Patented Vehicle Control Technology
Freedom Transit is a patented; number 8,483,895 Issued: 7/9/2013
Transportation system, system components and process enabling technology to control and manage vehicles in stations and on the automated roadways. That technology is critical to the promise of this innovative sustainable transportation mode. The general background and description of the vehicle control process follows: Commercial jet passenger plans fly by using broadcast beacons, and computerized auto pilots which are capable of landing a plane under zero visibility weather conditions. Commercial jets built over at least the last 25 years have also had their flight air control surfaces managed by computers with the pilot controlling the computer. So it is technically feasible to use computers to control the much less demanding task of controlling a vehicle in a protected single lane roadway going only one speed and turning only left and right.
The control strategy is the heart of the system. Unlike other known attempts at automated vehicle control, Freedom Transit uses a broadcast signal. Other attempts used optical sensors, range and speed lasers, or radar and logic to control the vehicles much the same as a human driver would do. The independent driver logic schemes have the same control problems as do human freeway drivers. There is an inherent instability in a system of independent vehicles all trying to maintain a relative constant speed and distance. Instability waves develop which grow in intensity over time and with the number of vehicles. This results in slow stop and go travel as traffic congestion grows. Freedom Transit’s control strategy avoids the instability problem by having each vehicle track a control signal. The relative speed and distances of other vehicles is not part of the control strategy except for an oversight safety function in case of malfunctions.
The control strategy is a distributed multi level functional hierarch. The distributed design is implemented at a functional level. Each functional part of the control strategy is implemented at the lowest physical control level. The vehicles track signals broadcast by each station in a distributed workflow with each station passing on control to the next station down the line. The first level of the multi level functional hierarch is the hardware layer and consists of a mechanical connection and tracking of a power and vehicle steering guide rail. The second layer is an electronic communications and basic control function with similarities to GPS functions. The third layer is a logical layer, which through programming logic, controls vehicle movement between second level vehicle control virtual slots.
Level 1 Physical control:
Prior designs for steering automated vehicles all use rail(s) which mechanically locks the vehicle steering mechanism to the rail. Therefore, the vehicle must follow the rail. The problem with this design is the vehicle is locked to the rail and an external rail switch must be switched for the vehicle to take another path. External mechanical switches cannot respond fast enough for vehicles following close together at high speed to select one out of a group of vehicles. There is also the problem of communicating which exact vehicles are going to be switched and which are not. And external mechanical switching system would have to know which vehicle is which and which ones are to switch and which are not. Mechanical switching would be a high probability failure point that is not needed.
In the new design, the vehicles will have a steering and power probes on both sides of the front of the vehicle. The normal running of the vehicle on the guideway extends only the left side probe for contact with the rail. The probe mechanism can retract all the way into the body of the vehicle and can extend out approximately 2 ½ ft to contact and track the rail. The probe has three functions: one to pick up the power for the vehicle, two to steer the vehicle by tracking the rail, and three to pick up the control signals.
Level 2 Electronic control:
The vehicle control process is relatively simple. Three control signals are decoded.
1. One signal controls vehicle spacing and is constant within a control segment.
2. The second is a vehicle to station messages signal for: See note.
a. Exit information and requests
b. System alerts and control information
c. Channel selection for entrance. exit, and interchange station speed control
3. The third signal codes the speed information and is broadcast on the channel specified by the control channel message
Note: a secure wireless internet connection to the stations could provide these functions.
Each vehicle decodes the spacing signal and a speed signal which has some similarities to GPS like functions, but does not use GPS signals. The spacing signal creats a virtual slot the vehicle tracks. The speed signal can be on one of several channels while the spacing single has but one channel. A separate localized third signals specifies which speed channel to track. The automated roadways or guideways are divided into control segments spanning many miles. For the local metropolitan area loops the control segment may be the length of the guideway in one direction. For the high-speed interconnect guideways, the control segment length will be determined by exit stations and intersections with other guideways. Most segments would be 10-50 miles in length.
