Minghe Jin

Multisensory five-finger dexterous hand: The DLR/HIT Hand II

This paper presents a new developed multisensory five-fingered dexterous robot hand: the DLR/HIT Hand II. The hand has an independent palm and five identical modular fingers, each finger has three DOFs and four joints. All the actuators and electronics are integrated in the finger body and the palm. By using powerful super flat brushless DC motors, tiny harmonic drivers and BGA form DSPs and FPGAs, the whole fingerpsilas size is about one third smaller than the former finger in the DLR/HIT Hand I. By using the steel coupling mechanism, the phalanx distalpsilas transmission ratio is exact 1:1 in the whole movement range. At the same time, the multisensory dexterous hand integrates position, force/torque and temperature sensors. The hierarchical hardware structure of the hand consists of the finger DSPs, the finger FPGAs, the palm FPGA and the PCI based DSP/FPGA board. The hand can communicate with external with PPSeCo, CAN and Internet. Instead of extra cover, the packing mechanism of the hand is implemented directly in the finger body and palm to make the hand smaller and more human like. The whole weight of the hand is about 1.5Kg and the fingertip force can reach 10N.

The Modular Multisensory DLR-HIT-Hand: Hardware and Software Architecture

This paper presents hardware and software architecture of the newly developed compact multisensory German aerospace research (DLR)-Harbin Institute of Technology (HIT)-Hand. The hand has four identical fingers and an extra degree of freedom for the palm. In each finger, there is a field-programmable gate array (FPGA) for data collection, brushless dc motors for control, and communication is accomplished with palms FPGA by point-to-point serial communication (PPSeCo). The kernel of the hardware system is a peripheral component interconnect (PCI)- based high-speed floating-point DSP for data processing, and FPGA for high-speed (up to 25 Mb/s) real-time serial communication with the palms FPGA. In order to achieve high modularity and reliability of the hand, a fully mechatronic integration and analog signals in situ digitalization philosophy is implemented to minimize the dimension and number of the cables (five cables including power supply), and protect data communication from outside disturbances. Furthermore, according to the hardware structure of the hand, a hierarchical software structure has been established to perform all data processing and the control of the hand. It provides basic air position indicator (API) functions and skills to access all hardware resources for data acquisition, computation, and teleoperation. With the nice design of the hands envelop, the hand looks more like a humanoid.

The HIT/DLR dexterous hand: work in progress

This paper presents the current work progress of HIT/DLR Dexterous Hand. Based on the technology of DLR Hand II, HIT and DLR are jointly developing a smaller and easier manufactured robot hand. The prototype of one finger has been successfully built. The finger has three DOF and four joints, the last two joints are mechanically coupled by a rigid linkage. All the actuators are commercial brushless DC motors with integrated analog Hall sensors. DSP based control system is implemented in PCI bus architecture and the serial communication between the hand and DSP needs only 6 lines(4 lines power supply and 2 lines communication interface). The fingertip force can reach 10N.

FPGA based hardware architecture for HIT/DLR hand

In this paper, FPGA (field programmable gate array) based hardware architecture for the HIT/DLR hand has been investigated. With the FPGAs for lower level control and DSP (digital signal processor) for higher level control, the whole hardware is very intelligent. By using the high capacity of FPGAs, the additional hardware such as communication controller and PWM generators, can be implemented in a single chip and the hardware system is more flexible and compact. In each finger there is an FPGA for data collection, brushless DC motors control and communication with palms FPGA by point-to-point serial communication (PPSeCo). The kernel of the hardware system is a PCI-based high speed floating-point DSP for data processing, and FPGA for high-speed (up to 25Mbps) real-time serial communication with the palms FPGA. There needs only 4 cables for the data transmission and the sampling cycle for each sensor is only 200 /spl mu/s. This paper presents the basic ideas behind the HIT/DLR hands hard- and software architecture adapted to new needs in data processing.

Experimental study on impedance control for the five-finger dexterous robot hand DLR-HIT II

This paper presents experimental results on the five-finger dexterous robot hand DLR-HIT II, with Cartesian impedance control based on joint torque and nonlinearity compensation for elastic dexterous robot joints. To improve the performence of the impedance controller, system parameter estimations with extended kalman filter and gravity compensation have been investigated on the robot hand. Experimental results show that, for the harmonic drive robot hand with joint toruqe feedback, accurate position tracking and stable torque/force response can be achieved with cartesian and joint impedance controller. In addition, a FPGA-based control architecture with flexible communication is proposed to perform the designed impedance controller.

