Passive Gravity Compensation in Parallel Kinematics Haptic Devices
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Solution Overview
Problem
Existing haptic devices face challenges in gravity compensation, leading to reduced force levels and transparency due to increased friction and complexity in active approaches, and sub-optimal results in both active and passive methods.
Innovation Solution
A haptic device incorporating a parallel kinematics structure with at least three translational degrees of freedom and passive gravity compensation means, such as elastic elements, to partially compensate for gravity-related forces and torques, while optionally using active actuators for further compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active actuators are used for gravity compensation, then gravity compensation is achieved, but friction increases and force levels are reduced
Solution Approach 1:
The patent employs passive gravity compensation means that generate counter-forces to gravity without using active actuators. The parallel kinematics structure is designed with passive elements that automatically balance gravitational forces on the end-effector, eliminating the need for friction-prone active actuators while maintaining high force levels.
Solution Approach 2:
The patent replaces the active actuator-based mechanical system with a passive mechanical structure. The parallel kinematics structure uses passive gravity compensation means (such as springs or counterbalancing mechanisms) instead of active motors, thereby eliminating friction losses and heat dissipation associated with active actuators.
2Reliability
If active actuators are used for gravity compensation, then gravity compensation is achieved, but power consumption increases
Solution Approach 1:
The passive gravity compensation means provide continuous counter-forces to gravity without requiring energy input. The parallel kinematics structure with passive elements automatically balances gravitational forces, eliminating the continuous power consumption that would be required by active actuators.
Solution Approach 2:
The patent replaces the energy-consuming active actuator system with a passive mechanical structure that uses stored potential energy (in springs or gravitational counterweights) rather than continuous electrical power input, thereby dramatically reducing power consumption.
3Reliability
If additional actuators are added for gravity compensation, then gravity compensation is achieved, but device complexity increases
Solution Approach 1:
The patent integrates passive gravity compensation means directly into the existing parallel kinematics structure, using the same mechanical framework to provide both motion control and gravity compensation. This approach avoids adding separate actuators and keeps the system architecture simple.
Solution Approach 2:
The parallel kinematics structure serves multiple functions: it provides the three translational degrees of freedom for haptic control and simultaneously incorporates passive gravity compensation means to balance gravitational forces. This multi-functionality eliminates the need for additional dedicated actuators for gravity compensation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances gravity compensation, reducing friction and power consumption, improving transparency and force levels, and simplifying the system by leveraging passive elements to minimize inertia and complexity, thus providing more effective and efficient haptic feedback.
Implementation Method 1
passive gravity compensation means, such as elastic elements
Data Source
AI summary
A haptic device comprising a base member (4), an end-effector (6), a parallel kinematics structure arranged between the base plate and the end-effector and providing at least three degrees of freedom including at least three translational degrees of freedom in relation to the end-effector, and at least one passive gravity compensation means being adapted to exert forces and/or torques on the parallel kinematics structure for at least partial compensation of gravity related forces and/or torques acting in at least one of the three translational degrees of freedom.