resulting value is sent to the controller as the retardive braking request as a percentage from 0% to 100% retardive breaking request. One example would be if the preset gain value is 3.3 and the brake pedal depression angle is 30% (in other words, the brake pedal is depressed 30% from the starting position of the brake pedal), the retardive braking request would be 99% to the controller and to the motor to increase resistance on the motor allowing the motor to perform the majority of the required deceleration of the vehicle to the safe speed limit and reducing wear and heat to the service brakes of the vehicle, increasing the life of the service brakes and reducing maintenance costs.

[0123] Once the required correction value 216 for retardive braking is calculated, the system determines if the gear (or traction mode) is in neutral 218. If yes, the required correction value is multiplied by the neutral gain value which produces a new required correction value 220. The neutral gain value has a range from greater than 0 to less than or equal to 1, preferably from 0.5 to 1 In this example, it is a value of 0.8. If no, meaning the gear is not in neutral, the correction value is determined with no neutral gain multiplier and is applied for the retardive braking 222 as described above. The neutral gain value serves to deter operators from moving to neutral. The system is always active and continues assessing all the sensors and carrying out calculations as needed.

EXAMPLE 2

[0124] The following is an example of a vehicle experiencing various conditions with

[0125] the speed controller system engaged and disengaged of the present disclosure. A vehicle having the following specifications:

TABLE-US-00001 Specification Relay Technical Data Drive 4WD Max. Speed Limited to 25 kph Power Peak: 150 kW Continuous: 100 kW Torque 1550 NM Peak Torque 680 Nm continuous Torque Suspension Suspension designed according to ISO 7096 Steering ISO 5010 Power Steering Brakes Regenerative Braking; Parking Brakes; Service Brakes Tyres 824 mm 295 mm wide AirBOSS Segmented Solid Tyres (Optional) Pneumatic Tyre 854691 [LT235/85R16] Operating 40 C. to 50 C. Temperature Range Expected Range 40 km expected, TBC at the mine (Ideal Conditions) Ramp Range TBC 1/4 Side Ramp Range TBC 1/8 Front/Rear Front 13.933/Rear 13.933 Differential Cab and Seating Cab Enclosed ROPS ISO 3471 FOPS ISO 3449: Level 2 NVH Level <76 dBs @ 30 km/h Seating Capacity 4 Seat Belts 4 sets Dimensions Wheelbase 2960 mm Width 2260 mm Operating [2056 mm Shipping] Height 2500 mm Ground Clearance 350 mm Deck Length 4865 mm Overall Length [875 mm Rear Box Length] Battery and Charging Charge Time 20 minutes (Ideal Conditions) Expected Offboard charging rate: 0.5-hour Charge rate nominal charge time Energy Storage Nominal Voltage: 533 VDC (Battery Module) Energy: 43 kWh Subpack Nominal 88.8 V Voltage Capacity 86 Ah (Rated @ C/2) 24-Volt Battery MAGNAVOLT SLA12-3 (2 12 V)
was taken on a road surface with various grades to test the speed controller. The controller used was Parker IQAN-MC master controller. The throttle/accelerator sensor used was Makersan accelerator pedal, MO450_H10_P009. The speed sensor used was TM4 inverter/controller, CO150-HV-A2. The brake sensor used was Parker ADS50 Analog distance sensor, 01710ECD. The FNR sensor used was Cobo OMNIA F-N-R switch, 01-1113-0000. The retardive braking system used was TM4 inverter/controller, CO150-HV-A2.

[0126] As best seen in FIGS. 9A and 9B, there is provided a chart of various parameters over time of a vehicle with a speed controller. The chart provides actual or current vehicle speed value 400, vehicle speed limit value 500, motor torque value 600, road pitch value 700, vehicle gear position 800, accelerator (throttle) pedal position 900 and brake pedal position 1000. From t=5 to t=48 seconds, the speed controller is engaged and the vehicle accelerates to 60 kilometers per hour (kph) and remains at or below the vehicle speed limit value 500 of 60 kph. At t=48 seconds, the vehicle operator disengaged the speed controller and the current vehicle speed value 400 accelerated immediately above the vehicle speed limit value 500 although the accelerator was not engaged (see accelerator pedal position 900 at t=51 to t=75 secs. The brake pedal was required to be engaged to avoid an overspeed situation (see brake pedal position 1000 at t=64 to t=87 secs). At each instance of brake pedal release and/or throttle pedal release (see t=86 to t=97 secs) the vehicle speed limit value 500 was adjusted as per the method described herein. At around t=105 secs, the speed controller system was engaged and the throttle was engaged bring the actual vehicle speed value to 60 kph which is at the vehicle speed limit value 500 of 60 kph. Although the throttle was engaged, the actual vehicle speed value went slightly passed 60 kph but the speed controller prevented unwanted acceleration and over speed regardless if the throttle is engaged or not (see t=123 to t=207 secs) and without having to apply the brakes of the vehicle. The smoothness of the speed controller system may be seen at FIG. 10 which provides an exploded view of the time interval of t=123 secs to t=138 secs of FIG. 9, the motor torque value 600 applied by the retardive braking system of the speed controller. As may be seen in FIG. 10, the smoothness of the fluctuation of the curve of the motor torque value 600 between t=123 secs to t=138 secs allows for the smooth operation of the vehicle maintaining the vehicle speed limit value 500 without vehicle operator discomfort.

