Integrated DC Motor Control Circuit for Surgical Robots
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Solution Overview
Problem
Current motor control systems for DC motors in surgical robots are large, obstructive, and lack sufficient resolution for precise control and measurement of speed, position, and torque, particularly in small-scale designs like minimally invasive surgery robots, where high dexterity and precision are required.
Innovation Solution
A compact, integrated mixed analog/digital circuit that includes a digital position and speed circuit for measuring motor speed, position, and direction, along with a programmable gain amplifier for regulating motor speed, integrated with a power amplifier and digital logic for system control, enabling precise control and measurement of DC motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a custom Low Power Motor Controller board is designed to provide sufficient resolution for precise motor control, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent combines multiple motor control functions (position sensing, speed control, torque measurement, and current regulation) into a single integrated circuit. The DPS circuit integrates quadrature decoder, counter, and PISO register, while the PGA integrates with power amplifier and current sensing, eliminating the need for separate control boards and reducing overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The integrated circuit is designed to control multiple types of DC motors (brushed and brushless) with a single device. The programmable gain amplifier can be configured for different motor parameters, and the digital position and speed circuit handles various encoder types, making the device universally applicable across different motor configurations without requiring separate specialized circuits.
2Adaptability or versatility
If multiple separate control boards are used to control multiple robot axes, then adaptability is improved, but device complexity and cable management difficulty increase
Solution Approach 1:
The patent integrates control capabilities for multiple robot axes into a single multi-functional integrated circuit. The device can sequentially or simultaneously control multiple DC motors with independent programmable gain amplifiers and position/speed circuits, reducing the number of separate control boards from multiple units to one consolidated device, thereby simplifying cable management while maintaining adaptability.
Solution Approach 2:
The integrated circuit incorporates programmable parameters that can be dynamically reconfigured for different motor types and control requirements. The PGA gain values, current limits, and control parameters can be adjusted via digital interfaces, allowing the single device to adapt to different robot axis requirements without physical reconfiguration or additional hardware.
3Manufacturing precision
If low-level speed control requires several resistor values to be set based on motor parameters, then manufacturing precision is improved, but ease of operation worsens
Solution Approach 1:
The patent replaces manual resistor selection and hardware configuration with a digital programming interface. The PGA gain values and control parameters are set through digital registers that can be programmed via software, eliminating the need to physically select and install different resistor values. This maintains precise speed control accuracy while dramatically simplifying the configuration process, as parameters can be adjusted through software without opening the device or replacing components.
4Adaptability or versatility
If a small-scale surgical robot is designed for high dexterity, then adaptability is improved, but the size of control components must be reduced
Solution Approach 1:
The patent integrates all motor control and measurement functions into a single compact integrated circuit, eliminating the need for large separate control boards. The combination of DPS circuit, PGA, power amplifier, and current sensing in one device dramatically reduces the volume required for control components, enabling their placement in space-constrained surgical robot environments while maintaining full control capability for high-dexterity tool manipulation.
Solution Approach 2:
The patent transitions from discrete external control boards to a highly integrated monolithic circuit design, effectively moving control functionality from a distributed external architecture to a centralized compact internal architecture. This dimensional consolidation reduces the physical footprint from board-level to chip-level, enabling the control system to fit within the constrained volume of small-scale surgical robots.
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
The solution provides a reduced-size, highly integrated motor control circuit capable of accurately controlling and measuring the position, velocity, and torque of DC motors, improving precision and dexterity in surgical robots by reducing the need for bulky external components and enhancing system configuration flexibility.
Implementation Method 1
an incremental encoder optically coupled to the motor for providing the pair of signals having a quadrature relationship
Implementation Method 2
at least one programmable gain amplifier (PGA) electrically coupled to the motor, the PGA being configured to receive a feedback signal indicative of the current flowing through the motor and to apply a second signal to regulate the speed of the motor
Implementation Method 3
one or more power amplifiers that sum the desired motor speed with the feedback signal from the PGA
Implementation Method 4
a resistor and buffer amplifier for sensing the output current of the motor
Data Source
AI summary
An integrated circuit for controlling a DC motor is disclosed. The integrated circuit includes at least one digital position and speed circuit (DPS) for providing measurements of speed, position, and direction of the motor, the DPS being in signal communication with the motor for receiving a pair of signals having a quadrature relationship; and at least one programmable gain amplifier (PGA) electrically coupled to the motor, the PGA being configured to receive a feedback signal indicative of current flowing through the motor and to apply a second signal to the motor for adjusting the speed of the motor; and at least two analog-to-digital converters (A/D), one A/D being used to quantize the output of the PGA for an off-chip processor; and another A/D to provide motor reference position from an analog sensor, such as a potentiometer; and at least two digital-to-analog converters (D/A), one D/A used to set the motor voltage; and another D/A used to set the motor current limit. The integrated circuit can be incorporated into a larger motor control loop which further includes a summing amplifier for providing the feedback signal to the motor that is indicative of current flowing through the motor; a buffer amplifier electrically for sensing the output current of the motor, and a processor for providing control signals to the system monolithic module and for receiving the measurements of speed, position, and direction of the motor.