On the guideway between stations each vehicles receives, decodes, and tracks the speed and spacing signals. staying within the virtual slot. All vehicles are assigned the same speed signal channel. When a vehicle reaches its exit point a new speed control channel will be assigned to that vehicle before it leaves the guideway. Each vehicle exiting has its own speed channel assigned by the exit station control system. See note.
Normal operation then tracks the left side rail. When the vehicle is to exit, the exit station point is detected and the right side probe extends to track the right side. Once contact has been established the right side probe takes over steering, power, and signal control duties and the left side probe is retracted partway into the body of the vehicle. Simply by tracking the right side the vehicle automatically takes the exit, leaving the following vehicles unaffected. Once the vehicle has exited the main guideway the left side probe extends again to make contact with the left side rail and the right side probe is retracted halfway. Steering control again tracks the left side rail. This is done to allow the exit station to “fan out” the vehicles into multiple parking stations. Every time a fan out exit is chosen by the station computer the vehicle shifts from lefts side to right side tracking and back to left side tracking again. The exit and merge functions are the only time right side tracking is done.
Level 3 Logical control:
The third layer is a logical layer, which through programming logic, controls vehicle movement between second level vehicle control virtual slots. Slot-jump is a process to remove empty spaces between vehicles. At high speed it saves energy to have the vehicles follow each other with no empty slots in between vehicles, thus greatly reducing air drag. After a set number of vehicles have formed a chain, the process is halted to leave space for more vehicles to enter the guideway. The number of vehicles in the train is set by a system variable for process tuning.
Exit Station Functions:
Exit stations have varying sizes and capacities for handling traffic. A maximum size exit station could handle the entire output of the guideway and bring every vehicle to a stop. In this case there could be 50-100 vehicles under the control of the exit station at one time. In the extreme case of all vehicles exiting, up to five vehicles at a time will exit together and be controlled together. All five would be assigned the same speed channel.
The exit process consists of the following steps. Computers at each station are assigned to handle the exit function with the following general exit function steps:
1. Check that all exit functions: processors, sensors, and signal generators are functioning correctly
2. Are open exit stalls available for exit and stops:
a. Exit to stop and park
b. Exit to stop and use manual control to exit the station to the street
3. Broadcast the availability of each type of exit (park or exit to street)
4. Attend to vehicles wishing to exit
a. assign a speed channel to the vehicle (see note)
b. synchronize the spacing signal with the guideway spacing signal
c. synchronize the speed signal with the guideway speed signal
d. signal the vehicle to switch to the exit station channel
e. set the exit path signals to the exit stop point
f. check for vehicle in exit guidepath
g. change the speed signal to slow the vehicle to a stop at exit point
Note: one to five vehicles may be controlled together by assigning each to the same channel.
The entrance process is controlled basically the same way the exit process is controlled. The entrance process is where the fault tolerant features are most important. While we may not think about it – every time a passenger jet takes off at some point down the runway that plane must take off – no matter what happens. This is a fail safe point after which if an engine fails the plane must still take off. Passenger jets have double the power required to ensure the take off can occur even if power is lost in one engine. Merging the guideway vehicles at high speed requires the same kind of over-engineering. As a vehicle accelerates to merge with traffic the fail safe point is passed and the vehicle must merge at the guideway speed. The vehicles must then have multiple engines and enough reserve power to complete the process.
The entrance/merge process is controlled by the station. All vehicles must pass physical, electrical, control, and power tests before proceeding to the entrance ramp. An in-station vehicle control system handles movement of the vehicles in the station. Each vehicle in the station has its own control channel. The entrance process starts when the vehicle enters the launch point at the base of the entrance ramp and stops. Then the merge process takes over.
Merge Process Steps:
1. Check for open space on guideway.
2. Notify passenger(s) of merge process start
3. Synchronize merge spacing signal with guideway spacing signal
4. Set start time for merge process
5. Start merge by accelerating vehicle up the ramp
6. Synchronize the merge speed signal with the guideway speed signal
7. Merge vehicle and change from in-station to guideway control
8. Vehicle now tracks left side guideway signals.
All vehicle control processes are done the same way. The vehicle systems just track the signals; the only variables are the speed control signal and channel. The same process is used for the local loop guideways, the high speed interconnect guideways, the exit process, the in-station control, and the merge process.
