Koyiro Minakata

University of California, Irvine, Irvine, CA, United States

Are you Koyiro Minakata?

Claim your profile

Publications (12)12.32 Total impact

  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a novel design for a 4 degree of freedom pneumatically-actuated upper-limb rehabilitation device. BONES is based on a parallel mechanism that actuates the upper arm by means of two passive, sliding rods pivoting with respect to a fixed structural frame. Four, mechanically-grounded pneumatic actuators are placed behind the main structural frame to control shoulder motion via the sliding rods, and a fifth cylinder is located on the structure to control elbow flexion/extension. The device accommodates a wide range of motion of the human arm, while also achieving low inertia and direct-drive force generation capability at the shoulder. A key accomplishment of this design is the ability to generate arm internal/external rotation without any circular bearing element such as a ring, a design feature inspired by the biomechanics of the human forearm. The paper describes the rationale for this device and its main design aspects including its kinematics, range of motion, and force generation capability.
    Biomedical Robotics and Biomechatronics, 2008. BioRob 2008. 2nd IEEE RAS & EMBS International Conference on; 11/2008
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A robot called the Closed-chain Robot for Assisting in Manual Exercise and Rehabilitation (CRAMER) was developed to assist impaired persons in making three degree-of-freedom movements of the forearm and wrist (forearm supination/pronation, wrist flexion/extension, and wrist ulnar/radial deviation). With a parts and machining cost of less than $1500, this robot was designed to be inexpensive by using a simple parallel mechanism design and off-the-shelf hobby servomotors. CRAMER is intended to engage patients in their rehabilitation therapy by having them play computer-based exercise games. Toward this goal, the remote for Nintendopsilas Wii was integrated into the handle of the robot in an attempt to allow patients to play the high-quality yet affordable motion-based games that have been developed for the Wii. A framework for planning robot joint trajectories capable of generating desired accelerometer measurements used by Wii games was developed using function optimization techniques. Results of a preliminary experiment with the bowling and golf games of Wii Sports show the feasibility of playing Wii using robot-assisted wrist movements. However, to make this approach clinically practical, an improved software communication with the Wii would be necessary.
    Biomedical Robotics and Biomechatronics, 2008. BioRob 2008. 2nd IEEE RAS & EMBS International Conference on; 11/2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: Training and evaluation of locomotion in animals with spinal cord injury will likely be improved with the development of techniques that increase stepping activity. We hypothesized that robot-assisted extension of the hindlimbs of spinal cord injured rats during stance would increase the probability that the swing phase of gait would be initiated. Thirty-three adult, Sprague-Dawley rats received a contusion injury to the mid-thoracic spinal cord. The animals' hindlimbs were pulled into extension using small robotic arms to pull at the ankle, as the rat stepped on either a reciprocating, robotic paw platform or a conventional treadmill belt. The animals demonstrated an increase in the probability of swing initiation with spontaneous recovery during the first 4 weeks following injury (p < 0.0001). The probability of swing initiation was found to be greater with the use of robot-assisted extension versus no extension force at the ankle (75+/-16.9% versus 38.9+/-16.6%, p < 0.001). Swing initiation occurred most frequently at a particular distance of hindlimb extension (50 mm caudal from the neutral position at stance), but was broadly tuned about this distance. These results indicate that a greater amount of stepping activity can be elicited by robot-assisted extension, thereby providing possible benefits to evaluation and training of gait following SCI.
    Journal of Neuroscience Methods 01/2007; 159(1):66-77. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: There is a critical need to develop objective, quantitative techniques to assess motor function after spinal cord injury. Here, we assess the ability of a recently developed robotic device (the "rat stepper") to characterize locomotor impairment following contusion injury in rats. In particular, we analyzed how the kinematic features of hindlimb movement during bipedal, weight-supported treadmill stepping change following contusion, and whether these changes correlate with the recovery of open field locomotion. Female, Sprague-Dawley rats (n=29, 8 weeks of age) received mid thoracic contusion injuries of differing severities (11 mild, nine moderate, nine severe, and four sham). In a first experiment, 16 of the animals were evaluated weekly for 12 weeks using the robotic stepping device. In a second experiment, 17 of the animals were evaluated every other day for 4 weeks. The contused animals recovered open field locomotion based on the Basso, Beattie, and Bresnahan Scale (BBB) analysis, with most of the recovery occurring by 4 weeks post-injury. Analysis of 14 robotic measures of stepping revealed that several measures improved significantly during the same 4 weeks: swing velocity, step height, step length, hindlimb coordination, and the ability to support body weight. These measures were also significantly correlated with the BBB score. The number of steps taken during testing was not directly related to intrinsic recovery or correlated to the BBB score. These results suggest that it is the quality of weight-supported steps, rather than the quantity, that best reflects locomotor recovery after contusion injury, and that the quality of these steps is determined by the integrity of extensor, flexor, and bilateral coordination pathways. Thus, by measuring only a few weight-supported steps with motion capture, a sensitive, valid measure of locomotor recovery following contusion injury can be obtained across a broad range of impairment levels.