A Novel Absolute Magnetic Rotary Sensor

To measure the angular position of motors, robot joints, etc., an absolute magnetic rotary position sensor is developed, which possesses small-size, light, robust, and easy-to-integrate properties. The sensor consists of two inductors, i.e., a code disc and a signal processing part. Both of the two inductors are embedded with a big planar spiral copper coil and four smaller copper coils by employing microelectromechanical system (MEMS) technology, and there are two circles of regular copper sheets listing on the surface of the code disc. In addition, mathematical analyses of the inductor structure as well as the relationships of position and dimension among the coils and the copper sheet are addressed. Finite-element simulation results demonstrate that one group of the optimal sine and cosine signals can be generated by each inductor. Then, the absolute position measurement method is validated by a mathematical method. Finally, experiments are performed on the high-speed and the low-speed testing platforms to assess effectiveness and accuracy of the sensor.

A dexterous humanoid five-fingered robotic hand

This paper presents a new developed multisensory five-fingered dexterous robot hand : the DLR/HIT Hand II. The hand has an independent palm and five identical modular fingers, each finger has three DOFs and four joints. All the actuators and electronics are integrated in the finger body and the palm. By using powerful super flat brushless DC motors, tiny harmonic drives and BGA form DSPs and FPGAs, the whole fingerpsilas size is about one third smaller than the former finger in the DLR/HIT Hand I. By using the steel coupling mechanism, the phalanx distalpsilas transmission ratio is exact 1:1 in the whole movement range. At the same time, the multisensory dexterous hand integrates position, force/torque and temperature sensors. The hierarchical hardware structure of the hand consists of the finger DSPs, the finger FPGAs, the palm FPGA and the PCI based DSP/FPGA board. The hand can communicate with external with PPSeCo , CAN and Internet. Instead of extra cover, the packing mechanism of the hand is implemented directly in the finger body and palm to make the hand smaller and more human like. The whole weight of the hand is about 1.5 Kg and the fingertip force can reach 10N.

High performance DSP/FPGA controller for implementation of HIT/DLR dexterous robot hand

The paper presents hardware and software architectures of the HIT/DLR Hand. The hand has four identical fingers and an extra degree of freedom (d.o.f) for the palm. In each finger, there is a re-configurable Field Programmable Gate Array (FPGA) for data acquisition, Brushless DC (BLDC) motor control and communication with the palms FPGA by Point-to-Point Serial Communication (PPSeCo). The kernel of the hardware system is a PCI-based high speed floating-point Digital Signal Processor (DSP) for data processing, and an FPGA for high speed (up to 25 Mbps) real-time serial communication with the palms FPGA. In order to achieve high modularity and reliability of the hand, a fully mechatronic integration and analog signals in-situ digitalization philosophy are implemented to minimize the dimension, number of the cables (5 cables including power supply) and protect data communication from outside disturbances. Furthermore, according to the hardware architecture of the hand, a hierarchical software architecture has been established to perform all data processing and control of the hand. The software structure provides basic Application Programming Interface (API) functions and skills to access all hardware resources for data acquisition, computation and teleoperation.

Development of a Multi-DOF Anthropomorphic Prosthetic Hand

Based on the underactuated mechanism and coupling principle, a five-fingered prosthetic hand is presented in this paper. The design of the finger is based on two types of four-bar linkage mechanisms. One is the underactuated linkage mechanism, which implements self-adapt grasp with wide variety of objects placed between base joint and middle joint. The other is the coupling linkage which employs between the middle and distal joints. The thumb, the index finger and other three fingers are actuated by a motor respectively. The multi-DOF hand is comprised of 13 joints and driven by three motors. Torque and position sensors are integrated into the fingers. The control system is based on two DSP processing boards. One implements the motion pattern classifier of the hand based on the EMG signals through two electrodes. The other implements the position and torque control of the fingers. All actuators, sensors and electronic boards are embedded into the hand, which presents a highly integrated mechatronics system. Grasping experiments demonstrate that this prosthetic hand has the high grasping capability and dexterity.

Design of a finger-tip flexible tactile sensor for an anthropomorphic robot hand

In this study, a thin and flexible tactile sensor using pressure-conductive rubber for a HIT/DLR Hand II dextrous robot hand is developed. A method of the curved surface approximate development is used to design the sensor shape, ensuring that the sensor can fine cover the three-dimensional (3D) finger-tip surface. In order to weaken crosstalk current and simplify electrical circuit of the sensor, a sampling-voltage-feedback-non-target-scanned-sampling-electrode (SVFNTSSE) method is proposed. Then a structure of tactile signal acquisition and processing circuit based on this method is described. Finally, the experiment of weakening crosstalk based on the SVFNTSSE method verifies the validity of this method, and the results of the other experiment show that this sensor system has integrated into the dextrous robot hand.