E-Pallet Tether Control for Operator Motion Compensation
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Solution Overview
Problem
Existing manual and machine-assisted load transportation methods, such as hand carts and fork lifts, are not optimized for smooth and efficient movement of loads in various facilities, particularly when operators need to navigate through tight spaces or make sharp turns, leading to potential instability and strain.
Innovation Solution
A motor-driven electric pallet (e-pallet) equipped with a flexible tether device connected to length and angle sensors, which communicates with an onboard electronic controller using PID control logic to generate motor control signals, enabling smooth and stable motion that matches the operator's natural movements, including arm swinging and turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual devices like hand carts and dollies are used, then device complexity is reduced, but stability and ease of operation deteriorate when navigating tight spaces or making sharp turns
Solution Approach 1:
The patent replaces the purely mechanical manual cart system with an electromechanical system featuring an electric motor, sensors (length sensor, angle sensor), and electronic controller. This substitution enables automated stabilization and precise motion control, resolving the contradiction by maintaining simplicity while improving stability through intelligent control algorithms that process sensor data and adjust motor output accordingly
Solution Approach 2:
The system implements feedback control by continuously monitoring tether length and articulation angle through sensors, processing this information through control logic, and adjusting motor torque and speed in real-time. This closed-loop feedback mechanism maintains stability during tight space navigation and sharp turns by dynamically compensating for operator movements and environmental constraints
2Device complexity
If manual devices like hand carts and dollies are used, then device complexity is reduced, but ease of operation worsens due to operator strain
Solution Approach 1:
The patent replaces manual mechanical effort with an electric motor-driven system that provides automated propulsion and steering assistance. The motor compensates for friction, inertia, and terrain variations, significantly reducing operator physical strain while maintaining operational simplicity through intuitive tether-based control
Solution Approach 2:
The system performs self-service by autonomously adjusting its motion characteristics based on sensor feedback. The control system automatically calculates required motor torque and speed adjustments, stabilizes the load without operator intervention, and adapts to changing conditions, thereby reducing the cognitive and physical burden on the operator
3Ease of operation
If the e-pallet responds directly to operator movements, then ease of operation is improved, but stability deteriorates due to natural hand or arm swinging motions
Solution Approach 1:
The system uses feedback control to distinguish between intentional operator steering inputs and unintentional arm swinging motions. By analyzing the frequency, amplitude, and pattern of tether angle changes through the angle sensor, the control system filters out high-frequency swinging motions while responding to low-frequency deliberate steering commands, thereby maintaining stability without compromising ease of operation
Solution Approach 2:
The control system dynamically adjusts its response characteristics based on operating conditions. It modulates the gain and time constants of the control loops to provide smooth, damped responses that naturally filter out high-frequency oscillations from arm swinging while maintaining responsiveness to deliberate operator maneuvers, achieving both stability and ease of operation
4Ease of operation
If motor assistance is increased to improve ease of operation, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The patent employs an electric motor with electronic control instead of complex mechanical transmission systems. The motor provides precise, programmable torque and speed control through software algorithms, replacing what would otherwise require complex mechanical linkages, variable geometry mechanisms, or multiple clutch systems. This electromechanical approach improves ease of operation while actually reducing overall device complexity compared to equivalent mechanical solutions
Data Source
AI summary
An electronic pallet (e-pallet) includes a superstructure mounted to a wheeled base platform. A tether device defines an articulation angle with respect to a leading edge of the superstructure, and is grasped by an operator towing the e-pallet. A motor connected to driven road wheels transmits a drive torque to the road wheels responsive to motor control signals, including a desired yaw rate and ground speed. A speed sensor, angle sensor, and length sensor are respectively configured to determine an actual ground speed of the e-pallet, the articulation angle, and a length of the tether device. An electronic controller, in response to the input signals, generates the motor control signals using proportional-integral-derivative (PID) control logic. Coupled lateral and longitudinal dynamics control loops respectively determine the desired yaw rate and ground speed to accommodate for motion of the operator.