    Journal of Neurotrauma 07/2006; 23(6):882-96. · 4.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This article reviews several tools we have developed to improve the understanding of locomotor training following spinal cord injury (SCI), with a view toward implementing locomotor training with robotic devices. We have developed (1) a small-scale robotic device that allows testing of locomotor training techniques in rodent models, (2) an instrumentation system that measures the forces and motions used by experienced human therapists as they manually assist leg movement during locomotor training, (3) a powerful, lightweight leg robot that allows investigation of motor adaptation during stepping in response to force-field perturbations, and (4) computational models for locomotor training. Results from the initial use of these tools suggest that an optimal gait-training robot will minimize disruptive sensory input, facilitate appropriate sensory input and gait mechanics, and intelligently grade and time its assistance. Currently, we are developing a pneumatic robot designed to meet these specifications as it assists leg and pelvic motion of people with SCI.
    The Journal of Rehabilitation Research and Development 01/2006; 43(5):657-70. · 1.78 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have developed a robotic device (the "rat stepper") for evaluating and training locomotor function of spinal cord injured rodents. This paper provides a detailed description of the device design and a characterization of its robotic performance capabilities.
    IEEE Transactions on Neural Systems and Rehabilitation Engineering 01/2006; 13(4):497-506. · 3.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the locomotor activity of spinal cord contused rats in response to robot-assisted extension of their hindlimbs. Nineteen rats received a contusion injury to the mid-thoracic spinal cord. We used a robotic gait-training device ("the rat stepper") and a robotic paw platform (the "slide") to pull the animals' hindlimbs into extension. The injured rats initiated swing with a significantly greater probability (p < 0.001) when the rat stepper pulled their hindlimbs into extension on a conventional treadmill (75+/-16.9%) as compared to the treadmill pulling their hindlimbs into extension with no robotic assistance (38.9+/-16.6%). Furthermore, using the rat stepper to extend one hindlimb and hold the other in stance while on the slide resulted in more unilateral stepping, rather than bilateral hopping activity, when compared to the extension of both hindlimbs simultaneously (81 ±0.24% vs. 43±0.34%, p < 0.001). Continuous training of one animal from each injury group with robot-assisted extension and appropriate interlimb phasing using the rat stepper and slide yielded substantially more steps in a two-minute training period when compared to training with a conventional treadmill (84 steps on average vs 12 steps on average). These results indicate that a greater amount of alternating stepping activity can be elicited by appropriately-phased, robot-assisted extension of an animal's hindlimb, thereby providing possible benefits to evaluation and training of gait following SCI.
    Rehabilitation Robotics, 2005. ICORR 2005. 9th International Conference on; 01/2005
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the ability of a robotic device, "the rat stepper", to assess intrinsic locomotor recovery following spinal cord contusion injury in adult rats. The device consists of a motorized body weight support mechanism that precisely controls the load to the hindlimbs during stepping, and two small robotic arms that measure and manipulate hindlimb movement. Sixteen rats received a contusion injury to the mid thoracic spinal cord with different severity levels (mild, moderate, severe, and sham). The animals were then evaluated weekly using the rat stepper, beginning one week after injury and continuing for a period of twelve weeks, across a range of body weight support levels. The contused animals demonstrated recovery in a standard locomotor assessment score (the BBB score), with most of the recovery occurring by four weeks post injury. We analyzed fourteen robotic measures of stepping and found that the measures that were most sensitive to intrinsic recovery were step velocity and inter limb coordination. These measures were also significantly correlated with the BBB score. The number of steps taken during testing was not sensitive to intrinsic recovery, nor correlated to the BBB score. These results suggest that step quality, rather than quantity, best reflects recovery after contusion injury in adult, untrained rats. Thus, robotic motion capture of only a few steps can provide a sensitive, valid measure of locomotor recovery after contusion.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2004; 4:2687-90.
  • [Show abstract] [Hide abstract]
    ABSTRACT: We are developing robotic devices for locomotion training after spinal cord injury. In this paper, we compare two approaches to controlling and quantifying bipedal stepping of spinal rats with robots. In the first approach, the rats stepped on a physical treadmill with robot arms attached to their lower shanks. In the second, the rats stepped on a virtual treadmill generated by the robots. The rats could step on the virtual treadmill, but stepping was more consistent, step height greater, and interlimb coordination improved on the physical treadmill. Implications for the role of sensory input in the control of locomotion and the design robotic of step trainers are discussed.
    Robotica 12/2002; 21(01):25 - 32. · 0.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We describe the design and testing of a robotic system to assist locomotion training of spinal-injured rodents. The goal of the system is to control and quantify spatial-temporal patterns of movement and forces during the stance and swing phases of rat locomotion. This approach will allow us to provide varying levels of assistance to limb movement during stepping and to quantify the effects of assistance on step training. Our initial finding was that the rat spinal cord could perform stepping on a virtual treadmill generated by the robot system, with careful design of the virtual environment. Based on the conditions required for this “virtual stepping”, we suggest several design principles for robot-assisted rehabilitative step trainers, including devices for humans
    Robotics and Automation, 2000. Proceedings. ICRA '00. IEEE International Conference on; 02/2000
  • Source