Robots That Don't Get Stuck: A Master-Slave Control System
This patent describes a robot control system where a human-operated 'master' robot guides a 'slave' robot, preventing either from getting into awkward, uncontrollable positions by carefully planning the master robot's movements.
Original patent title: “Master-slave system”
This patent describes a robot control system where a human-operated 'master' robot guides a 'slave' robot, preventing either from getting into awkward, uncontrollable positions by carefully planning the master robot's movements. Granted to Muscle in 2018 with 6 claims and 1 forward citation, and it is expected to expire in 2034.
Coverage
What does this patent actually cover?
This system connects a master robot, which is a haptic device controlled by a human operator, to a slave robot that performs tasks. It uses sensors to measure the movements of both robots (master displacement sensor, slave displacement sensor) and actuators to control their forces (master actuator, slave actuator). A 'master target displacement calculating device' takes the slave robot's movement and maps it to a desired movement for the master robot. Crucially, this mapping is designed to avoid any 'singular configurations' for the master robot, which are positions where the robot can get stuck or lose control. The system also uses a 'slave target driving force calculating device' to control the slave robot based on the force the operator applies to the master robot. This setup means the operator feels the slave robot's actions without needing an extra sensor on the slave robot to measure forces it applies to its surroundings, and it solves the problem of robots getting stuck for both the master and slave robots. For example, a surgeon using a haptic controller (master robot) to perform delicate surgery with a robotic arm (slave robot) would experience smooth, precise control without the robotic arm ever locking up.
The gap
What does this patent NOT cover?
- Does not cover master-slave systems that require a separate working force sensor on the slave robot to measure forces applied to the environment (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1).
- Does not cover systems where the master robot's movement mapping allows it to enter a singular configuration, a position where it loses control (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1).
- Does not cover systems where the operator feels the master robot's own internal movements or dynamics, rather than just the slave robot's actions (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1).
- Does not cover systems where the calculation for the master robot's inverse kinematics needs complex, iterative numerical methods to find a solution (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 3).
- Does not cover systems where the master robot has more than six degrees of freedom, or where its rotational joints do not cross at a single point (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 4).
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The truly clever part is the predefined mapping for the master robot's target movements. This mapping is specifically designed to *exclude* any singular configurations, meaning the master robot is guided away from positions where it might get stuck or lose control, even before it reaches them. This simplifies the control system and improves reliability.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Surgical robots with haptic feedback
Remote manipulation arms for hazardous materials
Telepresence robots for exploration
Industrial robots controlled by human operators
Why it matters
The bigger picture
This patent addresses a significant challenge in robotics: preventing 'singular configurations' where robots can become uncontrollable. By designing the control system to avoid these problematic positions from the start, it makes master-slave robotic systems more reliable and safer. This is particularly important for applications requiring high precision and safety, such as surgical robotics or remote manipulation in hazardous environments. It allows operators to maintain intuitive control without worrying about the robot suddenly losing its ability to move freely.
Filed
November 5, 2014
Granted
January 2, 2018
Market context
Who's building on this
Companies in this space
Muscle Corp, the assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, continues to develop advanced robotic systems. Companies in the surgical robotics space, such as Intuitive Surgical, and those developing advanced teleoperation systems for industrial or hazardous environments, like Sarcos Technology and Robotics Corporation, are actively working on similar challenges related to reliable and intuitive robot control.
Market impact
This patent contributed to the development of more robust and user-friendly master-slave robotic systems. By solving the singular configuration problem, it enabled greater precision and safety in applications like minimally invasive surgery, where haptic feedback and reliable control are paramount. This allowed for wider adoption of complex robotic tools in fields where human-like dexterity and real-time feedback are critical, reducing the risk of operational failures and improving overall performance.
Claim 1 — Plain English
What this patent covers
This system connects a master robot, which is a haptic device controlled by a human operator, to a slave robot that performs tasks. It uses sensors to measure the movements of both robots (master displacement sensor, slave displacement sensor) and actuators to control their forces (master actuator, slave actuator). A 'master target displacement calculating device' takes the slave robot's movement and maps it to a desired movement for the master robot. Crucially, this mapping is designed to avoid any 'singular configurations' for the master robot, which are positions where the robot can get stuck or lose control. The system also uses a 'slave target driving force calculating device' to control the slave robot based on the force the operator applies to the master robot. This setup means the operator feels the slave robot's actions without needing an extra sensor on the slave robot to measure forces it applies to its surroundings, and it solves the problem of robots getting stuck for both the master and slave robots. For example, a surgeon using a haptic controller (master robot) to perform delicate surgery with a robotic arm (slave robot) would experience smooth, precise control without the robotic arm ever locking up.
The clever bit
The truly clever part is the predefined mapping for the master robot's target movements. This mapping is specifically designed to *exclude* any singular configurations, meaning the master robot is guided away from positions where it might get stuck or lose control, even before it reaches them. This simplifies the control system and improves reliability.
What it does not cover
- Does not cover master-slave systems that require a separate working force sensor on the slave robot to measure forces applied to the environment (Claim 1).
- Does not cover systems where the master robot's movement mapping allows it to enter a singular configuration, a position where it loses control (Claim 1).
- Does not cover systems where the operator feels the master robot's own internal movements or dynamics, rather than just the slave robot's actions (Claim 1).
- Does not cover systems where the calculation for the master robot's inverse kinematics needs complex, iterative numerical methods to find a solution (Claim 3).
- Does not cover systems where the master robot has more than six degrees of freedom, or where its rotational joints do not cross at a single point (Claim 4).
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Early stage
Citation count
6/40
Early citations
Claim breadth
4/20
Moderate scope
Recency
10/20
Granted 5–10 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$27K – $86K
Midpoint $54K · 8.2 yr remaining · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
6 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Kikuuwe, R., & Kanaoka, K. (2018). Robots That Don't Get Stuck: A Master-Slave Control System (U.S. Patent No. 9,855,653). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/9855653/master-slave-system
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does Robots That Don't Get Stuck: A Master-Slave Control System cover?
This patent describes a robot control system where a human-operated 'master' robot guides a 'slave' robot, preventing either from getting into awkward, uncontrollable positions by carefully planning the master robot's movements.
Who owns patent US 9855653?
Muscle owns this patent, granted in 2018.
When does this patent expire?
This patent is expected to expire on November 5, 2034, when the invention enters the public domain.
What is patent US 9855653 cited by?
This patent has been cited by 1 later patents that build on its ideas.
What problem does this patent solve?
This patent addresses a significant challenge in robotics: preventing 'singular configurations' where robots can become uncontrollable. By designing the control system to avoid these problematic positions from the start, it makes master-slave robotic systems more reliable and safer. This is particularly important for applications requiring high precision and safety, such as surgical robotics or remote manipulation in hazardous environments. It allows operators to maintain intuitive control without worrying about the robot suddenly losing its ability to move freely.
What does this patent NOT cover?
Does not cover master-slave systems that require a separate working force sensor on the slave robot to measure forces applied to the environment (Claim 1).
Patent monitoring