Transportation system, system components and process enabling technology to control and manage vehicles in stations and on the automated roadways. That technology is critical to the promise of this innovative sustainable transportation mode. The general background and description of the vehicle control process follows: Commercial jet passenger plans fly by using broadcast beacons, and computerized auto pilots which are capable of landing a plane under zero visibility weather conditions. Commercial jets built over at least the last 25 years have also had their flight air control surfaces managed by computers with the pilot controlling the computer. So it is technically feasible to use computers to control the much less demanding task of controlling a vehicle in a protected single lane roadway going only one speed and turning only left and right.
The control strategy is the heart of the system. Unlike other known attempts at automated vehicle control, Freedom Transit uses a broadcast signal. Other attempts used optical sensors, range and speed lasers, or radar and logic to control the vehicles much the same as a human driver would do. The independent driver logic schemes have the same control problems as do human freeway drivers. There is an inherent instability in a system of independent vehicles all trying to maintain a relative constant speed and distance. Instability waves develop which grow in intensity over time and with the number of vehicles. This results in slow stop and go travel as traffic congestion grows. Freedom Transit’s control strategy avoids the instability problem by having each vehicle track a control signal. The relative speed and distances of other vehicles is not part of the control strategy except for an oversight safety function in case of malfunctions.
The control strategy is a distributed multi level functional hierarch. The distributed design is implemented at a functional level. Each functional part of the control strategy is implemented at the lowest physical control level. The vehicles track signals broadcast by each station in a distributed workflow with each station passing on control to the next station down the line. The first level of the multi level functional hierarch is the hardware layer and consists of a mechanical connection and tracking of a power and vehicle steering guide rail. The second layer is an electronic communications and basic control function with similarities to GPS functions. The third layer is a logical layer, which through programming logic, controls vehicle movement between second level vehicle control virtual slots.
Level 1 Physical control:
Prior designs for steering automated vehicles all use rail(s) which mechanically locks the vehicle steering mechanism to the rail. Therefore, the vehicle must follow the rail. The problem with this design is the vehicle is locked to the rail and an external rail switch must be switched for the vehicle to take another path. External mechanical switches cannot respond fast enough for vehicles following close together at high speed to select one out of a group of vehicles. There is also the problem of communicating which exact vehicles are going to be switched and which are not. And external mechanical switching system would have to know which vehicle is which and which ones are to switch and which are not. Mechanical switching would be a high probability failure point that is not needed.
In the new design, the vehicles will have a steering and power probes on both sides of the front of the vehicle. The normal running of the vehicle on the guideway extends only the left side probe for contact with the rail. The probe mechanism can retract all the way into the body of the vehicle and can extend out approximately 2 ½ ft to contact and track the rail. The probe has three functions: one to pick up the power for the vehicle, two to steer the vehicle by tracking the rail, and three to pick up the control signals.
Level 2 Electronic control:
The vehicle control process is relatively simple. Three control signals are decoded.
1. One signal controls vehicle spacing and is constant within a control segment.
2. The second is a vehicle to station messages signal for: See note.
a. Exit information and requests
b. System alerts and control information
c. Channel selection for entrance. exit, and interchange station speed control
3. The third signal codes the speed information and is broadcast on the channel specified by the control channel message
Note: a secure wireless internet connection to the stations could provide these functions.
Each vehicle decodes the spacing signal and a speed signal which has some similarities to GPS like functions, but does not use GPS signals. The spacing signal creats a virtual slot the vehicle tracks. The speed signal can be on one of several channels while the spacing single has but one channel. A separate localized third signals specifies which speed channel to track. The automated roadways or guideways are divided into control segments spanning many miles. For the local metropolitan area loops the control segment may be the length of the guideway in one direction. For the high-speed interconnect guideways, the control segment length will be determined by exit stations and intersections with other guideways. Most segments would be 10-50 miles in length.
On the guideway between stations each vehicles receives, decodes, and tracks the speed and spacing signals. staying within the virtual slot. All vehicles are assigned the same speed signal channel. When a vehicle reaches its exit point a new speed control channel will be assigned to that vehicle before it leaves the guideway. Each vehicle exiting has its own speed channel assigned by the exit station control system. See note.
