Radio pallet shuttle system selection and design

Few days ago, I came across what is called "Pallet shuttle system" which is used in pallet rack system as an alternative to "drive-in" and "drive through" of fork lifts to save time and increase safety levels.

The following table shows some useful selection criteria. It is also useful for people who are willing to design this piece of equipment. Based on the table below, and by some reversed engineering of the top brands manufacturing this equipment; I found that "Mecalux" is really the best design from all aspects.

Radio pallet shuttle system selection
All pallets are of the same item	Yes
Mixed items: Pick one item from one end and the other from the other end
Handling equipment	Fork lift and stacker
Shuttle dimensions	_
Minimum pallet size	_
Maximum pallet size	_
Maximum pallet overhang distance	_
Maximum pallet deflection	_
Maximum track distance	_
Lifting distance	_
Underneath ground clearance	_
Operating conditions
Operating temperature: Negative operating temperatures for refrigerators
Humidity
Ingress protection IP
Dynamics
Four wheel drive	Preferred
Maximum load [kg]	_
Full-load speed	_
No-load speed	_
Acceleration and deceleration profiles	_
Lifting speed	_
Weight-dependent acceleration
Number of wheels to extend life of wheels
Lift the whole upper plate
Energy and efficiency
Energy consumption to fully charge the battery	_
Regenerative breaking system	Preferred
Standby mode	Yes
Monitoring and control
Monitor battery charge remotely	Yes
Monitor battery remaining time remotely	Yes
Switching between manual and automatic modes	Yes
Remote control	Yes
Remote control communication technology requires no infrastructure	Yes
Handheld remote control	Yes
Rechargeable remote control	Yes
Remote control battery level indicator
Light display in remote control	Yes
Remote control drop down distance	3 meters
Magnetic mount remote control	Yes
Large buttons and icons in remote control	Yes
Iconic color-coded buttons	Yes
Single-hand operated remote control	Yes
Single remote controls multiple shuttles	Yes
No. of controlled shuttles using single remote	Unlimited
Remote control range [m]	_
No interference between multiple remote controls	Yes
User accounts and authentication	Yes
Configuration
PC programmable	Preferred
Programmable maximum speed	Preferred
Programmable maximum acceleration	Preferred
Programmable loading and unloading positions	Yes
First In Last Out Loading and unloading in the same location	Yes
First In First Out Loading and unloading are in opposite locations	Yes
Programmable home (for FIFO system)	Yes
Connectivity
RS232	Yes
RS485	Yes
Ethernet	Preferred
Wi-Fi	Preferred
Features
Shuttle power permanent push button	Yes
Power indicator light	Yes
Forward and backward blinking indication lights	Yes
Auto-homing	Yes
Auto-home and stop when battery is very low	Yes
Partial loading	Yes
Partial unloading (unload certain amount of pallets)	Yes
Automatic loading (LIFO)	Yes
Automatic unloading (LIFO)	Yes
Unload one-by-one, to reduce number of reallocations. This saves energy and increase the life time of the shuttle. In this mode, the default home position will be the unloading side and when the shuttle detects that the pallet is removed it will go back and bring the next pallet	Yes
Partial compacting	Yes
Full compacting	Yes
Self-align shuttle with pallet	Yes
Weight measurement	Preferred
Odometer	Preferred
On-deck pallet detection	Yes
Detect any pallet regardless the material: [1] Wood [2] Plastic [3] Steel	Yes
Detect any pallet regardless the color	Yes
Detect any pallet regardless the pattern	Yes
Pallet size detection	Preferred
Variable pallet size	Yes
Programmable pallet spacing	Yes
Counting number of pallets	Yes
Calculate remaining pallets to fully-load the track	Preferred
Wide-angle navigation camera on both sides	Optional
Flash light for camera	Yes
Speed monitoring	Preferred
Audible alarm	Yes