[0127] As best seen in FIGS. 11A and 11B, the vehicle undergoes the same test as above but now the gear is placed in neutral during a period of time of the test. At t=80 secs, the speed controller was turned off (disabled) and the vehicle gear was placed in neutral (at t=81 secs). The vehicle speed increased from 60 kph to 70 kph (above the vehicle speed limit value of 60 kph). At t=104 secs, the speed controller was turned on (enabled) and the vehicle gear was set to forward at t=106 secs. The speed controller applied a torque on the motor via the retardive braking system bringing the actual vehicle speed value to 60 kph by t=107 secs. With the speed controller engaged, the vehicle gear was placed in neutral at t=186 secs. The vehicle speed slowed but then increased due to a grade in the road surface but remained below the vehicle speed limit value 500 in neutral gear due to the speed controller system. The vehicle gear was moved to forward at t=197 s.

[0128] Referring now to FIG. 3, there is depicted a analog sensor 1100 for a brake and/or a throttle sensor. A lever 1110 at one end thereof may be attached to a brake and/or throttle pedal to determine the position of the brake and/or throttle pedal when disengaged (position is 0% and 0 inches travel of the lever) to fully engaged (position is 100% and 1 inch travel of the lever). The other end 1120 of the analog sensor 1100 is connected to a controller. The value from 0 to 100% in the form of a voltage signal (0.5 V for 0% and 4.5 V for 100%) is sent to the controller by the communication line 1130.

[0129] Referring now to FIG. 4, there is depicted a pressure sensor 2100 for a brake and/throttle pressure pad sensor. End 2120 is in communication with a pressure pad to determine the pressure applied to the pad when disengaged (0% or no pressure) to fully engaged (100% or maximum pressure). The other end 2110 of the pressure sensor 2100 is connected to a controller. The value from 0 to 100% in the form of a voltage signal (0.5 V for 0% and 4.5 V for 100%) is sent to the controller by a communication line 2130.

[0130] Referring now to FIG. 5, there is depicted a ground speed sensor 3100. The first end, 3110 measures by the Hall effect and with no contact, the rotations per minute of a magnet on a gear or a wheel or a motor of the vehicle. The other end, 3120 is in communication 3130 with a controller and sends a digital signal to the controller of the rotations per minute wherein the controller converts the RPMs to speed of the vehicle. Referring now to FIG. 6, there is depicted a true ground speed sensor (TGSS)

[0131] 4100. The TGSS sensor 4100 incorporates the Doppler shift to measure the true ground speed of the vehicle. The TGSS sensor 4100 may be positioned to transmit a signal to the road surface and the signal is reflected off the road surface and the reflected signal is received by the TGSS 4100. When the road surface is moving relative to the TGSS 4100, a change in the reflected signal (Doppler shift) frequency occurs. The true ground speed of the vehicle is calculated by measuring the frequency change.

[0132] Referring now to FIG. 7, there is depicted a controller (or computer) 5100 as part of the speed controller system. The controller 5100 is connected to the various sensors described herein and converts the sensor voltage signals to engineering units required to calculate the correction factor, based on the signals received from the various sensor described herein, to send a signal and engage the retardive braking system in order to control the speed of the vehicle such that the vehicle speed is not greater than the vehicle speed limit value. The controller may also calculate the maximum required retardive torque value for deceleration of said vehicle to zero speed, in one alternative, is based on TB=[rTWv(Fd+sin )]/RG, where TB=maximum required retardive torque, rT=radius of static loaded tire, Wv=gross vehicle weight, Fd=deceleration factor, =maximum angle of decline of the road surface, RG=overall gear ratio between motor and wheel assembly.

[0133] Referring now to FIG. 8, there is depicted a chart showing a rising edge 6100 and a falling edge 6110. In the present application, the controller records and adjusts the new vehicle speed limit value at the falling edge 6110 at throttle and brake disengagement.

[0134] As many changes can be made to the alternatives of the disclosure without departing from the scope thereof; it is intended that all matter contained herein be considered illustrative of the disclosure and not in a limiting sense.