Normal operation then tracks the left side rail. When the vehicle is to exit, the exit station point is detected and the right side probe extends to track the right side. Once contact has been established the right side probe takes over steering, power, and signal control duties and the left side probe is retracted partway into the body of the vehicle. Simply by tracking the right side the vehicle automatically takes the exit, leaving the following vehicles unaffected. Once the vehicle has exited the main guideway the left side probe extends again to make contact with the left side rail and the right side probe is retracted halfway. Steering control again tracks the left side rail. This is done to allow the exit station to “fan out” the vehicles into multiple parking stations. Every time a fan out exit is chosen by the station computer the vehicle shifts from lefts side to right side tracking and back to left side tracking again. The exit and merge functions are the only time right side tracking is done.
Level 3 Logical control:
The third layer is a logical layer, which through programming logic, controls vehicle movement between second level vehicle control virtual slots. Slot-jump is a process to remove empty spaces between vehicles. At high speed it saves energy to have the vehicles follow each other with no empty slots in between vehicles, thus greatly reducing air drag. After a set number of vehicles have formed a chain, the process is halted to leave space for more vehicles to enter the guideway. The number of vehicles in the train is set by a system variable for process tuning.
Exit Station Functions:
Exit stations have varying sizes and capacities for handling traffic. A maximum size exit station could handle the entire output of the guideway and bring every vehicle to a stop. In this case there could be 50-100 vehicles under the control of the exit station at one time. In the extreme case of all vehicles exiting, up to five vehicles at a time will exit together and be controlled together. All five would be assigned the same speed channel.
The exit process consists of the following steps. Computers at each station are assigned to handle the exit function with the following general exit function steps:
1. Check that all exit functions: processors, sensors, and signal generators are functioning correctly
2. Are open exit stalls available for exit and stops:
a. Exit to stop and park
b. Exit to stop and use manual control to exit the station to the street
3. Broadcast the availability of each type of exit (park or exit to street)
4. Attend to vehicles wishing to exit
a. assign a speed channel to the vehicle (see note)
b. synchronize the spacing signal with the guideway spacing signal
c. synchronize the speed signal with the guideway speed signal
d. signal the vehicle to switch to the exit station channel
e. set the exit path signals to the exit stop point
f. check for vehicle in exit guidepath
g. change the speed signal to slow the vehicle to a stop at exit point
Note: one to five vehicles may be controlled together by assigning each to the same channel.
The entrance process is controlled basically the same way the exit process is controlled. The entrance process is where the fault tolerant features are most important. While we may not think about it – every time a passenger jet takes off at some point down the runway that plane must take off – no matter what happens. This is a fail safe point after which if an engine fails the plane must still take off. Passenger jets have double the power required to ensure the take off can occur even if power is lost in one engine. Merging the guideway vehicles at high speed requires the same kind of over-engineering. As a vehicle accelerates to merge with traffic the fail safe point is passed and the vehicle must merge at the guideway speed. The vehicles must then have multiple engines and enough reserve power to complete the process.
The entrance/merge process is controlled by the station. All vehicles must pass physical, electrical, control, and power tests before proceeding to the entrance ramp. An in-station vehicle control system handles movement of the vehicles in the station. Each vehicle in the station has its own control channel. The entrance process starts when the vehicle enters the launch point at the base of the entrance ramp and stops. Then the merge process takes over.
Merge Process Steps:
1. Check for open space on guideway.
2. Notify passenger(s) of merge process start
3. Synchronize merge spacing signal with guideway spacing signal
4. Set start time for merge process
5. Start merge by accelerating vehicle up the ramp
6. Synchronize the merge speed signal with the guideway speed signal
7. Merge vehicle and change from in-station to guideway control
8. Vehicle now tracks left side guideway signals.
All vehicle control processes are done the same way. The vehicle systems just track the signals; the only variables are the speed control signal and channel. The same process is used for the local loop guideways, the high speed interconnect guideways, the exit process, the in-station control, and the merge process.