Shuttle number (ID) label on: [1] Front [2] Back [3] Bottom (large) [4] Top (large)	Yes
Bottom lights to easily recognize the shuttle specially when the shuttle is at elevated heights	Preferred
Possibility of two shuttles in the same lane (for FIFO)	Preferred
Forced operation function	Yes
Location signal To know where the shuttle cart is	Yes
Alarm when there is a place left for only one pallet and the labor place a pallet above it	Yes
Auto-seek remote coverage	Yes
Battery
Rechargeable battery	Yes
Battery technology	Lithium polymer Lithium ion
Sealed battery	Yes
Fire retardant casing	Yes
Battery life (years)	5
Battery life (number of charges)	1000
Battery price (cheaper battery is preferred)
Battery charger	Yes
Battery charger rating	220 V - 50 Hz
Battery charger stop after charging is complete	Yes
Battery full-charge alarm	Preferred
Battery charging time	< 8 hours
Battery charge percent indicator in the charging station	Yes
Battery discharge time at maximum load	> 8 hours
Battery location is close as possible to the side edge of the shuttle, so it can be removed ergonomically	Yes
Battery weight (for ergonomics)
Battery number label	Yes
Onsite charging	Preferred
Charging station for single battery	Yes
Spare battery	Yes
Standby operating time	_
Remove battery without any hand tools	Yes
Safety
Rail end stoppers	Yes
Pallet centralizers	Yes
Emergency push button on both sides (front and back)	Yes
Human hit safety (specially for ground racks)	Yes
Auto-home at enough distance from the rack end, so the fork lift will not hit it during unloading.	Yes
End of rail (track) detection (using two sensors)	Yes
End of rail (track) detection sensors can detect track end of any color	Yes
End of rail (track) detection sensors can detect track end full of dust	Yes
Open rail (track) detection	Yes
Anti collision with other pallet	Yes
Obstacle detection	Yes
Rail detection	Yes
Rail bump detection	Preferred
On-floor detection	Preferred
Bottom anti-slip surface to avoid slipping from fork lift	Yes
Electromagnetic locking system: Bottom very strong electromagnets to hold firmly with fork lift	Preferred
Electromagnetic locking system indictor light in the bottom	Preferred
Detect if it is lifted on fork lift, so it will not operate even if it is in automatic mode	Yes
Stop laser beams when it is lifted on fork lift	Yes
Rubber bumper at the front and end	Yes
Rubber stoppers at both sides in the front and back to avoid hitting track stoppers	Yes
Wheels are almost at the end of the shuttle to prevent flipping back	Yes
Pallet slip detection: Stop in case of pallet slip.	Yes
Pallet flip detection: Stop in case of pallet flip.	Yes
Side rollers to make sure that the shuttle is always on track	Yes
Anti-slip surface	Yes
Braking system	Yes
Sealing plugs (caps) for all communication interface ports on the shuttle	Yes
No wires, shrink wraps, clamps, frames can tangle with wheels	Yes
Ratchet lifting	Preferred
Human cart accessory (with chair inside)	Yes
Shuttle can not move if placed on normal floor	Yes
Reliability
Electromechanical lifting system	Yes
Overload protection: [1] Over current [2] Over temperature	Yes
Overload indication	Yes
Battery over-discharge protection	Yes
Spring loaded rail wiper to clean rails and avoid wheel slippage and wheel pitting	Yes
On-shuttle battery level indicator	Preferred
Wheel slip detection	Yes
Normally free to move when battery is dead	Yes
Normally not-elevated when battery is dead	Yes
Rust free materials	Yes
Dust proof sensors	Yes
Moisture proof sensors	Yes
Another shuttle can push or pull faulty shuttle	Yes
Shuttle can be lifted using fork lift if it is placed on flat floor	Yes
Shuttle have underneath pocket for forklift	Preferred
Front and back hooks for pulling it in case of getting faulty	Yes
Easy replaceable wheels	Yes
Protective guard for buttons and user interface when hit another object	Yes
Maximum load label on the top (readable from both sides)	Yes
Weight overload audible alarm	Yes